Reduction of voltage harmonics using optimisation-based combined approach

Voltage harmonics elimination problem in a micro-grid consisting of different types of distributed generation systems is addressed. In the proposed scheme, harmonic elimination is achieved by providing optimisation-based technique to some distributed generation-connected inverters and the sine pulse-width modulation (PWM) technique to other inverters connected to same micro-grid system. The lower order harmonics are eliminated with the help of particle swarm optimisation-based selected harmonic elimination technique applied to the PWM inverters. The higher order harmonics present in the micro-grid voltage waveform will be reduced by the dominant harmonics of same order generated in opposite phase by sine PWM inverter. This is achieved by varying the phase angle of the carrier wave of the sine PWM inverter, which generates the dominant harmonics with sidebands very close to the amplitude of prominent voltage harmonics present in the system but in opposite polarity. The same is validated by simulation as well as by suitable experiments.