Research of Control Strategy of Dynamic Voltage Restorer

Dynamic voltage restorer is a device with effective suppression of impact of voltage sag on sensitive load. When dynamic voltage restorer is working in asymmetric voltage, the inverter will continue to absorb active power from the supply side, trigger DC voltage rise, even damage energy storage and power switching devices in severe situation. For the problem, the paper proposed a composite control strategy, which uses phase shift control technology to reduce active power absorbing of the inverter, so as to suppress the rise of DC voltage of dynamic voltage restorer, and uses double closed loop control to suppress voltage sag of power grid to improve load stability. Simulation results showed that the composite control strategy allows the dynamic voltage restorer with better load adaptability, and makes the DC voltage well suppressed.