Fault Diagnosis For Turn-to-Turn Short Circuit Of Rotor Windings In Generator

As the main equipment of generating, generator play very important role in safety and stability of the whole power system. Shorted rotor winding is a usual electric fault of the generator. To protect the generator equipment, Online monitoring of generator can show turn-to-turn short circuit of rotor windings ahead of time, which can prevent occurring point or two ground of the rotor and further expansion of the fault. Therefore, developing an effective system on shorted rotor winding online monitoring and fault diagnosis is very significant. In this paper, the fault mechanism and magnetic characteristics of turn-to-turn short circuit of rotor windings are analyzed. Some usual methods of fault diagnosis and their respective advantages and disadvantages are introduced. Based on the difference of the shaft voltage when generator operates between normally and being inter-turn short circuit fault, author proposes a new method, which combines expertise and artificial neural network which has adaptive and self-learning features. It can not only judge whether shorted field turns exit but also estimate fault turns ratio. By means of generator rotor inter turn short circuit experiment of the dynamic analog unit and the data measured in the plant, the concerned theory above is verified, and the results coincide with the theory. On this basis, an insulation monitoring software system of generator rotor is developed. This system has other functions such as analyzing the data of generator rotor, displaying graphics and printing out reports, and it can help operating personals find out turn-to-turn short circuit of rotor windings ahead of time. This software operates friendly and simple. Measured data shows that the software can achieve the goal of the rotor inter-turn short circuit fault identification, and it has great practical value.