A Hybrid Fuzzy-Predictive Control for Smooth Transition Between Operating Modes of Voltage Source Inverters

Inverter-based distributed generations (DGs) have arisen as an efficient answer for the exploitation of renewable energies. In addition to regular power generation in the grid presence, DG systems must satisfy local loads during main grid outages. Hence, their inverters need to be able to operate in both grid-connected and islanded modes. These systems operate as current sources in grid-connected mode and as voltage sources for the load in islanded mode. The transition between operational modes might contort the voltage or current waveforms due to the mismatch between the inverter voltage and the grid voltage. Therefore, a comprehensive control method is required for smooth transitions without abrupt changes and distortions. In this paper, a hybrid fuzzy-predictive control strategy is presented, which leads to improved inverter dynamic behavior in transitions. This improvement has been measured using various control criteria in the simulations. The suggested control method mitigates total harmonic distortion (THD), enhances steady-state error, and reduces the overshoot/undershoot of the inverter time response.