【摘要】 电网电压不平衡时,若采用传统的电网电压定向矢量控制策略,双馈感应发电机(DFIG)定子侧除基波正序和负序电流外,还会产生相位互差120°的非零序三次谐波电流分量,不对称电流会加重电机绕组发热程度,影响双馈机组供电质量。为了抑制定子电流负序和非零序三次谐波分量,首先,详细分析了电网不平衡时,DFIG定子绕组负序和非零序三次谐波电流产生的原因;然后,建立了DFIG在负序和三次谐波同步旋转轴系下的数学模型,进而提出了引入负序和三次谐波控制的改进控制策略;最后,进行了仿真和实验研究,其结果与理论分析相一致,并且验证了所提改进控制策略能够有效抑制定子负序和非零序三次谐波电流分量。更多还原

【Abstract】 Based on the traditional vector control strategy oriented by grid-voltage,apart from the positive sequence and negative sequence currents,the nonzero sequence third harmonic current component whose phase difference is 120°can be detected at the stator side of doubly-fed induction generator(DFIG)under unbalanced grid voltage conditions.Asymmetric current components would aggravate the motor windings overheating and affect the power quality supplied by DFIG.To suppress the negative sequence and nonzero sequence third-order harmonic current components on the stator,their causes are analyzed in detail under unbalanced grid conditions first.Then a mathematical model for DFIG under negative sequence and third harmonic synchronized rotation axis is built,and a modified negative sequence and third harmonic current control is presented.Finally,simulation and experiment results are found in agreement with theoretical analysis,showing that the improved control method is feasible in suppressing negative sequence and nonzero sequence third harmonic current components at the stator side.更多还原