基于LMI优化法的多VSC接入弱网下的锁相环同步暂态稳定性分析

Transient Stability Analysis of PLL Synchronization in Weak-grid Connected Multi-VSC Based on LMI Optimization Method

本文针对弱连接条件下多电压源变流器并网系统的锁相环同步暂态稳定性进行研究。首先,建立适用于分析多电压源变流器并网系统锁相环同步尺度下暂态稳定性的降阶数学模型。然后,基于线性矩阵不等式优化法构建多电压源变流器并网系统的最大估计吸引域,并根据该最大估计吸引域揭示故障点电压大幅跌落时,系统存在小扰动稳定平衡点的情况下仍出现暂态失稳的原因。最后,在PSCAD/EMTDC搭建多电压源变流器接入弱网系统的详细开关模型进行仿真,仿真结果验证了本文构建的降阶数学模型及最大估计吸引域的有效性及可行性。

In this paper,the transient stability of phase-locked loop(PLL)synchronization in a multi-voltage source converter(M-VSC)grid-connected system under weak connection conditions is studied.First,a reduced-order mathematical model which is suitable for analyzing the PLL synchronization transient stability of the M-VSC grid-connected system is established.Then,based on the linear matrix inequality(LMI)optimization method,the largest estimated domain of attraction(LEDA)of the M-VSC grid-connected system is constructed.On this basis,when the voltage at the fault point drops sharply,the reason that causes the system transient instability in the case of an equilibrium point under mall disturbance is revealed.Finally,a detailed switching model for the weak-grid connected M-VSC system is built in PSCAD/EMTDC,and simulation results verify the effectiveness and feasibility of the reduced-order mathematical model constructed in this paper.