A new P-Q-V droop control method for an interline photovoltaic (I-PV) power system

This paper proposes a new droop control method for an interline photovoltaic (I-PV) system. In an I-PV system, the inverters in a PV plant are reconfigured in such a way that two or more distribution networks/feeders are interconnected. The I-PV system is operated as a flexible ac transmission system (FACTS) device to regulate the point-of-common coupling voltage on either feeder. One of the key features of the I-PV system is that real power can be exchanged between two feeders via the PV plant inverters. A P-Q-V droop control method is thus proposed, especially for systems with low X/R ratio, to facilitate simultaneous active and reactive power control to regulate the point of common coupling voltage. A MATLAB/Simulink-based simulation model is developed to evaluate performance of the system with the proposed controller. A lookup table-based approach is implemented to determine the P and Q droop coefficients. A performance comparison between P-V, Q-V and the proposed P-Q-V droop control methods is disclosed.