A doubly-fed wind power generation system under unbalanced grid voltage and a control method thereof

Abstract

The invention provides a doubly-fed wind power generation system under unbalanced grid voltage and a control method thereof, The stator side voltage of the fan remains three-phase balance under the unbalanced network voltage by adding a series network-side converter, which ensures the three-phase current balance of the stator and the rotor, and improves the operation performance of the doubly-fedfan under the unbalanced network voltage. Based on the second harmonic generation (SHG) of power generated by series grid-side converter (SSC), a new method based on proportional-difference (DDD) is proposed in this paper. The control strategy of the parallel-networked converter of the resonant power compensator maximizes the power doubling component generated by the parallel-to-grid converter tobe equal to the power doubling component generated by the series-to-grid converter, thereby simultaneously suppressing the active and reactive power doubling fluctuations of the doubly-fed wind powergeneration system, and improving the output quality of the system; The anti-jamming ability of doubly-fed wind power generation system under grid voltage fault is greatly enhanced.

Description

technical field [0001] The invention belongs to the control technical field of a doubly-fed wind power generation system, and more specifically relates to a doubly-fed wind power generation system under an unbalanced grid voltage and a control method thereof. Background technique [0002] With the continuous development and maturity of power electronic technology and automatic control technology, clean energy power generation technology represented by wind power generation has made great progress. Due to the advantages of small converter capacity, decoupling control of active and reactive power, and good operating performance, it has been widely used in wind power generation systems. In practical applications, due to the particularity of the distribution of wind energy resources, many wind farms are located in remote areas where the power grid is relatively weak, and are connected to the main power grid through long transmission lines. Power single-phase loads may cause vol...

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Problems solved by technology

[0004] However, the above control strategies have the following problems: ①When the grid voltage is unbalanced, the positive sequence component of the grid voltage also changes; the control goal of SGSC in this paper is to make the positive sequence component of the stator voltage equal to the positive sequence component of the grid voltage, and does not make the stator voltage equal to the positive sequence component of the grid voltage. The voltage is equal to the stator rated voltage of the fan

② PI control is still used in the parallel grid side converter (Parallel GridSide Converter, PGSC), because the controlled variables are limited, the control target is limited to a certain extent, and the double frequency of the output active and reactive power of the entire DFIG system cannot be suppressed at the same time fluctuation

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