基于拟合电流斜率特性的柔性直流配电线路纵联保护方法

光伏、风电等低碳清洁可再生能源和多样化负荷的接入促使直流配电网成为新的研究方向。为提高其供电可靠性,需对配电网系统进行故障特征分析。针对直流故障线路与换流器直流侧电容构成放电回路的前期阶段,提出一种适用于柔性直流配电线路的纵联保护新方法。该方法基于最小二乘法,并以故障电流采样数据拟合曲线斜率的方式,识别故障后直流线路两端电流的发展趋势,进而快速准确地判别直流线路故障。通过PSCAD/EMTDC建模仿真,验证了该方法的有效性及较高的可靠性。

Pilot protection method for flexible DC distribution lines based on fitted current slope characteristics

The integration of low-carbon clean renewable energy such as photovoltaics and wind power and diverse loads have projected studies of the DC distribution network into a new direction. To improve the reliability of power supply, the fault characteristics of a distribution network system are analyzed. Considering the early stage of the discharge circuit formed by the DC fault line and the DC side capacitor of the converter, a new pilot protection method suitable for flexible DC distribution lines is proposed. The method is based on the least squares method, and the slope of the curve is fitted by the fault current sampling data to identify the development trend of the current at both ends of the DC line after the fault, and then to identify DC line faults quickly and accurately. Through PSCAD/EMTDC modeling and simulation, the results show that the method is effective and reliable. This work is supported by the National Nature Science Foundation of China (No. 51877185) and the Xinjiang Uygur Autonomous Region University Scientific Research Key Project (No. XJEDU2021I009).