Distributed online optimal power flow for distribution system

Abstract

This paper proposes a distributed online OPF algorithm for distribution systems with high integration of electronic-interfaced distributed energy resources (DERs). The algorithm can coordinate the update of DER set-points on fast time scales only depending on local measurements and boundary information for each distribution area. Comparing with the existing distributed online algorithms that require some special setups (e.g., without considering the constraints on currents), the proposed algorithm can cope with various setups for the objective functions and constraints. The algorithm is based on solving the Taylor approximations of OPF problems by a distributed solution. In this solution, we design a strategy to formulate the second-order Taylor information in a distributed way by decomposing the sensitivities of the OPF targets among different areas; moreover, we design a method to simplify the constraints on DER outputs to accelerate the solution. The validity of the algorithm is verified by case studies, which show that it can continuously drive DER outputs towards the time-varying OPF targets composed of power losses and operation costs of DERs while satisfying the constraints on voltages and currents.