【摘要】 为消除交流侧系统发生不对称故障时对VSC-HVDC的影响,提出一类Lyapunov渐近稳定控制策略。通过建立电网不对称故障下VSC-HVDC的dq正负序数学模型,分析负序分量对系统功率传输的影响;为消除传输过程中的二倍频功率波动,应用Lyapunov理论设计基于功率补偿的外环控制策略,扩大系统稳定范围;为解决传统PI控制结构动态响应性能不佳问题,利用反步变结构方法设计可计及不确定因素的内环电流控制策略,提高系统动态响应性能。基于Matlab/Simulink环境,对VSC-HVDC系统受端侧发生两相接地故障的工况进行仿真,结果表明所提控制结构能有效抑制二倍频功率波动,控制性能良好。更多还原

【Abstract】 A novel control strategy based on Lyapunov asymptotically stability theory was proposed to eliminate the influences to VSC-HVDC system by asymmetrical fault of grid. The mathematical model of VSC-HVDC system in positive and negative sequence coordinates was established under unsymmetrical fault of grid. The effects of the negative sequence component of the power transmission system were analyzed. In order to remove the double harmonic power fluctuations in transmission lines,a outer loop control scheme for power compensation was designed based on Lyapunov asymptotical stability theory with enlarging the stabilization range of the system. To improve the dynamic response performance of traditional PI control structures,an inner loop current controller considering uncertainties was designed with back-stepping method. Under the proposed control strategy,the operation conditions of VSC-HVDC system were simulated in the Matlab / Simulink environment for short-circuit ground faults at two-phase AC-side. The results show that the double harmonic power fluctuations of transmission lines can be effectively suppressed by the proposed control strategy with good control performance.更多还原