Model predictive control-based smart impedance for harmonic load freewheeling

A novel smart impedance (SI) is introduced for load harmonics (distortion power) freewheeling in microgrids which are called predictive SI (PSI). 'PSI' provides solutions to the load harmonics conditioning, reactive power compensation, and parallel resonance suppression. The 'PSI' allows for harmonics, sub-harmonics, and inter-harmonics compensation with using only one control loop. The control model, which is used for the 'PSI' enables its impedance phasor variation in a wide and continuous range, including inductive and capacitive ones. The 'PSI' consumes small active power and can provide reactive power compensation without the need for a separate capacitor bank. The introduced 'PSI' does not generate parasitic harmonics and so does not need an additional passive filter in its output. The 'PSI' operates such as a harmonic isolator and only compensates for load harmonics and thereby prevents from the source side harmonics flowing into the load. It does not need the phased locked loop for synchronisation to the grid and can be designed for selective harmonic compensation if needed. A droop-boost control strategy is proposed for optimum and prioritised utilising of the SI capacity. At the end of the study, by using simulations in Matlab/Simulink, the figure of merits of the PSI are proved.