The turbine generator and electrical main wiring are like the heart and aorta of the electrical system. The hydraulic generator converts the rotating mechanical energy output by the hydraulic turbine into electrical energy and is the source of electrical energy output by the hydropower station. The efficiency of large hydroelectric generators can generally reach about 98%. At present, the maximum capacity of hydroelectric generators put into operation in my country is 889MVA. Electrical main wiring uses appropriate methods to connect hydroelectric generators, generator voltage equipment, main transformers, high-voltage distribution devices, power systems, etc. to realize functions such as transmission, boosting, collection, distribution, and sending of electrical energy. .
The generator voltage equipment transmits the electric energy generated by the hydrogenerator to the main transformer. This return flow has the characteristics of high voltage and large current. The power supply of the factory power system, unit excitation device, etc. is generally connected from here. The generator voltage level of hydropower stations currently in operation is up to 24kV. Considering that hydropower stations are often involved in peak shaving and unit switching is frequent, special circuit breakers for generators are often installed at the outlet of hydroelectric generators. The connecting conductor of the voltage circuit of the generator of a large-capacity unit usually uses an off-phase closed busbar.
The main transformer is the connection point between the generator voltage equipment and the high-voltage distribution device. It raises the generator voltage to the transmission voltage to reduce the transmission current, thereby effectively reducing grid transmission losses and material costs. Generally speaking, the larger the installed capacity and the farther the transmission distance, the higher the transmission voltage. At present, the transmission voltage level of hydropower stations in my country is up to 750kV.
High-voltage power distribution devices are used to collect electric energy from the main transformer and send it to the power system through the outlet field. They mainly include three types of open power distribution devices, gas-insulated metal-enclosed switchgear (GIS) and hybrid power distribution devices. Since most hydropower stations are located in high mountain and canyon areas, the layout of high-voltage power distribution devices is often restricted. Therefore, GIS, which has the highest reliability and most compact layout but the highest cost, has become the first choice for high-voltage power distribution devices in hydropower stations in my country. Its highest voltage level has reached 800kV. The high-voltage lead-out lines of hydropower stations usually use high-voltage power cables or gas-insulated metal enclosed transmission lines (GIL).
The power system of the plant obtains power from the unit, power grid, etc., and provides electric energy to loads (points) such as power station unit operation, lighting, public equipment, and dam area electrical equipment according to the needs of power facilities. The grounding system is used to ensure the normal operation of the electrical system of the hydropower station and the safety of people and equipment. At present, the grounding system of the hydropower station makes full use of reservoir water, underwater steel structures and natural grounding bodies to reduce grounding resistance. The power system and grounding system of the plant are important guarantees for the safe, reliable and economical operation of the hydropower station. Their equipment and wiring are widely distributed in various parts of the hydropower station.
