Waveform peak shaping by multi-frequency power transfer in internal, single-phase distribution systems

Internal distribution systems such as photovoltaic parks allow to use DC or AC with a frequency different from 50Hz. In this paper is instead proposed to use more than one frequency at the same time. The grid voltage amplitude at the fundamental frequency can be increased while the voltage peak value is kept constant by adding odd harmonics to the voltage waveform. The currents are decreased for the same power level which leads to reduced power converter losses. A further current reduction is achieved if waveform peak shaping is applied to the current waveforms. This paper presents the impact of multi-frequency power transfer on single-phase converters, and verifies the results with analysis and simulations. The impact of harmonic frequencies on cable losses due to the skin effect is taken into consideration in the analysis and effects on protection are discussed.