风机轴系考虑为多质块模型时,风电场经高压直流输送电力有可能引起次同步轴系扭振.当风电与附近火电机组捆绑送电时,有助于提高风电系统稳定性.但当系统发生扰动时,风电机组和火电机组均将产生严重的轴系扭振现象.本文首先分析风机轴系扭振产生机理,然后基于整体最小二乘-旋转不变技术估计信号参数(TLS-ESPRIT)辨识出在风机轴系和汽轮机轴系固有扭振模态下的系统传递函数,进而基于射影定理针对每个扭振模态设计阻尼控制器以实现分层控制,最后将阻尼控制器输出信号叠加到直流输电整流侧定电流主控制器上,实现轴系扭振的抑制.建立风电场与火电机组捆绑送电模型并进行仿真,仿真结果表明,设计的分层控制器可有效提高轴系固有扭振模态的阻尼比,可使轴系模块间的扭振迅速衰减,有效提高了电力系统稳定性,控制器阶数较低,便于实际工程实现,且具有较高的鲁棒性.%When the wind turbines and wind generators are two-mass or multi-mass shaft model, the control mode of power electronic equipment at rectifier may introduce negative damping to nearby generators, which could cause torsional vibration. This phenomenon is named sub-synchronous torsional interaction. The stability of wind power system may be improved when the wind power and thermal power bundle supply. However, the shaft system may cause torsional vibration when the system is disturbed. Firstly, this paper researched the mechanism of wind torsional vibration. Secondly, the system transfer function of every nature frequency of the shaft was identified base on total least square-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT). Finally, the controller was designed that aim at every nature frequency of the shaft base on projective theorem. This paper built the model of wind power and thermal power bundle supply through HVDC base on PSCAD/EMTDC. The simulation results show that supplementary subsynchronous damping controller (SSDC) can restrain sub-synchronous torsional interaction effectively, and the SSDC has the advantages of low order and facilitate project implementation.
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