scholarly journals On-Line Detection of Voltage Transformer Insulation Defects Using the Low-Frequency Oscillation Amplitude and Duration of a Zero Sequence Voltage

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 619 ◽  
Author(s):  
Hongwen Liu ◽  
Ke Wang ◽  
Qing Yang ◽  
Lu Yin ◽  
Jisheng Huang
Keyword(s):  
Low Frequency ◽  
Line Detection ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Voltage Transformer ◽  
Transformer Winding ◽  
Zero Sequence ◽  
On Line ◽  
Zero Sequence Voltage ◽  
Winding Insulation

The insulation degradation of a voltage transformer winding is not easy to find, but it may ultimately cause the transformer to explode, leading to accidents such as phase-to-phase short circuits. At present, power transformers, lightning arresters, and other equipment have on-line methods to detect the insulation state. However, there is no mature method for the on-line monitoring of voltage transformer winding insulation. In this study, a small current disturbance method based on a zero-sequence loop is proposed. The characteristic parameters of the low-frequency oscillation of zero-sequence voltage after a disturbance are used to evaluate the insulation state of the winding and detect faults. Theoretical modeling, simulation tests, and field tests show that when the insulation resistance of the voltage transformer winding is in the range 0–40 kΩ, a low frequency oscillation of about 10 Hz can be detected on the zero-sequence voltage, and its amplitude and duration are proportional to the degree of damage to the insulation. This can hence be used as a criterion for the on-line detection of voltage transformer winding insulation defects.

New Theories and Methods of Low Frequency Oscillation Analysis under Smart Grid Framework in Electrical Engineering

2013 ◽  
Vol 676 ◽  
pp. 186-192
Author(s):  
Zhi Jian Liu ◽  
Rong Huang ◽  
Shu Ming Zhou ◽  
Yu Cheng Hou
Keyword(s):  
Smart Grid ◽  
Power System ◽  
Electrical Engineering ◽  
Low Frequency ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Oscillation Analysis ◽  
On Line ◽  
Visualization Technology ◽  
The Stability

The low-frequency oscillation is one of the most important reasons that affects the stability of the power system. Under the background of building a unified and strong smart grid, the scale of the power system will continue to expand, the interconnection of systems will be more closely, the structure will be more complex, these factors will further increase the difficulty on the low-frequency oscillation control. This paper summarizes the methods to analysis low frequency oscillation signal, the way that suppresses the low frequency oscillation in electrical engineering. Further, based on smart grid framework, a on-line visualization technology and a self-recovery regulation strategy are proposed to damp low-frequency oscillation.

Research on Distribution Network Single-Phase To-Ground Faulty Line Detection

2013 ◽  
Vol 753-755 ◽  
pp. 2243-2246
Author(s):  
Guo Xing Nie ◽  
Ya Jun Dong
Keyword(s):  
Single Phase ◽  
Current Phase ◽  
Line Detection ◽  
Voltage Transformer ◽  
Small Current ◽  
Mode Transformation ◽  
Zero Sequence ◽  
Voltage Phase ◽  
Current Zero ◽  
Zero Sequence Voltage

The thesis is based on summing up the features of high voltage grounding grip single-phase to-ground process to analyze the characteristics of zero sequence current, zero sequence voltage, voltage phase mode transformation and current phase mode transformation. It provides solution to pick out single-phase to-ground faulty lines at the exit of converting stations by waveform recognition in the principle that voltage transformer injects signal to interfere zero sequence current, and the integrated faulty line detection that consists of waveform recognition, wavelet analysis and energy analysis, and it introduces the single-phase to-ground faulty line detection in small current earthed system.

Research Situation Analysis of On-line Detection Technology for Power Transformer Winding Deformation

2020 ◽  
Vol 13 (6) ◽  
pp. 823-832
Author(s):  
Zhenhua Li ◽  
Weihui Jiang ◽  
Li Qiu ◽  
Zhenxing Li ◽  
Yanchun Xu
Keyword(s):  
Detection Method ◽  
Theoretical Research ◽  
Line Detection ◽  
Response Analysis ◽  
Advantages And Disadvantages ◽  
Detection Technology ◽  
The Future ◽  
Transformer Winding ◽  
On Line ◽  
Winding Deformation

Background: Winding deformation is one of the most common faults in power transformers, which seriously threatens the safe operation of transformers. In order to discover the hidden trouble of transformer in time, it is of great significance to actively carry out the research of transformer winding deformation detection technology. Methods: In this paper, several methods of winding deformation detection with on-line detection prospects are summarized. The principles and characteristics of each method are analyzed, and the advantages and disadvantages of each method as well as the future research directions are expounded. Finally, aiming at the existing problems, the development direction of detection method for winding deformation in the future is prospected. Results: The on-line frequency response analysis method is still immature, and the vibration detection method is still in the theoretical research stage. Conclusion: The ΔV − I1 locus method provides a new direction for on-line detection of transformer winding deformation faults, which has certain application prospects and practical engineering value.

Low-frequency-oscillation characteristics of ionization distribution in Hall thruster channels

Vacuum ◽  
2021 ◽  
pp. 110320
Author(s):  
Tianyuan Ji ◽  
Liqiu Wei ◽  
Haifeng Lu ◽  
Shangmin Wang ◽  
Ning Guo ◽  
...  
Keyword(s):  
Low Frequency ◽  
Hall Thruster ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Oscillation Characteristics

A Parametric Study of Low-Frequency Damping of Mooring System

2014 ◽  
Author(s):  
Minglu Chen ◽  
Shan Huang ◽  
Nigel Baltrop ◽  
Ji Chunyan ◽  
Liangbi Li
Keyword(s):  
Low Frequency ◽  
Structure Design ◽  
The Body ◽  
Body Motion ◽  
Mooring Line ◽  
Offshore Structure ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Line System ◽  
Irregular Wave

Mooring line damping plays an important role to the body motion of moored floating platforms. Meanwhile, it can also make contributions to optimize the mooring line system. Accurate assessment of mooring line damping is thus an essential issue for offshore structure design. However, it is difficult to determine the mooring line damping based on theoretical methods. This study considers the parameters which have impact on mooring-induced damping. In the paper, applying Morison formula to calculate the drag and initial force on the mooring line, its dynamic response is computed in the time domain. The energy dissipation of the mooring line due to the viscosity was used to calculate mooring-induced damping. A mooring line is performed with low-frequency oscillation only, the low-frequency oscillation superimposed with regular and irregular wave-frequency motions. In addition, the influences of current velocity, mooring line pretension and different water depths are taken into account.

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