Power capacitor is divided into series capacitor and parallel capacitor, which can improve the voltage quality of power system and the transmission capacity of transmission line, and is an important equipment of power system. There are many kinds of power capacitors, which can be divided into indoor type and outdoor type according to the installation mode; low voltage and high voltage according to the rated voltage of operation; single phase and three-phase according to the number of phases; metal shell, porcelain insulation shell, plastic wooden shell and so on according to the shell material. The functions of power capacitor are as follows:

1. In the transmission line, the power capacitor can be used to form a series compensation station to improve the transmission capacity of the transmission line.

2. In large-scale substation, power capacitor can be used to form SVC to improve power quality.

3. At the end of the distribution line, power capacitor can improve the power factor at the end of the line and ensure the voltage quality at the end of the line.

4. The power capacitor installed in the middle and low voltage buses of the power station can compensate the reactive power consumed by the load and improve the power factor of the bus side.