Method for suppressing output harmonic wave and direct current component of single-phase grid-combined photovoltaic inverter

Abstract

The invention relates to a method for suppressing an output harmonic wave and a direct current component of a single-phase grid-combined photovoltaic inverter. In the invention, an original voltage and current detection device and a digital controller in a photovoltaic grid-combined generation system are utilized, and the controls to the Boost circuit duty ratio and an inverter are increased on the basis of an original control algorithm. A phase current signal output by the inverter is subjected to single-phase conversion, actually output current is compared with a reference value, and a difference value is subjected to PI regulation to obtain a voltage control command of a fundamental wave and a harmonic wave; a direct current component detection value obtained by calculating the phase current signal and a given calibration currents difference value are processed to obtain a direct current component suppression voltage command; and after a control command of instantaneous fundamentalwave voltage, a control command of instantaneous harmonic wave voltage and the direct current component suppression voltage command are added and processed to obtain a control command used for the inverter. The invention realizes the control of the active and reactive current of the inverter, the elimination of the designated harmonic wave and the suppression of the direct current component and can effectively improve the electric energy quality of the grids.

Description

technical field [0001] The invention relates to the field of inverter control, in particular to a method for suppressing output harmonics and DC components of a single-phase grid-connected photovoltaic inverter. Background technique [0002] With the improvement of people's living standards and the technological progress of society, electric energy has become the energy that people must rely on in their daily lives. However, the primary energy sources such as coal and oil are decreasing day by day, and when people use them, they also cause huge pollution to the environment. The fundamental way to solve the energy problem is to develop environmentally friendly renewable energy, among which solar power generation is an important development direction. [0003] As the scale and capacity of photovoltaic grid-connected power generation continue to increase, its impact on the power quality and stable operation of the grid is becoming more and more obvious. Strict standards have ...

AI Technical Summary

Problems solved by technology

Another simplest way to suppress the DC component is to connect a power frequency transformer between the grid-connected inverter and the grid, but it is bulky, consumes a lot of power, and is expensive

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