Investigation of Oscillations Caused by Voltage Control from Smart PV on a Primary System

This paper investigates oscillations caused by voltage control actions of autonomously controlled residential-size Smart Photovoltaic generators (PVs) responding to an undervoltage condition. We performed the analysis on a highly-detailed model of a real-world primary distribution system with hypothetical high penetration of Smart PV. We conclude that aggressive volt-var control settings can result in severe power quality problems in the form of voltage oscillations. In our simulations, applying a volt-var Ramp Rate Limit successfully eliminated these oscillations. The magnitude of the oscillations is highly dependent on the distance of the observation point from the substation - in the case of the investigated undervoltage scenario, larger magnitudes occurred at more remote locations due to the larger voltage drop. The occurrence of sustained oscillations depends on the shape of the volt-var control curve with Smart PVs controlled by curves that have steep slopes and no deadband being particularly prone to causing them. The work will be extended in the future by an investigation of smart PVs interacting with traditional voltage control equipment.