Reactive Power Support in Medium Voltage Networks by Coordinated Control of Distributed Generators in Dispatchable Low-Voltage Microgrid

Abstract

This paper proposes a strategy to coordinate distributed generators in low-voltage micro-grids to support its medium-voltage point-of-common coupling (PCC) with reactive power. The well-known voltage–reactive power function (volt–var) is applied directly at the PCC by a master controller. This approach enables this system to contribute with reactive power support to the medium voltage network as conventional capacitor banks that are switched on and off depending on the load/voltage profile. The power-based control strategy is used to coordinate the distributed generators in the microgrid in order to regulate the active/reactive power injection and ancillary services, which allows the active and reactive power flow at the PCC to be controlled according to the need of the distribution system operator. Simulation results based on a typical urban three-phase low-voltage network show that this method enables the microgrid to operate as a single-controllable entity, regulating the voltage and increasing the capacity of the medium voltage network to transfer active power.