Optimal Control of BESS in Microgrid for Islanded Operation Using Fuzzy Logic

The micro grid operates in grid-connect mode, but, when a fault occurs in the upstream grid, it should disconnect and shift into islanded operation mode. In grid-connect mode, the controlling power at the PCC(Point of Common Coupling) is necessary management function rather than the frequency and voltage. However, the controlling the frequency and voltage is asked in islanded mode. To achieve these management goals appropriately, the coordinated control strategy between Diesel generator and BESS(Battery Energy Storage System) is needed. This paper presents PI Controller that is used as BESS charge and discharge process in Micro grid for islanded operation. Most PI Controllers have fixed PI gains, but real-time updated gains are applied to PI Controller using Fuzzy logic in this paper. The performance of suggested PI Controller was simulated by PSCAD/EMTDC. As a result, output characteristic of BESS applied real-time updated gains to PI Controller using Fuzzy logic is faster and more accurate than using fixed gains.