Method for obtaining balanced and non-distortion total output current of double-fed window power system under the condition of imbalanced harmonic-distortion grid voltage

Abstract

The invention discloses a method for obtaining a balanced and non-distortion total output current of a double-fed induction window power system with a series grid-side converter under the condition of an imbalanced harmonic-distortion grid voltage and relates to control over the series grid-side converter, a parallel grid-side converter and a motor-side converter. A voltage controller adopted by the series grid-side converter can achieve rapid restraint of the negative sequence of a stator, a fifth-harmonics voltage component and a seventh-harmonic voltage component, and therefore safe and stable operation of the motor is guaranteed. A reference current order of the parallel grid-side converter under a positive synchronous rotation coordinate axis system comprises the positive sequence and the negative sequence of a fundamental wave, the fifth-harmonics voltage component and the seventh-harmonic voltage component. A current controller adopted by the parallel grid-side converter can achieve accurate and rapid adjustment of a direct-current component, a frequency-doubling alternating-current component and a sixfold-frequency alternating-current component, so that it is guaranteed that the total output current of the system is balanced and free of distortion, and the quality of electric energy of a power grid which the double-fed induction window power system is connected to under the condition of the imbalanced harmonic-distortion grid voltage is effectively improved.

Description

technical field [0001] The present invention relates to the technical improvement of the doubly-fed induction wind power generation system adopting the series grid-side converter, in particular to the method for realizing the total output current balance and no distortion of the doubly-fed induction wind power system adopting the series grid-side converter under unbalanced and harmonically distorted grid voltage , belongs to the technical field of power control. Background technique [0002] With the emergence of a large number of unbalanced or nonlinear loads in the power system, two unfavorable disturbances, unbalanced and harmonic distortion, are likely to appear in the grid voltage at the same time. For remote wind farms connected to weak grids, these two disturbances Coexistence is more likely. Unbalanced grid voltage and harmonic distortion will lead to unbalanced and distorted DFIG stator voltage, which will lead to unbalanced and distorted stator and rotor currents,...

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Problems solved by technology

Due to the limitation of the rotor current control variable, the method cannot simultaneously achieve stator and rotor current balance without distortion or generator output power fluctuations, so the unbalanced heating of the stator and rotor windings and harmonic loss or stator power fluctuations still exist in DFIG

[0007] In addition, due to the existence of the grid-side converter, the above-mentioned documents cannot achieve the suppression of the negative sequence and harmonic components in the total output current of the system when implementing their respective control schemes.

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