Basic knowledge of Substation

Substation

 

Power is transmitted through a power transformer. In the power system, the process of transforming the voltage from low level to high level (step-up) or from high level to low level (step-down) through certain equipment. Generally, the rated voltage of generator in power system is below (15-20) kV. The commonly used transmission voltage grades are 765kV, 500kV, 220kv-110kv, 35kv-60kv, etc.; the distribution voltage grades are 35kv-60kv, 3kv-10kv, etc.; the electrical appliances of the electrical departments have high-voltage electrical equipment with rated voltage of 3kv-15kv and low-voltage electrical equipment such as 110V, 220V, 380V, etc. Therefore, the power system is to connect different voltage levels to form a whole through power transformation. Substation is the place to realize the transformation.

 

Distribution principle

 

In the power system, the power plant transforms the natural primary energy into electric energy, and delivers power to the remote power users. In order to reduce the electric energy loss and the line impedance voltage drop on the transmission line, it needs to increase the voltage; in order to meet the safety needs of the power users, it needs to reduce the voltage and distribute it to each user, which requires that it can increase and reduce the voltage and distribute the power transformation. Electricity. Therefore, substation is an electrical device in the power system to transform voltage, receive and distribute electric energy. It is the intermediate link between the power plant and the power users. At the same time, it connects the power grid of each voltage level through the substation. The role of substation is to transform voltage, transmit and distribute electric energy. The substation is composed of power transformer, distribution device, secondary system and necessary auxiliary equipment.

 

Distribution device

 

Power distribution device is a device that all switching devices and current carrying conductor auxiliary equipment in substation are connected together. Its function is to receive and distribute electric energy. The power distribution device is mainly composed of bus, high-voltage breaker switch, reactor coil, transformer, power capacitor, lightning arrester, high-voltage fuse, secondary equipment and other necessary auxiliary equipment.

 

Secondary equipment refers to the equipment and devices for measuring, controlling, monitoring and protecting the primary system status. The circuit composed of these devices is called secondary circuit, which is called secondary system.

 

The equipment of secondary system includes measuring device, control device, relay protection device, automatic control device, DC system and necessary auxiliary equipment.