Hazards of Dry-Type Transformer Winding Deformation
In many power accidents, the winding failure of dry-type transformers is the main reason. At home and abroad, a lot of relevant research and analysis have been actively carried out, and it is expected that there will be an effective method for detecting and diagnosing the deformation of the winding structure. In the early stage of winding deformation of dry-type transformers, the centralized parameter detection method is a common analysis method. However, due to many restrictions and limitations, only severe winding deformation can be diagnosed in this method, and the operation process is not only complicated and sensitive. Alternatively, there is a very intuitive back cover method, but this method has many drawbacks. In addition to not being able to properly check the winding deformation, the operation is very difficult and requires a lot of manpower and material resources. At present, when choosing the winding deformation analysis method of dry-type transformers at home and abroad, the commonly used methods are low-voltage pulse analysis method, short-circuit resistance test method, frequency response analysis method and vibration analysis method.
The specific method is to input a stable low-voltage pulse signal source at the winding end of the dry-type transformer measured, record the voltage waveform data synchronously at the signal end and other ends, and then compare the time domain signal changes at the excitation end and the response end. In general, when the winding is deformed, the capacity within the winding and the induced equivalent parameters change synchronously, which means that the internal characteristics of the winding change. Therefore, the same low-voltage pulse signal is input into the dry-type transformer winding, and the state information of the winding is obtained according to the change of the response signal before and after its deformation. The low-voltage pulse method is a general method for testing the short-circuit endurance of dry-type transformers.
