双馈型风电系统电网故障不间断运行的研究

摘要

为保护变频器,需要采用Crowbar装置在电压跌落时为转子浪涌电流提供通路,并限制转子电流增大,在电压恢复时抑制电压骤升.因此提出了一种Crowbar控制策略,能有效抑制转子过电流、直流母线过电压,并可向电网注入无功电流以帮助电网电压的恢复.测量结果表明了控制方式能使双馈型感应发电机(DFIG)在大幅电压跌落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.%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. 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.