Development of Economic and Stable Power-Sharing Scheme in an Autonomous Microgrid with Volatile Wind Power Generation

This article investigates the problem of economic and stable power sharing in an autonomous microgrid including a variety of dispatchable distributed energy resources and wind turbine generator. To minimize the operational cost of the microgrid considering the nature volatile of wind power generation, the frequency-droop coefficient of each dispatchable distributed energy resource dispatchable distributed energy resource should be properly scheduled to yield the desired power sharing among multiple dispatchable distributed energy resource dispatchable distributed energy resources. Also, it has previously been shown that the selection of frequency-droop coefficients has a significant effect on the small signal stability of the system. Consequently, a microgrid may suffer economic or stability degradation as variations in wind power generation and load demand if inappropriate frequency-droop coefficients are employed. This article therefore presents a detailed procedure of obtaining optimal frequency-droop coefficients of dispatchable distributed energy resources. The optimal droop coefficients of dispatchable distributed energy resources are obtained according to an optimization problem. The eigenvalue-based stability constraints are imposed on the objective function, in particular, to ensure that the microgrid system has a sufficient stability margin at all possible operation conditions. Particle swarm optimization is used to solve this problem. The simulation results show that the economy and stability of the microgrid can be improved significantly using the proposed method.