Modal Identification of Subsynchronous Oscillation Caused by New Energy Grid Connection

The complex operation environment of new energy grid connected system and the sub-synchronous oscillation (SSO) caused by the dynamic interaction between the rapid response of power electronic equipment and the power grid may present the signals nonlinear and non-stationary characteristics, which is difficult to identify. In this paper, a nonlinear modal decomposition method is proposed, which is combined with the Teager Kaiser energy operator (TKEO) to identify the modal parameters of yhe SSO signals. Firstly, the ridge method is used to extract the features of the time-frequency analysis results of the signals, constructing the harmonic components; Then, the time-shift method is used to replace the data to distinguish the true and false harmonics, and the spectrum entropy feature discrimination is used for denoising, realizing the decomposition process of the dominant mode; Furthermore, the TKEO algorithm is combined to achieve the parameter identification of the dominant mode. Finally, the feasibility of this method is proved by the simulation of self-synthetic signal, the wind farm model and the measured data of a power grid, and the superiority of this method is proved by comparing with the simulation results of the traditional VMD method and HHT method.