低运行工况下直驱风电场电流内环主导的次同步振荡特性研究

SUB-SYNCHRONOUS OSCILLATION OF DIRECT DRIVE PMSG BASED WIND FARM UNDER LOW OPERATING CONDITIONS CONNECTED TO WEAK GRID

针对低运行工况下直驱风电场接入弱电网出现的次同步振荡(sub-synchronous oscillation,SSO)问题,搭建直驱风电场、汽轮发电机组联网线性化模型,基于特征值分析法,识别系统中存在的振荡模式,分析电网强度、电流内环控制参数和并网数量对SSO模式的影响。基于净阻尼分析法,分析直驱风电场与汽轮发电机组的动态交互机理。研究结果表明:电流内环控制参数设置不当是诱发直驱风电场发生SSO的主导因素,该振荡属于电气系统振荡;随着电网强度的降低,并网数量的增加,电流内环控制参数的减小,弱化系统阻尼,系统易发生SSO;该振荡模式并不会激发汽轮发电机组的轴系扭振。基于时域仿真模型,验证了理论分析的正确性与有效性。

Aiming at the sub-synchronous oscillation(SSO)problem that direct-drive permanent magnetic synchronous generator(PMSG)based wind farms under low operated conditions connects to weak grid,the linearization model of direct drive PMSG based wind farm and turbogenerator connecting to grid is established.The eigenvalue analysis is used to identify the oscillation modes existing in the system,and the influence of strength of grid,current inner loop control parameters and number of wind turbines on the SSO is analyzed.The dynamic interaction mechanism between wind farm and turbogenerator is analyzed based on net damping analysis.The research results show that:improper setting of current inner loop control parameters is the dominant factor to induce SSO of wind farm,which belongs to the oscillation of electrical system.With the decrease of power grid strength and the current inner loop control parameters and the increase of wind turbine number,the damping of the system is weakened and the system is prone to SSO.And this oscillation does not excite the shaft torsional vibration of turbogenerator.In EMTDC/PSCAD,the time domain simulation model of wind farm connected to the weak grid is built,which verifies the validity and effectiveness of the theoretical analysis.