A Coordinated Optimal Feedback Control of Distributed Generators for Mitigation of Motor Starting Voltage Sags in Distribution Networks

This article proposes a coordinated optimal feedback control approach to mitigate the induction motor starting voltage sag and support the transient restoration in distribution networks. The proposed technique is expected to reduce the starting high current to maintain the network voltage using neighboring voltage supporting distributed generation. An optimal feedback-based coordinated controller (CC) has been designed to estimate the reactive power to be injected at different locations of the network based on the motor loads. The CC on top of the existing local controller (LC) uses motor voltage feedback signals, thereby adjusting the reactive power support based on the voltage sag. The proposed voltage sag mitigation strategy is tested in both 12.4 kV network and 123 bus larger distribution networks containing single and multiple motor and distributed generation units. From simulation results, it is revealed that the proposed coordinated optimal feedback control of VSDGs can provide a fast restoration of the motor starting transient voltage dip.