Fault analysis and structure of doubly fed induction generator rotor winding neutral ring
                                       WEN Bin, LI Cheng chen, TONG Shi wei, CHENG Lin zhi, SU Feng yu
                                       （Xuchang XJ Wind Power Technology Co., Ltd., Xuchang 461000, China）


Abstract: Aiming at the rotor winding neutral ring problem of a double fed induction generator in the process of operating, the structure and the failure phenomenon of the double fed generator rotor winding neutral ring were analyzed and investigated. The statics and modal analysis of a double fed induction generator s neutral ring were used based on the ANSYS Workbench, and the micro observation contrast analysis of the fault generator and non fault generator s neutral ring connection lead was used. Due to the fault generator s abnormal phenomena was found by micro observation checking, the metallographic structure inspection was done for the other neutral ring connection lead of the fault generator. Finally, the relationship between the neutral ring s structure, the connection lead s metallographic structure and the neutral ring fault was established. The experimental results show that the neutral fault reason is the neutral ring s structure stress concentration and the neutral ring connection lead s hydrogen embrittlement. According to the cause of failure, the shortening length of the neutral ring connection lead, avoiding the special shaped structure, using the oxygen free copper solution are presented to prevent the rotor winding neutral ring problem. And, it provides reference basis for the product optimization and reason analysis in the future.
Key words: doubly fed induction generator; rotor winding; neutral ring problem; metallographic structure; hydrogen embrittlement