Novel coordinated secondary voltage control strategy for efficient utilisation of distributed generations

This study presents a novel coordinated secondary voltage control (CSVC) and reactive power management scheme for efficient utilisation of distributed energy resources in a smart distribution network. The proposed controller is developed to achieve efficient voltage regulation and to maximise the dynamic reactive power reserve in a distribution network to react during system contingencies. The simulated distribution system, including an on-load tap changer (OLTC) and distributed energy resources, is implemented using PSCAD/EMTDC. The CSVC is designed to provide slow and medium speed responses, using low-pass filters for OLTC and diesel generators, respectively, and a fast response by utilising inverter-based distributed energy resources. Therefore it applies a control strategy with different bandwidth dedicated by the decentralised voltage controllers and reactive power management scheme. The CSVC is used to enhance the bus voltage control by utilising the reactive power loading capabilities among distributed energy resources and on-load tap changers of the substation transformer. A comprehensive simulation has verified the superior performance of the proposed coordinated secondary voltage control with the reactive power management scheme for enhancing the voltage profile and the fault ridethrough capability, ensuring higher dynamic reactive power reserves in a distribution network, and improving the transient stability margin.