Analysis and Identification for Electromechanical Coupling and Shaft Stability of Doubly-Fed Induction Generator
Hao Zhenghang1, 2, Yu Yixin1
1. Key Laboratory Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China 2. Guizhou University Guiyang 550003 China
Abstract：In order to investigate the decoupling conditions for doubly-fed induction generator (DFIG), the coefficient of feed forward compensation is defined for the control strategy of rotor current. Firstly, both conditions of electromechanical decoupling and a quantitative index of coupling are presented by deducing a linear dynamic model of the DFIG. Based on analysis of the linear model, it is shown that feed forward compensation can produce negative electrical damping and result in torsional oscillation of shaft. Then, an on-line identifying scheme for mechanical modes and electrical modes is developed, which employs subspace identification algorithm to extract the dominating modes under the natural operation conditions. Finally, a simulation case illustrates that the coefficient of feed forward compensation influences the degree of electromechanical decoupling as well as stability of shaft system. The case also demonstrates that the proposed on-line identification scheme of oscillation modes, featuring a satisfied precision, can develop a component of security monitor system for DFIG.
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2011, Vol. 26 
