14 March 2018
power transmission protection, HVDC power convertors, power transformers, circuit breakers, reactors (electric), current transformers, gas insulated transmission lines, overvoltage, power transmission control, UHV power transmission systems, China, power demands, energy resource, ultrahigh voltage power transmission systems, optimal energy allocation, overvoltage suppression, external insulation design, electromagnetic environment control, UHV alternative current transformers, UHVAC transformers, circuit breakers, series compensated equipment, UHV direct current converter transformers, UHVDC converter transformers, smoothing reactors, converter valves, DC transmission control-and-protection systems, AC UHV projects, UHV projects, UHVAC line crossover, UHVAC gas-insulated lines, Yangtze River, UHVDC power transmission technology, large-capacity power transmission
The power demand increases rapidly in China; however, the areas of huge power demands are of long distance from most areas of abundant energy resource in the country. Therefore, China put in great effort to develop ultrahigh voltage (UHV) power transmission systems to optimise its energy allocation. This includes (i) systematically developing key technologies such as overvoltage suppression, external insulation design, and electromagnetic environment control, and (ii) developing key equipment such as UHV alternative current (UHVAC) transformers, circuit breakers, and series compensated equipment, and UHV direct current (UHVDC) converter transformers, smoothing reactors, converter valves, and DC transmission control and protection systems. Eight AC UHV projects and 11 DC UHV projects have been built in China, which play an important role in the optimal allocation of energy. Plus there are one more UHVAC and three more UHVDC transmission projects in construction, while UHVAC gas-insulated lines will be applied in the UHVAC line crossover the Yangtze River and the ±1100 kV UHVDC power transmission technology is in development. Here, the development and application of UHV power transmission technologies in China are described, some main challenges the UHV projects encountered are discussed, and experiences obtained from the operation of UHV systems are introduced. It is concluded that China obtained mature experience in developing, constructing, and operating UHV systems and successfully realised long-distance, large-capacity power transmission, and the UHV power transmission technology has become an important measure for energy allocation in large areas.