A three-phase photovoltaic grid-connected inverter control device

Abstract

The invention discloses a control device of a three-phase photovoltaic grid-connected inverter. A direct-current component suppression circuit is additionally arranged in an existing three-phase photovoltaic grid-connected inverter system, direct-current components of two path voltages in output voltages of three inverter bridge arms can be obtained by carrying out difference sampling and filtering on three-phase inverter bridge arm midpoint high-frequency PWM signals, and the two paths of direct current components are respectively adjusted by a direct-current component controller and converted by a rotating coordinate system to obtain controlled quantities of the direct current components on the rotating coordinate system. The two controlled quantities of the direct current components on the rotating coordinate system are loaded to the output end of a controller of an electric current loop dq of a grid-connected control circuit module to carry out closed loop negative feedback adjustment so as to eliminate the direct-current components in the output voltages of the three-phase grid-connected inverter, and the aim of suppressing the direct-current components in three-phase grid-connected currents to be zero is achieved. The control device is simple in structure and convenient to achieve, the characteristics of the original system are kept, and grid-connected direct current injection currents of the grid-connected inverter are eliminated.

Description

technical field [0001] The invention belongs to the technical field of new energy grid-connected power generation, and in particular relates to a DC component control device for a three-phase photovoltaic grid-connected inverter. Background technique [0002] Solar photovoltaic power generation is one of the hotspots that have attracted much attention today, especially with the world's energy crisis, it has attracted more and more attention and development from all countries. Solar photovoltaic grid-connected power generation system is mainly composed of DC power supply, grid-connected inverter and grid. The DC power supply is mainly a photovoltaic cell array module, and the grid-connected inverter is the interface between the DC power supply and the grid, and is the core of energy conversion and control of the photovoltaic system. [0003] Grid-connected inverter According to whether the output is equipped with an isolation transformer, the photovoltaic grid-connected syst...

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Problems solved by technology

[0010] The object of the present invention is a three-phase photovoltaic grid-connected inverter control device, to suppress the DC component in the grid-connected current output by the grid-connected inverter, and solve the problem of large volume, large power consumption and high cost of the power frequency isolation transformer system The problem

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