A Novel Fault Area Identification Scheme for Inverter Station of HVDC Based on Wavelet Energy Ratio

The existing inverter station protection will operate incorrectly when the external fault occurs. Based on this, a fault area identification scheme based on wavelet energy ratio for inverter station is proposed. This scheme compares the characteristics of the current fault component between the primary side of the converter transformer and the outlet of the AC filter, and finds that there are obvious differences between the internal and external faults. The paper uses wavelet energy to characterize the difference, so that the converter station protection has the ability to identify internal and external faults. Extensive simulations on ±800kV HVDC system built in PSCAD/EMTDC show that the proposed scheme is reliability and validity. The proposed scheme can not only identify internal and external faults correctly and quickly, but also has good adaptability under different fault types, fault locations and fault inception angles. Furthermore, the scheme is insensitive to high fault resistance and noise interference.