基于四桥臂逆变器的微电网不平衡负载补偿策略

摘要

微电网中存在大量非线性及不平衡负载,因而系统电压不平衡度、总谐波畸变率不断增大对微电网电能质量产生了严重影响.文中提出了一种基于三相四桥臂逆变器的负载不平衡补偿器,采用电压电流双闭环控制策略进行不平衡电流的补偿,提高独立微电网的电能质量.在PSCAD/EMTDC中搭建了含分布式电源的试验仿真模型,验证其有效性,包括光伏发电系统、柴油机发电系统、电池蓄能系统.通过带不平衡负载,研究了带有LUC微电网模型的功率潮流和系统稳定性.仿真结果表明,所提出的LUC有助于提高微电网的稳定性.所提出的基于三相四桥臂VSI的LUC及其控制算法可以充分应用到带有严重不平衡载荷的独立微电网中.%Presence of a large number of micro-grid non-linear and unbalanced loads gives rise to system voltage unbalance,and increasing of the system voltage unbalance and THD seriously affects the quality of micro-grid.This paper presents a three-phase four-leg voltage sourced inverter(VSI) based load unbalance compensator (LUC),which is a component of a micro-grid.The purpose of the proposed three-phase four-leg VSI based LUC is to improve power quality of the standalone micro-grid.In the paper,the simulation consisting of a photovoltaic power generation system,a diesel generator,a battery energy storage system,and a power management system is modeled in PSCAD/EMTDC.Power flow and stability of the modeled microgrid with the LUC are analyzed under variable irradiance and unbalance loads.The simulation results show that the proposed LUC helps to improve stability of the stand-alone microgrid.The proposed three-phase four-leg VSI based LUC and its control algorithm can be effectively utilized to the stand alone microgrid which has large unbalance loads.