HVDC Thyristor Valve Development

The development of the thyristor valve technology from the first designed air-cooled thyristor valve to the modern water-cooled thyristor valve is described. The design and design criteria for the modern water-cooled valve are briefly described. The performance of the previous air-cooled design and the water-cooled design is compared especially with regard to power handling capability including overload capacity, power losses, space requirements, seismic resistivity, and reliability. The valve control equipment, including its protection and monitoring functions, is treated and it is shown how the sophisticated design of today has been developed based on experience from previous designs.