变桨距双馈风力发电系统低电压穿越控制∗

摘要

As grid voltage occurs dip fault, the stator and rotor windings of the crowbar-based doubly-fed induction generator( DFIG) wind turbine would absorb the vast reactive power from grid and form the surge current. The model of the pitch controller was built by analyzing the operational characteristics of DFIG system at grid fault. During the crowbar circuit active, the slip of DFIG could be restrained to reduce the amount of reactive power consumption with regulating pitch angle. The setting rules of the series resistance were deduced in crowbar circuit, and the amplitude of transient current in generator were effectively suppressed by selecting reasonable resistance. With PSCAD/EMTDC simulation platform, the dynamic process of DFIG system was simulated during the grid voltage sag. The simulation results showed that the amount of reactive power absorbed by DFIG system from grid could be reduced, and the amplitude of transient current in rotor windings could be effectively restrained with cooperative action of pitch control and crowbar protection circuit during voltage sag. The low voltage ride-through ability of DFIG system was enhanced.%基于Crowbar电路的并网运行双馈风力发电系统( DFIG)，在电网电压发生跌落期间，发电机定、转子绕组需要吸收大量无功功率并产生冲击电流。基于低电压故障期间DFIG系统的运行分析，建立了变桨距角控制模型，通过调节桨距角，抑制发电机转差率增大，降低系统无功吸收量。建立了Crowbar电路中串联电阻整定规则，合理选定电阻值可有效抑制发电机暂态电流幅值。 PSCAD/EMTDC暂态仿真结果表明，在低电压故障期间，变桨距控制和Crowbar保护电路的协同作用，可有效降低系统无功功率吸收并抑制转子暂态电流幅值，从而提高了DFIG系统的低电压穿越能力。