220kV线路距离保护在V/X接线牵引变压器短路时的测量阻抗分析

Measured impedance of 220 kV line protection during short circuit of traction transformer with V/X connection

基于V/V接线牵引变压器低压侧短路时短路电流分析,推导出该短路情况下,电源侧变电所220 kV线路距离保护相间阻抗元件和接地阻抗元件的测量阻抗计算式,并根据计算式给出了V/V接线牵引变压器低压侧两相短路和三相短路时的220 kV线路距离保护的最小测量阻抗。对V/X接线牵引变压器的各种短路类型进行了分析,发现只要将牵引变压器等值参数Z变为Z′或Z″,V/V接线牵引变压器短路时对220 kV线路距离保护的测量阻抗的分析,同样适用于V/X接线牵引变压器短路情况。通过仿真实验,验证了所推导的测量阻抗计算式的正确性,其适用于V/X接线牵引变压器。最后基于上述理论分析和仿真实验结果,给出了220 kV线路距离保护整定计算公式和注意事项。

The low voltage side short circuit current of traction transformer with V/V connection is analyzed, based on which,the formulas for calculating the measured impedance of inter-phase impedance element and grounding impedance element of 220kV line distance protection are deduced. The minimal measured impedances of 220 kV line distance protection are thus calculated for two-phase and three-phase short circuits at low voltage side. Different short circuit kinds of traction transformer with V/X connection are analyzed and it is found that,the measured impedance of 220 kV line distance protection analyzed for the LV-side short circuit current of traction transformer with V/V connection is applicable to that with V/X connection as long as the equivalent parameter Z is replaced by Z＇ or Z＂,whieh is verified by simulative experiment. The formulas for calculating the settings of 220 kV line distance protection are given with notes.