Integrated Strategic System Planning

Distributed generation (DG), particularly customer-sited solar and battery storage, is increasingly influenced by a diverse set of policy and incentive mechanisms implemented by states and electric companies. These incentives, including upfront rebates, performance-based payments, export compensation mechanisms, tax incentives, and behavioral rate structures play a critical role in shaping customer adoption and long-term distributed energy resource deployment. This project reviews existing incentive-based distributed generation programs across the United States, with a particular emphasis on Midwest electric companies in the U.S. The study evaluates the combination of policy levers and how they contribute to sustained distributed resource growth. In addition, the research assesses how DG programs and adoption drivers are currently represented in Integrated Resource Planning (IRP) processes. This project evaluates current modeling approaches and explores opportunities for more integrated representations of DG within planning models. The findings highlight the importance of layered policy frameworks and improved modeling approaches to support more accurate forecasting of distributed generation and its role in future power system planning.

Integrated planning for low-carbon energy systems may require models that can coordinate long-term investments and short-term operations across electricity, hydrogen, heat, fuels and storage. This report provides a structured comparison of open-source frameworks to help researchers and practitioners understand the features of various open-source integrated planning models. The report evaluates each tool along five dimensions: 1) scope (e.g., sector coupling, network representation, temporal and spatial resolution), 2) modeling language and formulation (e.g., software implementation, formulations), 3) data management (e.g., inputs, workflows, standards compatibility) 4) treatment of uncertainty (e.g., support for stochastic analysis, decomposition techniques, sensitivity analysis, design for alternatives), and 5) usability and ecosystem (e.g., documentation, licensing, community support). The comparison shows the different modeling choices available to the practitioner that can shape the analysis in a resource planning study.

As regional energy systems experience higher levels of variable renewable generation, rising electricity demand, and increasing climate and weather-related risks, electric company resource planners are increasingly interested in understanding the extent to which the systems they plan may rely on neighboring regions during periods of high system stress. Modeling improvements with respect to how regional imports are characterized may support identifying more reliable resource portfolios. This report reviews current approaches for representing market interactions and other regional imports in long-term resource planning models. Ten integrated resource plans (IRPs) and other long-term planning documents are reviewed to identify methods for modeling market interactions and regional imports. In addition, a survey conducted with electric company planning practitioners and interviews with subject matter experts in electric system planning reveal additional insights into modeling practices. The findings from this analysis provide guidance for companies seeking to better understand current industry practices for modeling import availability and to adopt improved methods in their own long-term resource planning efforts.

Integrated resource planning processes are continuing to evolve as energy company planners seek to bridge the gap between IRP development and implementation. Changing system dynamics are pushing the need for new planning methods and metrics, infrastructure upgrades, and advanced operating strategies and management tools. This white paper outlines several practical realities associated with integrated resource planning.

Integrated Resource Plans (IRPs) look decades into the future, recommending generation portfolios that must meet customer demands over a wide range of possible and uncertain futures. Drivers of this uncertainty include carbon prices, natural gas prices, load, technology capital costs, and renewable generation. Stochastic analysis plays a key role in helping planners evaluate the risks posed by these uncertainties for each of their candidate portfolios. This report provides a review of stochastic planning practices employed by electric companies for their IRPs and other long-term resource plans. For this report, the IRPs and long-term plans from 21 companies were reviewed to identify trends in stochastic modeling practices. Five companies that extensively employ stochastic planning were also selected for a deep dive of their methods. The findings from both reviews informed guidance provided in this report for companies looking to adopt stochastic planning in their own IRPs. Additionally, an Excel workbook outlining illustrative examples for developing stochastic parameters from data is provided in an attachment to this report.

EPRI's Integrated Strategic System Planning (ISSP) Initiative developed a new framework and analytical toolbox for more comprehensively planning across generation, transmission, distribution, and end-use systems, and realizing cost-effective and reliable low-carbon electric power systems. The overall framework consists of a series of soft-linked power system modeling tools, including (1) an economic energy-systems planning model to develop regional technology pathways; (2) a detailed, nodal generation and transmission capacity expansion planning model to develop system-level resource expansion portfolios; (3) a series of grid operations simulation models to evaluate resource adequacy and system risk; and (4) distribution planning tools to assess potential distribution network upgrades and non-wires alternatives.

The research presented in this report focuses on the modeling linking efforts between tools identified in (1), (2), and a portion of (3) above. The motivation for this work is that cost-effective, low-carbon electricity transition planning requires analytical tools and processes that consider key policy, technology, and market impacts across broad, interconnected power systems; as well as critical grid operations and reliability needs given higher levels of variable renewable energy, distributed energy resources, and storage assets. And simply, existing long-term planning modeling tools do not adequately meet both requirements.

Focusing on the bulk power system, this research leverages and links a zonal economic energy-systems planning model, a nodal unit-level capacity expansion planning model, and resource adequacy and production cost models for planning low-carbon and high-renewable long-term resource portfolios that are robust to potential future reliability and resource adequacy deficiencies.

Electric companies are searching for new modeling approaches and tools to support strategic resource planning and asset investment across generation, transmission, and distribution systems, with an aim to identify cost-effective, resilient, and technologically-robust decarbonization resource strategies. Studying the capabilities of existing power system modeling tools and current practices is critical to understanding and advancing an integrated planning framework. This work reviews the objectives, features, and capabilities of various capacity expansion planning tools, production cost model tools, resource adequacy tools, and network reliability modeling tools; and provides an overview of select studies that have been completed over the past few years in the integrated electricity and energy system modeling space.

EPRI’s Integrated Strategic System Planning (ISSP) Initiative develops a new resource planning framework and supporting analytical toolbox. This framework uses a series of soft-linked existing power system modeling tools, selected based on the review of modeling tools enlisted in this work. The new framework is tool-agnostic however, and may be used for more comprehensively planning reliable, low-carbon resource portfolios across electric power system supply, delivery, and end-use.

The pace of utility-scale battery storage deployment has accelerated since 2020, partly driven by continued technology cost reductions, renewable portfolio standards and, more recently, by storage targets set by some U.S. states.

Given the growing importance of energy storage in the future, resource planners are interested in understanding how this technology should be integrated into their long-term planning studies and modeling tools. Energy storage is seen as a valuable resource to support grid decarbonization efforts because of its capability to provide flexibility to systems with an increasing penetration of renewables. Questions that planners are asking include:

• What types of energy storage technologies and features should be included? What services should be considered when modeling energy storage?
• How spatially- and temporally- detailed does the model need to be in order to accurately value energy storage?
• What simplifications affect the assessment of energy storage in long-term planning?

This technical brief reviews information from recent integrated resource plans (IRPs) and planning studies, peer-reviewed journal articles, and several EPRI technical reports, to understand approaches and modeling practices used by electric companies and planners, as well as use cases of storage in long-term resource planning.

Existing long-term electric power system resource planning tools do not fully account for the potential reliability challenges introduced by large-scale deployment of many decarbonization technologies such as renewables, energy storage, and distributed energy resources. This is because the stress a system may face from these technologies (e.g., inadequate generation flexibility, insufficient resource adequacy, network deficiencies) often occurs on timescales, at locations, and within sub-systems of the power system that long-term planning models do not typically capture to keep solutions tractable. Electric companies are thus searching for new modeling approaches to support resource planning and asset investments—across generation, transmission, and distribution systems—with the aim of identifying cost-effective, resilient, and technologically-robust decarbonization resource strategies.

EPRI’s Integrated Strategic System Planning (ISSP) Initiative develops such a new resource planning framework and supporting analytical toolbox. Using a series of soft-linked existing power system modeling tools, the new framework is generalizable and may be used for more comprehensively planning reliable, low-carbon resource portfolios across electric power system supply, delivery, and end-use. This report presents the ISSP modeling framework and an application of the analytical toolbox through an initial study on the New York electric power system. The demonstration study illustrates the process of enhancing traditional capacity expansion modeling tools with more spatially- and temporally-granular power system operations modeling tools to validate initially preferred resource portfolios and update portfolios when the more granular tool(s) uncover economic inefficiencies or reliability deficiencies. Key insights on implementing the ISSP framework and lessons learned from the demonstration study are shared.

This report documents the experiences of a set of electric companies in the United States that are performing coordinated planning activities across generation, transmission, distribution, and customer-sided resources. The transition to decarbonized energy systems will substantially transform the electric sector in the next few years, and companies are recognizing that a more integrated planning process may help guide planning more cost-effective and reliable power systems than planning individual parts of the system in isolation.

This report shows that applications of emerging integrated system planning processes are diverse across utilities. Their organizational structure, and market and regulatory environments influence the level of integration across departments and affiliated external organizations. This is particularly the case across planning functions, analytical tools, data environments and stakeholder engagement. For many utilities, integrated system planning is a new and evolving process. Companies are either implementing a process that is not yet mature, or they are engaging in preliminary discussions to delineate the nature of their collaborations.