Photovoltaic Inverter Reactive Power Control for Chance-Constrained Distribution System Performance Optimization

Distributed generation has many potential benefits including use of renewable resources, increased customer participation, and decreased losses. However, as the penetration of distributed renewable energy sources increases, the technical challenges of integrating these resources into the power system increase as well. One such challenge is the rapid variation of voltages along distribution feeders in response to photovoltaic (PV) output fluctuations, and the reactive power capability of PV inverters can be used to address this challenge. A method of achieving optimal expected performance with respect to a figure of merit of interest to the distribution system operator while maintaining appropriate system voltage magnitudes and considering the uncertainty of PV power injections is proposed. The method utilises reactive power injection both to improve system performance and to compensate for variations in active power injection. It requires infrequent communication between the distribution system operator and the PV inverters and bases its decisions on short-term forecasts, formulating voltage magnitude requirements as chance constraints. The proposed method is validated using the IEEE 123-node radial distribution test feeder and shown to improve the distribution system performance (with respect to existing methods) and maintain suitable voltages.