No Inverter Left Behind: Protection, Controls, and Testing for High Penetrations of PV Inverters on Distribution Systems

Abstract

The increased penetration of distributed energy resources (DERs) and interest in improved grid reliability, power quality, and resiliency have changed the characteristics of distribution systems. Inverter-based renewable energy sources, such as photovoltaic (PV) plants, are regarded as the fastest-growing and most crucial technologies in the proliferation of DERs on distribution systems. Many North American utilities have already begun experiencing high penetration of distributed (rooftop) and large-scale centralized PV systems on radial distribution feeders. In many areas?especially between 11 a.m. and 2 p.m.?PV generation can surpass feeder loading, causing reverse power flow and voltage rise toward the end of feeders. Bidirectional power flows, drastic changes in voltage profiles, and events with fast dynamics are becoming more common in today?s distribution systems, bringing complex planning and operational impacts. Understanding these issues requires a deep knowledge of distribution system dynamic behavior supported by detailed engineering studies and sophisticated testing methods.