基于改进下垂法的微电网逆变器并联控制技术

Paralleling Control Technique of Microgrid Inverters Based on Improved Droop Method

分析了典型微电网中逆变器并联系统的有功功率和无功功率环流模型,并针对传统下垂法控制的微电网并联逆变器的输出电压幅值和频率的不稳定问题,提出了一种改进的自调节下垂系数控制法,有效减小了微电网负荷突变等情况下母线电压幅值及频率的波动。同时,根据并联逆变器的输出无功功率调节自身输出阻抗,抑制微电网中逆变器之间的无功功率环流,减少由于无功功率环流引起的系统设备容量和线路损耗增加等问题,提高系统的稳定性和可靠性。仿真和实验均验证了该控制策略的可行性和有效性。

This paper analyzes the active and reactive power circulating current model of the paralleling inverters in typical microgrid and presents an improved adaptive droop controller to improve the performance of parallel-connected inverters. With the proposed control strategy, large fluctuations of bus voltage and system frequency caused by load variation can be avoided. It uses an adaptive integral loop gain to improve the dynamic performance of parallel systems. It also reduces unreasonable reactive power flow between the inverters in a microgrid, therefore avoids unnecessary power losses and additional equipment capacity. Simulation and experimental results confirm the validity of the proposed conti＇ol technique.