U.S. Department of Energy Energy Efficiency and Renewable Energy

Identification of Low-Impact Interconnection Sites for Wholesale Distributed Photovoltaic Generation Using Energynet Power System Simulation

November 30, 2011

California’s objective for more distributed renewable electric power sources strains existing processes to safely interconnect wholesale distributed resources to the grid. This study funded by the California Energy Commission demonstrates an approach using the Energynet® simulation, a regional power system model, to identify low‐impact interconnection sites for wholesale photovoltaic systems on the grid. The model, which integrates transmission and distribution, employs a rich set of criteria that includes power system characteristics at a project’s location and its potential power flow, loading, voltage, and power quality impacts, and includes direct simulation showing the project’s local and regional impact — all in an evaluation requiring a few minutes. Criteria include assessment of conditions that vary for different interconnection points within the distribution circuit, including the system’s resistance to voltage variation, or “strength.” Nearly 80,000 potential distribution sites were evaluated, the impacts of more than 500 projects were individually simulated, and more than 11,000 low‐impact sites within a regional power system were identified for wholesale distributed photovoltaic projects ranging from 500 kilowatts to 5 megawatts. Findings suggest that wholesale photovoltaic projects in this size range have low or manageable affects even at high penetrations without major system upgrades if their point of interconnection are at sufficiently strong network locations that consider upstream equipment ratings and avoid certain circuits with unusual sensitivity.

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