A Novel Control Method for Islanding Mode Microgrid with Unbalanced Load

摘要

Single-phase load in microgrid brings about negative sequence voltage and current, deteriorating the stability of microgrid system. The difference of micro-source(MS) parameters influences the sharing negative current and reduces the reliability of MS. Negative sequence voltage reduces power quality and stability of microgrid. In this paper, a comprehensive control method is proposed to improve the power stability of unbalanced load microgrid. The adjustable negative sequence virtual impedance is included in the method, which is regulated by the negative current amplitude of MS. Through the design of adjustable negative sequence virtual impedance, the accurate negative current sharing is realized under islanding mode. The effect of negative sequence virtual impedance character on unbalanced voltage factor of Point of Common Coupling (PCC) is also analyzed. In order to reduce PCC unbalanced voltage factor, a kind of secondary voltage compensation method is proposed in this paper. Experimental results validate the effectiveness of the proposed methods.