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The thyristor valve was first used in HVDC systems in 1972 on the Eel River Converter Station in Canada. [23] The thyristor is a solid-state semiconductor device similar to the diode , but with an extra control terminal that is used to switch the device on at a defined instant.
A valve hall is equipped with heating and cooling equipment to control the temperature of the mercury arc rectifiers (which operate best over a narrow temperature range) or thyristors. The valve hall also protects the valves from weather and dust. [1] Several valve assemblies, connected in a series for the required terminal voltage, may be ...
The converter is usually installed in a building called the valve hall. Early HVDC systems used mercury-arc valves, but since the mid-1970s, solid state devices such as thyristors have been used. Converters using thyristors or mercury-arc valves are known as line commutated converters. In thyristor-based converters, many thyristors are ...
The development of thyristor valves for HVDC began in the late 1960s. The first complete HVDC scheme based on thyristor was the Eel River scheme in Canada, which was built by General Electric and went into service in 1972. [17] Since 1977, new HVDC systems have used solid-state devices, in most cases thyristors. Like mercury arc valves ...
The thyristors, supplied by the German HVDC consortium (Siemens, AEG and Brown Boveri) used water cooling [10] for the first time in an HVDC project. Until that time, the relatively few HVDC schemes using thyristors had used either air cooling or, as on the Cahora Bassa project supplied by the same consortium, oil-cooling.
A back-to-back station has no transmission line and joins two separate AC grids at a single point. Historical HVDC systems used the Thury system of motor-generators but these have all been made obsolete by later developments such as mercury-arc valves (now also obsolete), thyristors, and IGBT power transistors.
The HVDC back-to-back facility Shin Shinano uses line-commutated thyristor converters. The station houses two converters, one of which opened in December 1977, [ 1 ] the other in 1992. The original 1977 converter was one of the first thyristor-based HVDC schemes to be put into operation in the world and used oil-insulated, oil-cooled outdoor ...
The current in the TCR is varied from maximum (determined by the connection voltage and the inductance of the reactor) to almost zero by varying the "Firing Delay Angle", α. α is defined as the delay angle from the point at which the voltage becomes positive to the point at which the thyristor valve is turned on and current starts to flow.