Reactive power compensation is called reactive power compensation. It plays a role in improving the power factor of the power grid in the power supply system, reducing the loss of the power supply transformer and the transmission line, improving the power supply efficiency, and improving the power supply environment. Therefore, the reactive power compensation device is in an indispensable and important position in the power supply system. Reasonable selection of compensation devices can minimize the loss of the power grid and improve the quality of the power grid. Conversely, if selected or used improperly, it may cause many factors such as power supply system, voltage fluctuation, harmonic increase and so on. Most of the electrical loads in the power grid, such as electric motors and transformers, are inductive loads, and corresponding reactive power is required to be supplied to these devices during operation. After installing a reactive power compensation device such as a parallel capacitor in the power grid, the reactive power consumed by the inductive load can be provided, and the reactive power supplied by the power supply to the inductive load and transmitted by the line can be reduced, because the reactive power is reduced in the power grid. The flow, therefore, can reduce the power loss caused by the transmission of reactive power of the line and transformer, which is reactive power compensation.