Detection On-Line Of Patial Discharge In GIS

Higher and higher quality electrical power supply is needed with the development of the society. So gas insulated switchgear(GIS) has more and more applications in the power system due to its characteristics advantage, such as small volume, high quality, etc. Essentially, GIS is designed not to need maintenance. However in case of an insulation breakdown, it takes a longer time for its restoration and the breakdown causes more serious damage to system operation.Currently, many methods which are effective enough can be available for examining the GIS before running, but its insulation condition monitoring hasn't been well done during operation, so we can't know the insulation condition in time, and therefore we can't eliminate the potential danger and prevent a breakdown. As is known to all, partial discharge(PD) is a symptom of an insulation breakdown occurring in GIS. So it's very important to develop a new diagnostic technique to detect a characteristic symptom when PD occurring. At present, signals of light, supersonic wave, current and electromagnetic wave which are emitted from GIS can be utilized to determine whether PD occurs, however, the results are not satisfying due to the processing methods and the strong noise at the sites. To solve this problem, this paper proposes a noncontact detection method by using antennas to receive signals of electromagnetic wave emitted and background noise, then we filter the high-frequency parts from the original signal against the background noise, and then we use the wavelet transform to analyze the results to determine whether PD occurs.This paper has three parts, the first part introduces basic knowledge such as PD's principle and detection methods used now whose shortcoming are also provided in brief, the second part introduces our experiment and provide the data for processing, the last part analyzes the data and discusses the results and get the conclusion.The results show that the method provided in this paper has its advance over other methods, the results are very ideal and achieve the level anticipated.