In power grid, voltage quality is closely related to reactive power compensation. Reasonable configuration of reactive power compensation device can improve the voltage quality. The reactive power compensation device improves the voltage quality by reducing the voltage loss in the line. The reactive power compensation device can reduce the electricity cost of power users by increasing the power factor, which can significantly achieve the economic benefits of power users. At the same time, the cost of power generation, power supply and power consumption is high, and the quality of power supply is poor. To a certain extent, it is also due to the low power factor of power users, which consumes more reactive power. Reactive power compensation device can improve all this.