Distributed Voltage Control for Network-level Optimization in Radial Power Distribution Systems

Effective management of variable power generation from distributed energy resources (DERs) in the power distribution systems requires new methods for voltage control and network-level optimization. In this paper, we propose a feedback-based distributed voltage control algorithm for smart inverters with the objective of minimizing the network power loss while maintaining the node voltages within the pre-specified operating limits. Each smart inverter requires solving a simple algebraic equation based on local measurements and communication with its physical neighbors. An analytical closed-form solution is obtained to update the decision variable, i.e., the reactive power dispatch from the smart inverters. The solution is then projected onto the feasible power flow space. The proposed method is validated using IEEE 13-bus and 123-bus test systems. Further, the proposed real-time control algorithm is compared against the optimal power flow methods based on centralized coordination and nonlinear programming. It is shown that the proposed algorithm is effective in reducing the line losses and maintaining the voltages within the operational limits irrespective of the DER generation variability.