基于二次型指标和蒙特卡洛方法的含STATCOM的LCC-HVDC系统的控制参数优化

Optimization of Control Parameters of LCC-HVDC System With STATCOM Based on Lyapunov Stability and Monte Carlo Algorithm

在电网换相换流器高压直流输电(linecommutated converter based high voltage direct current,LCC-HVDC)逆变侧交流母线处并联静止同步补偿器(staticsynchronous compensator,STATCOM),可有效调节交流母线电压从而抑制换相失败。然而,连接弱受端交流电网时,STATCOM与LCC控制系统之间的耦合作用会对整个系统的小扰动稳定性产生负面影响,甚至导致系统小信号失稳。该文采用小信号分析方法,将含STATCOM的LCC-HVDC非线性系统在稳定运行点处线性化,而后推导出能够定量衡量系统小扰动稳定性的二次型指标,并以此为目标函数,利用蒙特卡洛(Monte Carlo)方法对多组关键控制参数进行优化。二次型指标、特征根分析及PSCAD/EMTDC的电磁暂态仿真结果表明,采用优化后的控制参数,系统在低短路比下能够稳定运行,小扰动稳定性明显增强。该文提出的控制参数优化思路,同样适用于其他系统,具有一定的学术研究和工程应用价值。

Static synchronous compensator(STATCOM)can effectively adjust the AC voltage at the inverter bus of the line-commutated-converter based high voltage direct current(LCC-HVDC),and mitigate the commutation failures.However,the coupling of the STATCOM and LCC control systems has the negative impact on the small signal stability of the whole system,and may even cause small signal instability.This paper used the small signal analysis method to linearize the LCC-HVDC nonlinear system with STATCOM at the stable operating point,and derived the quadratic index which can quantitatively measure the small signal stability of the system.Then,taking the index as the objective function,the Monte Carlo method was used to optimize multiple sets of key control parameters.The quadratic index,eigenvalue analysis and the electromagnetic transient simulation based on PSCAD/EMTDC show that the optimized control parameters improve the small signal stability under low short circuit ratio(SCR)conditions.The optimization approach proposed in this paper is also applicable to other systems.Therefore,it is worthy of academic research and application in engineering.