A New Method of Smart Control of Single-Phase Photovoltaic Inverters at Low Voltage for Voltage Control and Reactive Power Management

This paper introduces a newly designed reactive power control method for single-phase photovoltaic (PV) inverters. The control focuses on easy application and autonomous actions. The regulation is designed with regard to the effective network operation and the saving of reactive power with the functionality of voltage control and optimization of active losses. This paper proves the easy application of the newly proposed control design using the implementation of a control algorithm into a dynamic photovoltaic power plant (PVP) model and supply point with PSCAD software. The long-term benefit of this control is illustrated by the MATLAB/Simulink case study of a one-week simulation over the CIGRE LV European benchmark four-wire network using data from smart meters and measured PVP generation, which was provided by the Distribution System Operator (DSO). The case study showed the benefits of the newly designed regulation in terms of saving reactive energy supply from the upstream system by up to 64% (the regulation contributes to the self-sufficiency of the LV network in terms of reactive power), a positive effect on the reduction of active losses by up to 1.5% and a simultaneous improvement of the voltage profile at the nodes of the modelled network is also observed. The case study also reveals the risks of autonomous control of $Q = f(V)$ single phase inverter on the voltage unbalance depending on its definition.