Disturbance identification method for lightning wave invading grid

Lightning stroke on line may lead to mal-operation of relay protection, possibly invades substation, and further results in over-voltage of system. A S-transform based method for monitoring and identifying lightning inrush in substations is proposed in this paper. By monitoring busbar voltage signals in real-time, the waveform characteristics of transient voltage signals in both time domain and frequency domain are extracted using S-transform technique. According to the amplitude difference between main harmonic and fundamental frequency of voltages, a discrimination criterion for general fault, lightning stroke with and without fault is established. PSCAD simulation results have tested the validity and correctness of this proposed method.