Power quality improvement for microgrid-connected PV-based converters under partial shading conditions using mixed optimisation algorithms
Swati Suman, Debashis Chatterjee, Rabindra Mohanty
Abstract
This paper outlines a method to reduce harmonic injection for PV-based distributed generation units using search-based optimisation techniques. The motivation to design such a scheme is due to the difficulty of keeping the DC bus and output voltage constant under partial shading conditions (PSCs) with a single boost converter. Novel series compensation supported by the auxiliary unit has been introduced to highlight new aspects in this area. Selective harmonic elimination pulse width modulation (SHEPWM) is used to selectively choose the order of harmonics to be removed and keep a check on the other harmonics within specified ranges. The metaheuristic technique fetches five optimised switching angles for driving inverters, and an auxiliary inverter is used to mitigate lower and higher order harmonics as well as regulate the wide voltage variation on the grid side using novel series compensation. These angles were preserved in processor memory for an online application using the 'piecewise mixed model of approximation'. The THD obtained was 1.48%. The proposed method has been modelled in MATLAB/Simulink and verified experimentally in a practical PV system. The cuckoo search and proposed IPSO have outperformed in terms of MPP tracking under PSC and harmonic reduction, respectively. The proposed scheme was simple yet efficient in terms of power quality, easier computation, and faster tracking of maximum power point (MPP).