A New Distributed Voltage Controller for Enabling Volt-Var Support of Microgrids in Grid-Connected Operation

Voltage support is one of ancillary services that can be provided by grid-connected microgrids. This paper presents a new microgrid-level voltage controller to enable microgrids to contribute to distribution system voltage regulation. Like the Volt-Var droop control of the smart inverters, the proposed controller makes sure that the voltage and reactive power flow at microgrid point of common coupling (PCC) follows a proportional relationship. To increase flexibility and avoid centralized computation, a distributed controller design is developed using the distributed averaging algorithm in order to achieve reactive power sharing among multiple distributed energy resources (DERs) within the microgrid. A large signal analysis is performed to study the stability and dynamic characteristics of the closed-loop system. Simulation results show that the proposed controller is effective in providing voltage regulation for distribution systems with multi-microgrid architecture.