Deadbeat Power Control Method of Grid-side Converter under Unbalanced Grid Voltage

Abstract

The invention belongs to the field of controlling power converters of wind power generation systems and relates to a deadbeat power control method for a grid-side converter under network voltage unbalance. The deadbeat power control method comprises the steps that three-phase network voltage, a three-phase alternating side current and direct current side voltage of the grid-side converter are detected, a network voltage sampling value and an alternating side current sampling value under a two-phase rest frame through 3 / 2 coordinate transformation, and network voltage retardation is obtained by delaying one fourth of a power grid period of the network voltage sampling value; an active power reference value is calculated, and an alternating side current reference value is calculated and obtained; transformer alternating current side voltage controlled by the deadbeat power is calculated; in order to compensate for time delay in the calculation and control process, the transformer alternating current side voltage at the next moment is predicted and serves as control voltage; a switch signal controlling a power switch component is obtained and is used for controlling on-off sequence and on-off time of the power switch component. According to the deadbeat power control method for the grid-side converter under network voltage unbalance, the grid-side converter can be effectively controlled to have good dynamic and static characteristics under the condition of network voltage unbalance, and reliable grid connection operation of a wind generating set is ensured.

Description

Technical field [0001] The invention relates to a control method for a grid-side converter under unbalanced grid voltage, which is suitable for the control field of power converters in wind power generation systems. Background technique [0002] Grid-side converters are widely used in distributed wind power generation systems due to their sinusoidal AC side current, controllable power factor, and bidirectional energy flow. Wind turbines are connected to the grid through power converters. When the grid voltage is unbalanced, the control effect of the power converter, especially the grid-side converter, directly affects the performance and efficiency of the wind power generation system. The unbalanced grid voltage will cause the AC side current distortion of the grid side converter and the double frequency fluctuation of the DC side voltage, which will affect the control performance of the rotor side converter, and then affect the operation status of the wind turbine. [0003...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the existing problems of the grid-side converter of the wind power generation system under the unbalanced fault of the grid voltage, and provide a dead-beat power control method based on the two-phase static coordinate system, which can effectively suppress the grid-side converter Current distortion on the AC side and voltage fluctuation on the DC side, while improving the dynamic response capability of the system, to meet the dynamic and static performance requirements of the wind power generation system for the grid-side converter when the grid voltage is unbalanced, and ensure reliable grid-connected operation of wind turbines

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