基于电子式互感器的R-L模型距离保护应用研究

Application of R-L model distance protection based on ECT

基于智能变电站中电子式互感器的优良传变特性,建立被保护线路的时域微分方程模型,用保护安装处的零序电流模拟故障点接地电流,以提高测量精度。仿真试验验证了R-L模型测量精度高、响应速度快、耐过渡电阻能力强的特点。针对仿真试验模型的稳态超越问题,利用故障点两侧的零序网参数特点对零序电流进行相位补偿。仿真试验结果表明,改进的R-L模型在金属性故障时测量精度高,近端故障耐过渡电阻能力强,并有效地解决了末端故障超越问题。最后,对基于R-L模型的距离保护在智能变电站中的应用作了介绍。

Based on the perfect transmit characteristics of ECT in the smart substation, the transmission line time-domain differential equation model is established, zero sequence current at the protection installment point is used to simulate ground fault current to enhance the measurement accuracy. Simulation verifies that the R-L model has high accuracy, fast response speed and strong bearing ability to transition resistance. In respect to the steady-state overreach of simulation model, this paper uses zero-sequence parameters characteristics on both sides of the fault point to carry on phase compensation of zero sequence current. Simulation results show that the improved R-L model has high precision when metallic fault occurs and strong bearing ability to the transition resistance at near-end fault, and effectively solve problems of the overreach of end fault. This paper finally introduces the application of R-L model based distance protection in the smart substation.