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A Regulator's Guide to the Use of Load Flow Study Tools for Transmission Planning

With support from the United States Agency for International Development (USAID) Bureau for Europe and Eurasia, the National Association of Regulatory Utility Commissioners (NARUC) has developed the following two primers:

  • “A Regulator’s Guide to the Use of Load Flow Study Tools for Transmission Planning”
  • “A Regulator’s Guide to the Use of Production Simulation Tools for Market Analysis”

National regulatory authorities (NRAs) from the regions of Europe and Eurasia are responsible for monitoring, reviewing, and approving network investment plans (and in most cases long-term network development plans) for the electricity market, and are directly involved in promoting the development of well-functioning electricity markets and the regional integration of national markets.

In this context, these primers were developed to help regulators better understand the benefits and challenges of market coupling and extend their knowledge of tools commonly used by transmission system operators (TSOs) and other relevant stakeholders to evaluate market scenarios and perform a wide range of analyses.


This document focuses on the use of load flow studies for transmission planning, on the one hand, and the evaluation of changes to market design, including in particular market coupling or other means of regional integration, on the other. It includes the following content:

  • the necessary background to understand the basic principles, rationale, benefits, and types of modelling tools for load flow studies that are commonly used in the electric power industry;
  • the key inputs and parameters that are required for using power system simulation software;
  • the use of tools for load flow studies when applied for the specific purposes of transmission planning and the assessment of market reforms;
  • an overview of the typical outputs of load flow studies tools and their relevance for the tasks of the regulators; and
  • the role of the regulator for accompanying, monitoring and approving the use of load flow studies within the context of their corresponding tasks in the electricity market.

You can access it here.

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