Additional modulation function of high-voltage direct current (HVDC) can significantly improve the stability of hybrid AC-DC power system. But the time-delay problem reduces the control performance of the controller severely. Meanwhile, the random jump of operation states may lead to system instability because it is more difficult to acquire the accurate model and the control strategy is not effective after jumping. Considering the complicated dynamic interaction of hybrid AC-DC power system and time-varying time-delay, the Markov switching model and time-delay control model are established using the full state feedback linearization. And then a nonlinear Markov switching control is proposed with unknown state transferring matrix. Simulation results show that the proposed model and control strategy can significantly improve system stability. The robustness of time-delay control method is hence proved.%高压直流输电的附加调制功能可以明显改善交直流混联系统的稳定性.远方反馈信息的不健全和时滞的影响,严重降低了控制器的控制性能和系统的安全稳定性.而电力系统运行状态发生随机跳变时,系统的精确模型更加难以得到,系统可能由于仍采用跳变前的控制策略而失稳.通过考虑交直流混联系统的复杂动态交互行为与广域测量系统的时变时滞特性,利用全状态反馈线性化理论,建立能反映交直流混联系统实时运行状态的Markov切换模型与时滞控制模型,并提出状态转移矩阵未知条件下非线性Markov切换控制策略,设计其稳定控制器.研究结果表明,所提出的基于Markov切换模型的交直流混联系统非线性控制方法可显著提高系统的控制性能,又具有一定的时滞鲁棒性.
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