Test of a LTT thyristor valve for next generation 500 kV HVDC transmission system

KII Channel HVDC system, the largest HVDC system in Japan, is under construction to start operation in 2000. Due to its large capacity and new test items, there have been several efforts in production and testing. In this report we introduce the tests of the thyristor valve for the KII Channel 1st stage project, explain "tests with transient forward voltage during the recovery period" which was to be added, and "nonperiodic firing test" which was to be the provided test conditions.