Voltage Regulation for Distribution Networks with Smart Photovoltaic Inverters

Abstract

Traditional mechanical device-based voltage regulation becomes less effective when the high penetration of photovoltaic (PV) generation introduces rapid and frequent voltage fluctuations to the distribution networks. The PV inverters which are able to provide fast and flexible reactive power compensation are thus encouraged to participate in the voltage regulation. Particularly, the smart PV inverters with sensing, communicating and computing capabilities are able to act autonomously and cooperatively. This dissertation studies the coordinated voltage regulation for distribution networks with smart PV inverters. For the coordination among the large number of smart inverters, we develop an adaptive coalition formation-based strategy. This strategy enables the PV inverters to determine their scope of cooperation according to the real-time network operating condition. The PV inverters are thus able to eliminate voltage violations and fairly share the required reactive power contribution according to their maximum available regulation capacity. For the coordination between the smart inverter group and the utility-controlled mechanical devices, we propose a bi-level optimization-based voltage regulation framework. This bi-level optimization model captures the interactions between the different types of devices and allows them to cooperatively optimize their voltage regulation goals. This two-timescale framework ensures global economical efficiency while maintaining satisfactory dynamic regulation performances. Both studies are demonstrated based on realistic distribution networks with field-recorded data.