Research On SSO Caused Of Doubly Fed Wind Power Generation Via Fixed Series Compensated Transmission

Doubly Fed Induction Generator has been widely used for its characteristics of variable speed constant frequency operation,flexible control performance and high generation efficiency.In order to make full use of wind energy resources to generate electricity wind power must be sent out by long-distance transmission because of the reverse distribution of wind energy resource and load center in China.One of the effective measures to realize large-scale wind power outputting is to use series capacitor compensation technology,but the sub-synchronous control interaction problem may be induced when the doubly-fed induction generator sends out wind power through a senes compensation line.In this paper,the mathematical models for the analysis of sub-synchronous control interactions are established.On the basis of these models,the occurrence mechanism and interference factors of SSCI are studied in depth.Based on the single machine infinite bus system,the model is built on the PSCAD/EMTDC simulation software,and the correctness of the theoretical analysis is verified by the time domain simulation method.The influence of the interaction between units on SSCI is theoretically deduced.The results show that both the number of wind turbine units and the parameters of variable current controller will affect the SSCI problem.The model of multi-typhoon machine is established on the PSCAD/EMTDC simulation software,and the correctness of the theory is verified by time domain simulation.Then,the characteristics of the two control modes of doubly-fed wind turbine are analyzed,and the simulation model of multi-typhoon generator is established on the PSCAD/EMTDC simulation software under the same and different control modes of each generator unit in the system.The oscillation characteristics of wind turbine under two control modes are analyzed.Through the above analysis,the reasonable collocation of the control mode of the fan in the future and the study of the system oscillation suppression measures are provided.