Multifrequency single-phase islanded grids

Islanded grids operate isolated from the main grid and they allow the use of ac with a different frequency from the main grid. In this paper, it is proposed to use more than one frequency at the same time in such autonomous systems. The grid voltage amplitude at the fundamental frequency can be increased while the voltage peak is constant by adding odd harmonics to the voltage waveform. The grid currents and the power converter currents are decreased for the same power level, which leads to reduced losses in the system. The currents can be minimized if waveform shaping is additionally applied to the current waveforms. The approach also offers the possibility of mitigating the influence of low power factor in single-phase systems. This paper presents the impact of multifrequency power transfer on single-phase converters and grid components such as power cables and protection, and verifies the results with analysis, simulations, and experiments.