Control of Distributed Generation Systems— Part II: Load Sharing Control

TLDR

The paper addresses control strategies for parallel operation of distributed generation systems in standalone AC power supplies. The proposed method fuses droop control with a low‑bandwidth average‑power scheme and a harmonic‑droop algorithm, using only local measurements and minimal communication to mitigate voltage/current errors. Experiments and simulations with two parallel three‑phase PWM inverters confirm the effectiveness of the control strategy.

Abstract

This work is concerned with the control strategy for the parallel operation of distributed generation systems (DGS) in a standalone ac power supply. The proposed control method uses only low-bandwidth data communication signals between each generation system in addition to the locally measurable feedback signals. This is achieved by combining two control methods: droop control method and average power control method. The average power method with slow update rate is used in order to overcome the sensitivity about voltage and current measurement errors. In addition, a harmonic droop scheme for sharing harmonic content of the load currents is proposed based on the voltages and currents control algorithm. Experimental and simulation studies using two parallel three-phase pulsewidth modulation (PWM) inverters are presented to show the effectiveness of the proposed control.