ЗАБЕЗПЕЧЕННЯ ВІДПОВІДНОСТІ СТАНДАРТАМ ЯКОСТІ СТРУМУВ ТОЧЦІ ПІДКЛЮЧЕННЯ ДО МЕРЕЖІ КОМБІНОВАНОЇ СИСТЕМИЕЛЕКТРОЖИВЛЕННЯ З ФОТОЕЛЕКТРИЧНОЮ БАТАРЕЄЮ

Abstract

The issue of ensuring compliance with the AC network current quality standard at the point of connecting a local object with a photovoltaic system in the case of non-linear load and nonsinusoidal voltage when using a multifunctional grid inverter is considered. In this case, the values of higher harmonics allowed by the standard for the voltage quality of general-purpose networks were taken into account. To reduce the corresponding current harmonics generated by the filter capacitor at the point of connection to the network, the use of an output LCL filter is considered, which allows to reduce the capacitance of the capacitor. It is proposed to implement this in combination with the compensation of the higher harmonics of the capacitor current by an inverter. The structure and definition of the parameters of power circuits and voltage at the inverter input with non-sinusoidal grid voltage are substantiated. The structure of the control system has been improved with the introduction of a communication line for the current of the capacitor of the output filter into the channel for forming the inverter current reference, and the parameters of the inverter current control loop are determined. At the same time, a filter is introduced into the circuit of the capacitor current signal to suppress of currents of modulation harmonics generated by the inverter. A model of the system "network - inverter - load" with the definition of power losses in the inverter keys in the case of sinusoidal and non-sinusoidal voltage is developed. This made it possible to clarify the parameters of the grid inverter. The simulation results confirm the possibility of providing a THD value of ≤5% in almost the entire range of the grid current change in the presence of one voltage harmonic, as well as a combination of voltage harmonics.