Multi-agent Coordination of DG Inverters for Improving the Voltage Profile of the Distribution Grid

Increasing penetration of distributed energy sources in distribution grids also introduces certain challenges, including regulation of voltages in the distribution system, particularly voltage rise issues in cases of low load and high generation. This paper proposes a methodology to achieve cooperation between the inverters that interface the DG units to the grid, so that the voltages across all the nodes of the distribution system maintain an acceptable profile. Each node in the distribution system acts as an agent, measuring its deviation from nominal voltage. Subsequently, all the nodes engage in a multi-agent consensus algorithm, to share their measurements. The algorithm is decentralized, and each node needs to communicate exclusively with its neighboring nodes. Utilizing the feedback of the observed total deviation of all the nodes from their desired voltage, each inverter adjusts its local reactive power injection, through a local PI controller. Control design of the local reactive power controller is also discussed in this work. Simulation results for the IEEE 123-node test feeder verify that the approach results in significantly improved voltage profile compared to the unity power factor control and it addresses the issue of voltage rise in the distribution grid by utilizing each unit's reactive power margin.