A Coordinated Control Approach for Mitigation of Motor Starting Voltage Dip in Distribution Feeders

This paper proposes a control approach to mitigate three phase induction motor (IM) starting voltage sag. The proposed technique reduces the starting inrush current and restores the network voltage quickly back to normal values using neighboring voltage supporting distributed generation (VSDG). For the controller design, an analytical model of the system has been developed to estimate the magnitude of voltage sag at different locations of the network. Then an approach to coordinate multiple VSDG's local control is proposed using feedback signals and subsequent gain adjustment for the PI controller. The proposed voltage sag mitigation strategy is tested in both MV (11kV) and LV (400V) networks. It has been shown that in MV networks, VSDG can restore the motor starting transient voltage dip quicker than a voltage regulator or an on-load tap changer (OLTC). In LV networks, DG can quickly recover voltage without the need for any voltage regulating devices.