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A High-Speed Protection Strategy for Bipolar CSC-Based HVDC Transmission System

Abstract This paper introduces a novel approach to high-speed fault protection strategy for bipolar Current Source Converter (CSC) based high voltage DC transmission line. The Bagged-Tree Ensemble-Classifier (BTEC) method is employed to detect the presence of a fault and categorizes the various types of faults in the DC transmission line. The implementation of the Wavelet Transform (WT) technique assists in diminishing the effect of deviation in the fault resistance value, fault location, and disturbances created due to noise on the performance BTEC method. The development of the predictive model through concatenating individual models is the prime objective of the ensemble schemes. Ensemble procedure assists to enhance the performance accuracy of the fault protection strategy. The local measurement at the rectifier end side is enough for the proposed strategy to realize the protection of the entire line with no use of communication channels. The AC sinusoidal voltage, DC current and DC voltage are recorded at the rectifier end terminal and sampled at 1 kHz, which is very less as compared to the other existing techniques. The proposed strategy detects the fault in the least possible time of 4 ms and able to classify all the tested faults with reasonable accuracy. The results convey that the proposed strategy offers high-speed detection of fault and preciseness in the classification of all types of faults, despite variation in the fault resistance up to 180 Ω. The proposed scheme is applicable for DC faults and also detects the presence of AC faults in either rectifier end as reverse fault and in inverter end as sub-sequent forward section fault.