Research On Identification Of Sub Synchronous Oscillation Of Direct Drive Wind Turbine Based On Fusion Of VMD-SOBI And Prony Algorithm

At present,our country attaches great importance to the utilization of clean energy.Due to the uneven distribution of domestic wind energy resources,large-scale wind plants often adopt efficient and long-distance transmission methods,resulting in a series of interconnection safety and stability issues,of which Sub-Synchronous Oscillation(SSO)is particularly prominent.In recent years,due to the large number of interconnections of Direct-Drive Permanent Magnet Synchronous Wind Turbine Generator(DDPMSG),it results in the frequent occurrence of new SSO.Accordingly,in order to analyze the impact and characteristics of SSO and eliminate the adverse effects,it is quite important to promptly and accurately identify the modal information of SSO in the measurement signal.Based on the situation,this paper studied the issues of SSO that occur with DDPMSG from the following three aspects:(1)A detailed DDPMSG mathematical model was stablished,including wind turbine model,shafting model,pitch angle control system model,Permanent Magnet Synchronous Generator(PMSG),Grid-Side Converter(GSC)control model,Machine-Side Converter(MSC)control model,and DC link mathematical model.(2)The principle and characteristics of Variational Mode Decomposition(VMD),Second Order Blind Identification(SOBI)and Prony algorithm are described,analyzed the specific calculation process of the three algorithms,and verified the excellent performance of the three algorithms in SSO signal identification through simulation.(3)Energy entropy and permutation entropy were used to improve the VMD algorithm,select the preset modal number K value and the penalty factor α value.Moreover,it combined the improved VMD and SOBI algorithms to obtain a complete and accurate SSO signal,and used the Prony algorithm to identify its modal parameters.Through simulation,the validity was verified.(4)Multivariate Variational Mode Decomposition(MVMD)algorithm is used to solve the identification problem of multi-channel direct drive wind farm SSO based on Wide Area Measurement System(WAMS).Combining the MVMD and SOBI algorithms,the SOBI algorithm directly identified the SSO modal parameters of different DDPMSGs.Through simulation,as well as identification and analysis of measured data,its practical application significance has been verified.The results show that the proposed method of SSO mode identification for direct-drive wind turbines,which combines the improved VMD-SOBI algorithm and Prony algorithm,has good decomposition effect and can extract the complete oscillation modes with high identification accuracy.For practical engineering problems,a fusion algorithm of MVMD and SOBI is proposed to solve the modal identification problem of multi-channel SSO signals generated by different DDPMSG in practice.Through the verification of measured data,the fusion algorithm has strong parallel ability and has more engineering application value.