scholarly journals CREATION OF A STRUCTURAL MODEL OF AN POWER TRANSFORMERS IN THE FORM OF AC TRANSFORMING COMPLEXES

2020 ◽  
Author(s):  
Dmytro Yarymbash ◽  
◽  
Mykhailo Kotsur ◽  
Keyword(s):  
Structural Model ◽  
Power Transformer ◽  
Geometric Model ◽  
Operational Reliability ◽  
Power Transformers ◽  
Thermal Processes ◽  
Design Data ◽  
Production Program ◽  
Specialized Software

Due to the multiple transformation of electrical energy, the rated capacity of power transformers can be 8 or more times the rated generation capacity. Therefore, the state of reliability of power transformers, their parameters and characteristics affecting on the reliability and efficiency of power networks, electrical production facilities, and electrical equipment of consumers. High indicators of operational reliability should be provided by the corresponding level of quality of design of power transformers both at a stage of development of tender offers, and during preparation of production of new or modernized types of power transformers. Im-proving approaches to design and increasing the accuracy of design data requires the use of modern specialized software for spatial modeling of electromagnetic and elec-tro-thermal processes in testing and rated modes of operation based on 3D geometric models of parts, assemblies, systems in the active parts of power transformers. To improve the design quality of power transformers, a unitary structure is proposed, which combines tuples of design data of certain types of power transformers. Crea-tion of a unitary structure of power transformer projects for the production program of the enterprise provides a significant time reduction to develop projects of new types of power transformers by importing the generated design data of the same parts, components, systems from previously developed power transformer projects. Application of unitary structure of power transformers projects allows to reduce time for creation and import of detailed 3D geometric model of power transformer in structure of specialized software of field modeling of electromagnetic and electro-thermal processes. This allows to significantly reduce the cost of design preparation of production, increase the accuracy of design data and implement design solutions to increase the level of reliability and efficiency of operation of power transformers. Therefore, the design data for the unavailable parts, components, elements of individual systems in a transformer are displayed in the corresponding design tuple "zero" elements. For development of projects of new types of power transformers, import of the structured design data of identical details, knots, systems of earlier developed projects of power transformers is carried out. Updating the unitary structure of power transformers is provided by supplementing the existing unitary structure with a tuple of design data of a new type of power transformer. This provides a significant reduction in design time and increase the accuracy of determining new design data.

scholarly journals Power transformer faults diagnosis using undestructive methods (Roger and IEC) and artificial neural network for dissolved gas analysis applied on the functional transformer in the Algerian north-eastern: a comparative study

2021 ◽  
pp. 3-11
Author(s):  
L. Bouchaoui ◽  
K. E. Hemsas ◽  
H. Mellah ◽  
S. Benlahneche
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Artificial Neural Network ◽  
Power Transformer ◽  
Gas Analysis ◽  
Power Transformers ◽  
Dissolved Gas ◽  
Dissolved Gas Analysis ◽  
Artificial Neural

Introduction. Nowadays, power transformer aging and failures are viewed with great attention in power transmission industry. Dissolved gas analysis (DGA) is classified among the biggest widely used methods used within the context of asset management policy to detect the incipient faults in their earlier stage in power transformers. Up to now, several procedures have been employed for the lecture of DGA results. Among these useful means, we find Key Gases, Rogers Ratios, IEC Ratios, the historical technique less used today Doernenburg Ratios, the two types of Duval Pentagons methods, several versions of the Duval Triangles method and Logarithmic Nomograph. Problem. DGA data extracted from different units in service served to verify the ability and reliability of these methods in assessing the state of health of the power transformer. Aim. An improving the quality of diagnostics of electrical power transformer by artificial neural network tools based on two conventional methods in the case of a functional power transformer at Sétif province in East North of Algeria. Methodology. Design an inelegant tool for power transformer diagnosis using neural networks based on traditional methods IEC and Rogers, which allows to early detection faults, to increase the reliability, of the entire electrical energy system from transport to consumers and improve a continuity and quality of service. Results. The solution of the problem was carried out by using feed-forward back-propagation neural networks implemented in MATLAB-Simulink environment. Four real power transformers working under different environment and climate conditions such as: desert, humid, cold were taken into account. The practical results of the diagnosis of these power transformers by the DGA are presented. Practical value. The structure and specific features of power transformer winding insulation ageing and defect state diagnosis by the application of the artificial neural network (ANN) has been briefly given. MATLAB programs were then developed to automate the evaluation of each method. This paper presents another tool to review the results obtained by the delta X software widely used by the electricity company in Algeria.

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 Structural Model to Determine the Factors That Affect the Quality of Emergency Teaching, According to the Perception of the Student of the First University Courses

2021 ◽  
Vol 13 (5) ◽  
pp. 2945
Author(s):  
Isabel del Arco ◽  
Òscar Flores ◽  
Anabel Ramos-Pla
Keyword(s):  
Online Teaching ◽  
Structural Model ◽  
Self Regulation ◽  
Digital Competence ◽  
Online Questionnaire ◽  
Student Interactions ◽  
Material Resources ◽  
Emotional Component ◽  
Total Participation

A quantitative study was conducted in order to know, from the perspective of university students, the relationship between the quality perceived (QP) during the period of confinement derived from the SARS-CoV-2 virus, with the variables teaching plan (PL), material resources (MR), interaction processes (IN), and the affective–emotional component (EM). An online questionnaire was designed, directed to students from 20 universities in Spain, with a total participation of 893 individuals. The results indicate that the perception of the students on the quality of online teaching is directly associated with the material resources provided by the professors and the professor–student interactions. However, this perception does not have any direct effect on the planning or the emotional state or affectation created by the unprecedented situation of confinement. Among the conclusions, we highlight the need for the universities to apply models of support and tutoring, especially for students in their first years at university, to develop competences such as autonomy, digital competence, and self-regulation, and the need for a change of approach of the students and the professors based on the new normality we are currently experiencing.

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 Retention Strategy to Minimize Nurse Turnover: A Systematic Review

2019 ◽  
Vol 1 (2) ◽  
pp. 99-109
Author(s):  
Rr.Tutik Sri Hariyati ◽  
Nurdiana Nurdiana
Keyword(s):  
Systematic Review ◽  
Communication Skills ◽  
Work Experience ◽  
Journal Article ◽  
Organization Culture ◽  
Communication Analysis ◽  
Design Data ◽  
Nurse Turnover ◽  
Nurse Communication

Background: Communication skills are essential for nurses in providing health services. Efficacious communication will impact in the quality of care and patient safety. This manuscript is to identify factors predisposing implementation of effective nurse communication. Method: This study that data was retrieved uses systematic review design. Data was retrieved from database ProQuest, SCOPUS, EBSCO, Science-Direct, JSTOR, and Wiley-Online in the period of 2011 – 2017. The study was done for journal, article and literature review by applying the keywords nurse communication, health’s communication, effective communication of nurse. Results: A total of 12518 studies was found from six databases. From, the number of these direct search, systematic review identifies conformity based on the title, so that it obtained 31 studies with a title that suitable for a selected discussion. The total of selected papers were 16 studies and identified Efficacious communication. Analysis result from the paper research was there were 16 papers that complement the criteria determined. Six factors are identified to have effect in an implementation of effective nurse communication: (1) intelligence and self-efficacy, (2) Communication Skills, (3) Work Experience, (4) Perceptions, (5) Socio-cultural, and (6) Organization culture.

scholarly journals Improving the quality of alumina-containing sinter using water-cooled furnace shell

2012 ◽  
Vol 44 (3) ◽  
pp. 281-286
Author(s):  
A.V. Aleksandrov ◽  
V.V. Aleksandrov
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Heat Exchange ◽  
Energy Balance ◽  
Cold Water ◽  
Sintering Temperature ◽  
Radiant Heat ◽  
Thermal Processes ◽  
Technical Solutions

This article deals with the use of computer modeling to develop technical solutions to ensure better quality of alumina-containing sinter. The simulation accounted for the influence of the feed materials on the thermal processes in the furnace. The energy balance (including thermal conductivity, heat convection and radiant heat exchange) was solved assuming steady state. A good correlation was observed for the actual and calculated temperatures of the solids and gases, with less than 15% discrepancy. Using the model of the furnace investigated the possibility of lowering the temperature of sintering by removing heat from the outside of the furnace shell. To reduce the sintering temperature to 1000 ?C length of the refractory lined steel is 5 m, the height of the lining should not exceed - 0.06 m, the required rate of cold water - 54.7 m3/h

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