Economic grid support services by wind and solar PV
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Economic grid support services
by wind and solar PV
a review of system needs, technology options,
economic benefits and suitable market mechanisms
Final publication of the REserviceS project Co-funded by the Intelligent Energy Europe
Programme of the European Union
September 2014
Economic grid support services
by wind and solar PV
a review of system needs, technology options,
economic benefits and suitable market mechanisms
Final publication of the REserviceS project
September 2014
RESERVICES PROJECT - Final publication - September 2014
Project partners
Principal Authors: Frans Van Hulle (XP Wind)
Iván Pineda and Paul Wilczek (The European Wind Energy Association, EWEA)
Authors (project partners): Manoël Rekinger (European Photovoltaic Industry Association, EPIA)
Paul Kreutzkamp (3E)
Hannele Holttinen y Juha Kiviluoma (Technical Research Centre of Finland, VTT)
Mariano Faiella y Diana Craciun (Fraunhofer Institute for Wind Energy and Energy System
Technology, IWES)
Gustavo Quiñonez Varela (Acciona Energía)
Andrej Gubina (University College Dublin, National University of Ireland, NUID)
Nicolaos Cutululis (Technical University of Denmark, DTU Wind Energy)
Florian Chapalain (EDSO for Smart Grids)
Joe Corbett (Mainstream Renewable Power)
Bernhard Ernst (SMA Solar Technology)
Stephan Wachtel, Goran Drobnjak, Bart Stoffer (GE Wind Energy)
Pedro Godinho Matos (EDP Distribuição)
Jorge Tello-Guijarro (Union Fenosa Distribución)
Raphael Rinaldi (Enel Distribuzione)
Project coordination and review: Sharon Wokke (EWEA)
Editing: Zoë Casey (EWEA)
Adrienne Margolis (freelance proofreader)
Acknowledgements (other project partners and Advisory Board):
Justin Wilkes, Jacopo Moccia, Manuela Conconi, Diletta Zeni (EWEA), Dana Dutianu (EASME), Gaëtan Masson, Myrto Papoutsi
and Scarlett Varga (EPIA), Carlos Diercksens and Aurore Flament (3E), Javier Lasa Garcia (Acciona), Ciara O’Connor and Mark
O’Malley (UCD), John Shaw (Mainstream), Christoph Frenkel and Oliver Führer (SMA), Christoph Gringmuth (GE), Carlos Costa
Rausa (Enel).
Hans Abildgaard (Energinet.dk), Jacobo Alvarez and Pavla Mandatova (Eurelectric), Joachim Balke and Tadgh O’Briain (Euro-
pean Commission), Miguel de la Torre (Red Electrica), Javier de la Torre (Fenosa), Kristof De Vos (KU Leuven), Yves Langer
and Thijs Engels (BELPEX), Alejandro Gesino and Andreas Thum (TenneT), Jon O’Sullivan (Eirgrid), Alexandre Torreele and
Manuel Galvez (ELIA).
Acknowledgements (workshop speakers and other contributors):
Ricardo Bessa (INESC TEC), Denis Cagney (CER), Karel De Brabandere (3E), Caitriona Diviney (IWEA), Sophie Dourlens-
Quaranta (Technofi), Eike Erdmann (Enercon), Pablo Frías Marín (IIT Comillas), Rubén Gutiérrez Otero (EDP Distribuição), Tony
Hearne (ESB Networks), Riccardo Lama (Enel Distribuzione), Miguel Lorenzo Sotelo (Red Electrica), Antonio Lopez Nicolas
(European Commission), Jane McArdle (SSE), John Mc Cann (SEAI), Simon Muller (IEA), Sophie Müller-Godeffroy (BMU),
Luca Colasanti (GSE), Javier Paradinas (EFET), Eckard Quitmann (Enercon), Marcus Merkel (EWE Netz), Ricardo Prata (EDP
Distribuição), Juan Rivier Abbad (Iberdrola Renovables), Stephanie Ropenus (BWE), Juan Saavedra (Fenosa), Irinel-Sorin
Ilie (GE), Matti Supponen (European Commission), David Trebolle (EDSO4SG), Andreas Wade (First Solar), Zoltan Zavody
(RenewableUK).
Björn Andresen, Frank Martin, and Henrik Kodahl (Siemens), Christian Benz Harald (DanFoss), Philip Carne Kjaer (Vestas),
Martin Heidl (Fronius), Lourdes Garcia Caballero (Alstom), REpower, Luis Pascual (Sunedison), Michel Ryser (Solarmax), Mads
Skjelmose (Vattenfall), Paula Souto Perez (WindVision), David Martinez and Javier Villanueva (Gamesa).
Layout: EWEA
Print: Artoos
Production coordination: Clara Ros and Zoë Casey (EWEA)
Cover photo: Thinkstock
4 RESERVICES PROJECT - Final publication - September 2014
Coordinator Partners Agreement no.: IEE/11/814/SI2.616374 Duration: April 2012 – September 2014 Coordinator: The European Wind Energy Association LEGAL DISCLAIMER The sole responsibility for the content of this leaflet lies with the REserviceS consortium. It does not necessarily reflect the opinion of the European Union. Neither this document nor the information contained herein shall be used, duplicated or communicated by any means to any third party, in whole or in parts, except with prior written consent of the “REserviceS” consortium. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained herein. RESERVICES PROJECT - Final publication - September 2014 5
6 RESERVICES PROJECT - Final publication - September 2014
Table of contents
1 EXECUTIVE SUMMARY AND POLICY RECOMMENDATIONS............................................... 11
1.1 RECOMMENDATIONS - EU ENERGY POLICY AND ELECTRICITY MARKET DESIGN........................... 12
1.1.1 Recommendations for policy makers............................................................................ 12
1.1.2 Recommendations for market design - frequency support.............................................. 13
1.1.3 Recommendations for market design - voltage support.................................................. 14
1.2 RECOMMENDATIONS - EU NETWORK CODES AND NATIONAL GRID CODES................................... 14
1.2.1 Requirements based on identification of system needs.................................................. 14
1.2.2 Contents and quality of requirements for generators for service delivery......................... 15
1.2.3 Management of grid code requirements........................................................................ 15
1.2.4 Harmonisation and standardisation.............................................................................. 15
1.3 RECOMMENDATIONS - RESEARCH AND TECHNICAL DEVELOPMENT............................................. 15
1.3.1 Hardware.................................................................................................................... 15
1.3.2 Software and methods................................................................................................ 16
1.3.3 System operational procedures, methodologies and GSS deployment strategies............. 16
1.4.4 Standards.................................................................................................................. 16
2 INTRODUCTION...................................................................................................................... 17
3 RESERVICES MAIN FINDINGS.............................................................................................. 20
3.1 SYSTEM NEEDS FOR GRID SUPPORT SERVICES BY WIND AND SOLAR PV.................................... 21
3.2 TECHNICAL CAPABILITIES OF WIND AND SOLAR PV AS SERVICE PROVIDERS................................ 21
3.3 ECONOMIC BENEFITS OF GRID SUPPORT SERVICES BY WIND AND SOLAR PV.............................. 22
3.4 MARKETS AND COMMERCIAL FRAMEWORKS............................................................................. 23
3.5 KNOWLEDGE GAPS AND NEED FOR R&D................................................................................... 24
4 SYSTEM NEEDS VS. GRID SUPPORT SERVICES FROM WIND AND SOLAR PV............... 25
4.1 INTRODUCTION....................................................................................................................... 26
4.2 CHANGING SYSTEM NEEDS WITH INCREASING WIND AND SOLAR PV PENETRATION..................... 26
4.2.1 General trend – increasing needs at rising penetration levels of VAR-RES........................ 26
4.2.2 Need for frequency support services............................................................................ 28
4.2.3 Requirements for voltage support services................................................................... 28
4.2.4 Requirements for system restoration services............................................................... 28
4.2.5 Regional differences in service requirements................................................................ 28
4.2.6 Methods of assessing system needs with VAR-RES are still evolving............................... 29
4.3 RECOMMENDED KEY SERVICES FROM WIND AND SOLAR PV...................................................... 29
4.4 HIGH VAR-RES PENETRATION ISSUES AT TRANSMISSION AND DISTRIBUTION LEVEL.................... 30
4.4.1 Transmission level...................................................................................................... 31
4.4.2 Distribution level......................................................................................................... 31
4.5 INTERACTION OF NEEDS AND SERVICES AT TRANSMISSION AND DISTRIBUTION LEVEL................ 31
4.6 CROSS-BORDER ISSUES OF NEEDS AND SERVICES................................................................... 31
4.7 SPECIFIC NEEDS REGARDING LARGE SCALE OFFSHORE WIND DEPLOYMENT............................... 32
4.8 SPECIFIC NEEDS REGARDING DISTRIBUTED SOLAR PV.............................................................. 32
4.9 CONCLUSIONS – SYSTEM NEEDS............................................................................................. 33
RESERVICES PROJECT - Final publication - September 2014 7
Table of contents
5 CAPABILITIES OF VAR-RES AS GRID SUPPORT SERVICE PROVIDERS............................ 34
5.1 INTRODUCTION....................................................................................................................... 35
5.2 TECHNICAL ASSESSMENT OF VAR-RES CAPABILITIES FOR SERVICE PROVISION............................ 35
5.2.1 Existing capabilities to provide frequency and voltage support........................................ 35
5.2.2 Existing capabilities for system restoration support (SRS) from VAR-RES......................... 36
5.2.3 Recent technical developments of capabilities for system services................................. 37
5.3 POWER SYSTEM IMPACT OF SERVICES PROVIDED BY VAR-RES................................................... 37
5.3.1 Frequency Control....................................................................................................... 37
5.3.2 Voltage Control........................................................................................................... 37
5.3.3 Provision of GSS with offshore wind plants................................................................... 38
5.3.4 Impact of aggregation and short term forecasting on GSS provision................................ 39
5.4 TECHNO-ECONOMIC ASSESSMENT OF SERVICE PROVISION (GENERATOR LEVEL)......................... 39
5.4.1 Comparing costs of providing GSS with wind and solar PV.............................................. 39
5.5 CHALLENGES FOR ENHANCING CAPABILITIES AND SOLUTIONS................................................... 41
5.5.1 Enhanced frequency and voltage support with VAR-RES: challenges and solutions........... 41
5.5.2 System Restoration Support with VAR-RES: technical challenges and solutions............... 45
5.6 CONCLUSIONS - CAPABILITIES.................................................................................................. 46
6 ECONOMIC BENEFITS OF VAR-RES BASED SERVICES....................................................... 47
6.1 INTRODUCTION....................................................................................................................... 48
6.2 VAR-RES IN FREQUENCY SUPPORT............................................................................................ 48
6.2.1 Cost-benefit of using VAR-RES in frequency support....................................................... 48
6.2.2 Cross-border sharing vs. VAR-RES in frequency support.................................................. 49
6.2.3 Other options for frequency support............................................................................. 49
6.3 COST BENEFIT OF VAR-RES IN VOLTAGE SUPPORT...................................................................... 50
6.3.1 Cost-benefit of using VAR-RES to support voltage at high voltage levels........................... 50
6.3.2 Cost-benefit of using VAR-RES to support voltage at low/medium voltage levels.............. 50
6.3.3 Other options for voltage management......................................................................... 51
6.4 COST-BENEFIT OF USING VAR-RES FOR SYSTEM RESTORATION................................................... 52
6.5 THE EXCESSIVE COST OF REQUIRING CAPABILITIES FROM ALL GENERATORS.............................. 53
6.6 CONCLUSIONS – ECONOMIC BENEFITS..................................................................................... 53
7 MARKET CONCEPTS (COMMERCIAL FRAMEWORKS)........................................................ 54
7.1 INTRODUCTION....................................................................................................................... 55
7.2 THE ELECTRICITY MARKET – INTERFACE TO RESERVICES........................................................... 55
7.2.1 Differences in self-dispatch market types...................................................................... 55
7.2.2 Markets for reactive power for voltage support.............................................................. 55
7.2.3 GSS market in Europe in monetary terms..................................................................... 56
7.3 IDENTIFICATION OF BEST PRACTICES IN DIFFERENT COUNTRIES................................................. 56
7.3.1 Frequency support services......................................................................................... 56
7.3.2 Voltage support services............................................................................................. 57
7.4 KEY MARKET DESIGN/PRODUCT ADAPTATIONS TO OFFER ON GSS MARKETS.............................. 57
7.4.1 Suitable product characteristics for frequency support services...................................... 57
7.4.2 Suitable product characteristics for voltage support services......................................... 59
7.4.3 Procurement models enabling TSO/DSO coordination of GSS......................................... 59
7.5 CONCLUSIONS – MARKET CONCEPTS....................................................................................... 59
8 RESERVICES PROJECT - Final publication - September 2014
8 KNOWLEDGE GAPS AND FURTHER RESEARCH................................................................. 61
8.1 INTRODUCTION....................................................................................................................... 62
8.2 KNOWLEDGE GAPS.................................................................................................................. 62
8.2.1 System needs for GSS................................................................................................ 62
8.2.2 Technology................................................................................................................. 62
8.2.3 Markets/costs/economics.......................................................................................... 63
8.3 R&D NEEDS............................................................................................................................ 64
8.3.1 System needs............................................................................................................ 64
8.3.2 Technology................................................................................................................. 64
9 THE RESERVICES PROJECT – A SYNOPSIS......................................................................... 65
10 REFERENCES......................................................................................................................... 67
11 LIST OF RESERVICES REPORTS (DELIVERABLES)............................................................. 69
System needs for GSS...................................................................................................................... 70
Wind and PV GSS capabilities and costs............................................................................................. 70
Wind and PV GSS in future systems – Case Studies............................................................................ 70
Recommendations for a future EU market for GSS.............................................................................. 70
RESERVICES PROJECT - Final publication - September 2014 9
Symbols and abbreviations
BESS Battery Energy Storage System NPV Net Present Value
CAPEX Capital Expenditure NWP Numerical Weather Prediction
CCGT Combined Cycle Gas Turbine OCGT Open Cycle Gas Turbine
CHP Combined Heat and Power OEM Original Equipment Manufacturer
DC Direct Current OPEX Operational Expenditure
DEV (project) Developer OS Operating System
DFIG Doubly Fed Induction Generator OLTC On Load Tap Changer
DG Distributed Generation OTC Over The Counter
DS Distribution System P Power
DSO Distribution System Operator PF Power Factor
eBOP Electric Balance of Plant POC Point of Connection
ENTSO-E European Network of Transmission System PQ Active versus Reactive Power
Operators for Electricity
PV Photovoltaic
ETS Emission Trading Scheme
REG Regulator
FACTS Flexible AC Transmission Systems
RM Ramping Margin
FCR Frequency Containment Reserve
RMSE Root Mean Square Error
FFR Fast Frequency Response
RoCoF Rate of Change of Frequency
FRCI Fast Reactive Current Injection
RR Replacement Reserves
FRR Frequency Restoration Reserves
SCR Short Circuit Ratio
GC Grid Code
SET Plan Strategic Energy Technology Plan
GCR Grid Code Requirement
SNSP System Non-Synchronous Penetration
GCT Gate Closure Time
SO System Operator
GSS Grid Support Services
SRS System Restoration Support
HV High Voltage
SSVC Steady State Voltage Control
ICT Information and Communication Technology
SVC Static Var Compensator
IEM Internal Electricity Market (EU)
TS Transmission System
LCOE Levelised Cost of Electricity
TSO Transmission System Operator
LV Low Voltage
VAR Volt Ampere Reactive
MPP Maximum Power Point
VAR-RES Variable renewable generation
MV Medium Voltage
WF Wind farm
NC Network Code
WPP Wind Power Plant
NCR Network Code Requirements
WT Wind Turbine
10 RESERVICES PROJECT - Final publication - September 2014© Shutterstock EXECUTIVE SUMMARY AND POLICY RECOMMENDATIONS RESERVICES PROJECT - Final publication - September 2014 11
Executive summary and policy recommendations
Wind power and solar PV technologies can provide transition of electricity networks. Revised governance
ancillary or grid support services (GSS) for frequency, for DSO/TSO interaction to properly coordinate fre-
voltage and certain functions in system restora- quency and voltage support, as well as restoration
tion. The REserviceS project confirmed that variable services provided by VAR-RES, is needed.
renew able energy sources like wind and solar PV
generation (VAR-RES) meet most of the capability If the political goal of achieving a truly inte-
requirements for delivering such services, as pre- grated Internal Energy Market goes beyond
scribed in Grid Codes. Where enhanced capabilities the energy-only market model, the roll-out of
would be required, technical solutions exist, but are GSS market models throughout the EU must
not used today because of economic reasons due be considered. Therefore, the following pro-
to additional costs, of which REserviceS has made ject recommendations need to be taken into
an assessment. While in some countries financial account, in particular in the revision of the EU-
incentives for VAR-RES with enhanced capabilities wide Target Model and more specifically in the
exist, this remains the exception rather than the relevant network codes as well as in national
rule in Europe. Appropriate operational and market grid connection requirements.
frameworks are therefore needed for enhanced par-
ticipation of VAR-RES in GSS.
1.1 Recommendations - EU energy
The need for VAR-RES’ participation in GSS provision, policy and electricity market design
especially at high penetration levels, depends on the
power system characteristics (for example its size and These recommendations relate to regulatory frame-
resilience) and how VAR-RES are integrated into it (for works at national and EU level directly affecting
example its dispersion and technical characteristics). GSS provision from VAR-RES. These frameworks
As GSS come with a cost, requirements for genera- include present and future energy market design, the
tor capabilities and service provision should demand EU-wide target model, commercial frameworks, etc.
only what is needed by the system to avoid exces- The recommendations are primarily addressing the
sive system costs. Importantly, REserviceS analyses European Network of Transmission System Operators
found that frequency management can be adequately for Electricity (ENTSO-E), national TSOs and DSOs,
and economically achieved with only a fraction of market operators, the EU Agency for the Cooperation
all installed VAR-RES generators participating in fre- of Energy Regulators (ACER) and national regulators
quency support. as well as the European Commission and national
energy policy makers.
Therefore, preparing for future for future electricity sys-
tems with large shares of VAR-RES requires detailed 1.1.1 Recommendations for policy makers
studies and simulations to make well-founded esti- • The role of GSS in the electricity market should
mates of the needs and technical requirements. be expanded in the context of an increased share
Moreover, detailed and clear specifications, as well as of VAR-RES, and as part of a truly integrated Inter-
market designs and products taking into account the nal Energy Market (IEM). In order to reap the full
characteristics of VAR-RES, are crucial for their partici- benefits from GSS provided by VAR-RES, adequate
pation in GSS provision. market frameworks and technical requirements are
needed;
An increase of VAR-RES means that generating • The right balance between a market system (which
capacity is increased in Distribution System Opera- is harder to predict and controlled by the system
tor (DSO) networks. Hence, DSO/TSO (Transmission operators responsible for power system stability)
System Operator) interaction will also be increasingly with multiple participants (to encourage competition
important in the future with large shares of VAR-RES. and drive innovation) and the provision of GSS must
DSOs in particular will have an increasing role in the be found in each power grid;
12 RESERVICES PROJECT - Final publication - September 2014• Commercial provision of some GSS as alternative investments, prices — be they related to bid-based market-based revenue streams for all generators markets, auctions or capability payments to genera- should be considered. This would increase inves- tors — should capture both the benefits provided to tors’ interest in power generation and help tackle the system in terms of system operation cost sav- any potential generation gap in the electricity sector ings and the value of such services; in a market-based way, as opposed to a subsidy in • To ensure adequate stakeholder involvement, a the form of capacity remuneration mechanisms; regular multi-year consultation on the appropriate • Recommendations on frequency and voltage support regulatory regime for GSS should be established need to be considered when implementing a revised including: EU-wide Target Model in the relevant network codes. –– Governance and financial arrangements Existing network codes must be amended or revised –– Power system studies in light of the findings in this study and new ones –– Technical capabilities - definition and assessment; considered to enable GSS provision from VAR-RES; • National and EU policy makers should require the • The functioning of existing day ahead and intraday relevant system operators and ENTSO-E to deliver markets must be improved with shorter gate closure mandatory cost-benefit analyses when EU network and more cross border integration in order to give codes or national grid connection requirements are VAR-RES producers (short term) opportunities to determined. Policy makers should also establish a trade their imbalances. A shorter forecasting time clear framework for how to carry out a cost-bene- horizon would not only help to set up a level playing fit analysis (CBA) in conjunction with a functional field for balancing conventional and variable gen- commercial framework determining how GSS are eration, but would also lower the system operation procured and remunerated; costs; • In addition to working out precise network codes, • Commercial provision of GSS should be taken into which encompass the market design provisions laid account in the revision of the EU-wide Target Model. out in the Target Model, a proper implementation and Today GSS provision from VAR-RES is not considered roll-out of GSS markets by the Member States and in either intraday or balancing markets. Moreover, facilitated by ACER and national regulators is key; the development of GSS markets is not envisaged • Using GSS will require extensive cooperation and in the Target Model, even if GSS would constitute clear boundaries between TSOs’ and DSOs’ rights part of the IEM, alongside trading electricity; and duties. With regards to the TSO/DSO interface, • The revision of the EU-wide Target Model should guidelines should be developed on how the distri- be accompanied by an implementation roadmap bution system can contribute to grid reliability and describing the capabilities and GSS needed with stability. Guidelines on implementing the results of increasing VAR-RES levels. There should also be a system studies in grid code requirements should set of pre-qualification and procurement methods also be drawn-up. pointing at requirements to be included in existing and future network codes; 1.1.2 Recommendations for market design - • Compulsory GSS requirements that are not remuner- frequency support ated should be minimised or replaced by remuneration • VAR-RES’ capability to provide frequency support, schemes, as it is neither cost-efficient nor necessary in particular Frequency Containment and Frequency to request services from all connected generators in Restoration Reserve (FCR and FRR), to the extent most systems. Market based remuneration provides that it is beneficial (reliability vs. cost) to the system incentives for cost-reduction irrespective of whether should be financially compensated, as well as its these are VAR-RES or conventional plants; readiness and utilisation costs; • Policy makers should properly evaluate the cost/ • Characteristics of products such as low minimum benefit ratio of the proposed solutions for market bid sizes, separation of up- from downwards bids, based frameworks and assign appropriate price inclusion of confidence intervals and aggregated ranges for the provision of GSS. To incentivise bids and offers are important for allowing VAR-RES RESERVICES PROJECT - Final publication - September 2014 13
Executive summary and policy recommendations
to participate cost-effectively in GSS provision; • If a tendering or auctioning process is applied, it
• Clear procurement rules together with clear techni- should involve:
cal specifications are of crucial importance for the –– An analysis of the need for reactive power carried
participation of VAR-RES in GSS provision; out by the relevant network operator (TSO/DSO)
• Frequency support related GSS provided by VAR-RES and a forecast for future locational needs;
require harmonised gate closure times as close as –– Based on such an investigation, a tender for
possible to delivery and minimised time frames reactive power within a certain perimeter should
(less than one hour); be published or an auctioning system should be
• For cost-efficient offers to be provided with high cer- put in place to receive the lowest cost reactive
tainty, the market design should encourage PV and power provision;
wind to offer reserve products from aggregated port- –– The best offer (or best offers) is awarded with
folios of several PV and wind power plants, which a fixed reimbursement for the reactive power
can be spread across wider areas. Alternatively, the provided to the system and a minimum off-take
uncertainty can be aggregated over all units par- guarantee to ensure investment security.
ticipating in the reserve. This function should be
facilitated by the system operator and would elimi- 1.2 Recommendations - EU net-
nate the need for overlapping safety margins due to work codes and national grid codes
forecast inaccuracy, unexpected power plant failure
and performance compliance; Recommendations in this section are addressed to
• Market participants should be incentivised to be in network operators, TSOs and DSOs. Some may spe-
balance in the Balancing Responsible Party’s (BRP) cifically address ENTSO-E and its working groups.
perimeter after gate-closure time. Flexibilities of
VAR-RES could then be used by the BRP manager 1.2.1 Requirements based on identification
when they prove to be the most cost-efficient. This of system needs
would also reduce the need for reserve power for • System studies should constitute the principal
balancing by the TSO. basis for network codes and grid codes in their for-
mulation of requirements for VAR-RES. The studies
1.1.3 Recommendations for market design - and their implementation in grid codes should con-
voltage support sider frequency support needs and voltage needs
• Voltage support induces costs for VAR-RES but can, at the appropriate system level (system wide and
in some cases, help system operators to manage cross-border versus localised needs);
their network in the most efficient way. In areas • Requirements based on system studies should take
with only a small amount of VAR-RES plants provid- into account (expected) VAR-RES penetration. Net-
ing the service needed by the network operator, a work operators should not ask for more than needed
non-remunerated mandatory band requirement as but, as a unit can last more than 20 years, expected
part of the grid code could be complemented with renewable energy penetration should also be taken
payment for additional support to grid operation, into account when defining capabilities (to avoid
provided such costs are recognised by the regula- costly retrofit and/or burdening new generators);
tor and recoverable by the system operator. If the • Frequency control (FCR and automatic FRR) capabil-
number of service providers is large enough to ity should not be required from all VAR-RES plants
create a competitive market, voltage support could connected to the network as it would not be cost-
be reimbursed in a competitive process, either in effective. How much is needed and where, should
a regular bidding process or an auctioning arrange- be based on system studies and further research;
ment, irrespective of whether the contracting is for • Voltage control capability should only be required
short time horizons i.e. from days to weeks, or for from VAR-RES when the analysis of the expected
longer time horizons up to several years; costs compared to all other voltage control provision
14 RESERVICES PROJECT - Final publication - September 2014methods shows it is the most cost-effective solution distributed generators;
for the particular combination of generator type and • Market frameworks should take into account the
primary energy source, considering the likely future characteristics of available and future power sources
expansion of generation, demand and grids. and their capabilities: the requirements should be
clear, precise and based on market design taking
1.2.2 Contents and quality of requirements existing capabilities into account;
for generators for service delivery • TSOs and regulators should establish clear proce-
• Network Codes and Grid Codes should provide dures and reporting rules distinguishing balancing/
detailed specifications for minimum technical congestion management and curtailment for system
capabilities for generators to participate in GSS. security. They should coordinate the implementation
Requirements should be function-oriented in of these rules with the DSOs.
addressing design capabilities and delivery per-
formance. They should not prescribe technical 1.2.4 Harmonisation and standardisation
solutions to reach a certain performance; • TSOs and DSOs should contribute to the develop-
• State of the art forecast methods should be imple- ment of European product standards (e.g. IEC,
mented in the operation of VAR-RES. TSOs should Cenelec) to avoid costly mismatches between grid
improve their forecasting utilising state of the art connection requirements and product standards.
techniques during operations, while increasing Standardisation is based on best practices and is
cross-border cooperation to reduce unexpected situ- essential for LV and MV connected systems. The
ations due to forecast errors; EN 50438 European Standard and the Technical
• Requirements for generators should take into Specification TS 50549 have to be considered when
account their specific technology and the primary specifying new grid connection requirements;
source driving it. Only by doing so can system • Exchange of data (including forecasts) between gen-
service provision be optimised. Different types of erating facilities and the relevant network operators
generators (e.g. wind turbine conversion Type 3 and (TSOs, DSOs) should be standardised. Common
Type 4) and different energy sources (PV vs. wind) forecast platforms, procedures and file formats will
need different levels of investment to roll-out their improve information exchange and reduce errors;
GSS provision. In order to create a level playing • Prequalification processes and testing procedures
field for all of them, these specifications need to be for generators providing GSS should be harmonised.
included in the requirements for specific GSS;
• When designing the requirements and the frame- 1.3 Recommendations - research
work for the procurement of GSS at the distribution and technical development
level, the spatial distribution should also be taken
into account to avoid cost inefficiencies that could REserviceS identified technology and process gaps
result from a one size fits all approach; that could be addressed by focused R&D efforts ena-
• Grid codes should consider the formulation of tech- bling improved (technically/economically) provision of
nical requirements for extremely fast frequency services by VAR-RES. The recommendations consist
response (e.g. full response faster than ¼ second) of research topics in four categories: hardware, soft-
for situations in the power system with low inertia; ware and methods, system operation procedures and
• Requirements at the European and national level standards. Stakeholders for these recommendations
should, where possible, make reference to speci- include the VAR-RES industry, TSOs, ENTSO-E and the
fications in existing or upcoming European or research community.
international standards.
1.3.1 Hardware
1.2.3 Management of grid code requirements Further development of hardware including designs
• In order to enable proper implementation and enabling VAR-RES to provide GSS:
monitoring of requirements, network operators • Communication infrastructure for the provision of
should organise the data exchange and visibility of services by portfolios of MV/LV connected systems
RESERVICES PROJECT - Final publication - September 2014 15Executive summary and policy recommendations
such as solar PV systems and wind farms; (especially using probabilistic forecast methods) in
• Metering devices for the provision of services by power system operation;
portfolios of MV/LV connected VAR-RES; • Optimisation strategies for the provision of GSS by
• Reliable communication hardware for very fast portfolios of MV/LV connected systems such as PV
system services; systems or small wind farms;
• Monitoring systems to enable HVDC connected wind • Common methodology for assessing system needs
farms (WF) and/or WF clusters to provide reliable of GSS with large amounts of VAR-RES;
frequency support; • Developing methods and tools power system
• Study of the effect of sustained GSS provision on models able to capture different operational time
wind turbine loads and possible impacts on its scales, i.e. models focusing on electromechanical
design. dynamics (20ms to 30s), focusing on system bal-
ancing (5 min to 24h), focusing on frequency quality
1.3.2 Software and methods for services such as FCR and FRR (s to min), for
Further development of software tools to improve power systems with high variability;
technical and operational capabilities for the deploy- • Definition (technical and economic) of new GSS and
ment of GSS by VAR-RES: study of their impact on the system;
• Improvement of probabilistic forecasts to be used in • Practices and tools for system planning and volt-
system operation; age profile simulations including the use of services
• Control and coordination algorithms to enable HVDC provided by inverters and novel components. This
connected WF and/or WF clusters to provide reliable would make the best of existing or future capabili-
frequency support; ties available at the distribution level;
• Advanced control strategies for improved grid • Investigation of technical requirements and opera-
friendliness of VAR-RES and enhanced capability of tional practices for VAR-RES to be included in power
providing system services; system restoration processes.
• Better understanding of technical requirements and
control strategies for VAR-RES operating in hybrid AC 1.3.4 Standards
and DC multi-terminal networks. Development of further standards required for large
scale deployment of GSS by VAR-RES:
1.3.3 System operational procedures, • IT standards to assure the secure and reliable
methodologies and GSS deployment strategies operation of the power system’s infrastructure;
Further development of methodologies and opera- • Communication protocols for very fast system
tional procedures for deploying GSS and improving services.
system operation:
• Probabilistic planning and operational procedures
16 RESERVICES PROJECT - Final publication - September 2014© Shutterstock INTRODUCTION RESERVICES PROJECT - Final publication - September 2014 17
Introduction
The anticipated high shares of wind and solar PV in in terms of network codes covering market design
the European electricity system will require fundamen- and network management rules. So far network
tal changes in the way transmission and distribution codes have only marginally covered intraday and
network operators use grid support services (GSS) balancing market design and have not yet been con-
from generators to manage network frequency, volt- sidered for GSS;
age and system restoration. These changes will be • Rapid developments in control and communication
twofold: the power system needs for GSS will change technologies with profound impact on control of gen-
as VAR-RES increase, and the technical and economic eration plants (including VAR-RES) and management
characteristics of VAR-RES change the way these ser- of electricity systems in general;
vices can be provided. The REserviceS study was set • An increased electrification of society, electricity
up to assess the provision of GSS by VAR-RES, in order consumers increasingly become “prosumers” by
to help design market mechanisms that would enable installing Distributed Generation (DG) at their facil-
power systems in Europe to function safely, reliably ity (household PV, industrial PV and CHP etc.).
and cost-efficiently with very high shares of VAR-RES.
The study carried out by the REserviceS consortium The REserviceS study has made a technical-eco-
has focused on wind and solar PV because these are nomic assessment of the provision of GSS — notably
expected to jointly produce the lion’s share of renewa- frequency and voltage support — as well as
ble electricity needed to reach the EU’s 2020 targets. preliminary analysis of system restoration by VAR-RES
themselves. The study adds to existing knowledge to
The setting for GSS in future European electricity establish costs and values for GSS that can be pro-
systems is characterised by the following important vided on a large scale by wind power and solar PV,
developments: installed both at transmission and distribution level in
• Fundamental changes in the generation mix, result- the power system. The REserviceS project aims to con-
ing in fewer traditional providers of GSS, the entry tribute to the development of effective market-based
of large numbers of decentralised renewable plants, approaches for GSS in Europe and to the design of
predominantly at low and mid voltage level, driven by electricity market mechanisms that enable the power
national and European climate and energy policies, systems in Europe to function safely, reliably and cost-
increased competitiveness of VAR-RES and chang- efficiently with very high shares of VAR-RES.
ing business cases for non-VAR-RES conventional
plants; Research questions in this report address five themes:
• The political aim to create an integrated Internal • System needs for GSS (frequency, voltage and
Energy Market (IEM) in the EU and creating competi- system restoration) to develop when the shares of
tion in wholesale and retail energy markets following VAR-RES are very high;
the unbundling of vertically integrated utilities. This • Technical and economic issues for VAR-RES to pro-
includes facilitating the entrance of new market vide the necessary services;
players and the integration of electricity markets • Economic benefits of large scale provision of ser-
throughout Europe on all timescales which would vices by VAR-RES;
entail GSS markets; • Suitable market conditions and commercial
• A regulatory framework at EU level for power market frameworks;
integration enshrined in the EU-wide target model • Knowledge gaps and needs for R&D.
outlining principles of cross-border capacity allo-
cation and market coupling, as well as increased These topics have been analysed at several stages
TSO cooperation through European bodies such as of the project. In the first stage, REserviceS analysed
ENTSO-E; how system needs for grid services change in the grow-
• A new legislative layer through binding EU regulations ing presence of wind and solar PV, and identified key
18 RESERVICES PROJECT - Final publication - September 2014services that should be provided by these VAR-RES. This publication also contains references to specific
In a second stage a technical and economic assess- reports (Project Deliverables) where detailed analyses
ment was performed on the capabilities of wind and and results can be found. A list of these Deliverables
solar PV for the provision of such services. The third can be found at the end of this publication.
stage consisted of case studies looking at technical
and economic impacts in transmission and distribu- Policy recommendations are aimed at EU Network
tion grids — simulating effects of large deployment of Codes (RfG, balancing, DCC, operation etc.), the
services and assessing costs and benefits. In the last EU-wide Target Model and related (regional) market
stage the findings have been integrated into a com- models, energy policy processes and scenarios, (grid)
bined report as well as a separate recommendations infrastructure (e.g. ICT), energy regulation and SET
report1. The integration of the project findings included Plan and R&D (see D7.2 Recommendations3). The
an initial exploration of procurement methods of fre- proposals have been made by the REserviceS con-
quency and voltage support services by TSOs and sortium, consisting of wind and solar energy industry
DSOs. It outlined possible market mechanisms in associations and industrial companies, knowledge
the context of the further integration of the European institutes specialising in VAR-RES energy markets and
electricity market. The study also helped to identify power system studies, as well as a European associa-
knowledge gaps and topics for further research into tion of distribution system operators.
the provision of GSS by variable generation.
The REserviceS consortium also interacted with
This publication presents a summary of the key find- stakeholders (industry and network operators) during
ings and recommendations of the project. More detail workshops4, through surveys and discussions with the
can be found in D7.1 REserviceS Synthesis Report2. Advisory Board.
© Acciona Energía
1
REserviceS D7.2
2
REserviceS D7.1
3
Available at http://www.reservices-project.eu/wp-content/uploads/140724_REserviceS_D7.1_Synthesis-report.pdf
4
For more information, please consult: http://www.reservices-project.eu/events/
RESERVICES PROJECT - Final publication - September 2014 19Introduction
© Acciona Energía
RESERVICES MAIN FINDINGS
20 RESERVICES PROJECT - Final publication - September 20143.1 System needs for grid support DSO/TSO interaction will be increasingly important in
services by wind and solar PV the future with large shares of VAR-RES, and DSOs
will have a growing role in the transition process in
REserviceS’ assessment of needs in European power electricity networks. Data exchange and ability to con-
systems focused on frequency and voltage support as trol a multitude of small generation units should be
the main categories of grid support services (GSS) that structured. Roles and responsibilities for coordinating
wind and solar PV generation can provide. Frequency frequency and voltage support as well as restoration
and voltage control constitute several services with dif- services need to be clarified.
ferent response times.
Generally, the system needs for identified frequency 3.2 Technical capabilities of wind
support services will increase with high shares of VAR- and solar PV as service providers
RES. There is a need for enhanced frequency support
in the system especially for manually activated system Technology analysis of wind power and solar PV con-
reserves or Frequency Restoration Reserves (FRR) with firmed their technical and operational capabilities
activation times of less than 15 minutes. VAR-RES may to provide GSS for frequency, voltage and certain
increase the need for voltage support because reac- functions in system restoration. This analysis was
tive power sources, both steady state and dynamic, validated through industry enquiries and assumes
that are available today to the system operator are adequate operational and economic frameworks are
likely to be reduced in the future. Also, the voltage put in place. The technical and operational functionali-
profile management will become more complex with ties required are either state of the art using existing
increasing shares of VAR-RES. New services will be hardware, or can be implemented at a reasonable
needed, mainly to achieve faster responses to devia- cost. The feasibility of providing services by enhanced
tions of normal operation conditions or faults as well plant capabilities is confirmed by TSOs, for example
as services/capabilities provided by synchronous gen- in Spain where voltage control by wind power plants
eration (for example mitigation of negative sequence on specific transmission nodes leads to a signifi-
voltages and damping of harmonics). The contribution cant improvement with fast response. Case studies
from wind and PV for system restoration services may performed by REserviceS in Spain and Germany dem-
need further assessment. onstrate that letting the DSO use GSS from VAR-RES
generation connected to its own system contributes to
The need for GSS with VAR-RES depends on the power cost-efficient voltage management. The participation
system studied (for example its size and resilience), of VAR-RES in system restoration has not yet been
and how VAR-RES are integrated into the system (for practiced.
example it dispersion, penetration levels and technical
characteristics). GSS come with a cost, so require- For wind power, potential technical enhancements for
ments for generator capabilities and service provision frequency and voltage support services include: faster
should demand only what is needed by the system in and reliable communication (a.o. between wind farms
order to avoid excessive costs. Preparing for future and system operators’ control rooms), dedicated con-
systems with a large share of VAR-RES thus requires trol tuned for delivering the required performances,
studies and simulations to make well-founded esti- estimation of available power/forecasting. Further-
mates of the needs and technical requirements. But more, structural, mechanical and electrical design
there is a lack of a common methodology to include changes in wind turbines need to be implemented to
VAR-RES in estimating system needs for services and take into account the changes in loading involved with
limited information on the combined effects of wind grid service oriented operation. Specifically for off-
and solar PV. As the method of assessing system shore wind power, service provision needs to consider
needs for GSS with VAR-RES is still evolving, new tools the differences between connection technologies
are needed. (HVAC or HVDC) as these have a fundamental impact
RESERVICES PROJECT - Final publication - September 2014 21REserviceS main findings
on the provision of voltage services and fast frequency services along with a set of pre-qualification and pro-
support. AC connected offshore wind plants can pro- curement methods including proper attention to the
vide active power reserve and frequency response characteristics of the sources.
(in all time domains: FCR, FRR, RR, FFR) in the same
manner as onshore AC wind plant projects. GSS can Implementing enhanced capabilities will involve addi-
be augmented by aggregating multiple offshore wind tional investment, and the deployment of the services
plants or clusters of wind plants. Regional coordi- will also involve costs. For both wind and solar PV the
nation of offshore wind plants in providing reactive additional investment costs (CAPEX) for enhanced pro-
power and voltage control at their respective onshore vision are relatively low and — provided appropriate
POC would strengthen system reliability. In the case cost recovery and market mechanisms are in place
of HVDC offshore grids, the onshore VSC HVDC can — their deployment should be commercially feasible.
provide reactive power/ voltage GSS regardless of Only for small PV systems today the impact of required
the offshore wind condition. Technical standards and communication components will result in high addi-
Network Codes currently in preparation are important tional CAPEX costs. In general, both for wind and PV,
enablers of offshore wind GSS. OPEX costs notably upward readiness cost represent
the highest costs to make frequency services avail-
For solar PV, potential enhancements of capabilities able. However, the enhanced capabilities should not
include: estimation of available power/forecasting, be required if there is no need for them as this would
faster and reliable communication and control within incur unnecessary additional cost. In general, fre-
the plant, control strategies for portfolios composed quency related GSS can be provided by a portion of
of numerous small and medium sized units, improving VAR-RES units and not all units need the capability.
interoperability of different networks and enhancing Utilising VAR-RES in voltage related GSS depends on
compliance to a multitude of non-harmonised grid their location in the network and should be judged on
code requirements. a case by case basis.
The implementation of better and faster communica-
tion systems together with the development of more 3.3 Economic benefits of grid
accurate forecasts are essential for both wind and support services by wind and solar PV
solar PV technologies. In general, aggregation of mul-
tiple VAR-RES power plants is desirable because it The REserviceS simulations of power systems of vari-
improves performance when providing a service and ous sizes across Europe and with shares of VAR-RES
reduces the relative implementation costs. However, up to 50% showed that it is beneficial to utilise wind
for very fast responses aggregation could cause addi- and solar PV in frequency support. Moreover, system
tional communication delays. Also, both for wind and benefits increase as the share of VAR-RES increases.
solar PV, control strategies should be tuned to obtain The greatest benefits in simulations were observed
the maximum power performance and flexibility from in downward Frequency Containment Reserves (FCR)
VAR-RES. with delivery times of less of five minutes and in auto-
matic FRR. The benefits for the system operator in
A precondition for provision is to have clear and well- the simulations are higher than the cost of equipping
defined requirements and procedures to integrate all VAR-RES with the capability to participate in the
wind and solar PV as GSS providers. In this respect, frequency support, especially for wind power plants.
poorly defined or non-existent technical specifications
in grid codes or pre-qualification procedures to allow Also, economic benefits were achieved even when only
VAR-RES to provide GSS constitute a significant barrier some VAR-RES participated in frequency support. In
that needs to be overcome. This is exacerbated by the a sensitivity analysis, the frequency response and its
lack of standardisation and harmonisation of proce- corresponding economic benefits remain adequate
dures across Europe. A clear GSS roadmap should be with 25% of the total installed wind power partici-
established describing the required capabilities and pating in frequency support services. Thus it should
22 RESERVICES PROJECT - Final publication - September 2014be sufficient to only equip part of the VAR-RES with necessary regulatory frameworks, the specific project
capabilities for FCR and automatic FRR services. recommendations on commercial frameworks in this
Cross-border sharing of frequency reserves creates section need to be considered in the revision of the
similar benefits as VAR-RES, but there are additional so-called EU-wide target model and more specifically
benefits when both VAR-RES and cross-border sharing in the relevant network codes. In order to enshrine the
are utilised. necessary market design in enabling legislation, exist-
ing network codes should be amended or revised and
REserviceS also performed case studies on volt- new ones considered, in light of these findings.
age support at different voltage levels (HV/MV/
LV) and with different VAR-RES shares. It concluded Not all generators in a system have to provide GSS to
that the cost/benefit ratio of voltage support from ensure safe system operation. Mandatory capability/
VAR-RES is case-specific and that the provision of provision for GSS is often not cost-efficient. Market
voltage support by VAR-RES should be compared to based remuneration, on the one hand, stimulates cost
other technology alternatives. As there will be a high reductions by incentivising provision by plants with the
number of locations where voltage support can be lowest costs, irrespective of whether these are VAR-
sourced, common and robust methods to assess RES or non-VAR-RES plants. On the other hand, in a
decisions of voltage sourcing with reproducible and market based approach it is more difficult to control
comparable results are needed. The case studies where the VAR-RES units with enhanced capabilities
demonstrate that voltage control capabilities from all are located. This can be crucial when utilising grid sup-
VAR-RES generators are not always the best choice port services. As a consequence, particular GSS could
and, therefore, an across the board requirement may be required in locations where the capability would be
lead to excessive costs. needed the most.
Detailed and clear specifications are of crucial impor-
3.4 Markets and commercial tance for the participation of wind and solar PV in GSS
frameworks provision. Without these, market participation and pro-
curement of such services is delegated to incumbent
In today’s energy-only markets the contribution of generators with long-term contracts already in place.
GSS in the system costs and revenues to generators Requirements should be defined in close cooperation
is very low compared to energy and capacity pay- between the TSOs and VAR-RES industry via consulta-
ments. As it is clear that VAR-RES can provide GSS tions, as is the case in Ireland5.
and their utilisation can decrease operational costs
of the power system, there should be sufficient incen- To enable the provision of GSS by VAR-RES, a multi-
tives to obtain these benefits along with the capability level procurement process should be defined involving
and availability requirements for VAR-RES. Currently, TSOs, DSOs and generators connected to their net-
only a few markets (e.g. Ireland, Great Britain) provide works. On the one hand, the participation of VAR-RES
arrangements for enhanced services where VAR-RES in a GSS market — run by the TSO — could breach
are incentivised to participate. In future systems with certain operational limits in the distribution grid. On
high shares of VAR-RES, revenue from GSS is bound the other hand, by solving local issues (congestion or
to increase, even if it remains a small part of total voltage management) with GSS provided by VAR-RES,
system costs and revenues. the actions of DSOs could have repercussive effects
on the transmission grid operation. Given the complex-
However, if the political goal of achieving a truly ity of coordinating the respective tasks, a hierarchical
integrated Internal Energy Market goes beyond the definition of the supervision and control actions is
energy-only market model, the roll-out of GSS markets necessary. A clear hierarchy of functions between TSO
throughout the EU must be envisaged. In terms of and DSOs should be established.
5
http://www.eirgrid.com/operations/ds3/
RESERVICES PROJECT - Final publication - September 2014 23You can also read
