Advanced point of common coupling voltage controllers for grid connected solar photovoltaic (PV) systems
The voltage rise of the low voltage (LV) power distribution grid to which multiple solar photovoltaic (PV) systems are integrated is a critical technical problem that should be addressed. With PV systems that are integrated to the LV power distribution grid (with an R to X ratio greater than unity) via voltage source converters, the opportunity exists to regulate the respective point of common coupling (PCC) voltages by dynamically controlling the active and reactive power response of PV systems. In this paper, two closed loop controllers that are able to regulate the PCC voltage by dynamically controlling the active and reactive power response of the PV system are presented. The design methodology is presented with considerable detail. The plant model of each controller is derived and the design procedure of each controller is explained in detail. By combining the dynamic active and reactive power controllers proposed in this paper, two novel operating strategies for PV systems, fixed minimum power factor operation and fixed maximum apparent power operation, are introduced. The latter operating strategy has been identified as the most efficient way of regulating the PCC voltage of a PV system. The simulation results and experimental validation confirm the accuracy of the derived plant models, the robustness of the designed controllers and the feasibility of implementing the proposed novel operating strategies in PV systems.