Optimal sizing and location of a PV system on three-phase unbalanced radial distribution feeder avoiding reverse power flow

A suitable procedure for optimal sizing and location of a single Photovoltaic Distributed Generation (PVDG) unit on three-phase unbalanced radial distribution feeder has been developed. The procedure avoids reverse power flow along the feeder. It considers the peak mismatch of the feeder load curve and the PVDG production curve. With such mismatch, the PVDG system can produce only part of its capacity at the time the feeder meets its peak demand. Hence, solving the optimization problem for maximum line peak power loss reduction could make no sense. Alternatively, minimization of the accumulated line power losses over the day (line energy loss) is more appropriate in this application. A suitable derivation has been developed to rate the line energy loss reduction considering only one time interval, namely Feasible Optimization Interval (FOI). Thus, the optimization procedure can be solved for maximum line energy-based benefits considering only the FOI. This avoids running the calculations for each time interval over the whole duration. The procedure has been applied successfully on two 11kV feeders within the Abu Dhabi Distribution network.