Development of a thyristor valve for next generation 500 kV HVDC transmission systems

A high voltage thyristor valve is the basic component of an HVDC transmission system. Development of a 500kV valve for next generation HVDC transmission systems is described. First, the power loss of the valve is analyzed to decide a reasonable wafer size for the light triggered thyristor. From these results, a six inch diameter wafer size is selected. The light triggered thyristor, with ratings of 8kV and 3.5kA, is developed using the six inch wafer. n e designing of the valve employing the thyristor and test results with the prototype valve prove that a 500kV valve can be realized by the design method.