Subsynchronous Oscillation Modal Identification Based On Coupled Duffing Oscillator Columns And FSWT

Taking into account the uneven distribution of energy and load in China,large-scale long-distance electricity transmission has become an effective way to solve the energy problem.But the long-distance electricity transmission also makes the sub-synchronous oscillation has become an important threat to the stability of the power system.In recent years,China has recently occurred several times the problem of synchronous oscillation.In the analysis of sub-synchronous oscillations,the modal identification based on the measurement signal has always been an important research direction.In this paper,a new method for identifying sub-synchronous oscillations is proposed.It is proved that the new method can accurately identify the sub-synchronous oscillation model of the multi-machine synchronous oscillation simulation example and the real-measured signal.In this paper,Duffing oscillator and frequency slice wavelet transform(FSWT)has been focused to identify the sub-synchronous oscillation mode.The method proposed in this paper can accurately identify the mode of subsynchronous oscillation and ha s a good immune effect on noise.Firstly,considering about the shortcomings of classical Duffing oscillator theory in identifying signals,this paper proposes a signal to identif y sub-synchronous oscillations using coupled Duffing oscillator columns.The performance of the composite attenuation signal and the IEEE first simulation model torque signal in noisy and non-noise conditions shows that the method proposed in this paper is a kind of strong noise immunity method,which can accurately identify the frequency of the sub-synchronous oscillation signal.Then,based on the identified frequency of sub-synchronous oscillation,the signal component would be fitted by frequency slice wavelet transform(FSWT).The parameters such as the attenuation coefficient and the damping ratio of the fitted signal component can be calculated by using the Hilbert transform.The algorithm is used to fit the composite attenuation signal and the oscill ation signal,and the results show that FSWT is a method to accurately fit the signal components,and it has better noise immunity than Prony analysis method.Finally,this paper presents the new sub-synchronous oscillation mode identification method using coupled Duffing oscillator columns and FSWT.The method combines the advantages of the coupled Duffing oscillator which can accurately identify the frequency of the sub-synchronous oscillation signal and FSWT which can calculate the attenuation coefficient and the damping ratio.The method is used to identify the multi-machine system synchronous oscillation signal and the measured signal.It is proved that this method is a method to accurately identify the divergence mode of sub-synchronous oscillation,and it has better anti-noise than the Prony analysis method.The method would have the engineering application value after further improving.