Abstract
UDC 621.314.572
DOI https://doi.org/10.52577/eom.2025.61.3.61
This article discusses the features of the synchronous regulation of inverter blocks of two topologies of the transformer-based photovoltaic installations based on two and three three-phase voltage source inverters operating in a specific over-modulation zone characterized by increased, close to maximum values, modulation indices of inverters. It is shown that, in the case of a two-range inverter control strategy in the over-modulation mode, the modified algorithms of a synchronous pulse-width modulation, including the use of specialized correction coefficients for each sub-range of the over-modulation zone, allowed for the continuous synchronization and symmetry of the basic voltage waveforms on the inverter-side windings of the power transformer of photovoltaic systems throughout the entire inverter over-modulation zone. The results of modeling the processes in the systems confirm the fact of the absence of harmonic components of even-order and subharmonics (of the fundamental frequency of photovoltaic stations) in the spectra of the basic voltages of the analyzed photovoltaic installations over the entire range of two-stage regulation of inverters in the over-modulation zone. Such an improvement in the harmonic composition of the basic voltages leads to a decrease in losses and an increase in the efficiency of the functioning of photovoltaic installations based on inverters with synchronous modulation, which is especially important for high-power systems characterized by a relatively low switching frequency of the power switches of the inverters.
Keywords: three-phase voltage inverter, synchronous pulse-width modulation, photoconverter installation, multi-winding power transformer, harmonic composition of voltage.