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

MSB SWG 4.2 Project Team Members

Hiroyuki Abe, NGK (JP) Gabriel Barta, IEC Jianbin Fan, SGCC (CN) Juan Hu, SGCC (CN) Peter Lanctot, IEC Caihao Liang, SGCC (CN) Enno Liess, IEC Puneet Pasrich, CU-Boulder Adam Reed, RASEI Toshiyuki Sawa, Hitachi (JP) Hong Shen, SGCC (CN) Giordano Torri, SpA (IT) Yoshimitsu Umahashi, TEPCO (JP) Zhankui Zhang, SGCC (CN)

Non-PT Workshop Experts

George Arnold, NIST (US)

Kara Clark, NREL (US)

Paul Denholm, NREL (US)

Steve Hauser, NREL (US)

David Hurlbut, NREL (US)

Lawrence Jones, Alstom Grid

David Kline, NREL (US)

Mike Knotek, RASEI (US)

Ernst Scholtz, ABB (CH)

William Wallace, NREL (US)

Philip Weiser, CU-Law (US)

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

Wind Energy Generation through 2035 by Region/Country

0

100

200

300

400

500

600

700

800

900

US OECD Europe Japan Russia China India Middle East Africa LatinAmerica

Brazil

TWh

Country /Region

1990

2009

2015

2020

2025

2030

2035

Sec. 2 – Solar Energy Projections

Solar PV Energy Generation through 2035 by Region/Country

0

20

40

60

80

100

120

140

160

180

US OECD Europe Japan Russia China India Middle East Africa Latin America Brazil

TWh

Country/ Region

1990

2009

2015

2020

2025

2030

2035

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

Variability & Uncertainty

System Flexibility

Conven. gener. outages

Grid faults

RE output fluctuation

Load variation

Grid-friendly RE gener.

Conven. gener. flexibility

Demand response

EES

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

• 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.

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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

• “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

Capacity

Adequacy

Assessment

System

Flexibility

Assessment

Production Cost

Simulaiton

Generation

Portfolio

If portfolio is unreliable in operation

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

5 alternatives

3 alternatives

The best alternative

Environmental, societal,

and political assessment

Deterministic technical

analysis, including N-1

principal

Probabilistic reliability

evaluation

Probabilistic economic

analysis

Sec. 4 – Operations Enhancement

Planning

Scheduling

Dispatch

Control

Re

al T

ime

Fu

turistic

What: Generation and transmission planningWho: System planners Time Frame: Years into future

What: Unit Commitment, Maintenance Scheduling, etc. Who: Operational planners Time Frame: Hours to Days, Seasonal, Annual

What: Economic Dispatch, Contingency Analysis, etc.Who: System operatorsTime Frame: Minutes to Hours

What: Automatic frequency/voltage control, relay protection, load shedding, etc.

Who: Automatic equipments and control systemsTime Frame: Seconds to Minutes

Op

era

tio

n

• 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

Sec. 5 – Large Capacity Electric Energy Storage for Supporting RE Integration • Harmonized with EES White Paper • Re-visits grid-friendly RE generation, conventional

generation flexibility, and demand response from Sec. 4 with an emphasis on energy storage technologies and applications, including case-studies. – Grid-side roles of EES: Time-shifting/arbitrage/load-

leveling, seasonal shifting, load-following/ramping, power quality and stability, operating reserves, efficient transmission network use, isolated grid support, and black-start capability.

– Generation–side roles of EES: Time-shifting, output smoothing, transmission utilization efficiency

– Demand-side roles of EES: Focus on electric vehicles

Sec. 5 – Technology Needs of EES for RE Integration

• “…optimization of storage placement and use within the context of the power system as a whole, both today and into the future.”

– Existing tools for storage are generally facility-specific, and presume that storage has already been installed.

– A need for tools that can help us know where to place EES for optimal grid usage.

Sec. 5 – EES Planning and Decision Tool Concepts

• An EES planning and decision tool for utilities and facility developers might consider the following factors, both at present and in future scenarios: – Amounts and net variability of RE generation on the grid; – Interconnectivity of the grid to other grids, and balancing

capabilities between them; – Conventional backup capacity available and desirable; – Demand-side management applications and capabilities; – System costs or market prices for operating reserves,

power quality services, and balancing energy; – Time-shifting/arbitrage potential in relevant energy

markets; and – Technological capabilities and flexibility of various EES

technologies.

Conclusion

• Sec. 6 (standards needs) and Sec. 7 (recommendations) covered by Dr. Fan.

• Thank you for your time and attention!