大规模双馈风电场次同步振荡的成因分析

Cause Analysis on Subsynchronous Oscillation in Large-scale Doubly-fed Wind Farm

为了探究大规模双馈风电场在无串补情况下发生次同步振荡现象的原因,文中在MATLAB/SIMLINK软件搭建了双馈风机无串补线路并网模型,结合时域仿真法研究了风机出力、RSC控制器参数、无功外环控制器参数和传输线路长度与次同步振荡的关系。结果表明:风速越大,并网台数越多,即风机出力越大,则更易发生次同步振荡。单独改变RSC内环电流控制器的Ki参数,不会产生系统振荡,然而调节Kp参数太大,系统更易发生次同步振荡。外环无功控制器比例系数Kp过大,控制器参数过于灵敏,会造成无功功率的超调,系统更易发生次同步振荡。传输线路的大小只影响电压波动的范围,不会造成系统发生次同步振荡。

To explore the reason why subsynchronous oscillation occursinlarge-scale doubly-fed wind farm without series compensation,the software MATLAB/Simulink is employed to build a grid model of doublely-fed wind turbinewith series compensation.The relations of the subsynchronous oscillation with the wind turbine output,the parameters of RSC controller and outer-loop reactive powercontroller,and the length of transmission line are investigatedbased on the time-domain simulation method.The results show that with the increase in the wind speed and turbine number in grid,the wind turbine output becomes larger,hence the subsynchronous oscillation is prone to occur.Only changing theof the RSC inner-loop current controller does not result in system oscillation,but if theis too large,the subsynchronous oscillation may happen more likely.If theproportional coefficient Kpof the outer-loop reactive power controller is too large or the parameters of the controller are too sensitive,the reactive power would be overshot and subsynchronous oscillation would happen more easily.The size of the transmission line only affects the range of voltage fluctuation,but will not cause the system’ssubsynchronous oscillation.