GRID INTEGRATION OF LARGE- CAPACITY RENEWABLE ENERGIES The Market Strategy Board White Paper Presentation by: Adam L. Reed, J.D., Research Associate Renewable and Sustainable Energy Institute (RASEI)
Boulder Workshop – 12-15 Mar. 2012 Non-PT Workshop Experts MSB SWG 4.2 Project Team Members George Arnold, NIST (US) Hiroyuki Abe, NGK (JP) Kara Clark, NREL (US) Gabriel Barta, IEC Jianbin Fan, SGCC (CN) Paul Denholm, NREL (US) Juan Hu, SGCC (CN) Steve Hauser, NREL (US) Peter Lanctot, IEC David Hurlbut, NREL (US) Caihao Liang, SGCC (CN) Lawrence Jones, Alstom Grid Enno Liess, IEC David Kline, NREL (US) Puneet Pasrich, CU-Boulder Adam Reed, RASEI Mike Knotek, RASEI (US) Toshiyuki Sawa, Hitachi (JP) Ernst Scholtz, ABB (CH) Hong Shen, SGCC (CN) William Wallace, NREL (US) Giordano Torri, SpA (IT) Philip Weiser, CU-Law (US) Yoshimitsu Umahashi, TEPCO (JP) Zhankui Zhang, SGCC (CN)
The White Paper(s) in Context “The present White Paper is the third in a series whose purpose is to ensure that the IEC can continue to contribute with its standards and conformity assessment services to the solution of global problems in electro- technology.” -- Executive Summary
Electricity Systems are Changing • Increasing interconnectedness of systems and equipment • Increasing complexity and quantities of data • Technical challenges are arising that do not have purely “device - level” solutions • What is the role of IEC standards and assessments in contributing to these “systems - level” problems, and their many potential solutions?
Introduction: Large Capacity RE and EES “Integration of RE is a poly -nodal problem involving multiple decision-makers at a variety of spatial and temporal scales and widely varying degrees of coordination. These decision- makers include … operators of renewable energy and energy storage resources, grid operators, energy market operators, and transmission planning bodies. As such, grid integration is not performed by any one entity in the power system, but instead involves the actions of a variety of entities, some highly coordinated and others discrete. The burgeoning development of smart grids adds still more tools, options, and players to the mix. Many of these actors engage with various technology standards, practices, procedures, and policies for the operation of individual generators, renewable energy clusters, substations, and the broader electrical energy system.” -- Section 1
In other words… - “RE integration” is not just about controlling RE itself — though that is one potential solution. -Rather, RE integration may involve changes to the operation of the entire power system.
Sec. 2 – RE Generation: present, future, and integration challenges • Drivers of RE development: – Decarbonization – Energy Security – Expanding Energy Access
Sec. 2 – Wind Energy Projections 900 800 700 600 1990 500 2009 TWh 2015 400 2020 2025 300 2030 200 2035 100 0 US OECD Europe Japan Russia China India Middle East Africa Latin Brazil America Country /Region Wind Energy Generation through 2035 by Region/Country
Sec. 2 – Solar Energy Projections 180 160 140 120 1990 2009 100 TWh 2015 80 2020 2025 60 2030 2035 40 20 0 US OECD Europe Japan Russia China India Middle East Africa Latin America Brazil Country/ Region Solar PV Energy Generation through 2035 by Region/Country
Sec. 2 – RE Grid Integration Challenges • Wind and Solar present 3 primary challenges to the grid (and at different time-scales!): – Variability in generation output (seconds-to-hours) – Uncertainty in future availability predictions (hours-to- days) – Locationally-dependent resources may be far from load-centers, and require new transmission or upgrading of existing transmission (years)
Sec. 3 – State of the Art • Overview of wind, solar tech: basics, types, characteristics • Transmission tech by region • VSC-HVDC advantages for RE discussed
Sec. 3 – Forecasting State of the Art • Short term most common, uses physical and statistical methods • Report has detailed table of short-term forecast programs used by different wind plants. • Forecast error is 10-20% of installed capacity for 36 hour horizon. Spatial aggregation greatly increases accuracy, but longer horizons decrease accuracy. Numerical Weather Prediction (NWP) Forecast Program Power Output Forecast
Sec. 3 – System Operational Practices • Extremely wide variance b/w countries and regions due to: – RE generation development level – Conventional generation fleet – Grid structure – Market and institutional environments • Report contrasts China, Denmark, Germany, Japan, Spain, and several U.S regions.
Sec. 4 – Future: Technical Solutions • System “Flexibility” from a variety of sources – Grid-friendly RE generation – Conventional generation flexibility – Demand response – Energy storage can act as generation or load – Operations enhancement within and between balancing areas, including consolidation – Transmission expansion RE output fluctuation EES Demand response Grid faults Conven. gener. outages Grid-friendly RE gener. Load variation Conven. gener. flexibility System Variability & Flexibility Uncertainty
Sec. 4 – “Grid - friendly” RE • Volt/VAR control/regulation through built-in capability, switched capacitor banks, SVC, STATCOM, etc. • Fault ride-through capability • Active power control, ramping, and curtailment through active-stall, pitch control, discrete tripping of units • Primary frequency regulation through pitch regulation • Inertial response • Short circuit current control • Improved generation modeling tools
Sec. 4 – Centralized Control of RE Plant Clusters 200MW 200MW 35kV line 200MW 200MW 200MW 330kV line 750kV line 300MW 200MW #3 Wind power plant #4 200MW #5 200MW 200MW 200MW 200MW #2 750kV 200MW Jiuquan #6 #1 Substation #8 #7 330kV #9 750kV Anxi 200MW Substation Substation 200MW 200MW #10 200MW 280km • RE plants may be clustered around central control points, and should be operated in a coordinated fashion to prevent conflicts between plant-level voltage and reactive power controllers.
Sec. 4 – Improved Conventional Generation Flexibility • Currently the major source of system flexibility: hydro, gas, coal, nuclear (in order). • Generation-level questions remains: – How does flexible use of thermal generators affect performance? – What might that mean for operational practices and incentive design? • System-level questions: How can we measure a power system’s “flexibility” in a universal fashion? – NERC Integration of Variable Generation Task Force (IVGTF) – IEA Grid Integration of Variable Renewables Project (GIVAR)
Sec. 4 – System Generation Planning System Capacity Production Cost Generation Flexibility Adequacy Simulaiton Portfolio Assessment Assessment If portfolio is unreliable in operation • “Simply having a specified number of megawatts of capacity may not be adequate for system security if that capacity is not flexible enough to respond to system variability. … In order to consider flexibility requirements, a new paradigm of generation planning is needed.” • Planners in high-RE systems will need to examine adequacy of both generation capacity AND generation flexibility
Sec. 4 – Transmission Expansion • Exploits geographic diversity of RE generation to reduce variability and uncertainty. • Supports interconnection between balancing areas. • A variety of technologies and applications reviewed: UHVAC, FACTS, UHVDC, VSC-HVDC, MTDC, DC-grids • Developments in probabilistic transmission planning explored. Initial 7 alternatives Environmental, societal, and political assessment 5 alternatives Deterministic technical analysis, including N-1 principal 3 alternatives Probabilistic economic Probabilistic reliability analysis evaluation The best alternative
Sec. 4 – Operations Enhancement Futuristic What: Generation and transmission planning Who: System planners Planning Time Frame: Years into future What: Unit Commitment, Maintenance Scheduling, etc. Who: Operational planners Scheduling Time Frame: Hours to Days, Seasonal, Annual Operation What: Economic Dispatch, Contingency Analysis, etc. Who: System operators Dispatch Time Frame: Minutes to Hours What: Automatic frequency/voltage control, Real Time relay protection, load shedding, etc. Control Who: Automatic equipments and control systems Time Frame: Seconds to Minutes • More accurate RE power forecasts • Enhancement of Operations Tools and Practices • How to bring these enhancements into the control room effectively?
Sec. 4 – Demand Response • DR Functions to aid RE integration: – Load Shifting – Demand-side Balancing Services • DR Practices: – Dispatchable Programs / Load Management – Reactive Programs (wholesale and retail) • DR Goals: – Improve reliability – Improve efficiency – Improve flexibility
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