逆变器无线并联虚拟阻抗分析

逆变器无线并联提高了分布式供电系统的可靠性和灵活性,其控制原理为PQ下垂法。传统PQ下垂法基于逆变器并联理想等效模型,各逆变模块参数完全一致,而实际系统中由于器件参数与输出线路阻抗不一致,导致各模块等效输出阻抗不同,造成模块间环流。在系统中加入自校正虚拟阻抗,校正输出阻抗特性,进一步满足等效内阻抗与下垂控制策略间耦合控制关系,进而减小模块间环流。仿真结果证实加入虚拟阻抗后,系统具有良好的均流性能。

Analysis of virtual output-impedance for parallel-connected inverters with wireless load-sharing control

The wireless control improves the reliability and the flexibility of DG (distributed generation) systems, this theory is base on the PQ droop control, which is derive from the ideal model of parallel inverters, and the parameters of inverters equal to each other in this ideal model. However, for practical applications, the parameters of devices and the impedance of inverters are difference among parallel modules, which leads to the circulating current among modules. In this paper, the adaptive virtual impedance is introduced to adjust the output impedance of inverters, satisfying the coupling between the output impedance and the droop control, thus, the circulating current between modules is reduced. Simulation results for two 2-kVA inverters systems are provided to validate this approach.