In the power supply system, on the one hand, nonlinear loads, such as static converters, industrial AC / DC converters, impact and fluctuating loads, such as electric locomotives, electric arc furnaces and large rolling mills, will not only produce a large number of high-order harmonics, but also make the voltage fluctuation, flicker and three-phase imbalance more and more serious, which will not only seriously affect the safety performance of the equipment, Moreover, it interferes with the economic operation of the power grid and causes public hazards; On the other hand, airports, banks, confidential electronic components manufacturing industry, computer networks and service monitoring centers are places with high power quality requirements. High precision equipment has an increasing demand for high-quality power. Therefore, it is very necessary to strengthen the monitoring and governance of power quality, whether considering the needs of power grid operation or the needs of users for power quality.

        The application of low voltage reactive power compensation device in power system mainly includes:

        ① System voltage control;

        ② Improve the static, dynamic and transient stability of the system, so as to improve the capacity of the transmission system;

        ③ Improve the damping of the system to power oscillation and subsynchronous oscillation;

        ④ Balancing of three-phase voltage;

        ⑤ Reduce temporary overvoltage;

        ⑥ Provide the required reactive power to the HVDC converter and implement voltage control.