Stochastic Optimal Power Flow for Islanded Microgrids Considering Droop Control

Abstract

Renewable power generators such as photovoltaic panels penetrate fast in islanded microgrids where micro-turbines can provide droop control to keep the system reliable and stable. However, renewable power generation is highly intermittent and uncertain, impairing microgrid operation. To address the uncertainty issue, this paper proposes a stochastic optimal power flow (OPF) approach for islanded microgrids considering droop control of the micro-turbines. In this OPF, micro-turbine generation set points are optimized to minimize the total operating cost while keeping operating constraints. Moreover, frequency and voltage droop control functions of the micro-turbines are modeled in the OPF. Monte Carlo sampling and a backward reduction method are applied to generation scenarios which model uncertainty realization in stochastic optimization formulation. Accordingly, a solution algorithm based on the backward forward sweep algorithm is developed to solve the proposed stochastic OPF problem. The proposed stochastic OPF is tested on an islanded microgrid system with real-time uncertainty realization simulation and the results show high operation reliability under the uncertainties.