不平衡负载下VSG平衡电压控制

VSG Balanced Voltage Control under Unbalanced Load

针对传统虚拟同步发电机(virtual synchronous generator,VSG)带不平衡负载能力较差,在孤岛微网中带不平衡负载运行时会导致输出电压不平衡问题,利用αβ坐标系下数学模型对不平衡负载下VSG输出特性进行了分析;对传统VSG底层控制进行了改进,提出一种改进型比例复数积分负序电压控制方法。考虑到不平衡电流沿线路阻抗产生的不平衡压降将导致负载电压不平衡度不满足相关标准,通过虚拟阻抗的方法补偿不平衡压降。仿真验证结果表明,所提控制策略有效。

In order to address the problem that the traditional virtual synchronous generator(VSG)has a poor ability to carry unbalanced loads and the output voltage is unbalanced when operating with unbalanced loads in isolated microgrids,the output characteristics of the VSG under unbalanced loads are analyzed using a mathematical model in theαβcoordinate system.Besides,an improved proportional complex integral negative sequence voltage control method is proposed for the underlying control of the traditional VSG.Considering the unbalanced voltage drop generated by the unbalanced current along the line impedance,which causes the load voltage unbalance not to meet the relevant standards,the unbalanced voltage drop is compensated by the virtual impedance method.The simulation results show that the proposed control strategy is effective.