Control method for three-phase PWM rectifier suitable for power grid waveform distortion

Abstract

The invention discloses a control method for a three-phase PWM rectifier suitable for power grid waveform distortion. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion mainly includes that extracting a current reference signal under input voltage distortion and unbalanced disturbance, and actively injecting negative-sequence current, improved dead-beat inner current loop which is forecast through combining with linear extrapolation, and outer direct voltage loop performed with active disturbance rejection control. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion plays roles of inhibiting the harmonic wave of the input current of the PWM rectifier, injecting proper negative-sequence current to eliminate the secondary power pulse of the output direct current voltage of the PWM rectifier, improving the transient response of the output direct current voltage, and compensating the influences of all kinds of delay on the dead-beat control. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion is capable of obviously reducing the secondary wave of the output direct current voltage under the disturbance of the input harmonic wave and unbalanced voltage, improving the transient response speed of the PWM rectifier, reducing the transient offset of the direct current voltage, and improving the system control precision.

Description

technical field [0001] The invention relates to the control field of a three-phase PWM high power factor rectifier, in particular to a control method for a three-phase PWM rectifier suitable for grid waveform distortion. Background technique [0002] With the development of power electronics technology, PWM rectifier technology has become increasingly mature, and the main circuit of PWM rectifier has developed from the early half-controlled device bridge to today's fully-controlled device bridge; its topology has changed from single-phase and three-phase circuits Developed to multi-phase combination and multi-level topology circuits. Due to the widespread use of diode uncontrolled rectification circuits or thyristor phase-controlled rectification circuits in conventional rectification links, a large amount of harmonics and reactive power are injected into the grid, which reduces the power factor and causes serious grid "pollution". In order to solve the problem of harmonics...

AI Technical Summary

Problems solved by technology

[0004] However, the power grid sometimes appears in an unbalanced state. Once the power grid is unbalanced, the PWM rectifier designed with the three-phase power grid balance as a constraint will appear in an abnormal operating state, which is mainly manifested in: the DC side voltage and grid side current of the PWM rectifier. The amplitude of low-order harmonics increases, and non-characteristic harmonics are generated, and the loss increases accordingly; the current on the side of the PWM rectifier is also unbalanced, and in severe cases, the PWM rectifier may fail, or even burn out the device

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