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This paper presents a new method to recognize the noise characteristics of power transformer. First, frame division and windowing are applied to pre-process the noise signals. Then Mel Frequency Cepstrum Coefficient (MFCC) combined with Principal Component Analysis (PCA) is proposed to calculate the feature vectors of noise signals for high accuracy. Finally, the vector quantization (VQ) models are...
Power transformers are always vibrated while working in power system. Those vibration signals are closely related to the mechanical properties of transformer winding. This paper deals with the harmonic response analysis of transformer winding based on finite element method to explore its inherent vibration feature, where a 3-dimensional model of some 10kV transformer winding is built. The frequency...
This paper deals with the vibration features of power transformer under DC bias with the method of multifractal spectrum. First, vibration mechanisms of power transformer are analyzed. Then the typical parameters of multifractal spectrum including the width of multifractal spectrum and the absolute value of density difference are calculated to describe the vibration signals of power transformer based...
In this paper, a nonlinear N-L-N Hammerstein-Wiener model is used to build the vibration model of power transformer for the online monitoring of winding condition. The vibration mechanism for the identification of power transformer is presented first. Then the Hammerstein-Wiener model is introduced and ways to estimate the parameters of the model is illustrated explicitly. Validation over an in-service...
How to design and implement the effective vibration on-line monitoring system is the key problem to carry out the condition monitoring of power transformer for its safe and stable operation. When considered the feasibility and sensitivity of vibration analysis method to monitor the operation condition of power transformer, vibration on-line monitoring system is designed and implemented based on LabVIEW/CompactRIO...
Modal parameters are inherent properties of power transformer winding and closely related to its variations of mechanical condition. To identify the modal parameter of winding more accurately, a modal experiment on a real transformer winding is made in this paper and the vibration frequency function is obtained. Then Hilbert-Huang Transform is introduced to identify the winding modal parameters from...
In order to further investigate the vibration performance of power transformer for the detection of winding deformation based on the vibration frequency response analysis (VFRA) method, the electro dynamic forces of the winding of power transformer are calculated first by virtue of the field-circuit coupled finite element method. Then the axial vibration model of the winding is built and the harmonic...
In the paper, a variable frequency constant current power supply is developed to provide the variable frequency current to vibrate the power transformer. A proportional resonant controller is applied to control the current constant. The designed experiment of vibration frequency response analysis for the 220kV transformer is made to validate the effective of the power supply. Experimental results...
In order to further recognize the relationship between the fault of winding deformation of power transformer with the measured tank vibration, the short-circuit test is done in a 220kV transformer. The vibration sweep frequency response curves for some pre-setting winding deformation fault are obtained by virtue of the vibration measurement system. Correlation coefficient is defined and calculated...
Base on the developed DC controlled current source to simulate the DC component in the earth, experimental researches are made to study the effects of DC-bias to the power transformer. Experiment results show that the magnetizing currents of the power transformer are distorted badly with the increase of the injected direct current which is controlled by the software system under the Lab VIEW environment,...
In the paper, the DC controlled current source (DCCCS) is developed to simulate the DC component in the earth to study the ability of power transformer enduring the DC bias. The designed DC-bias experiment is applied to validate the effectiveness of the DCCCS. Experimental results show that the developed DCCCS works well and could provide the desirable and controlled direct current required by the...
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