Data Window Selection Method Applied to Sampled Value Differential Protection

摘要

In this paper, the characteristics of the saturation current waveform are analyzed, and the instantaneous value of the differential current and the instantaneous value of the braking current and the rate of change of the differential current and the rate of change of the braking current are compared in the case of CT saturation. A data window of each wave cycle selection method for sampled value differential protection is proposed, and the real time digital simulation (RTDS) test is carried out. The test proves that the differential protection used this principle is not affected by the system frequency, the current non-periodic component and the CT transfer characteristic. The sampled value differential protection can operate quickly for the internal fault, and cannot operate reliably for the external fault. In the case of complex transferring faults, the rapidity and reliability of the differential protection operation can still be guaranteed. The data window selection method is accurate and reliable, and the sensitivity of the sampled value differential protection operation is improved.