不平衡工况下四桥臂VSG控制策略研究

Research on Control Strategy of Four-leg VSG under Unbalanced Condition

针对微网中虚拟同步发电机的不平衡运行工况,以四桥臂逆变器构成三相四线制微网结构,采用QPIR电压控制器有效避免了对输出电压的正负零序分离。考虑到微网多处于配电网侧,输电线路阻抗通常呈阻感性,存在功率耦合和母线电压不平衡度升高的问题,基于DCCF和SOGI提出了构造分序负阻抗特性的虚拟定子阻抗,实现了不平衡工况下有功、无功的解耦并有效降低了微网母线电压的不平衡度。

For unbalanced operation condition of virtual synchronous generator in microgrid,a three-phase four-wire microgrid is constructed with four-leg inverter,and the QPIR voltage controller is adopted,which effectively avoids the positive and negative zero sequence separation of the output voltage.Considering that the microgrid is mostly on the side of the distribution network,the impedance of the transmission line is usually resistive and inductive,and there are problems with power coupling and increased bus voltage imbalance.Based on DCCF and SOGI,a virtual stator impedance with sequential negative impedance characteristics is proposed,which realizes the decoupling of active and reactive power under unbalanced conditions and effectively reduces the unbalance of the microgrid bus voltage.