面向暂态稳定性能提升的VSG参数灵活控制策略

Transient Stability Enhancement of a VSG Based on Flexible Switching of Control Parameters

虚拟同步发电机(virtual synchronous generator,VSG)在模拟传统同步发电机(synchronous generator,SG)稳态输出特性的同时,也将面临与SG类似的暂态稳定性问题。相比SG,VSG的强非线性使其暂态稳定性分析愈加复杂,目前鲜有研究综合系统状态极限与故障持续时间极限对VSG暂态稳定性能进行量化分析。该文从极限切除角(critical clearing angle,CCA)与极限切除时间(critical clearing time,CCT)两个表征VSG暂态稳定性能的核心指标出发,对VSG进行暂态分析与控制。首先,基于扩展等面积法则,并借助于Runge-Kutta算法与最小二乘法等数学分析手段,对CCT与CCA进行定量分析,指出转动惯量对CCA与CCT的作用效果不一致;基于此,提出一种基于转动惯量灵活控制的等比例面积准则(equal proportional area criterion,EPAC),可为VSG转动惯量的控制提供指导;然后,基于定量的理论分析提出一种面向暂态稳定性能提升的VSG参数灵活控制策略,从CCA与CCT两方面提高VSG的暂态稳定性。仿真与实验证明理论分析与所提方法的正确性。

Virtual synchronous generators(VSGs) are widely used in new energy grid connection due to due to their inertial and damping features. Similar to synchronous generators(SGs), VSGs may lose transient stability when large disturbances occur. In addition, the strong nonlinearity of VSGs makes their transient characteristics more complex, but there are few corresponding quantitative analyses. Based on these,two core indexes affecting the transient stability of VSG,including the critical clearing angle(CCA) and critical clearing time(CCT), were studied in this paper. At first, Runge-Kutta algorithm, least square method and other mathematical analysis methods were used to carry out quantitative analysis on CCT and CCA in combination with the extended equal area rule. It was concluded that the effect of inertia on CCA and CCT was opposite. Secondly, an equal proportional area criterion(EPAC)based on the flexible control of virtual inertia was proposed,which could provide guidance for the control of virtual inertia in VSG. Then, A transient stability enhancement of VSG based on control parameters flexible switching was proposed, which could improve the transient stability of VSG from CCA and CCT. Finally, simulation and experimental tests were performed to validate the performance of theoretical analysis and the proposed method.