Method for restraining total output active power fluctuation of double-fed wind power system under unbalanced and harmonic distortion network voltage

Abstract

The invention discloses a method for restraining total output active power fluctuation of a double-fed wind power system through a series-connection network side converter under an unbalanced and harmonic distortion network voltage and relates to the field of control over series connection network side converters, parallel connection network side converters and motor side converters. A voltage controller adopted for the series connection network side converter can be used for rapidly restraining stator negative-sequence harmonic voltage components, five-time harmonic voltage components and seven-time harmonic voltage components and safe and stable operation of an electric generator is guaranteed. A reference current order of a parallel connection network side converter comprises fundamental harmonic positive-sequence current components, fundamental harmonic negative-sequence current components, five-time harmonic current components and seven-time harmonic components under a forward-direction synchronous revolution coordinate system. A current controller adopted for the parallel connection network side converter can simultaneously, accurately and rapidly adjust direct components, second harmonic generation alternating components and sixth harmonic generation alternating components. Total output active power second harmonic generation fluctuation and sixth harmonic generation fluctuation of the system can be guaranteed and the electric energy quality and stability of a power grid connected to the double-fed sensing wind power system are effectively improved.

Description

technical field [0001] The present invention relates to the technical improvement of the doubly-fed induction wind power generation system using series grid-side converters, in particular to a method for suppressing fluctuations in total output active power of doubly-fed induction wind power systems using series grid-side converters under unbalanced and harmonically distorted grid voltages , 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, especially for some asymmetrical faults, two unfavorable disturbances will appear in the grid voltage at the same time, unbalanced and harmonic distortion. In terms of distance from the wind farm, the possibility of the coexistence of these two disturbances is greater. Unbalanced grid voltage and harmonic distortion will lead to unbalanced and distorted DFIG stator voltage, which in turn will cause unbalanced and distor...

AI Technical Summary

Problems solved by technology

The control strategy described above is unable to guarantee the balance of the stator and rotor current without distortion due to the limitation of the rotor current control variable, so the unbalanced heat generation and harmonic loss of the stator and rotor windings or the fluctuation of stator power and electromagnetic torque still exist in DFIG

In addition, due to the existence of the grid-side converter, the proposed control strategy cannot suppress the fluctuation of the total output active power of the system

[0006] Document (2) proposes to use the proportional-integral-dual-frequency resonance controller under the forward synchronous rotating shaft system to coordinate the control of the rotor-side converter and the grid-side converter, so as to suppress the fluctuation of the electromagnetic torque and the total output active power of the system , under the control strategy, the stator and rotor currents are unbalanced and harmonically distorted at the same time, so the extra heat of the stator and rotor windings still exists, which will affect the life of the winding insulation materials

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