A detection method for HVDC commutation failure based on the variation rate of commutation inductance energy

Abstract

Concerning the insufficient accuracy of the criterion for identifying commutation failure in HVDC transmission systems, a new detection method for commutation failure based on the variation rate of commutation inductance energy is proposed. First, the conducting states of the converter valves in both normal commutation and commutation failure conditions are analysed, and the correlation between the differential of valve‐side line current and the conducting state of the converter in different commutation scenarios is established. On this basis, combining the topologies of D/Y‐bridge converters, a model to calculate the variation rate of commutation inductance energy is built. Then, considering the fault characteristics of DC current, DC voltage and valve currents, it is found that the calculated value of the variation rate of commutation inductance energy is consistent with the actual value under normal commutation conditions but inconsistent under commutation failure conditions. This allows for the construction of a criterion for identifying the commutation failure. Finally, the simulation results obtained with the RT‐LAB platform verify that, the proposed method can detect the occurrence of commutation failure quickly without measuring the valve currents, and it remains accurate when dealing with commutation failure near the threshold.