Operating the distribution grid with an increasing amount of distributed energy resources (DER) is an area of focus for the electric utility industry and especially for the utilities within the Electric Power Research Institute’s (EPRI’s) multi-year Smart Grid Demonstration Initiative. This report provides a summary of the challenges and methods to overcome these challenges in planning for and operating the grid as the amount of DER increases and changes over time. In order to better understand how a distribution feeder would respond to various operating conditions, the report documents a time-series analysis for a test feeder over a four-day period in which the feeder, PV generation, and the other DER connected to the test feeder are modeled for varying weather and load conditions. The operational changes for the test feeder modeling exercise are documented from the perspective of how the distribution voltage regulation devices perform. An additional section, Section 4, was added in 2015 to extend the time series work in order to look at effects of changing the settings of voltage regulation device controllers on device operations and whether the changes could enable higher penetration levels of DER, specifically photovoltaic installations. In addition, the report contains lessons learned from a questionnaire given to the utilities of the Smart Grid Demonstration Initiative on how they planned for and are presently operating one of their feeders with a high penetration of DER.
The EPRI initiative includes core Smart Grid research and a number of large-scale Smart Grid projects currently conducted with 23 funding utility members.
This report will help utilities and other stakeholders understand the challenges of planning for and operating a distribution system with an increasing amount of DER. Learnings from a modeling exercise of a distribution test feeder and a utility questionnaire on the research topic are documented to aid utilities in understanding these challenges and to provide insights on how to better manage and operate the distribution grid with DER.
The report provides a general description of the types of planning analyses that may need to be performed on a distribution feeder in order to safely and reliably interconnect DER to a distribution feeder. In addition, the distribution operating practices and solutions to issues that may arise from operating the distribution grid with an increasing amount of DER are briefly discussed. The practices, especially those centered on the operation of the distribution voltage regulation devices, are further explored in the modeling simulation of the test feeder to provide the reader knowledge of how the operation of the distribution feeder varies as the amount and type of DER changes.
The report contains an assessment of how utilities are presently operating feeders with a high penetration of DER. A summary of the Smart Grid host utilities planning and operating practices are documented for five feeders. The results of the test feeder modeling exercise provide insights on how the operation of the feeder voltage control devices varies during a study period and techniques on how to lessen the impacts of higher penetrations of DER to voltage regulation devices.
Applications, Values, and Use
This strategic research topic report is part of the EPRI multi-year collaborative initiative, with multiple utility participants focused on the integration of distributed energy resources. EPRI provides the expertise for this industry collaboration effort, thus bringing significant value to the members while avoiding duplication of work. This report describes the planning and operational practices used by utilities when operating the distribution grid with a high penetration of DER. Results from the modeling exercise of the test feeder with a high penetration of DER and the utility questionnaire provide a better understanding of how the distribution system can be impacted by the inclusion of increasing amounts of DER.