风电并网用全功率变流器谐波电流抑制研究

电网低次谐波电压和电力电子器件的非线性将使得风电并网变流器产生较重的并网谐波电流,为改善风电并网用全功率变流器系统的输出电能质量,在详细分析网侧变换器的谐波数学模型的基础上,提出一种抑制并网低次(5、7、11、13次)谐波电流分量的交叉耦合控制策略。该控制策略通过在多同步旋转坐标系下检测各次并网谐波电流的直流分量,采用电流交叉耦合控制方式实现对各次谐波电流的准确控制,详细分析并设计谐波电流交叉耦合控制器。所提控制方案考虑了各次谐波电流回路的交叉耦合影响,可有效降低各次谐波电流以及基波电流之间的相互影响作用,有利于提高系统工作的稳定性。仿真和实验结果验证了所提控制方案的正确性和可行性。

Harmonic Currents Suppression for Full Size Power Grid-connection Converter Used for Wind Power Generation

The low order harmonic in grid voltage combined with the nonlinear characteristics of the power electronics devices will cause great amount of harmonic currents from the grid-connection converter used for wind power generation system,this will degrade the operational performance of the generation system.In order to improve the power quality of the full size power converter for the wind power generation system,a method was proposed to suppress the harmonic currents of the grid-side converter(GSC) in this paper.The harmonic mathematic model of the GSC was investigated in detail,and the cross-coupling control strategy was proposed to suppress the low order(5th,7th,11th,13th) harmonic current components.In the proposed control scheme,the DC components of each order harmonic currents could be detected in the multiple synchronous rotating reference frames,and they could be accurately controlled to be zero with the cross-coupling current controller which was analyzed and designed.Taking into account the cross-coupling influence of the each order harmonic current circuit,the proposed control strategy can effectively reduce the interactive effects among the each order harmonic currents and fundamental current,which improving the operation stability of the system.Both the simulation and experiment results verify the proposed control scheme.