Abstract:

Aimed at the voltage sag compensation of sensitive loads,this paper proposed a DC type voltage sag protector (VSP) and its optimal control method.The super capacitor is used as the energy storage unit,and a bidirectional DC-DC is used to realize voltage sag compensation and super capacitor charging,which improves the efficiency and power density of the VSP.The optimized control method based on DC bus detection proposed in this paper does not need to detect the AC side,which greatly simplifies the control method and further improves the response speed and reliability.The method is applied on a 200 kW VSP prototype which is used on an adjustable speed drive (ASD) of a factory.The operation results show that the control method can response within 1ms,and the effect is obvious.

Key words: voltage sag, bidirectional DC-DC converter, super capacitor, optimized control method