基于动态电流偏差控制的连续换相失败抑制方法

Suppression Method for Continuous Commutation Failure Based on Dynamic Current Deviation Control

为降低高压直流输电系统发生连续换相失败的概率,提出一种动态电流偏差控制器设计方法。从换相失败机理出发,利用关断角增量与电流偏差控制斜升函数斜率的关联性,采用二阶广义积分器实时检测逆变端换流母线三相电压及零序电压幅值的动态变化;以此为依据,在不同类型的交流故障发生后,使电流偏差控制斜升函数输出的关断角增量上限值做出相应的动态调整,从而改变控制曲线斜率,实现对关断角整定值的自适应调节。PSCAD/EMTDC仿真表明,所提方法能较好地抑制单相及三相短路故障导致的连续换相失败,改善直流系统的运行特性。

To reduce the possibility of continuous commutation failures in a high voltage direct current(HVDC)trans⁃mission system,a design method for a dynamic current deviation controller is proposed.Starting from the mechanism of commutation failure,this method makes use of the relation between the extinction angle increment and the slope of the current deviation control ramp function,and adopts a second-order generalized integrator to detect the dynamic changes in three-phase voltage and zero-sequence voltage amplitude at the receiving converter bus in real time.On this basis,the upper limit of the extinction angle increment in the current deviation control ramp function is dynamically regulated to change its slope under different AC faults,thus implementing the adaptive adjustment to the extinction angle setting.Simulations in PSCAD/EMTDC show that the proposed method can better suppress the continuous commutation failure caused by single-and three-phase short-circuit faults,thereby improving the operating characteristics of HVDC systems.