Harmonic injection type directly-driving wind electric converter

Abstract

Disclosed is a power unit of a harmonic injection direct-drive wind-power converter, comprising a rectifier circuit, a voltage booster chopper circuit and an inverter circuit. The rectifier circuit adopts three-phase bridge uncontrolled rectification mode; two controllable power tubes and two fast diodes are additionally arranged on the dc side to construct the dc voltage booster chopper circuit, so the voltage in dc link is controlled, and the energy is fed to grid under low wind speed through the voltage boosting on dc side. The inverter adopts three-phase half-bridge controllable output constructed by full-controllable power tubes. The neutral point of a voltage booster half bridge and a filter capacitor group is connected with the neutral point of a harmonic current injection circuit to provide a channel for the injection of zero-sequence current and ensure the high power factor rectification and input current to be sine, and avoid the power factor reduction of power generator and the oscillation of power generator torque.

Description

technical field [0001] The present invention relates to a wind power converter, in particular to a harmonic injection with a direct-drive structure, which can balance and control the DC link voltage, realize sinusoidal input current, and maintain energy fed to the power grid at low wind speeds. type converter. Background technique [0002] Along with the increasingly acute energy and environmental problems, the research on wind power generation technology has received unprecedented attention in the past two decades. As a big energy consuming country, our country's wind power industry has developed very fast in recent years, but our country's wind power technology, especially the technology related to wind power generator drive control and conversion, is still far from mature. Traditional large-scale wind turbines generally use pitch-controlled doubly-fed wind turbines, such as figure 1 As shown, including wind turbines, gearboxes, induction machines, PWM inverters and DC s...

AI Technical Summary

Problems solved by technology

However, the current converters that have been adopted have the following problems, such as the serious distortion of the current at the input side of the rectifier bridge, and the relatively large harmonic content, which reduces the power factor of the generator and oscillates the torque of the generator; the voltage on the DC side is also It is difficult to achieve balance control, and the fluctuation of capacitor voltage will definitely affect the overall output performance of the device

In addition, there is an insurmountable shortcoming, that is, the output voltage of the synchronous generator is low at low wind speed, and the energy cannot be fed back into the grid.

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