摘要
当前,我国陆上风电场大多采用双馈机组,虽然其变流器容量小、成本低,但是通常只能在±30%的转差率范围内运行,在低转速下无法正常并网。为了提高低转速工况下双馈风电机组的发电量,文章提出一种双模并网控制方案。其建立了双馈电机定子短接的异步数学模型,以确定最终短接电阻的取值范围;提出了双模柔性切换策略,即在转速较低时机组以异步模式运行,转速升高后机组以常规的双馈模式运行,从而实现低转速也能发电运行。仿真结果表明,低转速下,异步模式相较双馈模式,转子电流畸变率最大可降低55%,功率控制精度也更高(功率波动幅值可控制在3 kW以内);且采用柔性切换策略后,暂态冲击电流减小36%以上,仅150 ms就可达到新稳态,验证了风电机组双模并网控制策略的有效性和可行性。
At present,most of China's onshore wind farms use doubly-fed induction generators(DFIG)with small-capacity and and low-cost converters,but generally,these DFIGs can only operate within the slip rate range of±30%,and can not be connected to the grid normally under low-speed conditions.In order to improve the output of DFIGs under low-speed conditions,the paper proposes a dual-mode grid-connection control scheme.The author first established an asynchronous mathematical model for stator shorting of doubly-fed motor to finally identify the value range of short-circuit resistance,and then put forward the dual-mode flexible switching strategy,that is,units operate in the asynchronous mode when the speed is low,and in the conventional doubly-fed mode when the speed is high,thus realizing power generation operation at low speed.The simulation results show that,at low speed,in the asynchronous mode,the rotor current distortion rate can be reduced by 50%and the power control accuracy is higher,with the power fluctuation amplitude controlled within 3 kW,compared with those in the doubly-fed mode,and after the flexible switching strategy is adopted,the transient impulse current can be reduced by more than 36%and the new steady state can be reached in only 150 ms.This verifies the validity and feasibility of the dual-mode grid-connection control strategy for DFIGs.
作者
廖敦华
李炳璋
贺西
戴茜茜
LIAO Dunhua;LI Bingzhang;HE Xi;DAI Xixi(Zhuzhou CRRC Times Electric Co.,Ltd.,Zhuzhou,Hunan 412001,China;CCRC Zhuzhou Institute Co.,Ltd.,Zhuzhou,Hunan 412001,China)
出处
《控制与信息技术》
2024年第2期49-56,共8页
CONTROL AND INFORMATION TECHNOLOGY
关键词
风电机组
双馈异步电机
定子短接
双模并网
柔性切换
低转速
wind turbine
doubly-fed asynchronous generator
stator shorting
dual mode grid connection
flexible switching
low revolution speed
