Stability Constrained Optimal Operation of Inverter-Dominant Microgrids: A Two Stage Robust Optimization Framework

Abstract

To mitigate the stability issues in the droop-controlled isolated microgrids brought by aleatory renewable energy sources (RESs), which can be added at any given time, this paper proposes a two-stage robust coordination strategy to optimize the operation of multiple flexible resources. In the first stage, a day-ahead unit commitment (UC) schedule of microturbines(MTs) is formulated considering the uncertainty of RESs and loads. In the second stage, an hourly power dispatch and droop gains adjustment scheme for the energy storage devices are developed to minimize the operation cost and ensure the small signal stability. An adaptive column and constraint generation (C&CG) algorithm is developed to solve the stability-constrained two-stage robust optimization problem. Simulation results on a 33-bus microgrid system reveal that compared to benchmarking approaches, the proposed coordination strategy is able to guarantee the small-signal stability with lower cost. And a sensitivity analysis validates the robustness of the methodology against the uncertainties of RESs.