应对电网电压骤降的双馈感应风力发电机Crowbar控制策略

双馈感应发电机(doubly fed induction generator，DFIG)具有有功、无功功率独立调节的能力及励磁变频器所需容量小等优点，在风力发电系统中得到了广泛应用，但由于励磁变频器的容量较小，使其在电网故障下的控制能力受到限制。为保护励磁变频器，需要采用Crowbar装置在电压骤降时为转子浪涌电流提供通路，并限制转子电流增大。文章提出了一种Crowbar控制策略，能有效抑制转子过电流、直流母线过电压以及电磁转矩的振荡，并可向电网注入无功电流以帮助电网电压的恢复。仿真结果验证了这种控制方式能使DFIG在大幅电压骤降故障下实现不间断运行，有效提高了DFIG风电机组运行的可靠性。

Crowbar Control Strategy for Doubly Fed Induction Generator of Wind Farm During Power Grid Voltage Dips

Due to the advantages of doubly fed induction generator(DFIG)such as controlling active and reactive power independently and smaller capacity of AC excitation converter is required;they are widely used in wind power generation systems.However,the smaller capacity of AC excitation converter restricts the control ability of DFIG set while disturbance occurs.To protect AC excitation converter,it is necessary to limit the high inrush rotor current and provide a bypass for it via a Crowbar connected to the rotor windings.In this paper,a novel Crowbar control strategy is proposed to limit the over current in the rotor and the over voltage of the DC bus as well as the transient oscillation of the electromagnetic torque. Moreover,a capacitive current is injected into the grid to assist the recovery of the grid voltage.Simulation results prove that with this control strategy the DFIG is able to ride through the more severe grid voltage dips;thereby the operation reliability of DFIG sets can be effectively improved.