A Decentralized Secondary Voltage Control and Unbalance Voltage Compensation Method in Islanded Microgrids

In order to stabilize the voltage and improve the power quality at the point of common coupling (PCC), a decentralized voltage compensation method is proposed for secondary voltage control and unbalance voltage compensation based on the small-ac-signal (SACS) injection. Compared with the previous SACS injection based decentralized voltage control method, the proposed method fully utilizes only one injected SACS to achieve both secondary voltage control and unbalance voltage compensation simultaneously, which reduces the control complexity and total harmonic distortion at PCC. Meanwhile, this method is completely independent of communication links and remains effective under inaccurate PCC voltage estimation, making it suitable for practical applications. The simulation and experimental results demonstrate the effectiveness of the proposed method.