Monitoring of Winding Deformation of Power Transformer by Using Nanosecond Pulses

2011 ◽  
Vol 128-129 ◽  
pp. 190-195
Author(s):  
Hua Lin Liu ◽  
Yin Bo Zhan ◽  
Xiao Lei ◽  
You Yuan Wang ◽  
Hua Rong Zeng ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Low Voltage ◽  
Power Transformer ◽  
Test System ◽  
Power Transformers ◽  
Distribution Transformer ◽  
Frequency Method ◽  
Nanosecond Pulses ◽  
Measurement Results

As we know, the TF method is more sensitive to changes in the power transformers at higher frequencies. Although measurement based on low voltage impulse (LVI) is definitely faster than that based on swept frequency method (SFM), the available frequency band is narrow because of the typical microsecond impulse. In this paper, the characteristics of the nanosecond impulse in the frequency domain were investigated. A test System based on Nanosecond low voltage impulse was developed. The proposed method was applied to a 10kV/100kVA distribution transformer in the laboratory. Measurement results with two different impulses were compared.

A Mathematical Model for Studying the Pulse Flaw Detection of High-Voltage Transformer Windings

2021 ◽  
pp. 50-57
Author(s):  
Alexey V. LAVRINOVICH ◽  
◽  
Alexey V. MYTNIKOV ◽  
Keyword(s):  
Mathematical Model ◽  
Frequency Spectrum ◽  
Low Voltage ◽  
Power Transformer ◽  
Flaw Detection ◽  
Pulse Frequency ◽  
Voltage Transformer ◽  
Nanosecond Pulses ◽  
Transformer Winding ◽  
A Chain

The article presents the results from elaborating a power transformer mathematical model for modeling the processes of diagnosing the mechanical state of windings using the method of low-voltage nanosecond pulses. The model includes a chain representation of the transformer windings taking into account the dependence of the resistance and reactance of the turns on the frequency spectrum of the pulse supplied from the probing generator. The study of the pulse flaw detection processes carried out on the developed mathematical model has shown that the probing pulse frequency spectrum plays an essential role in locating the transformer winding flaw, in determining the flaw type (displacement of turns, inward radial displacement, buckling). The response signals obtained from application of the simulated probing pulse coincide satisfactorily with the response signals obtained during experiments on the transformer physical model. The developed model opens the possibility of determining, by calculation, transformer winding flaw location and type based on comparing the results of experimental responses during examinations of transformers using the method of low-voltage nanosecond pulses with the simulation results.

scholarly journals A Comparative Study of the Voltage Sag Propagation under Un-Symmetrical Faults through Distribution Transformer on Low Voltage Power Network

2021 ◽  
Vol 19 (1) ◽  
pp. 90-94
Author(s):  
Abdul K. Junejo ◽  
Muhammad U. Keerio ◽  
Mohsin A. Koondhar ◽  
Munawar A. Memon ◽  
Muhammad I. Jamali ◽  
...  
Keyword(s):  
Control Strategy ◽  
Low Voltage ◽  
Power Transformers ◽  
Voltage Sag ◽  
Power Network ◽  
Distribution Transformer ◽  
Sequence Components ◽  
The Impact ◽  
Symmetrical Sequence

In this paper, the characterization of the voltage sag propagation under unsymmetrical faults through distribution transformer for low voltage power network is tested with the help of a power analyzer, which is based on sequence components. The voltage sag is a big issue of the power quality (PQ) for the power system networks, which must be analyzed and characterized for the suitable protection schemes and the control strategy, separately. In this study, the voltage sag characterization is fully examined under the unsymmetrical faults through the delta-star with ground (D-Yg) connection, which is commonly imlemented in the distribution power transformers. The MATLAB/Simulink and power analyzer tools are used to characterize the voltage sag propagation. The power analyzer works on the symmetrical sequence component’s method of the voltage. Moreover, the phasor diagram of the voltage sag is also given in this paper for better understanding. The obtained results would help in the design of the protection schemes for low-voltage and controlling the impact of voltage sag through filters.

scholarly journals Frequency Diagnostics of Insulating System of Power Transformers

2020 ◽  
Vol 16 (1) ◽  
pp. 1-7
Author(s):  
Miroslav Gutten ◽  
Daniel Korenciak ◽  
Peter Brncal ◽  
Roman Jarina
Keyword(s):  
Power Transformer ◽  
Operating Temperature ◽  
The Other ◽  
Power Transformers ◽  
Frequency Method ◽  
Comparative Measurement ◽  
The Individual ◽  
Diagnostic Measurement ◽  
Experimental Diagnostics ◽  
Operational Aspects

AbstractThe paper presents experimental diagnostics of the oil-paper insulating system of power transformers using progressive frequency method. The first part of the paper deals with the basic information about diagnostics of power oil transformers. The second part of the paper deals with the use of frequency domain spectroscopy (FDS) for power oil transformers. This method is used in the analysis of insulating condition of power transformer with the system of oil-paper. It was found that the results of these tests are highly influenced by the operating temperature during the experimental measurement. Moisture and conductivity between the insulating transformer paper and oil in an insulating system are highly dependent on the temperature. In the other part, the paper presents experimental results of the diagnostic measurement for a real traction oil transformer at different operating temperatures and states (with oil and without). Finally, the paper presents comparative measurement among several autotransformers with the same power. In experimental measurements, the correlation between the measured values and the operational aspects of the individual oil autotransformers are shown.

scholarly journals Frequency Domain Diagnostics of Transformer Insulation

2019 ◽  
Vol 10 (4) ◽  
pp. 353-359
Author(s):  
M. Gutten ◽  
M. Šebok ◽  
D. Korenčiak ◽  
P. Brnčal ◽  
M. Kubiš ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Chromatographic Analysis ◽  
Single Phase ◽  
Power Transformer ◽  
Operating Temperature ◽  
Power Transformers ◽  
Insulating Paper ◽  
Recovery Voltage ◽  
Transformer Insulation ◽  
Diagnostic Measurement

The first part of paper deals with the base information about diagnostics of power transformers. In this part are presented differently insulating methods, for example method of recovery voltage method, method of polarization and depolarization currents and chromatographic analysis.The second part of paper deals use of method of frequency domain spectroscopy for oil power transformers. This method is used in analysis insulating condition of power transformer with system of oil-paper. It was found, that the results of these tests are highly impacted by the operating temperature during the experimental measurement. Moisture and conductivity between insulating paper and oil in an insulating system are highly dependent from temperature.In the other part, the paper presents experimental results of the frequency diagnostic measurement for a real single-phase traction transformer 110/27 kV at different operating temperatures and states (with oil and without).Finally in the last part, the paper presents comparing frequency insulating measurements among several the same single-phase transformers 110/27 kV.

scholarly journals Fault Identification of In-Service Power Transformer using Depolarization Current Analysis

2017 ◽  
Vol 7 (2) ◽  
pp. 559
Author(s):  
M.A. Talib ◽  
N.A. Muhamad ◽  
Z.A. Malek ◽  
B.T. Phung
Keyword(s):  
Power Transformer ◽  
Diagnostic Testing ◽  
Cost Effective ◽  
Power Transformers ◽  
Depolarization Current ◽  
Significant Information ◽  
Extended Application ◽  
Catastrophic Failures ◽  
Measurement Results

Preventive diagnostic testing of in-service power transformers require system outage and expert’s knowledge and experiences in interpreting the measurement results. The chemical oil analysis may cause significant variance to measurement results due to the different practices in oil sampling, storage, handling and transportation. Thus, a cost effective measuring technique by means of a simpler method that is able provide an accurate measurement results is highly required. The extended application of Polarization and Depolarization Current (PDC) measurement for characterization of different faults conditions on in-service power transformer has been presented in this paper. The oil sample from in-service power transformers with normal and 3 different faults type conditions were sampled and tested for Dissolved Gases Analysis (DGA) and PDC measurement. The DGA results was used to confirm type of faults inside the transformer while the PDC pattern of oil with normal, partial discharge, overheating and arcing were correlated to the oil sample conditions. The analysis result shows that depolarization current provides significant information to defferenciate fault types in power transformer. Thus this finding provides a new alternative in identifying incipient faults and such knowledge can be used to avoid catastrophic failures of power transformers.

A Solid-State On-Load Tap Changer for the Power Transformers of 10—0.4 kV Distribution Networks

Vestnik MEI ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 82-90
Author(s):  
Dmitriy I. Panfilov ◽  
◽  
Mikhail G. Astashev ◽  
Aleksandr V. Gorchakov ◽  
◽  
...  
Keyword(s):  
Solid State ◽  
Physical Model ◽  
High Speed ◽  
Power Transformer ◽  
Voltage Control ◽  
Power Transformers ◽  
Control Algorithms ◽  
Load Voltage ◽  
Tap Changer ◽  
Load Tap Changer

The specific features relating to voltage control of power transformers at distribution network transformer substations are considered. An approach to implementing high-speed on-load voltage control of serially produced 10/0.4 kV power transformers by using a solid-state on-load tap changer (SOLTC) is presented. An example of the SOLTC circuit solution on the basis of thyristor switches is given. On-load voltage control algorithms for power transformers equipped with SOLTC that ensure high reliability and high-speed operation are proposed. The SOLTC performance and the operability of the suggested voltage control algorithms were studied by simulation in the Matlab/Simulink environment and by experiments on the SOLTC physical model. The structure and peculiarities of the used simulation Matlab model are described. The SOLTC physical model design and its parameters are presented. The results obtained from the simulating the SOLTC operation on the Matlab model and from the experiments on the SOLTS physical model jointly with a power transformer under different loads and with using different control algorithms are given. An analysis of the experimental study results has shown the soundness of the adopted technical solutions. It has been demonstrated that the use of an SOLTC ensures high-speed voltage control, high efficiency and reliability of its operation, and arcless switching of the power transformer regulating taps without load voltage and current interruption. By using the SOLTC operation algorithms it is possible to perform individual phase voltage regulation in a three-phase 0.4 kV distribution network. The possibility of integrating SOLTC control and diagnostic facilities into the structure of modern digital substations based on the digital interface according to the IEC 61850 standard is noted.

The Heating System of Agricultural Facilities Using Excess Heat Power Transformers

2020 ◽  
Vol 67 (1) ◽  
pp. 42-47
Author(s):  
Anatoliy I. Sopov ◽  
Aleksandr V. Vinogradov
Keyword(s):  
System Design ◽  
Heat Supply ◽  
Cooling System ◽  
Power Transformer ◽  
Electric Heating ◽  
Heating System ◽  
Power Transformers ◽  
Large Power ◽  
Excess Heat ◽  
Power Centers

In power transformers, energy losses in the form of heat are about 2 percent of their rated power, and in transformers of large power centers reach hundreds of kilowatts. Heat is dissipated into the environment and heats the street air. Therefore, there is a need to consume this thermal energy as a source of heat supply to nearby facilities. (Research purpose) To develop methods and means of using excess heat of power transformers with improvement of their cooling system design. (Materials and methods) The authors applied following methods: analysis, synthesis, comparison, monographic, mathematical and others. They analyzed various methods for consuming excess heat from power transformers. They identified suitable heat supply sources among power transformers and potential heat consumers. The authors studied the reasons for the formation of excess heat in power transformers and found ways to conserve this heat to increase the efficiency of its selection. (Results and discussion) The authors developed an improved power transformer cooling system design to combine the functions of voltage transformation and electric heating. They conducted experiments to verify the effectiveness of decisions made. A feasibility study was carried out on the implementation of the developed system using the example of the TMG-1000/10/0.4 power transformer. (Conclusions) The authors got a new way to use the excess heat of power transformers to heat the AIC facilities. It was determined that the improved design of the power transformer and its cooling system using the developed solutions made it possible to maximize the amount of heat taken off without quality loss of voltage transformation.

scholarly journals Modeling of German Low Voltage Cables with Ground Return Path

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1265 ◽  
Author(s):  
Johanna Geis-Schroer ◽  
Sebastian Hubschneider ◽  
Lukas Held ◽  
Frederik Gielnik ◽  
Michael Armbruster ◽  
...  
Keyword(s):  
Low Voltage ◽  
Measurement Data ◽  
Analytical Calculation ◽  
Laboratory Measurement ◽  
Model Parameters ◽  
Calculation Methods ◽  
Modeling Approach ◽  
Measurement Results ◽  
Simulation Results ◽  
Return Path

In this contribution, measurement data of phase, neutral, and ground currents from real low voltage (LV) feeders in Germany is presented and analyzed. The data obtained is used to review and evaluate common modeling approaches for LV systems. An alternative modeling approach for detailed cable and ground modeling, which allows for the consideration of typical German LV earthing conditions and asymmetrical cable design, is proposed. Further, analytical calculation methods for model parameters are described and compared to laboratory measurement results of real LV cables. The models are then evaluated in terms of parameter sensitivity and parameter relevance, focusing on the influence of conventionally performed simplifications, such as neglecting house junction cables, shunt admittances, or temperature dependencies. By comparing measurement data from a real LV feeder to simulation results, the proposed modeling approach is validated.

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