Detection of Commutation Failure in LCC-HVDC Transmission System Based on Converter Transformer Valve Side Current

In the line-committed converter-based high voltage direct current (LCC- HVDC) transmission systems, commutation failure (CF) is a prevalent defect, to accurate and reliable detection can provide a basis for system control and protection. The valve side current of the converter transformer, which was easily obtainable in practical engineering, was chosen as the research object to accomplish precise commutation failure detection. The features of this current during commutation failure were researched. Subsequently, a commutation failure discrimination technique was put out, which relied on the converter valve side current's three-phase symmetry and the identical length of each phase's conduction time. A CF detection technique was constructed and tested using a simulation of the CIGRE LCC-HVDC standard testing model. Through simulation, the validity of the theoretical analysis and then the efficacy and precision of the offered CF detection technique were confirmed. This research can provide support in favor of practical engineering.