Substation: What does the substation include?
The transformer is the main technical equipment of the substation. It consists of dual windings through transformers, three-winding transformers, and automatic control transformers (that is, the high-voltage and low-voltage systems share a fairly large winding, and a head enterprise can be drawn from the middle of the high-voltage winding. Outgoing transformer for low voltage winding). The voltage is proportional to the winding composition, and the current is inversely proportional to the winding composition.
Transformers can be divided into step-up transformers, step-down transformers and transformers according to their functions. The former is used in the transmission side substation of the power system, and the latter is used in the receiving side substation.
According to the split joint switching method, the transformer has a load-carrying and non-loaded voltage regulating transformer and a non-loaded regulating transformer.
The working mode of voltage transformer and current transformer is similar to that of transformer. In rated operation, the secondary voltage of the voltage transformer is 100V, and the secondary current of the current transformer is 1A. The secondary winding of the current transformer is often close to short-circuit with the load. Can't open the way. Otherwise, the high voltage will endanger the equipment and personal safety, or burn the current transformer.
Substation switch equipment includes circuit breakers, isolating switches, load switches, high-voltage fuses, etc. The circuit breaker is used to close and disconnect the circuit when the power system is working normally. When a fault occurs, under the control of the relay protection device, the fault device and circuit can be automatically disconnected, and the automatic reclosing function can be used.
The main function of the isolation control switch (knife switch) is to isolate the working voltage when the equipment or circuit is maintained to ensure information security. The load current and short-circuit current cannot be separated, so it needs to be used with a circuit breaker. When the power fails, pull the circuit breaker first, then pull the isolating switch. When supplying power, the isolating switch must be combined first, and then the circuit breaker must be closed. Improper operation may cause equipment damage and personal injury.
The load switch of the substation can separate the load current during normal operation, and has no ability to separate the fault current. It is usually used with a high-voltage fuse for a voltage above 10kV, and is used for a transformer or solid line that does not work frequently.
In order to reduce the occupied area of the substation, sulphur hexafluoride totally enclosed combiner (GIS) is widely used. The combination of circuit breaker, isolating switch, bus, grounding switch, and transformer is small in size, unaffected by atmospheric conditions, and has long maintenance intervals. With the advantages of electric shock accidents and electrical noise interference, 765KV has been put into use in the substation before power generation.
