Multi-Objective Coordinated Planning of Active-Reactive Power Resources for Decentralized Droop-Controlled Islanded Microgrids Based on Probabilistic Load Flow

The intermittency of distributed generation and the fluctuation of load will derive uncertainties to the decentralized droop-controlled islanded microgrids (IMGs) operation. In order to describe and analyse the probabilistic characteristics of the operating state of an IMG, this paper proposes an analytical method based on cumulants to solve the probabilistic load flow (PLF) for decentralized droop-controlled IMGs, considering the correlation of input variables. Nataf transform is used to deal with the correlation, and the PLF is solved using the cumulant method and the Gram-Charlier series expansion. On this basis, a multi-objective coordinated planning model of active-reactive power resources is presented, considering the annual comprehensive cost and operating risk simultaneously. The Pareto optimal solution set is found using non-dominated sorting genetic algorithm-II to provide a set of alternative planning schemes. The proposed PLF based on cumulant method is compared with Monte Carlo simulation to verify its accuracy and efficiency. Besides, the simulation results also demonstrate that the proposed coordinated planning model of active-reactive power resources can coordinate the security and economy of the IMG operation.