Distributed Cooperative Reactive Power Control of PV Systems With Dynamic Leader

This article proposes a reactive power control technique to regulate voltage profiles in low voltage (LV) distribution networks with high penetration of photovoltaic (PV) systems. The proposed strategy is a combination of a local controller and a distributed cooperative reactive power controller with a dynamic leader, which tracks the location of the critical bus(es), to coordinate all PV systems for voltage regulation. In this strategy, the local controller calculates each PV system's initial reactive power ratio that is applied to the distributed control. Then, unlike the existing distributed control method for voltage control, our proposed algorithm dynamically finds the PV system at the critical bus using the local data and neighbors’ information transferred via communication links. The PV system at the critical bus serves as the leader agent and coordinates all PV systems through distributed cooperative control. Indeed, this approach can improve the voltage profile of the LV distribution network in both normal and voltage ride-through conditions with a fair use of each PV inverter's reactive power capacity. Moreover, this method preserves plug-and-play capability and is robust to network reconfiguration, communication malfunction, and variation of loads and weather conditions (variation of the maximum active power and the reactive power capacity of PV inverters). Simulation results are exhibited to validate the successfulness of the proposed control method under ideal and delayed communication networks. It should be noted that the proposed approach is scalable to multiple feeders with several branches.