Voltage fluctuation mitigation: Fast allocation and daily local control of DSTATCOMs to increase solar energy harvest

Abstract

This study presents a methodology for reactive power compensation provided by distribution static synchronous compensators (DSTATCOMs) to mitigate the voltage fluctuation and increase the solar energy harvest via photovoltaic (PV) inverters accordingly in medium-voltage distribution systems. An approximate method that uses one power flow run with the base-case system is analytically developed to offer a fast estimation of the location and size of DSTATCOMs to enhance the local voltage controllability over sunshine hours. This study then presents daily local reactive power control, where the control signals are calculated based on instantaneous measurements of the voltage at each bus without requiring any communications. The control method involves estimating the amount of reactive power support by the installed DSTATCOMs to reduce the voltage fluctuation during daytime while PV inverters are fully used to harvest the solar energy. At night-time, the DSTATCOMs operate as a master in voltage-controlled mode with other PV inverters in load mode if required to minimise the energy loss while improving the voltage profile. The proposed method has been tested on a 69-bus distribution system with 1 min load and 1 s solar power profiles and validated using a repeated power flow-based exact solution.