Power quality improvement of microgrid fed electric ship using fuzzy controlled multi-pulse/multi-level converter-based VFD

This paper investigates a harmonic mitigation technique for modern electrical propulsion ships (EPS) microgrids (MG) using a fuzzy controlled multi-pulse rectifier (MPR) and multi-level inverter (MLI)-based variable frequency drive (VFD). In this paper, the proposed MPR-MLI-VFD system is studied using different-pulses rectifiers and different-level inverter-based VFD to achieve proper mitigation of the harmonics in the main generating power system of the ships within the marine classification society's limitations for harmonics. This is achieved using a proposed low harmonic multi-pulse rectifier based on zigzag transformers. Moreover, the voltage harmonic distortions at propulsion motor feeder buses are minimised using the proposed MLI. A simple fuzzy logic control system is proposed for the VFD speed control. The voltage balancing control system for the diode clamped multi-level inverters is implemented using a fuzzy control system. MATLAB/Simulink is used for the simulation and validation process.