Method for judging transient energy of active power fault component

The active power fault component is calculated by extracting the voltage fault component and current fault component at the protection installation. According to the difference of the high and low frequency energy of the signals on both sides of the boundary element of the hybrid bipolar high voltage direct current transmission line, and considering the influence of different transition resistance on the result, a protection scheme based on the transient energy ratio of the active power fault component is constructed and specific protection criteria are given. In the protection scheme, the difference value of energy ratio between positive and negative poles is used to distinguish single and bipolar faults; the amplitude of energy sum of positive and negative bands is used to distinguish positive and negative faults and the amplitude of energy ratio is used to identify internal and external faults. The ±500kV hybrid bipolar HVDC transmission system is built by PSCAD/EMTDC electromagnetic simulation software. The active power fault component is decomposed by wavelet packet transform, and the transient energy of each node is obtained, which is verified by the protection criterion. The verification results show that the protection scheme has high resistance to transition resistance and the data time window is only 3ms. Under the different working conditions, it can quickly and accurately identify internal and external faults and perform fault pole selection.