Abstract：Thyristor valve is the core device of UHVDC transmission project. In order to ensure the operation reliability of valves and to meet the research needs of its test methods, it is necessary to study the operation performance and failures mechanism of UHVDC valves. In this paper, each of the operation conditions of valves is analyzed, and the characteristics of different operation conditions and the simulation waveforms are illustrated. Then the operation status of valves in different duty cycles (turn-on, on-state, turn-off and off-state) is discussed and the equivalent turn-on/off model is established. Finally, combined with the internal physical characteristics of the device, the development process of the valve failure is analyzed and the failure mechanism is demonstrated.
2014, Vol. 15 
