Alternating-current powerline thunderbolt shielding failure and counterattack recognition method

The invention relates to a method for recognizing lighting shielding failure and counterattack of an AC transmission line. The different theories generated by the electromagnetic transient component of the lighting shielding failure and the counterattack of the high-voltage DC transmission line and different paths of transmission of the thunderbolt electromagnetic transient component on the circuit cause that the energy distribution of different frequency bands of the generated current transient state signals are different greatly. Therefore, in a travelling wave analysis and high-speed acquisition system at the protective installation position, the small wave analysis is adopted to extract the energy of the zero modulus current in different frequency bands. The shielding failure and the counterattack are differentiated according to the property of the energy distribution. A large amount of emulations show that the method is reliable and effective and can recognize accurately the shielding failure and the counterattack of the AC transmission line. The method has intuitive theory base and clear physical concepts, thereby being easy to implement, being widely applied to an AC system protective device, providing important data for the lightening protection design of the AC transmission line and providing reference for the operation and maintenance of the transmission line.