Optimal Controller Design for Inverter-Based Microgrids

This paper presents a comprehensive control scheme for inverter-based distributed generations (DGs) in grid-connected microgrids (MGs). The proposed control strategy regulates active and reactive power of DGs in order to adjust output voltages of the DGs under balanced/unbalanced loading and fault conditions. In this paper, an adaptive hyper-plane sliding mode controller is developed for positive and negative sequences of active and reactive power in dq0 reference frame based on quasi-dynamic phasor. All the parameters of controllers are derived via particle swarm optimization algorithm in order to minimize an appropriate cost function. This controller is fast, stable and robust against uncertainties of the output filter of the inverter, variations of the network parameters and load disturbances. In addition, the fault ride-through capability of the system can be improved. In the presence of unbalanced loads and faults, output voltages the DG are controlled to remain balanced and unchanged. Performance of the proposed controller is compared with a conventional PI controller and a conventional sliding mode controller. Effectiveness and accuracy of the proposed control strategy are verified through simulating a test microgrid in the presence of unbalanced loads and some faults.