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电网短路故障时交流励磁用双脉宽调制(PWM)变换器应提供足够的励磁电压实现交流励磁发电机的不间断运行,要求双PWM变换器直流链电压在故障时波动较小。分析并提出一种电网短路故障时交流励磁风电机组电网侧变换器的控制策略,该方案在电压跌落时仅利用电流内环控制电网侧变换器,并于电压正常时采用带前馈的双闭环电压控制策略控制电网侧变换器。通过仿真验证了所提出的方案在电网短路故障发生和切除时稳定控制直流链电压的有效性,为故障过程发电机不脱网励磁控制奠定了基础,同时该方案也能有效保护直流侧电容及提高系统的稳定性。
In the event of a short circuit in a power grid, a double pulse width modulation (PWM) converter for AC excitation should provide enough excitation voltage to realize the uninterrupted operation of the AC excitation generator, requiring the DC link voltage of the dual PWM converter to have less fluctuation in the event of a fault. This paper analyzes and proposes a control strategy for grid-side converter of AC excitation wind power generator when the grid is short-circuited. This scheme uses only the current inner loop to control the grid-side converter during voltage sag and adopts double loop with feedforward Voltage control strategy controls grid side converter. The simulation results show that the proposed scheme can effectively control the DC link voltage during the occurrence and removal of grid faults and lay a foundation for the control of the generator during the fault process. At the same time, the scheme can effectively protect the DC side capacitor Improve the stability of the system