计及主动故障限流策略的柔性直流电网纵联保护

In view of the problems of low reliability and sensitivity when the traditional DC protection principle is applied to flexible DC grid, the pilot protection of flexible DC grid considering active fault current limiting strategy of converter is proposed. The polarity characteristics of fault current in the capacitor discharge stage and active fault current limiting stage of converter are analyzed. Then the improved polarity sequence of fault current is constructed, and the current waveform identification method based on Spearman correlation coefficient is introduced to realize the fault area identification of flexible DC grid. The simulative results show that the proposed protection principle can identify the fault area of flexible DC grid in the capacitor discharge stage and active fault current limiting stage of converter, and has high reliability and sensitivity.