Thermal design of high power thyristor valves for HVDC and SVC applications

High power thyristor valves are used as the switching elements in high voltage direct current (HVDC) power convertors, and to switch shunt capacitive or reactive components for control of reactive power in static VAr compensator (SVC) schemes. The author describes the methods used for cooling the major electrical loss-dissipating components in these thyristor valves, and the analytical techniques employed for the prediction of the thermal response of the valve to transients, both in simulations at the design stage, and in the real-time monitoring systems