一种同名相转换性故障变压器差动保护防拒动的研究

为解决变压器差动保护在发生区外故障CT饱和转区内同名相故障CT饱和导致的差动保护拒动问题，提出一种差流点差饱和开放识别方案。若为单电源CT饱和时饱和段差流采样点将会很小或出现间断。若为多电源单CT饱和时差流趋于正常波形。利用差流采样点的比率制动关系及制动电流间断角的特性，通过识别一周波内满足比率制动特性与间断点的总采样点数，来判断是否区内故障。仿真结果表明，该方法适用于变压器差动保护同名相转换性故障识别。

Research of a transformer differential protection against refusing action about the same phase transformation faults

To solve the problem of transformer differential protection refusing action, when outside fault CT saturation transfering the same phase inside fault with CT saturation, this paper puts forward a scheme based on differential current sampling points differentia saturated open. For a single power supplying when differential current sampling points of CT saturation periods will be small or presenting interruptive angles; if multiple power supplying and single CT saturation, differential currents return to normal waveforms. It uses ratio braking relations of differential current sampling point and characteristics of the braking current interruptive angle, by identifying total sampling points of meeting ratio braking characteristics and interruptive points within a cyclic wave, to judge whether the fault in the area. The simulation results show that this method is suitable for the identification of the same phase fault about transformer differential protection.