一种降低直流输电换相失败概率的控制方法

A Control Method to Reduce Commutation Failure Probability in HVDC Power Transmission

为减小直流输电系统发生换相失败的概率,分析了换相失败机理,得出促进换相过程的关键。首先,基于数字信号处理器实时监测装置,结合故障电压和故障电流特征,提出了一种功率分量检测法。然后,利用该方法的故障检测结果,提出了一种基于电流指令速动的控制方法,能迅速减小直流电流。理论分析表明,功率分量检测法具有更好的灵敏性与准确性,而电流指令速动控制不仅能快速减小换相面积,而且在一定程度上增大了换相电压。在PSCAD/EMTDC中搭建了双馈入直流输电系统模型。仿真结果与理论分析相符,证明所提出的功率分量检测法与电流指令速动控制具有一定的优越性,能降低换相失败发生概率,减小换相失败的影响范围。

ABSTRACT：To reduce the probability of commutation failure in HVDC power transmission system, the mechanism of commutation failure is analyzed and the key factors to promote the commutation process are obtained. Firstly, based on real-time monitoring device composed of digital signal processor and combining with the features of fault voltage and fault current, a power component detection method is proposed; secondly, based on the fault detection results a quick current order limiter based control method, which can quickly reduce the DC current, is put forward. Theoretical analysis shows that the proposed power component detection method possesses better sensitivity and accuracy, and the quick current order limiter based control can reduce the commutation area while increasing the commutation voltage. A model of dual-infeed HVDC power transmission system is constructed in the environment of PSCAD/EMTDC, and the simulation results conform to the results of theoretical analysis, thus it is proved that the proposed power component detection method and quick current order limiter based control possess a certain superiority, and using them the probability of occurring commutation failure and be reduced and the impacting range of commutation failure can be narrowed down.