基于励磁注入激励法测试并辨识机组扭振模态参数

Identification of torsional modal parameters based on excitation-injection tests on turbine-generators

该文提出一种基于励磁注入激励法来测试和辨识机组模态频率和模态阻尼的方法,用以正确评估次同步谐振风险和研究应对策略。方法包括3个步骤:首先对运行机组励磁系统注入模态信号激发可控扭振,精确检测轴系次同步模态频率;然后采用模态滤波和DFT(discrete Fouriertransform)校正算法计算各扭振模态幅值;最后利用最小二乘算法辨识模态阻尼。采用仿真分析验证了方法的理论正确性,并将其成功应用于上都电厂4台机组的扭振参数测试。结果表明:该方法具有精度高、试验成本低、激发模态可控等优点。

This paper describes an approach to identify torsional modal parameters using excitation-injection tests on turbine-generators,one of the key issues for mitigation of subsynchronous resonance.The identification process uses accurate detection of the modal frequencies based on controllable triggered torsional vibrations through the injection of modal signals into the excitation system.Then the torsional vibration amplitudes are caluculated using modal filtering and a modified discrete Fourier transform（DFT） algorithm with the modal damping identified using the least-squares method.After verification of the approach through digital simulations,the method was used to identify torsional vibration parameters in the four turbine-generators in the Shangdu Power Plant.The results demonstrate the advantages of this accurate,low cost approach using controllable modal excitation.