scholarly journals Influence of the load of the power transformer on the magnetizing current

2021 ◽  
Vol 2131 (4) ◽  
pp. 042097
Author(s):  
S Ivankov ◽  
S Zagulyaev ◽  
D Gukov
Keyword(s):  
Cross Section ◽  
Magnetic Circuit ◽  
Power Transformer ◽  
Magnetic Core ◽  
Significant Error ◽  
Continuous Operation ◽  
Power Transformers ◽  
Magnetic Scattering ◽  
Testing Power ◽  
Magnetizing Current

Abstract Data on the magnetizing current of power transformers are taken from the experience of idling. It is considered that it does not change under load. The experience of idling does not take into account the uneven saturation of the magnetic core when working under load. The hypothesis of a significant error caused by this assumption is put forward. The experiments carried out confirmed the hypothesis. The differences in the measurement of the magnetizing current at idle and under load in the experiments reached 28-32%. This determines the inaccuracy in the calculations of currents and losses in power transformers, which, taking into account the continuous operation of transformers and their large number, can be significant. It is proposed to add the experience of working at rated load when testing power transformers. This experience will not only allow us to clarify the val-ue of the magnetizing current under load and magnetic losses, but also to re-fine the design of the transformer in the direction of reducing the magnetizing current by eliminating uneven saturation of the magnetic circuit when working under load, due to the influence of magnetic scattering fields. This is possible by locally increasing the cross-section of the magnetic circuit in the busiest places of the magnetic circuit.

scholarly journals Modelling of magnetostriction of transformer magnetic core for vibration analysis

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 803-808
Author(s):  
Janis Marks ◽  
Sandra Vitolina
Keyword(s):  
Power Transformer ◽  
Operation Mode ◽  
Magnetic Core ◽  
Power Transformers ◽  
Normal Operation ◽  
Elastic Deformations ◽  
Properties Of Materials ◽  
Transformer Core ◽  
Normal Operation Mode

Abstract Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

scholarly journals A Poisson-Fault Model for Testing Power Transformers in Service

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Dengfu Zhao ◽  
Zheng Zhao ◽  
Qihong Duan ◽  
Gongnan Xie
Keyword(s):  
Failure Rate ◽  
Working Conditions ◽  
Classical Method ◽  
Power Transformer ◽  
Fault Model ◽  
Power Transformers ◽  
Bayes Estimate ◽  
Testing Power ◽  
Simulation Results ◽  
Periodic Inspections

This paper presents a method for assessing the instant failure rate of a power transformer under different working conditions. The method can be applied to a dataset of a power transformer under periodic inspections and maintenance. We use a Poisson-fault model to describe failures of a power transformer. When investigating a Bayes estimate of the instant failure rate under the model, we find that complexities of a classical method and a Monte Carlo simulation are unacceptable. Through establishing a new filtered estimate of Poisson process observations, we propose a quick algorithm of the Bayes estimate of the instant failure rate. The proposed algorithm is tested by simulation datasets of a power transformer. For these datasets, the proposed estimators of parameters of the model have better performance than other estimators. The simulation results reveal the suggested algorithms are quickest among three candidates.

Calculation of inrush current using adopted parameters of the hysteresis loop

2014 ◽  
Vol 33 (5) ◽  
pp. 1794-1808 ◽  
Author(s):  
Ramezan Ali Naghizadeh ◽  
Behrooz Vahidi ◽  
Seyed Hossein Hosseinian
Keyword(s):  
Power Transformer ◽  
Fitness Function ◽  
Magnetic Core ◽  
Power Transformers ◽  
Model Parameters ◽  
Inrush Current ◽  
Hysteresis Phenomenon ◽  
Hysteresis Model ◽  
Content Type ◽  
Transformer Model

Purpose – The purpose of this paper is to propose an accurate model for simulation of inrush current in power transformers with taking into account the magnetic core structure and hysteresis phenomenon. Determination of the required model parameters and generalization of the obtained parameters to be used in different conditions with acceptable accuracy is the secondary purpose of this work. Design/methodology/approach – The duality transformation is used to construct the transformer model based on its topology. The inverse Jiles-Atherton hysteresis model is used to represent the magnetic core behavior. Measured inrush waveforms of a laboratory test power transformer are used to calculate a fitness function which is defined by comparing the measured and simulated currents. This fitness function is minimized by particle swarm optimization algorithm which calculates the optimal model parameters. Findings – An analytical and simple approach is proposed to generalize the obtained parameters from one inrush current measurement for simulation of this phenomenon in different situations. The measurement results verify the accuracy of the proposed method. The developed model with the determined parameters can be used for accurate simulation of inrush current transient in power transformers. Originality/value – A general and flexible topology-based model is developed in PSCAD/EMTDC software to represent the transformer behavior in inrush situation. The hysteresis model parameters which are obtained from one inrush current waveform are generalized using the structure parameters, switching angle, and residual flux for accurate simulation of this phenomenon in different conditions.

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.

Study of power transformer loading in rural power supply systems

2021 ◽  
Vol 13 (4) ◽  
pp. 282-289
Author(s):  
I. V. Naumov ◽  
D. N. Karamov ◽  
A. N. Tretyakov ◽  
M. A. Yakupova ◽  
E. S. Fedorinovа
Keyword(s):  
Energy Efficiency ◽  
Power Supply ◽  
Rural Areas ◽  
Power Transformer ◽  
Electric Energy ◽  
Power Transformers ◽  
Electric Networks ◽  
Load Factors ◽  
Optimal Load ◽  
Supply Systems

The purpose of this study is to study the effect of loading power transformers (PT) in their continuous use on their energy efficiency on a real-life example of existing rural electric networks. It is noted that the vast majority of PT in rural areas have a very low load factor, which leads to an increase in specific losses of electric energy when this is transmitted to various consumers. It is planned to optimize the existing synchronized power supply systems in rural areas by creating new power supply projects in such a way as to integrate existing power sources and ensure the most efficient loading of power transformers for the subsequent transfer of these systems to isolated ones that receive power from distributed generation facilities. As an example, we use data from an electric grid company on loading power transformers in one of the districts of the Irkutsk region. Issues related to the determination of electric energy losses in rural PT at different numerical values of their load factors are considered. A computing device was developed using modern programming tools in the MATLAB system, which has been used to calculate and plot the dependence of power losses in transformers of various capacities on the actual and recommended load factors, as well as the dependence of specific losses during the transit of 1 kVA of power through a power transformer at the actual, recommended and optimal load factors. The analysis of specific losses of electric energy at the actual, recommended and optimal load factors of PT is made. Based on the analysis, the intervals of optimal load factors for different rated power of PT of rural distribution electric networks are proposed. It is noted that to increase the energy efficiency of PT, it is necessary to reduce idling losses by increasing the load of these transformers, which can be achieved by reducing the number of transformers while changing the configuration of 0.38 kV distribution networks.

scholarly journals A Novel Excitation Approach for Power Transformer Simulation Based on Finite Element Analysis

2021 ◽  
Vol 11 (21) ◽  
pp. 10334
Author(s):  
Wen-Ching Chang ◽  
Cheng-Chien Kuo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Magnetic Flux ◽  
Flux Density ◽  
Power Transformer ◽  
Core Loss ◽  
Power Transformers ◽  
Magnetic Flux Density ◽  
External Excitation ◽  
Element Method

Power transformers play an indispensable component in AC transmission systems. If the operating condition of a power transformer can be accurately predicted before the equipment is operated, it will help transformer manufacturers to design optimized power transformers. In the optimal design of the power transformer, the design value of the magnetic flux density in the core is important, and it affects the efficiency, cost, and life cycle. Therefore, this paper uses the software of ANSYS Maxwell to solve the instantaneous magnetic flux density distribution, core loss distribution, and total iron loss of the iron core based on the finite element method in the time domain. . In addition, a new external excitation equation is proposed. The new external excitation equation can improve the accuracy of the simulation results and reduce the simulation time. Finally, the three-phase five-limb transformer is developed, and actually measures the local magnetic flux density and total core loss to verify the feasibility of the proposed finite element method of model and simulation parameters.

scholarly journals Electron Transport in Argon - Hydrogen Mixtures

1980 ◽  
Vol 33 (6) ◽  
pp. 975 ◽  
Author(s):  
GN Haddad ◽  
RW Crompton
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Cross Section ◽  
Transport Coefficients ◽  
Velocity Distribution Function ◽  
Significant Error ◽  
Cross Section Data ◽  
Section Data ◽  
Hydrogen Mixtures ◽  
Legendre Expansion

The transport coefficients υdr and D⊥/μ have been measured in mixtures of 0.5 % and 4 % hydrogen in argon. All measurements were made at 293 K. It is shown that for these mixtures the use of the solution of the Boltzmann equation based on the two-term Legendre expansion of the velocity distribution function introduces no significant error in the analysis of the transport data. All the experimental data have been predicted to within � 3.5 % using previously published cross section data.

scholarly journals Recycling Heat Losses of an Oil-Immersed Transformer: Feasibility Study

2021 ◽  
Vol 21 (1) ◽  
pp. 48-54
Keyword(s):  
High Efficiency ◽  
Power Transformer ◽  
Heat Losses ◽  
Power Transformers ◽  
Passive Mode ◽  
Active Mode ◽  
Short Circuits ◽  
Definition Of ◽  
The Relationship ◽  
Novel Design

The paper investigates the feasibility of adding a liquid heater to an oil-immersed transformer. It proves that design the high efficiency of power transformers, losses due to idling and short circuits are substantial and are scattered in the environment as heat. The paper proposes a novel design that implements a liquid (coolant) heater to enable the unit not only to convert electricity, but also to generate heat. In order to analyze the feasibility of such heat recycling, the authors have developed an equivalent thermal circuit and a mathematical model thereof. Said heater can operate in two modes. In the passive mode, the coolant it contains only absorbs the heat emitted (lost) by the power transformer. In the active mode, it also receives the heat emitted due to the passage of electric current through the pipes of the heater. The paper further introduces the definition of heater efficiency. Studies have shown that up to 50 % of transformer heat losses can be recycled by heating the coolant in the heater. The paper presents the relationship between utilized heat and transformer losses, as well as heater efficiency as a function of coolant flow rate. The heater efficiency exceeds 90 % in the active mode.

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