Research On Typical Mechanical Faults Diagnosis Of On-Load Tap Changer In Power Transformers

Considering the on-load tap-changer mechanical faults of high frequency,and in all the failure types of high proportion,in order to have a thorough understanding the characteristics for typical mechanical failure of on-load tap-changer,and to formulate rational and effective on-load tap-changer mechanical fault diagnosis strategy,thus providing effective detection method and early warning for the maintenance staffs,and to maintain the safe and stable operation of distribution power grid,in this paper,the research on typical mechanical faults diagnosis of on-load tap changer is carried out.By combining theoretical analysis with simulated experiment,algorithm design with hardware construction,the mechanism of mechanical faults of on-load tap changer,detection methods,the development of defect model,the construction of fault sample library,feature extraction,graph analysis,pattern recognition and other aspects are deeply discussed.A physical platform for simulated experiment is set up to build a mechanical fault sample library for on-load tap-changer.First,an experimental mechanical defect model is established using the SYJZZ-35 on-load tap-changer.The failure simulation method is determined by analyzing typical mechanical faults and their mechanisms.Next,the method of collecting and analyzing the mechanical fault sample data of the on-load tap-changer is described.Furthermore,a vibration test experiment was carried out to obtain the mechanical vibration and drive current waveforms corresponding to various typical mechanical faults,and a sample library of typical mechanical faults for on-load tap-changer could be constructed.The fault diagnosis method of on-load tap-changer based on typical graph analysis is studied.Based on the analysis of mechanical vibration and drive current signal,envelopment analysis is used as the main method,and various analysis methods are also used,such as parity comparison,high and low frequency decomposition,energy spectrum analysis,etc.Meanwhile,various methods of comparison are used,such as single analysis,horizontal comparison or vertical comparison,etc.Therefore,the typical characteristic maps of on-load tap changer can be obtained.According to the different types of mechanical faults,the corresponding fault judgment basis and threshold value are established,so a mechanical fault diagnosis method of on-load tap-changer based on typical graph analysis is formed.A method for identifying mechanical fault modes of on-load tap-changer based on Hilbert-Huang transform(HHT),Volterra model of chaotic time series and Directed Acyclic Graph SVMs is proposed.The HHT-Volterra algorithm is used to realize the feature extraction of the vibration signal during the switching of the on-load tap-changer.The Directed Acyclic Graph SVMs model is constructed to realize the classification of the mechanical faults of the on-load tap-changer.Finally,comparison with other existing methods of pattern recognition is performed.The results showed that the proposed method for mechanical fault diagnosis of on-load tap-changers has a high accuracy rate of fault identification,and can effectively identify typical mechanical faults of on-load tap-changer.