Development of VBO-free large capacity light-triggered thyristor valve

Following the recent development of 6 kV class VBO (voltage break-over)-free light-triggered thyristors (LTTs) in Japan, a field verification test has been conducted by applying these thyristors to an actual 100 MVA class SVC valve, and satisfactory results were obtained. The authors describe the characteristics of the VBO-free large-capacity LTTs, the effects that can be expected when it is applied to SVC or HVDC valves, design and manufacturing, the results of factory tests for the SVC and valve, and the results of a verification test in the field