Ettepanek elektrituruseaduse muutmise seaduse eelnõule

ESTONIA Ministry of Economic Affairs and Communications Francesco Bertolini GE Renewables Senior Sales Manager Tallinn, April, 3rd 2013 Agenda Review GE’s experiences supporting grid connection rules and processes for the Paldiski I & II Wind Farms 1. Introduction : GE Francesco Bertolini Senior Sales Manager 2. Renewable energy strategies in Europe … Izabela Kielichowska, GE Global Operations, EU Policies 3. Paldiski I & II Execution Experience - Carsten Aue, Director Project Management Wind Europe 4. Comparative overview of grid code requirements and WPP’s technical capabilities - Stephan Wachtel, Principal Engineer Energy Consulting Executive Summary 1. RULES: Establish and communicate clear, detailed grid connection requirements that are in line with common European practice 2. PROCESS: Establish clear processes and timing for entire connection process 3. EXECUTION: Don’t allow rules to be modified or re- interpretated during the execution of a project 2010 Revenue GE Energy $37.5B Healthcare $16.9B GE Capital $47.0B GE power generation equipment creates a quarter of the world’s Energy Services electricity Aviation $17.6B every day. Home & Business $25.5B Solutions, Media Oil & Gas Transportation $3.4B Power & Water $12.6B earnings ~$150B Revenue $14.7B cash flow GE Power & Water Renewables
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Finance-ability … evolutionary design using “proven technology” © 22013 General Electric Company.  GE’s portfolio • 8 businesses operating in more than 100 countries … 125+ years • >300,000 employees worldwide • 2011 revenue ~$147B Home & Power & Energy Oil & Gas Aviation Healthcare Transportation Business GE Capital Water Management Solutions • Thermal • Drilling & • Digital Energy • Commercial • Healthcare • Locomotives • Appliances • Commercial Surface Systems • PG Services • Power • Military • Services • Lighting • Consumer • Renewables • Global Services Conversion • Service • Life Sciences • Propulsion • Intelligent • Real Estate • Industrial • Healthcare IT Systems Platforms • Aero- • Measurement Systems • Avionics/ • GECAS derivatives & Control Systems • Molecular Diagnostics • EFS • Water • PII Pipeline • Gas engines Solutions • Nuclear • Subsea Systems • Turbo- machinery GE wind in the World Europe HQ Service Ctr. Service Ctr. Parts Distribution Ctr. Parts Operation Ctr. Parts Distribution Ctr. Central Warehouse 2 Service Energy Centers Learning Ctr. Renewable Energy HQ Services Offices Parts Operation Ctr. Remote Operations Ctr. Services Ctr. Service Ctr. Parts Distribution Ctr. Energy Services HQ Services Office Customer Support Ctr. Parts Distribution Ctr. Parts Distribution Centers Global resources, local support GE Wind in Eastern Europe Strong presence in Europe as a whole • From over 21.000 global installed units, 4000+ are located in Europe • The 1.5MW platform has over 14 years of experience … latest model is 1.6-100 • The fleet in Europe has in over 94 Mil operating hours and produced over 45 TWh of green and enviromentially friendly energy Eastern Europe as one of the leading markets for GE • Market leader in Romania (customers: CEZ, Monsson Alma...) • Top rated OEM in Poland (customers: Invenergy, EON, Iberdrola.....) • Installed base in Baltics (customers: EESTI Energia, 4Energia, ...) Strong focus on emerging markets • South East Europe: Croatia, Serbia, Montenegro, Bosnia & Herzegovina, Macedonia, Albania, Kosovo • Baltics: Estonia, Latvia, Lithuania • CIS: Ukraine, Kazakstan, Moldova Policy landscape Iza Kielichowska GE Global Growth and Operations, Government Relations Tallinn, April, 3rd 2013 Renewable energy strategies in Europe 2010- Introducing renewable energy in Europe - 10% indicative target - Financial and administrative support to eliminate market failures 2020 - Strengthening the role of renewables in Europe - 20% binding target - Financial and administrative support to eliminate market failures - Harmonization and European market integration 2030 - Maturing renewable energy market in Europe -30% binding target? - European market redesign - Phase out of financial support 2050- Renewable energy in the heart of the European energy market - 50-90% share renewables share in the energy mix Renewable energy is an increasingly important part of the European energy landscape  2020 strategy – key elements Targets Support schemes • 20% renewable energy by 2020 on the EU level • Needed to eliminate market failures • 25% renewable energy for Estonia • To be harmonized across the EU and gradually eliminated along with market developments post 2020 Monitoring of progress – 2013 conclusions • Europe needs to take more effort to meet the target Permitting procedures should be • Key areas for improvement: • Transparent - Stability of support schemes • Proportionate - Administrative barriers • Coordinated and limited in time - Grid integration Grid improvements • Wind power development requires most attention to meet the Member States plans • Needed to facilitate intake of electricity from renewable energy • Estonia on track but administrative barriers still • Infrastructure build out exist • Rules for grid operation and market design reform to meet the variable capacities needs Estonian support for onshore wind Strenths • High RE target accompanies very good wind conditions • Estonian support scheme level satisfactory at the first glance Areas for consideration • Production cap (600 GWh) - Unique solution in Europe - Decreases economic attractiveness for investors • EU countries normally support the production of green energy from the Source: Renewable energy progress report, Ecofys 2012 beginning of the production of the first kWh and add a test period up to 2 years for confirmation Support scheme can be further improved to increase investment attractiveness and limit system costs Administrative simplification 6 Overall ranking of administrative procedures 5 • Estonia does not report administrative barriers 4 • But is ranked low in facilitating RE investments 3 • Financial support not provided until full grid 2 connection 1 • Estonia has a relatively long grid connection lead time: 0 Estonia Denmark Germany Sweden 45 months vs. 26 months EU average Source: Renewable energy progress report, Ecofys 2012 Areas for consideration Other good practice examples • Increase transparency in the decision making Automatic entry into the support scheme process • Provide support for every kWh produced, also in the testing period Single administrative body responsible for processing authorization, certification and • Reduce lead time, especially for grid connection licensing applications for renewable energy by applying transparent rules and requirements installations and providing assistance to applicants Deadline for handling applications: No response = automatic approval Reduction of administrative barriers can effectively decrease the overall cost of renewable energy Execution Update Paldiski I & II Carsten Aue Director Project Management Wind Europe Tallinn, April, 3rd 2013 Global Projects Operation Global Field Operations Business Development ss • Site management Project execution & systems integration • Extended scope proposals • Technical advisors for all GE Power& Water technologies… • EPC partner relationships … on more than 1,200 active projects Project Engineering • Total plant Project Operations engineering • Development and … totaling 70B+ USD in contract value • Innovation and competitiveness Run by the Segments training Led by the Regions • Best-in-class processes Supported by the … with 2,500+ global resources Functions Contract Management … in more than 100 countries • Contract Project Management • Project CEO negotiations • Risk and change Project Controls & • Customer interface management Logistics … to be the largest Power & Water EPC • Schedules and cost control globally • Logistics management PM Segments Regions Support Functions Thermal North America Project Finance Renewables Latin America BOP Sourcing Aeroderivative GT Europe Quality Nuclear Middle East EHS Water Africa HR Energy Services India Gas Engines Asia Oil & Gas 15 / Our range of capabilities in Europe 16 / GE / April 4, 2013 GE Internal - Privileged and Confidential Project Management Wind Europe EU’s Largest Onshore WF Finland Fintinele , CEZ PM Team Expertise Norway Sweden 600MW 240x GE2.5MW Year MW Projects Units Estonia 2009 - 2012 Latvia 2009 345 20 170 NORTH SEA Lithuania Denmark 2010 472 20 225 Ireland Belarus 2011 678 20 245 Great Britain Poland Germany 2012 738 38 286 Czech Ukraine Republic Slovakia Moldova ATLANTIC OCEAN France Austria Hungary Romania Slovenia Croatia Serbia Bulgaria Italy Monte- Portugal negro Spain Albania Turkey Greece MEDTERRANEAN SEA 17 / Project Timeline example 2 weeks 6-12 month 1 unit/week + 4 weeks 1 month Sales/ITO Launch Fulfillment (Foundations) Site execution Closeout • Site & Logistic • Creating an EHS culture Assessment & • Pre-Installation Meeting Consulting • Installation and commissioning • Partner selection • Project planning and logistics • Problem solving throughout process • Clarify customs and invoicing execution • Project and BOP • Supply chain coordination • EPC partner fulfillment Engineering • Wind Farm turnover to • Internal project hand-off from Customer & O&M Commercial to Projects (GPO) • WF acceptance • Establish project team • Punch List & Closeout • Customer kickoff meeting preparations • Establish local presence • Lessons Learned • EPC partner kickoff meeting • Internal project hand- off to Service & PS&W 18 4/4/2013 Paldiski – Project Overview Paldiski I Paldiski II New customer : New customer : Paldiksi Tuulepark OÜ EESTI Energia AS (4Energia AS) Location: Location: Estonia Estonia Project scope Project scope 9 x 2.5xl-100, 85m Hub Height 9 x 2.5xl-100, 85m Hub Height 9 x Foundations 9 x Foundations Key dates Key dates Contract Signature: 04-Jul-11 Contract Signature: 04-Jul-11 Foundation start: 27.Sep 2011 Foundation start: 27.Sep 2011 Installation start: 11. Apr 2012 Installation start: 26. Jun 2012 Commissioning start: 26.Apr 2012 Commissioning start: 04.Jul 2012 Trail run End: 04-Oct-12 Trail run End: 04-Oct-12 Windfarm Compl. : open Windfarm Compl. : open 19 / GE / 04 April 2013 Share of local content - only GE scope • Complete foundation construction work subcontracted locally in Estonia. • Complete in country main component logistic subcontracted locally in Estonia • > 2200 Hotel nights booked by Installation / Crane / Commissioning and Project crews • 3 additional Estonian foundation subcontractors technically qualified by GE Foundations Harbor & Logistics > 3.200.000 Euro‘s investment in Estonian economy by GE 20 JRI GLM 4/4/2013 GE Proprietary Information Unauthorized Disclosure and Use are Prohibited Turbine Erection & Commissioning July 4, 2011 Signature Turbine Sales agreement Identify & qualify September 27, 2011 Foundation start foundation sub- October 17, 2011 Delivery of PSS/E models contractor in Estonia January 31, 2012 Signature of GE licensee agreement for the PSCAD model by the clients February 2, 2012 Delivery of PSCAD models March 1, 2012 Signature grid agreement (client scope) April 11, 2012 Installation start April 26, 2012 Commissioning start: TURBINE READY FOR PRODUCTION May 31, 2012 TSO Remark on Electrical models work June 1, 2012 Permission to consume Energy from the grid September 17, 2012 Permission to backfeed Energy to the Estonian grid September 18, 2012 Trail run start Trail Runs started late November 17, 2012 Start PQ test due to missing December 17, 2012 Start functional test backfeed permission December 18, 2012 Signature of GE licensee agreement for the PSCAD model by the TSO December 19, 2012 Delivery the PSCAD models on individual level January 30, 2013 Acceptance of the PSCAD models February 14, 2013 Issue PQ report February 14, 2013 Issue functional test report March 12, 2013 Remarks on the PQ report March 12, 2013 Remarks on the Functional test report open Final acceptance of the PQ report open Final acceptance of the functional test report 21 4/4/2013 Grid Acceptance July 4, 2011 Signature Turbine Sales agreement September 27, 2011 Foundation start October 17, 2011 Delivery of PSS/E models January 31, 2012 Signature of GE licensee agreement for the PSCAD model by the clients February 2, 2012 Delivery of PSCAD models March 1, 2012 Signature grid agreement (client scope) April 11, 2012 Installation start April 26, 2012 Commissioning start May 31, 2012 TSO Remark on Electrical models work June 1, 2012 Permission to consume Energy from the grid September 17, 2012 Permission to backfeed Green Energy to the Estonian grid September 18, 2012 Trail run start November 17, 2012 Start PQ test December 17, 2012 Start Functional test December 18, 2012 Signature of GE licensee agreement for the PSCAD model by the TSO December 19, 2012 Delivery the PSCAD models on individual level January 30, 2013 Acceptance of the PSCAD models 1 year to accept February 14, 2013 Issue PQ report PSCAD models! February 14, 2013 Issue functional test report March 12, 2013 Remarks on the PQ report Requirements still March 12, 2013 Remarks on the Functional test report unclear open Final acceptance of the PQ report open Final acceptance of the functional test report 22 4/4/2013  Available Simulation models and their provision Purpose Type Software Scope best practice EE specific requirement requirement System Rms PSSe, PF Aggregated WF X X study model Project Rms PSSe, PF, Individual WT model X design Special Emt PSCAD, 3- phase WF model (x) X purpose PF, EMTP- Exceptional ATP cases 23 4/4/2013 Project Execution Challenges Grid acceptance / connection requirements 1. Clarity on the (initial) requirements. Eliminate generic requirements … too much room for interpretation 2. Comments, Concerns & Rejections need to be actionable, deliverables need to be clearly defined 3. Acceptance process and/or calibration protocols of measurement devices should follow international standards Elimination of redundancy. 1. LVRT (Low Voltage Ride Through) test which are part of the electronic simulation need to be repeated at site for a certified CE compliant turbine. 2. The requirement to provide PSCAD models on individual turbine level is unique. The biggest Wind farms in the World and in Europe did not require this degree of electrical modelling. 24 GE Wind Energy Comparative overview of grid code requirements and WPP’s technical capabilities Stephan Wachtel GE Energy Consulting Tallinn, April, 3rd 2013  DRAFT Grid Connection Requirements and WTG’s/WPP’S technical capabilities GE Internal - For internal distribution only. Grid Connection Requirements: What works best? General approach  Reflects system performance & reliability standards  Only necessary requirements…openness for new solutions  Determining the “What” but not the “How“  Well structured, exhaustive, explicit and unambiguous  Clear application and references (e. g. to POI)  Proportionate: compulsory performances vs. ancillary services  Avoid project specific applications to save time and costs Considering inherent characteristics of technologies  FRT time limits for synchronous generators  Power reduction at under frequencies for gas turbines  Very limited reserves from variable RES / Wind Drafting, Implementation and Maintenance  Open and transparent stakeholder involvement… Review Panel, Public Consultations  Considers Cost Benefit Analyses  Sufficient transition time for new requirements 27 Stephan Wachtel - Energy Consulting 25.3.13 Operation ranges and Power Quality Voltages & Frequency ranges  Well defined in Estonia, but complex description  Drawing could help  Estonian Grid Code: up to 53Hz, tough!, see below at Frequency Control  ENTSO-E NC RfG: up to 51.5 Hz for the Baltic SA ROCOF-requirements  NC RFG: to be determined by TSO  Estonian Grid Code:  §22 (6) talks about fast frequency variations, but not quantifying it. Impossible to assess or to give a compliance statement Power Quality  WTGs certified according to IEC 61400-21  Connecting assessment in EU countries: typically w.r.t. IEC standards  WPP tests only, of studies indicate issues 28 Stephan Wachtel - Energy Consulting 25.3.13  FRT-requirements: Comparison to the GE 2.5-120 WTG Voltage [%] Time [s] 29 Stephan Wachtel - Energy Consulting 25.3.13 FRT-requirements: Fault current provision GE 2.5 WTG@FRT-test: 3-phase 18.5% retained voltage, Estonian Grid Code: 700ms fault: P, Q (MW, Mvar)  “Maximize reactive current IR” ENTSO-E NC RfG  Some framework requirements  Leaves things open to requests by the TSO Best practice  Some minimum performances for IR …  … by keeping flexibility and considering the wide range of possible transients Proving Compliance  Most WTGs are LVRT type tested (IEC, FGW)  Validated models based on such tests available  No specific compliance tests in most EU and non-EU networks,  Commonly applied: monitoring WTG supports grid during voltage depression 30 Stephan Wachtel - Energy Consulting 25.3.13 Reactive power capability Example: Eirgrid Estonian Grid Code:  Q: +/-10% PRated Well accepted requirement: Eirgrid Grid Code  0.95 PF lead/lad at PRated  Limited range at low output (e.g. below 50% PRated)  No requirement for very low output (< 10% PRated) ENTSO-E NC RfG GE 2.5-120  Determines a extremely wide framework,  EWEA: “not really practical, going much too far!!” 31 Stephan Wachtel - Energy Consulting 25.3.13 Voltage control by controlling reactive power from WPPs measurements from a 162MW WPP Paldiski WFs: Wind Plant Voltage Voltage at POI  VAR range available  WTGs controlled by GE WindCONTROL.  Either Q- or Voltage Droop control  Switching via remote control State of the art / best practice Wind Plant Power Output  OLTC at HV/EHV-connected WF substation transformers  Voltage control by WPPs connected Average Wind Speed top HV/EHV networks  Power factor control still widely used, Field Test but not providing the available Recording: Dynamic performances response  Some WFs could even provide this at no wind (GE WindFREE) 32 Stephan Wachtel - Energy Consulting 25.3.13 Active Power Controls / Frequency Control Status and Trends in Europe Established best practice for WPPs:  Active power curtailment  Ramp rate limitation at start up  Active power reduction at large over frequencies (e.g. > 50.2 Hz in DE)  In some power systems: WPPs need to be able to provide full Primary Response (e.g. IR, RO, UK) ENTSO-E NC RfG:  Active Power Control  Frequency Sensitive Mode (FSM) (Primary Response)  Over- and Under frequency Limited FSM reg. large Active Power range: +/- 2..10% Pmax frequency excursions Insensitivity: 10-30mHz  Open to TSO: Inertial response (“Synthetic Inertia”) Deadband: 0 – 500 mHz Droop s1 : 2 – 20 %  Available solution: GE WindINERTIA Initial delay t1: ≤2s Full activation time t2: ≤ 30 s 33 Stephan Wachtel - Energy Consulting 25.3.13 Active Power Controls / Frequency Control Estonian Grid Code & Paldiski WF Primary Control capability requested  Normally: OFF  2 Curves: 5% und 12% Reserve  Droop from 2%..8%,  settable by remote… quite special, but doable Power reduction at over frequencies  Available for each WTG in Paldiski  Not requested Fast active power reduction with 2 seconds  Doable, but only by tripping WTGs  needs time for restart  Reasoning not fully clear 34 Stephan Wachtel - Energy Consulting 25.3.13  DRAFT Grid Connection Process GE Internal - For internal distribution only. Best practice reg. exchange of data & documentation Applicant  TSO TSO  Applicant Data for steady state analyses Explicit and complete scope of studies Models for dynamic power system studies Accurate and complete power system data, (PSS/E, etc.) enabling the Applicant to carry out the  Validated models based on type test can requested studies in accordance with the be provided by GE scope  Sufficient documentation WTG Power Curve for production forecasts Requested study reports Validated data from compliance tests Only in very exceptional cases: models for EMT-type studies (PSCAD, etc…) Confidentiality to be maintained!!! NON STANDARD REQ. 36 Stephan Wachtel - Energy Consulting 25.3.13 Process phases and steps Feasibility Best practice: “No one size fits all”  Lots of variations from system to Planning & Application system, depending on various local Engineering factors, policies, processes and needs Most important: Detailed Engineering A clear definition of the process  Timeline (generic Gant Chart?)  Data to be exchanged Plant Energization  Deliverables Construction &  Responsibilities Commissioning  Arbitration Gen. System Commissioning  Cooperation and communication Operation Compliance Testing 37 Stephan Wachtel - Energy Consulting 25.3.13 Process phases and steps Detailed comments Feasibility  Studies to be done by TSO  TSO to specify requested data  Applicant to provide specific data where reasonably possible  TSO to respond within e.g. 8 weeks after receiving all data  Deliverable: Feasibility Study Report Application  Key deliverable: Connection Agreement (CA) to confirm o Applicants access right to the grid o TSO obligation to execute their scope  Shall amongst other things include complete set of o Specific technical requirements for a WPP, if not already determined in the GCR o Study scope and grid data to engineer and prove a compliant WPP design o Points of contact and procedures for effective communication between involved parties 38 Stephan Wachtel - Energy Consulting 25.3.13 Process phases and steps Detailed comments Detailed Engineering  Studies to be carried out by the Applicant  Deliverables: Study reports  Reports to be timely reviewed by TSO, e. g. 10 days to respond  To be finalized latest till start of Commissioning. o Except reports necessary for procurement on the TSO side o More risk to the project than finalization till start of Construction… o …but allows fast project execution o Any risk for TSO? Plant Energization  Essential for construction of WPPs: Auxiliary power  To be in place: WF Substation including Protections, metering (and some SCADA?)  Deliverables: Commissioning Reports for theses sub-systems 39 Stephan Wachtel - Energy Consulting 25.3.13 Process phases and steps Detailed comments Generating System Commissioning  Only to start after a specific Commissioning and Compliance Testing Program (CCTP) was agreed by the TSO  Grid Code should include a template which can be adopted to specific project needs  Deliverables: Commissioning Reports Compliance Testing  To be carried out in accordance with the CCTP  WPP should be allowed to sell produced energy  Time needed depends on wind conditions…flexibility needed  Deliverable: Compliance Testing Report 40 Stephan Wachtel - Energy Consulting 25.3.13  DRAFT Conclusions GE Internal - For internal distribution only. Conclusions 1. RULES: Establish and communicate clear, detailed grid connection requirements that are in line with common European practice • Separate grid acceptance to start support scheme • Accept aggregated PSCAD wind farm model • Improve stakeholder involvement and set up a formal grid code review panel (e.g. UK, IR) • Use the above for optimized implementation of the NC RfG • Leverage over frequency response to re- consider fast active power reduction need. 2. PROCESS: Establish clear process and timing for entire connection procedure • Ensure the grid connection process has predictable lead time • Implement one time review practice • Eliminate redundant tests by Compliance Monitoring (e.g.FRT) 3. EXECUTION: Don’t allow rules to be modified or re-interpretated during the execution of a project Thank you for your attention.  REVIEW OF THE ESTONIAN GRID CODE Client Estonian Renewable Energy Association Contact Raul Potisepp Document No. 103822-DEOL-01 Issue C Status Final Classification Client’s Discretion Date 04 June 2013 Author: Nils Richter Checked by: Ronan McDermott Approved by: Paul Gardner Garrad Hassan Germany GmbH M arie-Curie-Straße 1, 26129 Oldenburg, Deutschland, Tel: +49 441 36116 880  IMPORTANT NOTICE AND DISCLAIMER 1. This report (“Repor t”) is prepared and issued by Garrad Hassan Ger many GmbH (“GH” or “Garrad Hassan”) for the sole use of the client named on its title page (the “Client”) on whose instructions it has been prepared, and who has entered into a written agreement directly with Garrad Hassan. Garrad Hassan’s liability to the Client is set out in that agreement. 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The report does not imply that any infor mation is not subject to change. KEY TO DOCUMENT CLASSIFICATION For disclosure only to named individuals within the Client’s Strictly Confidential : organisation. For disclosure only to individuals directly concerned with Private and Confidential : the subject matter of the Report within the Client’s organisation. Commercial in Confidence : Not to be disclosed outside the Client’s organisation GH only : Not to be disclosed to non GH staff Distribution for information only at the discretion of the Client’s Discretion : Client (subject to the above Important Notice and Disclaimer). Available for information only to the general public (subject Published : to the above Important Notice and Disclaimer and Disclaimer). © 2013 Garrad Hassan Germany GmbH Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final REVISION HISTORY Issue Issue Date Summary A 13.03.13 Original issue (electronic version only) B 18.03.13 Final issue adding additional information C 04.06.13 Final Issue following Client’s comments Garrad Hassan Germany GmbH i Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final CONTENTS COVER PAGE DISCLAIMER REVISION HISTORY LIST OF TABLES LIST OF FIGURES 1 INTRODUCTION 1 2 BACKGROUND 2 3 COMPARISON WITH OTHER EUROPEAN GRID CODES 3 3.1 Voltage and Frequency Range Requirements 5 3.2 Reactive Power Capability 6 3.3 Voltage control 6 3.4 Low Voltage Ride-Through (LVRT) 7 3.5 Frequency control 7 4 CONFORMITY WITH THE ENTSO-E STANDARDS 9 4.1 General 9 4.2 European Requirements Comparison with Estonian Regulation Code 184 9 4.2.1 Frequency Range 10 4.2.2 Active Power Control 11 4.2.3 Voltage Range 12 4.2.4 Low Voltage Ride Through (LVRT) 14 4.2.5 Reactive Power Provision 16 4.2.6 Protection Schemes 19 5 CONCLUSION 21 5.1 Comments on the Technical Requirements of the Estonian Grid Regulation 21 6 REFERENCES 23 APPENDIX 1: DETAILED ANALYSIS OF THE ESTONIAN NETWORK REQUIREMENTS [2] 24 Garrad Hassan Germany GmbH ii Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final LIST OF TABLES Table 3.1 – Summary of main Swedish/Finnish Wind Energy Grid Code requirements ............................................... 4 Table 4.1 – Frequency range comparison between ENTSO-E and the Estonian Grid Code..................................... 10 Table 4.2 – Power control requirements comparison between ENTSO-E and the Estonian Grid Code.................. 12 Table 4.3 - Voltage range requirements comparison between ENTSO-E and the Estonian Grid Code................... 13 Table 4.4 - LVRT requirements comparison between ENTSO-E and the Estonian Grid Code ................................. 15 Table 4.5 – Reactive power control requirements comparison between ENTSO-E and the Estonian Grid Code.. 19 Table 4.6 – Protection scheme requirements comparison between ENTSO-E and the Estonian Grid Code ......... 20 Table 5.1 – Summary of Estonian Wind Energy Grid Code requirements [2] in need of adaptation for Renewable Energy Generation .................................................................................................................................................................. 22 Table A1.1 – Requirements for power plants with rated power up to 1 MW................................................................. 27 Table A1.2 – Requirements for power plants with rated power from 1 to 10 MW........................................................ 28 Table A1.3 - Requirements for power plants with rated power over 5 MW ................................................................... 32 Table A1.4 – Supplementary requirements applied for wind turbines and wind farms................................................ 34 LIST OF FIGURES Figure 3.1 – Frequency and Voltage Range requirements of the Nordel WT requirements [7]................................... 5 Figure 3.2 – Low Voltage Ride Through requirements of the Nordel WT requirements [7].......................................... 7 Figure 4.1 – Fault-ride-through-profile ................................................................................................................................. 14 Figure 4.2 – Reactive Power Profile for Maximum Capacity Output............................................................................... 16 Figure 4.3 – Reactive Power Output below Maximum Capacity ..................................................................................... 16 Garrad Hassan Germany GmbH iii Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 1 INTRODUCTION The scope of work for the review (the “Project”) is defined in GL GH Proposal 103822-DEOL-P-01, dated 12 December 2012 [1]. A working group of the Estonian Renewable Energy Association (the “Client”) has requested GL Garrad Hassan Germany GmbH (GL GH) to conduct a review of the Estonian Grid Code Requirement Regulation No. 184, which entered into force on 1 July 2003 [2]. This report presents not only a review of the relevant Estonian regulation, but also provides a cross-comparison with selected issues addressed in the European ENTSO-E standard and other European Grid Codes. For this purpose, GL GH has selected the current renewable energy specific aspects of the Nordel Grid Code [6,7] applicable to the Scandinavian regions of Norway, Sweden, Denmark and Finland; as well as the tailored Finnish requirements applicable to wind energy connected to Finland’s Fingrid TSO network [8,9]. References are highlighted throughout this report using square parenthesis, for example [10]. A list of references is given at the end of this report. Direct citations of the Estonian grid code [2] are presented throughout this report in italic. Main items relating to requirements believed to be directly applicable to renewable generators, and general points which are useful for the Client to note are highlighted in this Section in bold text. Garrad Hassan Germany GmbH 1 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 2 BACKGROUND Estonia has a unique global position insofar as indigenous shale oil is the main source of energy used to supply the electrical power sector. While the country does not produce significant amounts of coal, oil or gas, Estonian shale oil mining accounts for about 70% of the world production. Two oil shale power stations account for 95% of the Estonian electricity production, while natural gas imported from Russia provides most of the heating energy requirements. Renewable Energy does not presently play an important role in the country’s energy sector. However, it is believed that hydroelectric power potential is much higher than the current use. In the process of Estonian EU membership there have been concerns regarding pollution and environmental impact caused by shale oil mining and heavy use. The Estonian governmental goal is now to increase the renewable energy share significantly. The level of bureaucracy and technical hurdles should not undermine or discriminate against the process of renewable energy development. The Estonian Renewable Energy Association is understood to play a key role to target fair regulations, with the government and the country’s System Operators. Garrad Hassan Germany GmbH 2 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 3 COMPARISON WITH OTHER EUROPEAN GRID CODES In established wind markets (such as Europe and North America) there are varying requirements for wind farms to comply with Grid Codes. These regulations require wind farms and other generating stations to comply with various technical performance criteria, such as active and reactive power control, low voltage fault ride through, and minimum power quality requirements. GL GH has compared the similarities and differences of the Estonian grid regulations [2] with primary grid code requirements applicable to Swedish and Finnish wind energy markets, which are considered good reference points given their geographical proximity to Estonia. The main reference documents are Nordel’s ‘Nordel Connection Code Wind Turbines ‘(2007) [7] - applicable to Sweden, Norway, Denmark and Finland– and the Finnish specific Fingrid document ‘Connection Code for Connection of Wind Power Plants to Finnish Power System’ (2009) [8]. These primary references are referred to as ‘the Nordel WT requirements’ and ‘the Fingrid WT requirements’ throughout this section. Secondary references such as the Nordic Grid Code [6] are also noted. Clearly these requirements are more specifically tailored toward wind energy than any other form of renewable generation, as a reflection of wind energy’s stature as the leading renewable electricity generation technique over the last 10 to 20 years. GL GH believes as such, the requirements of [7] and [8] are worth cross referencing in order to illustrate the attempts made by TSOs and regulators in other countries to accommodate renewable energy generation and to test the Estonian authority’s attempts to do the same. Table 3.1 overleaf presents a summary of the findings of GLGH’s cross comparison of the Nordel, Finnish and Estonian grid codes, with further text of this Section explaining the findings in greater detail. Garrad Hassan Germany GmbH 3 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Grid Code Nordel Requirements Fingrid Requirements GLGH comment on Estonian Requirement [6,7] [8, 9] comparison [2] Power control Ramp Rates specified as Ramp Rates specified as Requirements almost identical to well as power curtailment well as power curtailment Nordel [7] but language used is requirements requirements unclear and cause for misinterpretation Reactive Wind farm must provide At 0.9 to 1.0 pu voltage, §14 (4), §18 (10) states reactive power unity power factor (zero wind farm must provide power transfer kept to a minimum, provision reactive power 0.95 overexcited power with maximum range of +/- 10% exchange) in normal factor to network. At 1.0 to Pmax. GLGH notes this is equivalent operating conditions. 1.05 pu voltage, wind farm to Nordel requirements; although must operate at 0.95 power factor can vary to 0.995 lag- underexcited power factor 0.995 lead Voltage Reactive power (Q) Likely site specific Not detailed in [2]. Section §18 (10) control output to be requirements, Fingrid 2) notes that wind installations >200 automatically controlled mentions requirement for kW should provide reactive power to as function of Voltage to zero reactive power flow the network during disturbances, but provide voltage control. between network and wind no detailed requirements are Detailed settings to be plant provided agreed with TSO Voltage Stay connected 0.85pu to Stay connected 0.85pu to §23 Similar to Nordel requirements, tolerance 1.1 pu Voltage 1.1 pu Voltage not as clearly defined due to lack of diagram Low-voltage Stay connected at zero Similar to Nordel Noted as being identical [2] ride through voltage conditions for a Requirements (LVRT) minimum of 250ms. Frequency Operation up to 53 Hz, Similar to Nordel §22 is almost identical to Nordel Range stay connected for 3 requirements requirements, not as clearly defined minutes min. due to lack of diagram. Noted that Operation down to 47.5 changing §22 (1) 1) from 51 Hz to Hz, stay connected for 3 50.3 Hz would make more sense and minutes min. would align with Nordel requirements Frequency Turbines must be Reduction of power above Similar to Nordel requirements, not control equipped with active 50.3Hz: not mandatory. as clearly defined power control as a Reduction of power in function of frequency as under-frequency conditions per Section 4. Only is allowed, level of 15% limited power reduction in max. reduction at 47.5% under-frequency condition allowed Power quality Short term, long term Short term, long term Not covered - flicker values given values given Power quality Max. THD levels and Max. THD levels and Not covered - harmonics individual levels given individual levels given in [9] Table 3.1 – Summary of main Swedish/Finnish Wind Energy Grid Code requirements Garrad Hassan Germany GmbH 4 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 3.1 Voltage and Frequency Range Requirements The Nordel WT requirements [7] are that a wind farm should have the capability to operate between 90 % to 110 % Voltage when operating at frequencies of nominal 50Hz +/- 0.3 Hz. The wind farm should be able to remain connected for at least 60 minutes when in the extreme voltage ranges of 85 % to 90 % Voltage and 105 % to 110 % Voltage, as per regions C and D of Figure 4 below [7]. Most wind turbines on the market specify the normal operating frequency range as in the region of 47.5 Hz to 51.5 Hz of the nominal 50Hz. However, as per region F of Figure 4 below taken from the Nordel WT requirements [7], unlimited operation is required up to a level of +6% Frequency, or 53 Hz for a duration of a minimum of 3 minutes. Figure 3.1 – Frequency and Voltage Range requirements of the Nordel WT requirements [7] GL GH notes the figure above bears some relation to the requirements of Chapter 2 of [2], particularly sections §22 and §23 which describe almost identically the requirements of Section 7 of the Nordel WT requirements. However the lack of a diagram, as is standard for Grid Codes leaves the written requirements of [2] confusing and GLGH notes that some amendments are required, such as: • Sections §22 (1) 1) should change 51 Hz to 50.3 Hz as the text contradicts §22 (1) 3) which states a ‘certain’ power decrease is allowed over 50.3 Hz, while §22 (1) 1) requires maximum power output in this range • Sections §22 (3) and §22 (4) are contradictory in their requirements for the plant to stay connected above 51 Hz. It is noted that the §22 (4) requirements are identical to those of Area F of the Nordel requirements, whereby the plant must stay connected for 3 minutes, with significantly reduced power output allowed. It is possible that Section §22 (3) is only applicable to conventional thermal synchronous generation but this is not made clear in the text Garrad Hassan Germany GmbH 5 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final • Section §23 (1) to (3) are worded in a confusing manner and should be reworded with the aid of a diagram. 3.2 Reactive Power Capability The Nordel WT requirements [7] require that at the point of connection, whilst the wind farm is within area A of Figure 3.1 (i.e. nominal band of frequency and voltage), the wind farm must provide unity power factor (i.e. zero reactive power exchange) at the point of connection. The Fingrid WT requirements [8] require that at the point of connection, whilst the wind farm is operating between voltages of 90% and 100% the wind farm must provide 0.95 power factor overexcited (provision) at the point of connection. Conversely, for wind farm operation in the range 100% to 105%, the wind farm must provide 0.95 power factor under excited (absorption) at the point of connection. The Estonian grid code requirements are similar with Sections §14 (4) and §18 (10) of [2] stating reactive power transfer must be kept to a minimum at the connection point, with maximum range of +/- 10% Pmax - a power factor of 0.995 lag-0.995 lead. GLGH notes this is broadly equivalent to Nordel requirements, and as Section §18 is the relevant clause relating to supplementary wind farm requirements, these would be anticipated to be applied for most forms of renewable energy generation. 3.3 Voltage control The Nordel WT requirements [7] require voltage control by means of reactive power control of the wind farm as standard, with the specific details set by the TSOs involved. This is made clear in Section 6.2 of [7], although detailed engineering criteria such as slope settings etc. are omitted, presumably to be set in connection offers/agreements with the relevant local TSOs. In the case of the Finnish requirements, Fingrid require that ‘A Wind plant has to have an automatic voltage control: • zero reactive power flow between network and wind plant under normal operation, dead band shall be adjustable • reactive power statics must be adjustable and is capable of regulating in given range’ The above does not clarify the timescales involved in voltage control on the Fingrid system; it is likely that such requirements are site specific. The Estonian grid requirements contain very little in the way of Voltage Control definition, although GLGH notes that Section §18 (10) 2) asks that wind installations >200 kW should provide reactive power to the network during disturbances (LVRT conditions). No detail regarding the scale of the reactive current injection or the timescale of such are provided. Garrad Hassan Germany GmbH 6 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final It is notable that the Nordel and adapted Fingrid requirements do not appear to have adopted similar requirements regarding reactive power provision during network fault conditions, although such requirements are included in many European Grid Codes e.g. TenneT Germany’s Offshore and Onshore Grid Codes. 3.4 Low Voltage Ride-Through (LVRT) In relation to compliance with the Nordel WT requirements [7], the Nordel Voltage-time envelope requires units to stay connected at zero voltage conditions for a minimum of 250ms as shown in Figure 3.2 below. Figure 3.2 – Low Voltage Ride Through requirements of the Nordel WT requirements [7] In the case of the above, the 1pu value is the voltage level before the disturbance, and the requirements are related to transmission system connected wind farms, as defined by local TSOs. The Fingrid WT requirements [8] place no additional requirements beyond the Nordel recommendations. As per Section §23 (6) of [2], the Estonian grid requirements require the same connection time at the minimum voltage level of 0% for 250ms. Section §23 (6) 2) and 3) appear to mimic the requirements of the Nordel WT requirements, but as they are presented verbally rather than with the aid of a diagram, the message is made unnecessarily unclear. 3.5 Frequency control Many grid codes now require wind farms to operate in a frequency control mode, which adjusts the available active power export of the wind farm in response to the frequency on the system. This requires that the wind farm implements a number of pre-defined frequency (and, correspondingly, power) set points. Garrad Hassan Germany GmbH 7 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final The Nordel WT requirements [7] require that automatic control of power as a function of frequency must be provided at each turbine in accordance with detailed TSO specific requests. It also states the control function must be provided proportional to frequency deviations (GLGH note: usually provided as a slope, or set of slopes) and must be provided with a dead-band. The Fingrid and Nordel Grid Code high level requirements in this instance both state that above 50.3 Hz up to 51 Hz, the active power output “may be slightly reduced’’, with minimum operation time without tripping of 30 minutes. In addition, above 51 Hz and up to 53 Hz the active power output ‘may be reduced to any level’ with minimum operation time without tripping of 3 minutes. Below 49 Hz, “The active output is allowed to decrease as a linear function of the frequency from zero reduction at 49.0 Hz to 15% reduction at 47.5 Hz.”. Clearly, the Finnish and Nordic requirements are much less stringent than many European counterparts which require active power increase in under-frequency conditions and clear target active power setpoints in over- frequency conditions. The Estonian requirements mimic the Finnish and Nordic requirements insofar as the generic power reduction requirements during under and over frequency conditions are concerned, albeit as noted previously that some amendments are required, such as: • Sections §22 (1) 1) should change 51 Hz to 50.3 Hz as the text contradicts §22 (1) 3) which states a ‘certain’ power decrease is allowed over 50.3 Hz, while §22 (1) 1) requires maximum power output in this range. • Sections §22 (3) and §22 (4) are contradictory in their requirements for the plant to stay connected above 51 Hz. It is noted that the §22 (4) requirements are identical to those of Area F of the Nordel requirements, whereby the plant must stay connected for 3 minutes, with significantly reduced power output allowed. It is possible that Section §22 (3) is only applicable to conventional thermal synchronous generation but this is not made clear in the text. Garrad Hassan Germany GmbH 8 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 4 CONFORMITY WITH THE ENTSO-E STANDARDS 4.1 General Published in June 2012, the ENTSO-E Network Code document defines framework European requirements for grid connections applicable to all kind of generators [4]. It is a European level document, following on from the request of the EU Agency for Co-operation of Energy Regulators, ACER, which aims at ultimately harmonising the requirements in different regions of Europe to make it easier for manufacturers to build equipment suitable for all European markets. It should be noted that in cases of conflict between local requirements (e.g. those specified in national TSO grid codes) and the ENTSO-E requirements, the local requirements presently take precedence. GL GH reviewed the code, with the purpose of comparison with the Estonian Regulation No. 184. The ENTSO-E code differentiates between four types of generating modules by size and by several locations within Europe. Further additional requirements relate to power park modules (which widely include larger renewable energy plants) and offshore park modules (which is understood mainly to be relevant for Offshore wind farms). For the Baltic States ‘Power Generating Modules’ are defined as type B having a capacity of 0.5 MW – 10 MW, type C having a capacity of 10 MW – 15 MW and type D having a capacity of 15 MW and above, while type A is generally limited to 0.8 kW to 0.5 MW. All sizes of generating modules can apply to renewable energy generation facilities, as the generating module is defined to have one connection point as a total and could therefore consist of several generators in a wind farm or solar plant. 4.2 European Requirements Comparison with Estonian Regulation Code 184 GL GH reviewed technical aspects of the ENTSO-E requirements [4] to identify the key similarities and differences with the Estonian Regulation Code [2]. In the European Code, the wording leaves no doubt that it is addressed to all kind of generating “modules”. The Estonian code [2] seems to be limited to conventional thermal fired turbogenerators, hydro facilities and wind turbines and does not appear to include solar power and photovoltaic systems as part of the present regulation. The changes of the Estonian code implemented in 2007 seem to have targeted wind energy issues mainly although GL GH notes that as per Chapter 3 of this report, there are still areas in need of better definition. The European code several times refers to Article 4 (3) of [4], which leaves the electrical requirements open to determination according to national laws and regulations, but shall be established with the principle of transparency, proportionality and non-discrimination. Particular technical requirements compared are discussed in the following sections. Garrad Hassan Germany GmbH 9 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 4.2.1 Frequency Range Specifically for Baltic countries and for all types of generation modules (A, B, C and D) the ENTSO-E code defines requirements for frequency control. The generation modules shall stay connected to the grid for the defined durations and shall be capable of automatic disconnection if operating outside the respective frequency limits. Frequency ENTSO-E requirement Estonian requirement range Ref: Title 2, Chapter 1, Table 2 [4] Chapter 2, § 22 [2] 47.5 Hz – To be defined by each TSO while Generators must operate for 30 minutes 48.5 Hz respecting the provisions of Article 4(3), but not less than 30 minutes 48.5 Hz – To be defined by each TSO while Generators must operate for 30 minutes 49.0 Hz respecting the provisions of Article 4(3), but not less than the period for 47.5 Hz – 48.5 Hz 49.0 Hz – Unlimited Unlimited for 49 Hz. to 50.3 Hz. 51.0 Hz Operation 50.3Hz – 51 Hz only allowed for 30 minutes max. per occasion, 10 minutes cumulative per annum 51.0 Hz – To be defined by each TSO while See below in ‘Other’ 51.5 Hz respecting the provisions of Article 4(3), but not less than 30 minutes Other 51 Hz - 52 Hz, 5 seconds operation while the generator is under disturbance 51 Hz – 53 Hz, 3 minutes operation, power decrease is allowed These appear to be contradictory requirements as noted in Section 3 of this report GL GH Conclusion: The Estonian code predominantly conforms to the European code regarding frequency range issues, but does not define clearly the duration to stay connected for frequencies range 51 Hz – 52 Hz. As noted earlier, the relevant Estonian regulations are heavily based on Nordel equivalents, but are provided as text only thus increasing probability of misinterpretation. Table 4.1 – Frequency range comparison between ENTSO-E and the Estonian Grid Code Garrad Hassan Germany GmbH 10 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 4.2.2 Active Power Control In regard to the Limited Frequency Sensitive Mode – Overfrequency (LFSM-O) and active power reduction with falling frequency, the following shall apply according to the ENTSO-E code compared with the Estonian Code: Frequency in ENTSO-E requirement Estonian requirement the Grid The Power Generating Module shall be If the operation frequency exceeds 50.3 Hz, a capable of activating the provision of Active certain power decrease is permitted if the 50.2 Hz - Power Frequency Response for the defined maximum active power can be restored when 50.5 Hz frequency (within the given range). It shall the frequency drops below this value. follow a droop∆P according to an also defined ∆f. Any The power generation module shall be The output power may decrease up to 10% in capable of maintaining constant output at its the range 49.7 Hz – 50.3 Hz if the network target active power value regardless of voltage drops to 85-90% or rises to 105-110%. changes in frequency, unless the requirement above and below. Below 49.5 Hz The Relevant TSO shall define admissible If the frequency drops below 49 Hz, the output or 49 Hz Active Power reduction from maximum power can decrease according to a slope output with falling Frequency within the defined as 0% at 49 Hz to 15 % at 47.5 Hz boundaries:  Below 49.5 Hz by a reduction rate of 10 % of the Maximum Capacity at 50 Hz per 1 Hz Frequency drop;  Below 49 Hz falling by a reduction rate of 2 % of the Maximum Capacity at 50 Hz per 1 Hz Frequency drop. 49.5 Hz - Generating modules of type C and D shall be No direct match is available for this 49.8 Hz capable of providing a power increase up to requirement. maximum possible power output in the range of 2 – 12%. The provision depends on operating and ambient conditions. Active power With regard to loss of angular stability or loss The active power of the wind farm shall remain output of control, a power generating module shall within the limits ±5% prescribed by the reduction be capable of disconnecting automatically transmission network operator. from the network in order to support preservation of system security and/or to Section § 26 indicates start-up times of Garrad Hassan Germany GmbH 11 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final prevent damage from the power generating production equipment shall be as short as module. The power generating facility Owner possible after outages dependent on the and the relevant network operator in energy source in use. Wind turbines shall start coordination with the relevant TSO shall up within 15 minutes if wind conditions allow. agree on the criteria to detect loss of angular stability or loss of control. The output must be possible to be minimised to 10% or less for hydro, gas and wind The system operator has the right to require turbines/wind farms. simulation models of the power generation facility. In agreement with the system operator the power output shall be controlled by frequency- sensitive controller or wind turbine controller. Section § 27 indicates that particularly for wind turbines the power output must be controllable at a rate of at least 8% of rated power per minute if wind conditions allow adjustment in the range of 20-100% and in steps of 30% of rated power. Section § 18 requires power reduction of a wind farm down to 20 % of rated power within 2 seconds. GL GH conclusion: The Estonian Code gives little clear definition for active power reduction dependent on the grid frequency, but allows conformity with the European Code. The renewable energy provision of primary reserve (in case of decreasing grid frequency) should be considered to be limited as the technology (with the possible exception of hydro-electric schemes) does not generally provide this, at this time. The Estonian requirement to reduce wind farm active power down to 20 % within 2 seconds has no equivalent in the ENTSO-E Code. The requirement appears excessive in terms of likely costs. The actual need of this requirement should be discussed with the responsible Estonian TSO or regulator. From GL GH experience, a usual requirement of the system operator is the ability to reduce the active power output automatically, in response to a signal from the TSO. The ENTSO-E code does not specifically define any procedure in this case. Table 4.2 – Power control requirements comparison between ENTSO-E and the Estonian Grid Code 4.2.3 Voltage Range The ENTSO-E code defines voltage ranges for Baltic generating modules of type D, which relates to plants totalling 15 MW rated power or more. Specific voltage range requirements for offshore power plants show no difference to the onshore Baltic requirements of the ENTSO-E. Garrad Hassan Germany GmbH 12 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Voltage range ENTSO-E requirements Estonian requirements for connection at 110 kV to 300 kV Understood to be 1 hour from 0.85 pu – Stay connected for 30 minutes Section § 23 0.90 pu ‘the generator must operate within the voltage range of 85-90% of the normal voltage for one hour. In this case the output power may decrease up to 10% of the full power.’ Understood to be unlimited in the 0.90 pu – Stay connected unlimited range 0.9pu to 1.05pu from Section 1.12 pu § 23 (1) Understood to be 1 hour in the 1.12 pu – Stay connected for 20 minutes range 1.05pu to 1.1pu from Section 1.15 pu § 23 (3) Voltage range ENTSO-E requirements Estonian requirements for connection at 300 kV to 400 kV Understood to be 1 hour from 0.88 pu – Stay connected for 20 minutes Section § 23 0.90 pu ‘the generator must operate within the voltage range of 85-90% of the normal voltage for one hour. In this case the output power may decrease up to 10% of the full power.’ Understood to be unlimited in the 0.90 pu – Stay connected unlimited range 0.9pu to 1.05pu from Section 1.10 pu § 23 (1) Understood to be 1 hour in the 1.10 pu – Stay connected for 20 minutes range 1.05pu to 1.1pu from Section 1.15 pu § 23 (3) GL GH conclusion: The Estonian Regulation shows considerably different voltage range requirements and time lengths to remain connected to those presented in the ENTSO-E Code. Table 4.3 - Voltage range requirements comparison between ENTSO-E and the Estonian Grid Code Garrad Hassan Germany GmbH 13 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 4.2.4 Low Voltage Ride Through (LVRT) The ENTSO-E Code was found to significantly differentiate between the power sources when addressing LVRT requirements. All Onshore and Offshore power park modules (which are understood to mainly correspond to wind and solar energy sources) have to fulfil changed or additional requirements to the general standard if they are bigger than the defined generator type A with up to 0.8 kW power output. Those small energy sources do not have to fulfil any LVRT requirements. LVRT requirements are standard in the member states of the European Union. It is found usual that Wind Turbines are tested and certificated for grid code requirements to prove their capabilities. GL GH assumes that it is not necessary to perform LVRT test procedures for each new wind farm if feasible LVRT test certificates are available for the particular Wind Turbine Type. For the review of this section GL GH focused on ENTSO-E requirements for larger on- and offshore power park modules. The Estonian requirement in this section only applies to producers of more than 5 MW rated power output. According to the ENTSO-E code the fault ride through requirement could be presented by the following profile: Uret is the retained voltage at the connection point during a fault tclear is the instant when the fault has been cleared Urec1, U rec2, trec1, trec2, and t rec3 specify certain points of lower limits of voltage recovery after fault clearance Figure 4.1 – Fault-ride-through-profile Garrad Hassan Germany GmbH 14 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final LVRT ENTSO-E requirement Estonian requirement requirement Pre-and post- The system operator shall define: No equivalents available fault conditions  conditions for the calculation of the pre- fault minimum short circuit capacity at the Connection Point;  conditions for pre-fault active and Reactive Power operating point of the Power Generating Module at the Connection Point and Voltage at the Connection Point; and  conditions for the calculation of the post- fault minimum short circuit capacity at the Connection Point. For type B and C For low voltage side generators: connection: tclear: 0.14 – 0.25 s tclear: 0.25 s Uret: 0.05 - 0.15 pu Uret: 0.25 pu For type D For high voltage side generators: connection: Uret: 0 pu Uret: 0 pu Voltage Uclear: Uret + 0.15 trec1 : tclear - - parameters according to Figure 1 Uret1: Uclear trec2 : t rec1 - - For low voltage side connection: Uret2: 0.85 trec3 : 1.5 – 3.0 s trec3 : 0.5 s Uret2: 0.95 For high voltage side connection Uret2: 0.90 GL GH conclusion: The Estonian LVRT requirement is at the upper limit of the grade of the European requirement for the durations generators have to stay connected during fault conditions, while the recovery time of the grid with just 0.5 seconds is shorter in Estonia. Table 4.4 - LVRT requirements comparison between ENTSO-E and the Estonian Grid Code Garrad Hassan Germany GmbH 15 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 4.2.5 Reactive Power Provision The ENTSO-E code was found to differentiate between typical synchronous generator systems and power park modules in regard to reactive power provision requirements. While operating with maximum capacity the power plant shall be defined within the profile of Figure 4.2, where Pmax is the maximum active power capacity, Q is the reactive power, and Vpu is the per unit voltage level. When operating below maximum capacity the power park module shall operate according to the profile in Figure 4.3. Figure 4.2 – Reactive Power Profile for Maximum Capacity Output Figure 4.3 – Reactive Power Output below Maximum Capacity Garrad Hassan Germany GmbH 16 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Reactive ENTSO-E requirement Estonian requirement power requirement Reactive The system operators have the right to Section §18 (10) 2) asks that wind installations current require fast acting (10 milliseconds) >200 kW should provide reactive power to the injection in additional reactive current injection in case of network during disturbances (LVRT case of LVRT symmetrical LVRT. conditions). No detail regarding the scale of the reactive current injection or the timescale of Further the system operators have the right such are provided. to introduce requirements for asymmetrical current injection. Supplementary Type C and D generators can be required by No equivalent found in [2]. reactive power the system operator to inject reactive power into the high-voltage terminals of its step-up Section §18 (10) 2) asks that wind transformer. installations>200 kW should provide reactive power to the network during disturbances The reactive power capability applied to the (LVRT conditions). No detail regarding the connection point in Baltic states and scale of the reactive current injection or the achievable for maximum power output or timescale of such are provided. less, shall be at least in the range: Q/Pmax=0.80 lag-lead (i.e. the range between Q/Pmax (leading) = 0.4 and As a general comment. it is rare for a Q/Pmax (lagging) = 0.4). This is equivalent European Grid Code to omit detailed reactive to a power factor of 0.93 lagging to 0.93 power requirements in this way. leading. The maximum requirement achievable for any power output below the maximum capacity shall be limited to: Q/Pmax(lagging)=0.65 and Q/Pmax(leading)=0.50. This is equivalent to a power factor of 0.84 lagging to 0.89 leading The required reactive power for operation shall Allowed No equivalent found. be provided on site. reactive power The permitted deviation of reactive power deviation supplied or consumed from the network must consumed by be ±10% of the rated active power (for the grid generators with more than 200 kW rated power) which equates to +/- 0.995 power factor Reactive The power park module shall be capable of The following shall apply to reactive power providing reactive power automatically by Garrad Hassan Germany GmbH 17 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final power control either voltage control mode, reactive power control of (only) wind farms: control mode or power factor control mode. • The network operator must have the For the purposes of voltage control mode, possibility to control the full reactive the power park module shall be capable of power capabilities of wind turbines contributing to voltage control at the over 200 kW beside further automatic connection point by provision of reactive control power exchange with the network with a • Current compensation shall be used setpoint voltage covering at least 0.95 to for reactive power controlled on low- 1.05 pu in steps no greater than 0.01 pu with voltage side a slope with a range of at least 2 to 7 % in steps no greater than 0.5 %. The reactive • The reactive power output shall be power output shall be zero when the grid controlled by one central signal voltage value at the connection point equals the voltage setpoint. The reactive power measurements of wind farms exceeding 200 kW shall be sent to the The setpoint may be operated with or without network operator control centre a deadband selectable in a range from zero to +-5 % of nominal network voltage in steps no greater than 0.5 %. Following a step change in voltage, the power park module shall be capable of achieving 90 % of the change in reactive power output within a time t1 to be specified by relevant network operator in the range of 1 - 5 seconds and settle at the value defined by the operating slope within a time t2 to be specified by relevant network operator in the range of 5 - 60 seconds, with a steady-state reactive tolerance no greater than 5 % of the maximum reactive power. For the purposes of power factor control mode, the power park module shall be capable of controlling the power factor at the connection point within the required reactive power range, defined by the relevant network operator with a target power factor in steps no greater than 0.01. The relevant network operator shall define the target power factor value and the tolerance expressed in Mvar or % on the reactive power value issued from conversion of power factor value, within a period of time, following a sudden change of active power output. With regard to priority to active or reactive power contribution, the relevant TSO shall define whether active power contribution or Garrad Hassan Germany GmbH 18 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final reactive power contribution has priority during faults for which fault-ride-through capability is required. If priority is given to active power contribution, its provision shall be established no later than 150 ms from the fault inception. GL GH conclusion: In comparison to the ENTSO-E code standards the Estonian reactive power requirements do not contain the same level of detail. The Estonian regulation does not clearly define any range of reactive power provision to the network, nor provision of reactive power during faults. The Estonian reactive power control requirements do little to clarify the level of reactive power support to be provided to the network in both normal operation (e.g. a simple voltage control droop parameter for wind farm output: typically provided on a timescale of seconds/minutes) or in the case of extreme network dips due to faults (LVRT events: typically provided on a timescale of milliseconds). This is an area which requires further attention as the future grid will likely have an increasing amount of renewable energy sourced generation. Table 4.5 – Reactive power control requirements comparison between ENTSO-E and the Estonian Grid Code 4.2.6 Protection Schemes Both the ENTSO-E and the Estonian code refer to protection schemes to be installed at the respective power plant. The ENTSO-E list is required for all kind of generators, irrespective of technology or size. Garrad Hassan Germany GmbH 19 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final ENTSO-E requirement Estonian requirement Following protection schemes are suggested: Following protection schemes are required: • external and internal short circuit; • overload protection; • asymmetric load (Negative Phase • overcurrent protection; Sequence); • overvoltage and undervoltage protection; • stator and rotor overload; • frequency protection; • over-/underexcitation; • voltage unbalance protection; • over-/undervoltage at the Connection Point; • anti-motoring and rotation overspeed • over-/undervoltage at the Alternator protection terminals; • external fault protection; • inter-area oscillations; • internal fault protection; • inrush current; • rotor earth fault and stator earth fault • asynchronous operation (pole slip); protection; • protection against inadmissible shaft torsions • phase current unbalance protection; (for example, subsynchronous resonance); • stator or rotor overload protection; • Power Generating Module line protection; • frequency increase and frequency drop • unit transformer protection; protection; • backup schemes against protection and • asynchronous operation protection; switchgear malfunction; • failure protection for generator breaker, if • overfluxing (U/f); installed. • inverse power; • rate of change of frequency; and • neutral voltage displacement. GL GH conclusion: The requirements for protection schemes described in both codes are predominantly similar. Differences identified mainly originate from the Estonian code general limitation on classic rotating generators with no consideration of converter-connected wind turbines and solar power systems. Table 4.6 – Protection scheme requirements comparison between ENTSO-E and the Estonian Grid Code Garrad Hassan Germany GmbH 20 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 5 CONCLUSION In this section of the report GL GH discusses how the Estonian Grid regulation [2] conforms to expectations, and the main shortfall areas noted over the course of GLGH’s review. It should be noted that GL GH has relied on an English translation shown in [2], which although apparently validated officially, has been found to have several weaknesses in the wording used. The following comments are assumed to be valid for the original Estonian version, but it may be later found that the original meaning has been lost in translation. 5.1 Comments on the Technical Requirements of the Estonian Grid Regulation GL GH found the code to have some limited suitability for connection of renewable energy facilities, although the fact that many of the wind-specific clauses included are dispersed throughout the document rather than as a separate Annex is seen as a disadvantage. Furthermore, the fact that the regulation [2] does not indicate technical items with diagrams, as is the norm across Europe is a distinct disadvantage to the reader and greatly increases the chances of misinterpretation. It appears that the code was originally limited to conventional synchronous generators, as many requirements of [2] address issues such as synchronism and variable speed behaviour which are not directly applicable to more common forms of renewable generation, in particular photovoltaic and wind generation. Requirements for small generators with rated power below 1 MW or even 200 kW, as explicitly discussed in the document, would be interesting for private solar energy users, but some of the requirements for such installations are prohibitive in terms of cost of implementation. GL GH recommends implementing a separate section for those particular generators, with the target to simplify the process of connection, or some other way to discuss requirements on a neutral basis as presented in the ENTSO-E code. Further, it should be discussed if the effort of the process of application for connection for small generating modules could be reduced. Annex 2 of the code presents technical data to be provided to the network operator. GLGH believes it can be questioned if all the data listed would be useful for private user generating facilities. Further requirements discussed in chapter 2 of the code seem to be likely to be misunderstood. For example the producer shall define a number of planned and expected outages and their durations. Probably this is meant to be an availability clause, but this is not seen by GLGH as being applicable to renewable generators which have variable outputs based on local weather or resource conditions. The wording for the requirements [2] is noted as unclear in several cases, with several requirements found to be either repeated or contradicted in separate chapters and subsections. One possible reason for this may be the number of changes made in 2007 and 2010, mainly to accommodate wind energy, but there is scope for confusion on several points, as highlighted in this review. Many of GL GH’s key concerns are summarised in Table 5.1 overleaf: Garrad Hassan Germany GmbH 21 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Item GLGH comment on Estonian Regulation [2] Diagrams Lack of diagrams throughout [2] raises the probability of misinterpretation of technical contents considerably. Should be amended to include diagrams in future editions. Frequency Range §22 is almost identical to Nordel requirements, not as clearly defined due to lack of diagram. Noted that changing §22 (1) 1) from 51 Hz to 50.3 Hz would make more sense and would align with Nordel requirements. Contradictory scope noted in Section §22 (1) 1) and Section §22 (1) 3). Frequency Control Contradictory scope noted in Section §22 (3) and Section §22 (4). Likely that Section §22 (4) which mimics Nordel WT requirement is most relevant to renewable generators. Voltage control Requirement not found in [2]. (second/minute timescale) Voltage control Section §18 (10) 2) mentions requirement but scale and timescale are not detailed. (millisecond timescale) Rapid Curtailment The requirements of Section §18 (9) 1) are not to be found in any European Grid Code for wind energy presently, and the requirement for reduction of 80% energy in 2 seconds would be particularly prohibitive to smaller renewable generators, possibly only achievable by switching the generation off the grid. This should be checked with TSO. Primary/secondary Noted throughout [2], but not made clear in document that renewable energy generating control and reserve devices (with the possible exception of hydroelectric power) should be exempt due to their limited inertial capabilities. Inrush A ‘zero inrush’ characteristic is required at energisation, which may not be feasible particularly for asynchronous generating devices. Island operation Chapter 2 of [2] indicates many island operating requirements – it should be made clear that due to their technology, many renewable devices rely on grid connection for excitation/synchronism and are incapable of operating in island mode. The term generation “isolated from the system” should be noted to be unsuitable for renewable generation facilities. Generation Data Data requirements of Annex 2 may be excessive, particularly for small installations (200 kW – 5 MW) Table 5.1 – Summary of Estonian Wind Energy Grid Code requirements [2] in need of adaptation for Renewable Energy Generation Garrad Hassan Germany GmbH 22 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 6 REFERENCES [1] GL GH Proposal 103822, dated 12 December 2012. [2] Regulation No 184 of the Government of the Estonian Republic, 26 June 2003, established on the basis of subsection 42 (2) of the Electricity Market Act. Approved by Regulation No 184 of the Government of the Estonian Republic of 26 June 2003 (RT1 I 2003, 49, 347), entered into force 1 July 2003. Amended by the following Regulations: No 142 (10 May 2007) entered into force 25 May 2007- (RT I 2007, 37, 255), No 52 (15 April 2010) entered into force 25 April 2010 (RT I 2010, 16, 89), No 90 (01 July 2010) entered into force 19 July 2010 (RT I 2010, 48, 295), No 118 (23 August 2010) entered into force 01 January 2011 (RT I 2010, 60, 407) English Language version reviewed is available at: http://www.legaltext.ee/et/andmebaas/tekst.asp?loc=text&dok=XXXX010&keel=en&pg=1&ptyyp=RT&tyyp=X &query=v%F5rgueeskiri [3] GENI, an Energy Overview of the Republic of Estonia (http://www.geni.org/globalenergy/library/national_energy_grid/estonia/EnergyOverviewofEstonia.shtml), 19 February 2003 [4] ENTSO-E, Network Code on Requirements for Grid Connection applicable to all Generators, 26 June 2012 [5] ENTSO-E, Frequently Asked Questions on the Network Code, June 2012 [6] Nordel, Nordic Grid Code (Connection Code), 15 January 2007 [7] Nordel, Nordel Connection Code Wind Turbines, 15 January 2007 [8] Fingrid OYJ, Connection Code for Connection of Wind Power Plants to Finnish Power System, 31 March 2009 [9] Fingrid OYJ, Power Quality in Fingrid’s 110 kV grid (Unofficial Translation), 3 January 2007 Garrad Hassan Germany GmbH 23 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final APPENDIX 1: DETAILED ANALYSIS OF THE ESTONIAN NETWORK REQUIREMENTS [2] GL GH has reviewed technical aspects of Regulation No 184 of the Government of the Estonian Republic, 26 June 2003, updated in May 2007 and in April, July and August 2010 [2] to identify possible misunderstandings and its technical adequacy in relation to most common renewable energy plant schemes. This regulation is the closest document to a ‘Grid Code’ available in Estonia, although GL GH notes that the document has no diagrams included, as would be standard practice in other countries where the Grid Code is written by Transmission System Operators (TSOs) with a focus on technical aspects. The content of the code targets requirements for both energy producers (including renewable energy producers) and system operators. Most adaptations of the 2007 and 2010 amendments to [2] were specifically found to apply to integration of wind power in Estonia. Chapter 8 (balance responsibility) was not found to directly target renewable energy issues, but issues between system operator and balance provider, and was therefore excluded from the review. Citations of the Estonian grid code are presented in italic. Main items relating to requirements believed to be directly applicable to renewable generators, and general points which are useful for the Client to note are highlighted in this Section in bold text. Garrad Hassan Germany GmbH 24 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Supply Security of the System Chapter 2 of [2] relates to issues of system security of supply requirements. As such it is mostly applicable to the system operator in defining the requirements for the entire grid system although it carries some information applicable to generators. For example N-1, N-2 and N-X requirements of the electrical network are discussed in great detail in Chapter 2, sections §3, §10, §11 and §12 of [2], but are considered by GLGH as mainly included for system operator information rather than directly applicable to generating units. It is not unusual in Europe that the technical requirements are issued in one document which every party using the electricity system must abide to. However in other European countries there are separate documents for generators and system operators. It highlights another key issue with the Estonian legislation that Regulation No 184 is a subsection of the Electricity Market Act, and there is not a clear structure which allows each class of users of the electricity system to readily identify the documents and requirements which apply to them. GLGH notes the following sections of Chapter 2 of [2] which may be cause for consideration for future renewable energy generating schemes: • Chapter 2, §4 indicates the generator must provide a guarantee to the network operator regarding reliability of the generating plant which ‘shall be expressed in the contract by the number of planned outages, the number of expected outages and the duration of outages.’ GL GH believes this is most applicable for conventional thermal generation plant which has a high load factor and has a high impact when disconnected. A figure for hours/year downtime of a renewable energy generating plant for scheduled maintenance can be provided to the network operator, but is unlikely to be of the same value, as renewable plants will by their nature have frequent occasions where production is negligible or zero. • Chapter 2, §4 (2) indicates that the system operator has an obligation to inform generators and consumers of any availability issues or likely outages. This data should be gathered by the developer in advance of connection as it will provide valuable availability statistics for financial models etc. • Chapter 2, §5 (2) states ‘The capacity of production equipment in the system shall […] ensure the required level of short-circuit currents’. GL GH expects that required short-circuit levels are demanded from the system operator to generators. For a new renewable generation project, short-circuit studies might be required to be presented to the system operator. Chapter 2, §6 (2) describes system stability requirements. The requirements define static stability margins for generation plant. Again, this is more applicable to conventional thermal plant than renewable energy generation schemes. In the paragraph and Annex 1 it is not discussed how renewable energy generators could contribute to rising system stability. GL GH expects that the contribution of renewable energy generators to system stability also depends on the size and complexity of the single system. The particular requirements for wind power generators according to frequency and voltage (and Low Voltage Ride Through) deviations are discussed in a later section [Table A1.4 – Supplementary requirements applied for wind turbines and wind farms] of this appendix. The grid stability contribution of those facilities is expected to be fully covered with those requirements. Garrad Hassan Germany GmbH 25 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Division 4 of Chapter 2 discusses requirements for production supply for meeting the demand. GL GH expects the system operators in Estonia being fully responsible to avoid probable unbalances of power supply and consumption. Technical Requirements Applied to Generating Installations Chapter 3, Division 2 of [2] discusses connection issues to power generation equipment. The code covers general requirements for all generators and also differentiates the size of the energy production equipment by up to 1 MW, 1 to 10 MW and over 5 MW. Further supplementary requirements are added specifically for wind turbines and farms following amendment of the legislation in 2007. The general requirements in Chapter 3, § 14 relate to generation equipment with rated power over 1 MW production data. Hereby, bi-directional real-time active and reactive energy meters have to be installed measuring production and consumption of the utility as is standard practice worldwide in the electricity industry. Specified data defined in Annex 2 of [2] shall be submitted to the system operator for installations generating more than 1 MW. Certain sections of this sheet relate to all types of generators, some questions are particular for wind turbines and asynchronous generators. GL GH would expect most data to be available for developers of wind farms if a specific wind turbine manufacturer has been selected in advance. One main component with significant influence for electrical parameters of wind power generation, which also relates to photovoltaic power, is the frequency converter system. Such systems are not discussed in Annex 2. It has to be mentioned that almost none of the question list relates to connection of larger photovoltaic collection systems (for above 1 MW having the duty to fill out the list in Annex 2) with DC generation. In such a case, GLGH notes that the information provided in Annex 2 would have to be supplemented by the PV developer with detailed information on the plant equipment and characteristics. GLGH notes from extensive experience in 1 MW + PV projects in the UK that in general such projects rarely disobey strict grid requirements and the use of large frequency converter systems generally allows such systems a great degree of flexibility, e.g in meeting reactive power requirements. Tables 1 to 4 on the following pages offer greater detail on the applicable requirements of [2]. Garrad Hassan Germany GmbH 26 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Requirements applied to production equipment of power plants with rated active power up to 1 MW (§ 16) Item Detail 1 Relay protection (have to Overload protection; overcurrent protection; overvoltage and undervoltage be approved by the protection; frequency protection (if rated active power is over 200 kW); system operator) voltage unbalance protection; anti-motoring and rotation overspeed protection (for more than 200 kW rated power) 2 Inrush prevention Generators switched to the network shall be switched synchronised with a maximum defined inrush current. 3 Switching back to the After recovery of the network the generator may switch back after 5 min network after tripping 4 System operator Production equipment with rated power over 200 kW shall send results of monitoring active and reactive power produced to the system operator control centre in real time. The measuring devices have to be in accordance with the connection contract. GL GH Conclusion: The inclusion of main protection items in 1 is standard, although anti-motoring and rotational overspeed protection is likely only to be applicable to hydro-electric and biogas plants in terms of renewable energy systems. A study on voltage drops due to current inrush is advisable for new plant in order to design a compliant energisation sequence. A maximum allowable voltage drop is not specified in [2]. Table A1.1 – Requirements for power plants with rated power up to 1 MW Garrad Hassan Germany GmbH 27 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Requirements applied to production equipment of power plants with rated active power from 1 to 10 MW (§17) Item Detail 1 Relay protection (have to Overload protection; overcurrent protection; overvoltage and undervoltage be approved by the protection; frequency protection; voltage unbalance protection; anti-motoring system operator) and rotation overspeed protection The network operator defines the relay set points and shall install a further backup protection. 2 Inrush prevention Generators switched to the network shall be switched synchronised with a maximum defined inrush current. 3 Switching back to the A soft starting device shall be installed to asynchronous generators. network after tripping 4 System operator The producer shall send results of active and reactive power feed in the monitoring network to the system operator control centre in real time. The measuring devices have to be in accordance with the connection contract. 5 Primary control The dead band of the speed controller of the turbine generators shall not exceed ±0.1 Hz. GL GH Conclusion: The inclusion of main protection Items in 1 is standard, although anti-motoring and rotational overspeed protection is likely only applicable to hydro-electric and biogas plants in terms of renewable energies. A study on voltage drops due to current inrush is advisable for new plant in order to design a compliant energisation sequence. A maximum allowable voltage drop is not specified in [2]. The primary control requirements of Item 5 should not be made applicable to wind turbine generators due to key differences in their design from conventional synchronous turbines as speed control of the wind turbine is separate from the frequency control function. However frequency control of Wind Turbines is feasible and they can operate in a reasonably wide range of grid frequencies (typically -6%/+4%) Table A1.2 – Requirements for power plants with rated power from 1 to 10 MW Power plants with a size of more than 5 MW have to fulfil much wider requirements than generation equipment of smaller size. It is explicitly stated that wind farms are also included in those requirements summarised in Division 2 of Chapter 2, with certain stated exceptions (which were excluded from the review if no relation to renewable energies was identified). The regulation was not found to clearly apply to photovoltaic systems. Garrad Hassan Germany GmbH 28 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Requirements applied to production equipment of power plants with rated active power over 5 MW (§ 18; § 20 - § 27) Item Detail 1 Relay protection (have to External fault protection; internal fault protection; rotor earth fault and stator be approved by the earth fault protection; phase current unbalance protection, stator or rotor system operator) overload protection; frequency increase and frequency drop protection; asynchronous operation protection; failure protection for generator breaker, if installed. The network operator approves the electrical part of the installation, defines and approves the relay set points and shall install a further backup protection for power plants with less than 30MW rated power output. 2 Inrush prevention Generators switched to the network shall be switched synchronised with a maximum defined inrush current. 3 System operator The producer shall send results of active and reactive power feed in the monitoring network to the system operator control centre in real time. The measuring devices have to be in accordance with the connection contract. Signals indicating the position of circuit breakers shall be sent to the system operator in real time. 4 Primary and secondary The dead band of the speed controller of the turbine generators shall not control exceed ±0.1 Hz. The power plants shall also participate in secondary control (GL GH understands this as quasi-static control in small time scales). 5 Requirements applied to Frequency varies between 49-51 Hz: generators in case of • continuous operation within the voltage range of 90-105% U frequency variations • if the operation frequency is above 50.3 Hz a certain power decrease is permitted Frequency varies between 47.5-49 Hz: • the generator must operate for 30 min in the voltage range between 95% of the minimal normal voltage and 105% of the maximum normal voltage • the power must not decrease if the frequency drops to 49 Hz • the power can decrease 15% when the frequency drops to 47.5 Hz Frequency varies between 51-52 Hz: • the generator must operate under disturbance conditions for 5 seconds in the voltage range between 95% of the minimal normal voltage and 105% of the maximum normal voltage • the output power may decrease if restored when power drops back Garrad Hassan Germany GmbH 29 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final to 50.3 Hz Frequency varies between 51-53 Hz: • the generator must operate isolated from the system for 3 minutes in the voltage range between 95% of the minimal normal voltage and 105% of the maximum normal voltage • power must be decreased, with the system operator evaluating the drop Frequency drops under 47.5 Hz: • the generator may be disconnected from the network Frequency exceeds 55 Hz: • the power plant must be disconnected from the system Fast frequency deviations due to faults or communications in the high- voltage network shall not cause the generator to switch off. 6 Requirements applied to Voltage varies between 95-105% Un: generators in case of • the equipment must withstand continuous full load with the voltage variations frequency range of 49-50.3 Hz and network voltage range 90-105% Un • frequency over 50.3 Hz a power decrease is permitted Voltage varies between 85-90% Un: • if the frequency varies between 49.7-50.3 Hz the plant must operate for one hour • the power may decrease up to 10% of rated power Voltage varies between 105-110% Un: • if the frequency varies between 49.7-50.3 Hz the plant must operate for one hour • the power may decrease up to 10% of rated power 7 LVRT requirements The generator must withstand mechanically one, two- and three-phase faults. Faults going out from a power plant shall be eliminated in 0.1-0.37 second at 330 kV level and 0.6-1 seconds at 200 kV and 11 kV level. If the point of connection to the power network is on the low voltage side of the transformer connecting the power plant with the system, the following LVRT must be withstand: • sudden drop to 25% Un up to 0.25 seconds • linear increase of the system voltage after the drop up to 95% of the rated voltage within 0.5 seconds • the generator voltage shall be kept at a level, which is 95% of the rated voltage of the generator. The rated power may decrease up to 10 % of the rated power If the point of connection to the power network is at high-voltage side of the transformer connection the power plant to the system, the generator must withstand following LVRT: • sudden drop to 0% Un within up to 0.25 seconds, • Linear increase of the system voltage from 25% to 90% within 0.5 seconds • The voltage at the connection point shall be kept at a level, which is 90% of the generator rated voltage. The power output may decrease up to 10% of the rated power. Garrad Hassan Germany GmbH 30 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final 8 Lost synchronism If the synchronism of a power plant is lost, it can be disconnected. 9 Transformation ratio The transformer connecting the power plant with the network system shall allow constant reactive power generation and consumption. 10 Reactive power supply The generator must be able to consume reactive power continuously. 11 Verification of conformity The producer shall verify regularly the conformity of production equipment of to the requirements his power plant to the requirements established by regulation no. 184. The following test agreed with the system operator and concerning the power network shall be made for commissioning: • Voltage dips • Auxiliary load • Checking conformity of control characteristics of the equipment • Further tests not applying to wind turbines 12 Primary and secondary The power plant shall be able to participate in primary control with adjustable control speed controller dead band, with the primary regulator frequency set to 50 Hz. Further the generators shall obtain primary reserve of ±5% of the rated power. In the alert state production equipment over 1 MW shall have a primary reserve of ±12.5% of rated power and ±5% of secondary control. The primary reserve of wind turbines shall be at least 12.5 % of rated power. 13 Power control in the case This requirement reverts to item 13 to reserve power for disturbances and of system disturbance refers to solid fuel generators. GL GH Conclusion: Solar, hydro or biogas generators are expected being able to follow most of the requirements and procedures but some of the language/terms/requirements are judged as less favourable to wind and PV plant as detailed below. The inclusion of main protection Items in 1 is standard, although anti-motoring and rotational overspeed protection is likely only applicable to hydro-electric and biogas plants in terms of renewable energies. A study on voltage drops due to current inrush is advisable for new plant in order to design a compliant energisation sequence. A maximum allowable voltage drop is not specified in [2]. The primary and secondary control requirements of Item 4 and 13 should not be made applicable to wind turbine generators due to key differences in their design from conventional synchronous turbines as speed control of the wind turbine is separate from the frequency control function. However frequency control of Wind Turbines is feasible and they can operate in a reasonably wide range of grid frequencies (typically -6%/+4%). Similarly, wind and PV plant are presently unable to provide inertia as per Item 13. Requirements in item 5 are considered unclear at certain points. It is unclear why the generators under disturbance shall “operate for 5 seconds in the network” in the frequency range 51-52 Hz, while it shall stay connected for 3 minutes in the range 51-53 Hz. For the latter it is also written that the generator “isolated from the system” must operate in this range. GL GH notes that wind turbines usually cannot operate in island conditions and the requirements of Item 5 are thought not applicable to wind or PV solar energy generation. The requirements of item 6 appear to tie voltage ranges and frequency ranges together, whereas GLGH considers, that as in the case of most European Grid Codes, it would be more beneficial to treat voltage Garrad Hassan Germany GmbH 31 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final ranges and frequency ranges separately. The LVRT requirements with 0.25 seconds at low voltage for item 7 are found reasonable in comparison to similar requirements from other countries’ grid codes. The very short grid recovery time of 0.5 seconds after a fault incidence is found unusual, but could make the requirement less critical for wind turbines. In addition, most European Grid Codes now contain clauses regarding the power injected by wind turbines during LVRT conditions which makes it clear that the power to be injected is dependent on the available power, which can be influenced by e.g. the variability of wind speeds. Item 9 requires attention as most double-fed asynchronous generator systems used in wind turbines are likely to have very limited reactive power consumption capability when active power output is zero. To comply with this requirement single wind farms are likely to need additional static reactive power compensation. Item 12 specifies wind turbines to provide at least 12.5 % of primary reserve, which is in conflict with the characteristics of the inconstant energy source in use. Table A1.3 - Requirements for power plants with rated power over 5 MW Garrad Hassan Germany GmbH 32 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Supplementary requirements applied to wind turbines and wind farms (§18 of [2]) Item Detail 1 Connection to the The connection shall be approved by the network operator within 30 days distribution network after application. Wind farms over 10 MW active power shall be connected to the transmission network. 2 Relay protection Overload protection; overcurrent protection; overvoltage and undervoltage protection; frequency protection; overspeed protection The set points shall be approved by the network operator. 3 After tripping The wind turbine may be switched back, if voltage and frequency in the network remain in the permitted limits. 4 Backup protection Backup protection shall be installed for wind turbines with rated power over 1 MW towards the network. 5 Power variation speed “It must be possible to control the power variation speed of the wind turbines control and of the wind farms to be connected to the transmission network in case of changes in wind speed. The requirements for control shall be laid down in the connection contract concluded between the operator and producer.” 6 Reactive power control The following shall apply to reactive power control: • The required reactive power for operation shall be provided on site. The permitted deviation of reactive power supplied or consumed from the network must be ±10% of the rated active power • The network operator must have the possibility to control the full reactive power capabilities of wind turbines over 200 kW beside further automatic control • Current compensation shall be used for reactive power controlled on low or high-voltage side of the wind turbine • The reactive power output shall be controlled by one central signal • The reactive power measurements of wind farms exceeding 200 kW shall be send to the network operator control centre • The remote control must be capable of switching the wind farm on 7 Special requirements and off in real time. • The status code of the wind turbine shall be sent in real time to the transmission network operator. The device must be specified. • Technical specifications and projects of the electrical part of the Garrad Hassan Germany GmbH 33 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final wind turbine and wind farm shall be approved by the transmission network operator within 30 days before commencement of work. GL GH Conclusion: Some requirements identified in § 18 seem to conflict with requirements announced in other paragraphs regarding production equipment especially over 5 MW, where wind turbines are specifically noted to be included. The main part of issues discussed in § 18 can be considered wind turbine generation standard. Others are listed below: Item 5 discussing speed variation could be misunderstood in the way that wind turbines can vary their power independent from the wind speed. The requirement is most likely related to other grid code requirements which specify ramp rates for wind farms, so that generation increases at a rate along or below a set slope function. However, this is not clear from the present wording of Item 5. Full remote control of the reactive power capability of wind turbines by the network operator requires specific IT/SCADA solutions for both the wind farm operator and the network operator but is achievable. Table A1.4 – Supplementary requirements applied for wind turbines and wind farms Garrad Hassan Germany GmbH 34 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final Conditions for Technical Cooperation between the System Operator and the Undertakings Concerned of the Neighbouring States Chapter 4 of the grid code is underlining the responsibility of the system operator to maintain balance of its interconnection system. As they shall ensure safe and reliable operation of the transmission network, it is not fully clear how this issue could affect the operation of renewable energy sources. GL GH expects no curtailment issues regarding this issue, as it is explained that energy import from other states will not have an effect on the domestic consumption and production and will not cause limitations of quality. The chapter does not discuss issues of possible national energy overload and sales to neighbouring states to exclude curtailments of power plants. Connection to the Network and Amendment of the Consumption or Production Conditions Chapter 5 of the grid code discusses procedures for entry to the Estonian transmission network. Particular procedures for wind turbines are supplementary listed in § 18 of the code (technical conditions) reviewed in Table A1.4 – Supplementary requirements applied for wind turbines and wind farms] beside other technical requirements. Several details were found repeated and are not separately discussed in this section of the report. GL GH would expect specific wind turbine and wind farm details from § 18 having preference in cases of conflict. According to § 32 the connection agreement shall be discussed on the basis of the connection application of the plant developer including location and financial issues. The connection to the transmission network can be made at the rated voltage of 110 kV or 330 kV. This seems infeasible for smaller plants of wind and solar power. Voltage levels for connection at the distribution network (medium voltage level) are not defined. Distribution network operators shall issue connection contracts within 30 days, while transmission network operators will have 90 days. The final offer is valid for 60 days for the distribution network and 12 months for the transmission network. 60 days to realise a distribution connection seems to be a relatively short period in comparison to other European Countries. § 33 of the code discusses the calculation of charges for grid connection to address to the network operator. The charge shall be related to the costs for justified expenses like new equipment, installations and construction works necessary for the particular connection. GL GH would consider this to be an equitable procedure. The next paragraph § 34 defines the possible connection point of a new energy production utility in either low- voltage (up to 1000 V), medium voltage or transmission network. The low voltage connection is usually planned at a simple connection board, which would be suitable for private photovoltaic use. Higher voltage connection is expected to be located at substation switchgears or poles at overhead lines, which is a standard European procedure. The responsible network operator then shall be informed about the putting into service (commissioning) of the electrical production equipment, which has been agreed by the two parties previously. Garrad Hassan Germany GmbH 35 Document No.: 103822-DEOL-01 Review of the Estonian Grid Code Issue: C Final This commissioning procedure is described in § 35. The connection point or voltage level of connection can be changed, if technically feasible and described in § 36. The initiative might originate from the system operator or generator owner. In this case the connection agreement has to be amended. GL GH would not expect the connection process to discriminate against renewable energy resources as the procedure appears to be similar to practice in other countries. Measurements Chapter 6 of [2] describes both requirements for measurements of energy consumption and production. Both would have to be utilised for renewable energy resources connection to the grid. The chapter is separated into connections for low-voltage utilities and for medium and high voltage utilities (over 1000 V). The requirements do not differ from connection of conventional plants, including hydro-electric facilities, except the measurement according to forms of energy. In § 41 it is stated that the producer shall ensure that the produced and consumed power are bi-directional. This is expected to be crucial due to different charges in each direction. GL GH could not identify any further issue in chapter 6 of [2], which could lead to any differentiation from other power resources. Garrad Hassan Germany GmbH 36