For the three-terminal line commutated converter-modular multilevel converter ( LCC-MMC) hybrid DC transmission sys-tem, the DC transmission power reducing or interrupting problem caused by AC side fault at the rectifier station is studied.And an AC fault ride-through coordination control strategy for rectifier converter station is presented.Firstly, the mathematical models of different types of converters are established and the characteristics after AC system faults are analyzed.Secondly, according to the different op-eration modes and the fault characteristics of DC voltage decrease and DC line contain 100 Hz harmonic, the coordination control strat-egy between the minimum trigger angle control at rectifier side and the maximum modulation ratio control at converter side is pro-posed.Thirdly, the original 100 Hz protection values are changed then the control modes can be switched automatically without sta-tions communication .Finally, a hybrid DC transmission system model is established in PSCAD/EMTDC, and the control characteris-tics of the system under different working conditions are simulated and analyzed.Results show that the proposed control strategy can improve the transmission power of the DC system and reduce the probability of power transmission interruption when short curcuit fault occurs at the rectifier AC side.%针对整流站采用电网换相型换流器(LCC)、 逆变站采用并联两端模块化多电平换流器(MMC)的三端混合直流输电系统,重点研究了整流站交流侧故障导致直流输送功率减小或中断的问题,并提出了一种整流站交流故障穿越协调控制策略.首先,建立了混合直流系统中不同类型换流器的数学模型并分析了其交流故障特征;其次,针对不同的系统运行方式及故障时直流电压降低、 直流侧含有二倍频分量的故障特征,提出了整流站最小触发角控制与逆变站最大调制比控制的站间协调策略;再次,通过改进原有100 Hz保护定值,实现了控制模式可自主切换;最后,在PSCAD/EMTDC中建立了混合直流输电系统的模型,对该系统在不同工况下的控制特性进行了仿真分析.结果表明:所提控制策略在整流站交流故障情况下可相应提高直流系统的输送功率,降低整流侧发生交流短路故障时引起功率输送中断的概率.
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