电网电压不平衡时双馈感应发电机的运行特性

Operating characteristics of double-fed induction generator under unbalanced grid voltage

分析了电网电压不平衡理论,建立了电网电压不平衡时双馈感应发电机在正、负序参考坐标系下的数学模型,在此基础上,推导出了电网电压不平衡时双馈电机输出功率、电磁转矩以及网侧变频器电压和电流方程,研究了电网电压不平衡时双馈感应发电机的运行特性.研究表明,当电网电压存在负序分量时会导致双馈电机的电磁转矩存在2倍频波动,定子输出有功功率中有偶数次频率的波动,交直交变频器的网侧变频器的交流侧产生奇数次谐波,而直流侧电容电压产生偶数次纹波分量.仿真结果证明了理论分析的正确性.

A mathematical model of double-fed induction generartor （DFIG） under the unbalanced grid voltage is built in the positive and negative rotary coordinates. On this basis, the equations of output pow- er, electromagnetic torque and voltage and current in the grid side converter under the unbalanced grid voltage are deduced. The operating characteristics of DFIG under unbalanced grid voltage are studied. The research results show that the negative sequence component of grid voltage could have impact on double-fed generator, including that the second harmonic wave of electromagnetic torque occurs; and the active power of stator output is in fluctuation o（ even times frequency. The AC side of the grid side converter produces odd harmonics while the DC bus produces even times harmonics. The simulation results prove the validity of the theoretical analysis.