EFFECT OF LIGHTNING ON PROTECTION BASED ON TRAVELLING WAVES

Protection based on travelling waves may mal-operate when transmission line is hit by lightning and no fault is generated. Based on the detail analysis of current component when lightning occurs on transmission line, lightning criterion using current component and wavelet transform is brought forward to distinguish whether fault takes place or not when lightning hits on transmission line. New criterion can be fulfilled either by current itself or by fault component of current. Elements that are needed in new criterion are obtained by using wavelet transform. Analysis and EMTP simulations show that lightning criterion can correctly differentiate whether transmission line takes place fault or not when lightning occurs. Therefore, reliability of protection based on travelling waves can be improved by using new scheme.