基于EWT改进限流电抗电压的柔性直流配电网故障保护方法OA北大核心CSTPCD

Fast and reliable identification of DC line faults is key to the stable operation of a flexible DC distribution network.Based on the characteristics of boundary conditions of a current-limiting reactor,an improved current-limiting reactance voltage fault protection method for such a network based on empirical wavelet transform(EWT)is proposed.First,EWT is used to extract the high-frequency component of the DC line voltage,and an improved voltage gradient algorithm is adopted as the starting criterion.Then,from the different peaks of the high frequency transient voltage of the current limiting reactor on both sides of the DC line,a protection criterion using a kurtosis algorithm to identify the internal and external fault is proposed.Finally,using the Teager energy operator,this paper calculates the ratio of the instantaneous energy maximum of the high-frequency transient voltage of the positive and negative pole lines.This forms the criterion for fault pole selection.The experimental results show that this method can accurately distinguish the fault pole and internal and external faults,has low communication requirements and good anti-interference ability.It can work reliably in different working conditions,and can better meet the speed and selectiveness requirements for protection of a flexible DC distribution network.