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NREL, SolarCity Complete Experimental Evaluation of PV Inverter Anti-Islanding with Grid Support Functions in Multi-Inverter Island Scenarios

July 26, 2016

Distributed energy resources (DERs) such as solar photovoltaic (PV) systems have long been required to disconnect from the electric grid when an electrical island is formed. Typically, PV inverters perform the islanding detection function autonomously using one or more of a variety of methods. But as more and more PV and other DER systems connect to the grid, island detection may become more challenging.

A new report by NREL and SolarCity describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in the report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called "solar subdivision" scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters.

Crucial to the work was the Energy Systems Integration Facility's power hardware-in-the-loop simulation capability, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. 

Learn more about NREL's collaboration with SolarCity to address the safety, reliability, and stability challenges of interconnecting high penetrations of distributed PV with the electric power system.

—Devonie McCamey