基于暂态电压Pearson相关系数的柔性直流配电网纵联保护方法

Longitudinal protection method of flexible DC distribution network based on transient voltage Pearson correlation coefficient

柔性直流配电网故障特征复杂,快速可靠的故障保护方法是柔性直流配电网亟需突破的关键技术。基于此提出了一种基于直流线路限流电抗器暂态电压皮尔逊(Pearson)相关系数的直流配电网纵联保护方法。首先,分析了区内外不同故障类型下直流线路两端限流电抗器暂态电压的特征差异。其次,利用正、负极线路电压的变化率构成保护启动判据,通过直流线路两端限流电抗器暂态电压的Pearson相关系数识别区内、外故障,并利用直流线路正负极电压变化率间的正负关系设计故障选极判据。最后,在Matlab/Simulink仿真软件中搭建柔性直流配电网仿真模型验证所提保护方法的可行性。结果表明所提保护方法能满足柔性直流配电网保护速动性和选择性的要求,且耐过渡电阻能力强,受通信延迟影响小,具有一定的抗干扰能力。

The fault characteristics of the flexible DC distribution network are complex,and the rapid and reliable protection of faults is a key breakthrough technology urgently needed for flexible DC distribution networks.Based on this,a longitudinal protection method for DC distribution networks based on the transient voltage Pearson correlation coefficient of DC line current-limiting reactors is proposed.First,the differential characteristics of transient voltages of current-limiting reactors at both ends of DC lines under different fault types inside and outside the region are analyzed.Secondly,the rate of change of the positive and negative line voltages is used as a criterion for protection initiation.The Pearson correlation coefficient of transient voltages of current-limiting reactors at both ends of DC lines is used to identify faults inside and outside the region,and the positive and negative relationships between the rates of change of positive and negative DC line voltages are utilized to design fault polarity selection criteria.Finally,a simulation model of a flexible DC distribution network is built in Matlab/Simulink to verify the feasibility of the proposed protection method.The results show that the proposed protection method can meet the requirements of rapid action and selectivity for the protection of flexible DC distribution networks,with strong transient resistance capability,minimal impact from communication delays,and a certain degree of anti-interference ability.This work is supported by the National Natural Science Foundation of China(No.52377185).