Dispatchable Virtual Oscillator Control for Single-Phase Islanded Inverters: Analysis and Experiments

The increased penetration of renewable energy sources into the power system has resulted in a need for dispatchable control for the inverters. Dispatchable generation enables intelligent use of power sources thus enhancing the system's efficiency, reliability and reducing the stress on the distribution lines. In this article, a dispatchable control for virtual oscillator controlled-inverters is presented to achieve simultaneous regulation of both the active and reactive power in a single-phase system of \boldsymbol{m}-controlled and \boldsymbol{n}-uncontrolled inverters. Further, a set of security constraints is derived to determine the achievable power set-points for each controlled inverter present in the system. The dispatchable controller parameters corresponding to the desired power set-point can be determined using the presented control laws. A technique to design the control parameters and line impedance for the uncontrolled inverters is presented to enable optimal power sharing proportional to their power ratings. Simulation and experimental results are presented for the power regulation of multiple virtual oscillator controlled-inverters connected to a load through respective line impedances. The proposed dispatchable control strategy effectively regulates both the active and reactive power of the controlled inverters for a number of cases and in a wide operating range.