Model predictive control method for voltage source rectifier when grid voltage is unbalanced

Abstract

A model prediction control method for a voltage source-type rectifier when the voltage of a grid is unbalanced, comprising: (1) three-phase grid voltage and current are converted via abc / αβ coordinates into grid voltage and current in a two-phase static coordinate system; (2) a positive and negative sequence coordinate separation is performed on the grid voltage in the two-phase static coordinate system to acquire a positive sequence voltage and negative sequence voltage of the grid; (3) an active power reference value is calculated; (4) a current reference value of the rectifier in the two-phase static coordinate system is calculated; and, (5) a model prediction current control is performed to select the optimal switch state. The method, while ensuring rapid and accurate tracking of a current in two phases of static coordinates, effectively eliminates voltage fluctuations at an alternating current side, and improves the quality of electric power of the system.

Description

technical field [0001] The invention relates to a control method of a voltage source rectifier under unbalanced grid voltage, belonging to the field of power converter control. Background technique [0002] The voltage source pulse width modulation rectifier has the advantages of sinusoidal grid side voltage, unit power factor, bidirectional energy flow and constant DC voltage control, and can realize "green conversion" of electric energy. Power compensation, new energy (such as solar energy, wind power) and other fields have broad application prospects. The advantages of the above-mentioned rectifier are realized by using the double-closed-loop linear control strategy and nonlinear control strategy of the current inner loop and the voltage outer loop under the assumption that the grid voltage is balanced. However, in engineering practice, the voltage source rectifier works in an unbalanced state (such as unbalanced amplitude and phase, voltage drop, parameter unbalanced, e...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the existing problems of voltage source rectifier control when the grid voltage is unbalanced, and to provide a simple and easy-to-implement model predictive current control method for enhancing DC side voltage stability control, which can ensure fast and accurate current control under static coordinates While tracking, effectively eliminate the fluctuation of the DC side voltage and improve the power quality of the system; at the same time, realize the reliable grid-connected operation of the voltage source rectifier when the transient grid voltage is unbalanced, and improve the dynamics and stability of the entire system

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