Model prediction control method of voltage source type rectifier when network voltage is unbalanced

Abstract

The invention belongs to the field of power converter control and relates to a model prediction control method of a voltage source type rectifier when a network voltage is unbalanced. The model prediction control method of the voltage source type rectifier when the network voltage is unbalanced comprises the steps of converting three-phase network voltage and a three-phase current into network voltage and a current which are under a two-phase static coordinate system through an abc / alpha beta coordinate, obtaining network positive sequence voltage and negative sequence voltage by carrying positive and negative sequence component separation of the network voltage under the two-phase static coordinate system, calculating reference values of active power, calculating current reference values of the rectifier under the two-phase static coordinate system, and carrying out model prediction current control and selecting an optimal on-off state. The model prediction control method of the voltage source type rectifier when the network voltage is unbalanced is capable of quickly and precisely tracing the current under the two-phase static coordinate and effectively eliminating fluctuation of direct current side voltage at the same time, power quality of the system is improved, a reliable network-connected operation of the rectifier when transient state network voltage is unbalance is achieved, and dynamics and stability of the whole system are improved.

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...

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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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