Plug-in direct multi-swarm repetitive controller for the sine wave inverter — On keeping particles diversified in a dynamic and noisy environment

The paper discusses selected modifications to a constricted, i.e. canonical, version of the particle swarm optimizer (PSO) enabling effective operation of a repetitive controller. The recently developed plug-in direct multi-swarm repetitive controller (PDMSRC) for the sine wave constant-amplitude constant-frequency (CACF) voltage-source inverter (VSI) with an output LC filter serves as a case study. Online dynamic optimization problems (DOPs), i.e. those solved without switching into some sort of offline/commissioning mode, impose restrictions that are challenging for population-based optimization techniques. In the PDMSRC samples of the control signal are directly stored in the particles. Solutions available for swarms operating in dynamic and noisy environments are briefly discussed and candidates for the PDMSRC are indicated. Geometric versus statistical and cumulative versus dimension-wise diversity measures are tested. The advantages of replacing the frequently used non-dimension-wise repulsion with a dimension-wise mechanism are demonstrated here. The effectiveness of the proposed approach is illustrated with the help of numerical experiments.