scholarly journals Frequency and time fault diagnosis methods of power transformers

2018 ◽  
Vol 18 (4) ◽  
pp. 162-167 ◽  
Author(s):  
Miroslav Gutten ◽  
Daniel Korenciak ◽  
Matej Kucera ◽  
Richard Janura ◽  
Adam Glowacz ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
High Voltage ◽  
Impact Test ◽  
Power Transformer ◽  
Short Circuit ◽  
Small Deformation ◽  
Short Circuit Current ◽  
Diagnostic Methods ◽  
Response Analysis ◽  
Short Circuit Currents

Abstract The authors describe experimental and theoretical analyses of faults of power transformer winding. Faults were caused by mechanical effect of short-circuit currents. Measurements of transformer were carried out in high-voltage laboratory. Frequency and time diagnostic methods (method SFRA - Sweep Frequency Response Analysis, impact test) were used for the analyses. Coils of transformer windings were diagnosed by means of the SFRA method and the time impact test. The analyzed methods had a significant sensitivity to a relatively small deformation of coil. In the analysis a new technique for analyzing the effects of short-circuit currents is introduced. This technique is developed for high-voltage transformers (different types of power). The proposed analyses show that it is necessary to analyze the value of short-circuit current. Short-circuit current represents a danger for the operation of the power transformer. The proposed approach can be used for other types of transformers. Moreover, the presented techniques have a potential application for fault diagnosis of electrical equipment such as: transformers and electrical machines.

scholarly journals Comparative Analysis of High-Voltage Power Line Models for Determining Short-Circuit Currents in Towers Earthing Systems

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4729
Author(s):  
Rafał Tarko ◽  
Jakub Gajdzica ◽  
Wiesław Nowak ◽  
Waldemar Szpyra
Keyword(s):  
High Voltage ◽  
Current Distribution ◽  
Single Phase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Power Line ◽  
Power Lines ◽  
Distribution Analysis ◽  
Short Circuits ◽  
Short Circuit Currents

The article deals with the problems of single-phase short-circuit current distribution in overhead power lines. Short-circuit disturbances cause many negative phenomena in power networks. Since experimental studies of short-circuits in real networks are practically impossible to perform, these effects can be evaluated only theoretically, based on short-circuit current calculations with the use of appropriate mathematical models. Although short-circuit modeling is considered to be one of the simplest power system calculations, the exact mathematical description of the phenomena occurring at short-circuits is complex. Simplified normative methods are often used for short-circuit current calculations; however, this does not give ground for a thorough analysis of short-circuit current distribution in power lines. The distributions are analyzed using power line models with different degrees of complexity in line with the assumptions made for a given model. The paper presents the problem of current distribution analysis in high-voltage overhead lines for single-phase faults to the tower structures. Simulation studies were conducted on the models developed for the calculation of short-circuit currents in the high-voltage power line earthing. The objective of the analysis was to assess the validity of simplification assumptions followed by practical recommendations on the applicability of the models.

Fault diagnosis of actual large-power high-voltage windings using transfer function method

2011 ◽  
Vol 60 (3) ◽  
pp. 269-281 ◽  
Author(s):  
Ebrahim Rahimpour ◽  
Stefan Tenbohlen
Keyword(s):  
Fault Diagnosis ◽  
Transfer Function ◽  
High Voltage ◽  
Function Method ◽  
Power Transformer ◽  
Short Circuit ◽  
Large Power ◽  
Transfer Function Method ◽  
Comparison Algorithms ◽  
Test Objects

Fault diagnosis of actual large-power high-voltage windings using transfer function method The transfer function (TF) method is presently a well-known method used to detect various types of winding damage in power transformers. Although abundant research has been done on this subject using laboratory windings as test objects, it is hard to find one, whose test objects are actual large-power transformer windings. Hence, a 400 kV disc winding consisting of 86 discs is used in this paper to study turn-to-turn short circuit with the help of the TF method. To evaluate the effects of this type of fault on TF curves, some mathematical comparison algorithms are used in this research.

Impacts of UHV on Short Circuit Currents in China's Central 500kV Grid and Its Countermeasures

2014 ◽  
Vol 960-961 ◽  
pp. 891-895
Author(s):  
Xu Zheng ◽  
Jiang Hong Wang ◽  
Mei Li ◽  
Shuang Zhao ◽  
Bu Han Zhang ◽  
...  
Keyword(s):  
Power System ◽  
High Voltage ◽  
Sharp Increase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Central China ◽  
Fault Current ◽  
Access Scheme ◽  
Short Circuit Currents ◽  
Lower Voltage

Ultra-high voltage (UHV) projects are making power system growing lager and resulting in sharp increase of short circuit currents in some area especially in the vicinity of UHV access points. The paper presented the damage of short circuit current increases and common methods to limit fault current. Taking the construction and development of UHV grid in a province of central China as background, the over short circuit currents in 500kV Grid within UHV were showed and several countermeasures including choosing proper UHV access scheme, implementing UHV substation lower voltage bus partition running, installing reactors, optimizing power grid network based on UHV connection point were proposed and then verified by PSASP simulation. The results show those measures are useful to reduce the short circuit current to a reasonable level.

Na and Cl Transport across the Isolated Anterior Intestine of the Plaice Pleuronectes Platessa

1981 ◽  
Vol 90 (1) ◽  
pp. 123-142
Author(s):  
M. M. P. RAMOS ◽  
J. C. ELLORY
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Negative Potential ◽  
Loop Diuretics ◽  
Significant Part ◽  
Cl Transport ◽  
Anterior Intestine ◽  
Short Circuit Currents ◽  
Na Uptake

1. The tissue was found to have a serosa negative potential, and short-circuit currents equivalent to the net Cl transport. 2. A significant part of the Cl uptake was Na dependent and a similar fraction of the Na uptake was Cl dependent. 3. Short-circuit current and uptake of both ions were inhibited by loop diuretics and analogues. 4. I80 and P.D. were abolished by ouabain. 5. The observations are consistent with the idea of a coupled NaCl entry into the cell, using the energy inherent in the Na gradient; Na being pumped out of the cells by the Na pump and followed electrically by Cl−. Net chloride transport and the serosa negative potential would be a consequence of the permselective properties of the junctions allowing Na but not Cl to recycle back to the mucosal solution.

scholarly journals Symmetrical Loss of Excitation Fault Diagnosis in an Asynchronized High-Voltage Generator

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3054 ◽  
Author(s):  
Yanling Lv ◽  
Yuting Gao ◽  
Jian Zhang ◽  
Chenmin Deng ◽  
Shiqiang Hou
Keyword(s):  
Neural Network ◽  
Fault Diagnosis ◽  
High Voltage ◽  
Short Circuit ◽  
Open Circuit ◽  
Voltage Generator ◽  
Three Phase ◽  
Circuit Loss ◽  
High Voltage Generator ◽  
Short Circuit Fault

As a new type of generator, an asynchronized high-voltage generator has the characteristics of an asynchronous generator and high voltage generator. The effect of the loss of an excitation fault for an asynchronized high-voltage generator and its fault diagnosis technique are still in the research stage. Firstly, a finite element model of the asynchronized high-voltage generator considering the field-circuit-movement coupling is established. Secondly, the three phase short-circuit loss of excitation fault, three phase open-circuit loss of excitation fault, and three phase short-circuit fault on the stator side are analyzed by the simulation method that is applied abroad at present. The fault phenomenon under the stator three phase short-circuit fault is similar to that under the three phase short-circuit loss of excitation. Then, a symmetrical loss of the excitation fault diagnosis system based on wavelet packet analysis and the Back Propagation neural network (BP neural network) is established. At last, we confirm that this system can eliminate the interference of the stator three phase short-circuit fault, accurately diagnose the symmetrical loss of the excitation fault, and judge the type of symmetrical loss of the excitation fault. It saves time to find the fault cause and improves the stability of system operation.

Modeling Analysis of Impedance Characteristics of Saturated Core Superconducting Fault Current Limiter

2013 ◽  
Vol 389 ◽  
pp. 1089-1095
Author(s):  
Jun Zhen Peng ◽  
Kun Nan Cao ◽  
Da Da Wang ◽  
Meng Song ◽  
Nan Nan Hu ◽  
...  
Keyword(s):  
High Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Element Analysis ◽  
Superconducting Fault Current Limiter ◽  
Saturation Properties ◽  
Modeling Analysis ◽  
Current Limiter

As one of the most applicable to high-voltage network superconducting fault current limiterSCFCL(saturated core superconducting fault current limiter) ,which use of core saturation properties can be achieved the current-limiting function without delay ,will be the most widely applied in the future,By analyzing the working principle of SCFCL,this paper use of PSCAD and finite element analysis software Ansoft to build the 500kV\/3150A grade SCFCL model and accurate calculation coil self-inductance and mutual inductance, the harmonic of each size and analyzed its Impedance characteristic on the different external parameters,The results show that SCFCL has a excellent performance for high voltage power network short-circuit current limitation, and provides important reference for design.

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