基于自适应虚拟阻抗的下垂控制策略研究

Research on droop control strategy based on adaptive virtual impedance

低压微电网系统在多逆变器并联运行时,传统下垂控制策略由于自身原因会产生无功分配不均和系统环流,进而影响系统性能。加入虚拟阻抗虽能改善无功分配不均和系统环流,但会导致系统母线输出电压与标准值偏差过大。提出一种基于自适应虚拟阻抗的下垂控制策略,该策略基于传统电压电流双闭环控制环节引入自适应虚拟阻抗,通过自适应控制策略,该虚拟阻抗值能随着母线电压幅值的波动实时调整,补偿逆变器输出电压参考值,降低母线输出电压偏差,改善系统电能质量。仿真结果表明,该控制策略对抑制系统环流和减小母线电压偏差具有一定的可靠性与有效性。

when the low-voltage microgrid system is running in parallel with multiple inverters,the traditional droop control strategy will produce uneven distribution of reactive power and system circulation due to its own reasons,which will affect the system performance.Adding virtual impedance can improve the uneven distribution of reactive power and system circulation,but it will lead to excessive deviation between the output voltage of the system bus and the standard value.This paper proposes a control strategy based on adaptive virtual impedance prolapse,which is based on the traditional voltage current double closed loop control operation and adaptive virtual impedance.Through the adaptive control strategy the virtual impedance value can be adjusted as the bus voltage amplitude fluctuations in real time,to compensate the inverter output voltage reference value,reduce the output voltage deviation,and improve power quality.System simulation results show that the proposed control strategy can suppress system circulation and reduce the bus voltage deviation.