Grid Integration Studies

A grid integration study is an analytical framework used to evaluate a power system with high penetration levels of variable renewable energy (RE). The study will generally simulate the operation of the power system under different variable RE scenarios; identify reliability constraints; and evaluate the costs of alleviating those constraints. The study results can help build confidence among policymakers, system operators, and investors to continue increasing the amount of VRE on the grid.

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A grid integration study is an analytical framework used to evaluate a power system with high penetration levels of variable renewable energy (RE). Generally, a grid integration study:

  1. Simulates the operation of the power system under different variable RE scenarios;
  2. Identifies reliability constraints; and
  3. Evaluates the cost of actions to alleviate those constraints.

The variable RE scenarios in a grid integration study establish where, how much, and over what timeframe to build generation and transmission capacity, ideally capturing the spatial diversity benefits of wind and solar resources. The results help build confidence among policymakers, system operators, and investors to move forward with plans to increase the amount of VRE on the grid.

Key Video

Greening the Grid: Best Practices in Conducting Grid Integration Studies

This webinar addresses fundamental questions about grid integration studies, best practices for engaging key stakeholders, and the kinds of analysis and data that are involved in conducting a grid integration study. It includes several case studies to highlight lessons learned.

Reading List

Energy Systems Integration Group

Energy Systems Integration Group (ESIG)

ESIG—a forum for practitioners that provides resources for information on the status of wind and solar technology deployment—curates a list of grid integration studies and summary reports. Many reference documents for the studies cited in the Grid Integration Study Examples below (among others) can be found in this library.

Variable Renewable Energy Grid Integration Studies: A Guidebook for Practitioners

National Renewable Energy Laboratory, 2020

The purpose of this guidebook is to introduce power system policymakers, regulators, operators, and supporting organizations to RE grid integration studies. Countries around the world are establishing ambitious goals to scale up the contribution of renewable energy (RE) toward meeting national energy demand. Because RE resources such as wind and solar generally increase variability and uncertainty associated with power system operations, reaching high penetrations of these resources on the grid requires an evolution in power system planning and operation. To plan for this evolution, power system stakeholders can undertake a grid integration study. A grid integration study is a comprehensive examination of the challenges and potential solutions associated with integrating significant variable RE generation in the electricity grid.

Staff White Paper on Guidance Principles for Clean Power Plan Modeling

Federal Electricity Regulatory Commission, 2016

This white paper identifies guiding principles that can assist power system planners in conducting analysis of grid reliability impacts associated with meeting carbon dioxide emission reduction targets, with specific reference to the United States’ Clean Power Plan (CPP). The CPP, issued in August 2015 by the U.S. Environmental Protection Agency, sets limits on carbon dioxide emissions from existing fossil fuel-fired generators, and requires states to consider grid reliability impacts in their compliance plans. This white paper aims to promote robust analysis of the reliability impacts of the CPP by recommending guiding principles related to: 1) transparency and stakeholder engagement; 2) study methodology and interactions between studies; 3) study inputs, sensitivities and probabilistic analysis; and 4) tools and techniques. Though specifically crafted with reference to the CPP, the principles and analysis considerations presented in this white paper are generally applicable to other grid integration studies in different power system contexts.

Renewable Electricity Grid Integration Roadmap for Mexico: Supplement to the IEA Expert Group Report on Recommended Practices for Wind Integration Studies

NREL, August 2015

This white paper provides guidance for Mexico’s electricity system planners and other stakeholders on how to develop a comprehensive grid integration study. Drawing from the IEA’s Expert Group Report on Recommended Practices 16. Wind Integration Studies, this report contextualizes recommendations and best-practices specifically to support Mexico’s goals of increasing the contribution of RE to the nation’s electricity supply. Throughout the report, the authors provide expert insights into how Mexico can prioritize near-term versus long-term data collection, analyses, and other actions to understand and address the impacts of higher wind and solar penetration levels associated with Mexico’s 35% by 2024 RE goal.

Expert Group Report on Recommended Practices: 16. Wind Integration Studies

International Energy Agency Wind Task 25 (IEA Wind), September 2013

Based on more than 8 years of work by the IEA Wind Task 25 (Design and Operation of Power Systems with Large Amounts of Wind Power), this Expert Group Report represents the best available synthesis of current knowledge on conducting large-scale wind integration studies. The recommendations presented in the report are generally applicable to the development of wind integration studies within a variety of country- and/or system-specific contexts. The report also contains a section-by-section reference list of technical literature for further reading.

Grid Integration Study Examples

LADWP 100% Renewable Energy Study

In 2017, the Los Angeles Department of Water and Power (LADWP) partnered with NREL to launch their 100% Renewable Energy Study which will help LADWP determine which investments will need to be made in the coming years to achieve a 100% renewable energy supply. The study considers:

  • how to maintain system reliability under high RE penetrations;
  • the types and availability of renewable energy resources available in the LA region;
  • the role energy storage, energy efficiency, demand response and California's Energy Imbalance Market (EIM) can play in achieving the 100% renewable energy target;
  • the grid infrastructure upgrades that will be necessary to reach 100% RE;
  • how to achieve a 100% RE supply while minimizing costs;
  • the impact to the local economy (e.g. local job growth); and
  • the impact to LADWP's rate payers.

NREL is providing technical assistance to LADWP in this project, particularly in the area of scenario developments, analysis and modeling. A final report is expected in 2020. More information can be found at LADWP's website.

Solar Potential Analysis Report for Minnesota

Clean Power Research, 2019

This report, released by Clean Power Research, is part of the Minnesota Solar Pathways initiative, a three-year project sponsored by the U.S. DOE EERE Solar Technologies Office designed to explore least-risk, best-value strategies for meeting the state of Minnesota’s solar goals. The report details the results from the Solar Potential Analysis modelling tool, which helps estimate and optimize the generation cost and resource capacities required to serve a specific percentage of Minnesota’s load, subject to given production requirements. In the report, the SPA model the generation cost to achieve 10% of Minnesota’s electricity from solar by 2025 and 70% of Minnesota’s electricity from solar and wind by 2050. Among the report’s findings:

  • Solar and wind can serve 70 percent of Minnesota’s load at generation costs that are comparable to the levelized generation cost of new natural gas generation.
  • Additional capacity coupled with energy curtailment is considerably less expensive than, and a viable alternative to, long-term or seasonal storage in a high renewables future.
  • Storage is an important part of a high renewables future as it expands the dispatch capabilities of wind and solar assets.

 India Renewable Integration Study

The two-volume report Greening the Grid: Pathways To Integrate 175 Gigawatts of Renewable Energy into India's Electric Grid Vol. I—National Study and Vol. II—Regional Study resolves many questions about how India's electricity grid can manage the variability and uncertainty of India's 2022 renewable energy (RE) target of 175 GW of installed capacity, including 100 GW of solar and 60 GW of wind, up from 9 GW of solar and 29 GW of wind installed in early 2017.

Using advanced weather and power system modeling, the study explored operational impacts of meeting India's 2022 targets and identified actions that are favorable for integration.

Solar and Wind Grid Integration Study for the Luzon-Visayas System of the Philippines

USAID, 2018

To support Philippine power sector planners in evaluating the impacts and opportunities associated with achieving high levels of variable RE penetration, the Department of Energy of the Philippines (DOE) and the United States Agency for International Development (USAID) have spearheaded this study, which seeks to characterize the operational impacts of reaching high solar and wind targets in the Philippine power system, with a specific focus on the integrated Luzon-Visayas grids. The study finds that RE targets of 30% and 50% are achievable in the power system as planned for 2030, and that achieving these high RE targets will likely involve changes to how the power system is operated.

Operational Analysis of the Eastern Interconnection at Very High Renewable Penetrations

National Renewable Energy Laboratory, 2018

Building on previous work modeling the Eastern Interconnection in the United States, such as the Eastern Renewable Generation Integration Study below, this work analyzes the impact of high penetrations (70%) of variable renewable energy (VRE) on power system operations. The study explores how various flexibility scenarios impact the ability to reliably integrate high penetrations of VRE, including on total system costs. These flexibility scenarios include modeling higher penetrations of VRE (75%), limitations on how coal and nuclear generators can be flexibly operated, limitations on what share of regional demand must be met from thermal or hydropower resources, and limitations on power transfers from neighboring energy markets. The study found that in all scenarios it was possible to balance supply and demand at each 5 minute interval for an entire year at 70% - 75% annual penetration of VRE, although the assumed flexibility in each scenario had important implications for how thermal generators were operated and how much renewable energy was ultimately curtailed.

Eastern Renewable Generation Integration Study

National Renewable Energy Laboratory, 2016

This study analyzes the ability of the Eastern Interconnection of the United States, one of the largest power systems in the world, to accommodate high penetrations of wind and solar power. Using advanced modeling and computing techniques, the project team simulated the large-scale adoption of wind and solar energy at a temporal resolution up to 5 minutes. The study represents the cutting-edge of power system modeling, employing a high spatial resolution to include all synchronous components of the Eastern Interconnection. Results suggest that the Eastern Interconnection can reliably integrate upwards of 30% variable renewable energy in the power mix. However, meeting the 30% target will require increased balancing area coordination, incentives for transmission and generation to provide necessary ancillary services, and increased flexibility of traditional generators. In addition to the technical report, the full dataset as well as animations showing net interchange for two study scenarios are available for free download. 

Western Wind and Solar Integration Study

National Renewable Energy Laboratory, 2010-2014

The Western Wind and Solar Integration Study examines the benefits and challenges of integrating significant wind and solar energy to the Western Interconnection, which covers the power system operated by the WestConnect group of utilities in Arizona, Colorado, Nevada, New Mexico and Wyoming. The study consists of three phases. Phase 1 investigates the operational impacts of increasing the penetration of wind, solar photovoltaics (PV), and concentrating solar power to up to 35% in 2017. Phase 2 analyzes the wear-and-tear costs and emissions impacts associated with increased cycling by conventional generation due to wind and solar integration. Phase 3 evaluates the transient stability and frequency response of the Western Interconnection under high penetration solar and wind scenarios and identifies ways to mitigate adverse impacts through transmission reinforcements, storage, advanced control capabilities, and other mechanisms.

Hawaii Solar Integration Study

National Renewable Energy Laboratory, 2013

Developed in response to the ambitious RE targets established by the Hawaii Clean Energy Initiative, the Hawaii Solar Integration Study evaluates the operational impacts of high penetrations of solar PV (including both centralized and distributed PV) on the electricity grids of two Hawaiian islands: Maui and Oahu. The two islands provide examples of small power grids with differing levels of firm and RE capacity. The study examines variability, the ability to curtail power output, grid support, and load characteristics in the context of increasing variable RE on these systems. The technical reports underlying the summary are available here.

Eastern Wind Integration Transmission Study

National Renewable Energy Laboratory, 2010

The Eastern Wind Integration Transmission Study examines the operational impact of up to 20-30% wind energy penetration in the Eastern Interconnection, one of the three synchronous grids in the contiguous United States. The study addresses a variety of issues related to wind energy and transmission development, including the costs, impacts, and enabling mechanisms (e.g., geographic diversity, forecasting, operating reserves) associated with significant wind penetration. A follow-on study, the Eastern Renewable Generation Integration Study, is anticipated to be released in winter, 2015.

European Wind Integration Study

European Network of Transmission System Operators for Electricity (ENTSO-E), 2010

Initiated by the European Network of Transmission System Operators for Electricity (ENTSO-E), this study evaluates transmission-related challenges associated with four wind penetration growth scenarios (no wind growth from 2008 levels, best estimate of wind growth, optimistic but feasible growth, and growth when further grid enhancements are made beyond 2015). The study includes recommendations related to network finance, reinforcements, grid security and flexibility, consents, coordinated operation, grid code, network access rules, market development, offshore grids, and control of wind generation.

New England Wind Integration Study

Independent System Operator (ISO) New England, 2010

ISO New England (which serves as the regional transmission organization for the New England region of the United States) commissioned the New England Wind Integration Study to assess the operational, planning, and market impacts of integrating up to approximately 12GW of wind power. The study finds that wind energy could supply up to 24% of New England’s total annual electricity needs by 2020 if the system implements transmission upgrades.

All Island Grid Study

Ireland Department of Communications, Energy and Natural Resources, 2008

The All Island Grid Study represents a comprehensive assessment of the power system on the island of Ireland to accommodate significant renewable energy penetration (including variable RE as well as dispatchable RE resources) by 2020.  The study is divided into four “workstreams:” resource assessment, portfolio screening study, dispatch study, network study, and costs and benefits. The results include the climate change and energy security impacts, as well as the investment costs, associated with the RE scenarios.

Analysis of Wind Generation Impact on ERCOT Ancillary Services

Electricity Reliability Council of Texas, 2008

The Electricity Reliability Council of Texas (ERCOT) commissioned this study of the ancillary services requirements for its system to accommodate up to 15,000 MW of wind energy.  The Study evaluates and makes recommendations related to the methodology used by ERCOT to determine ancillary service needs; estimates the impacts of wind generation on the costs of ancillary services; and identifies changes to procedures related to severe weather conditions. ERCOT re-evaluated—and largely validated—the results of this study in a 2013 update.

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