scholarly journals ANALYSIS OF CONSTRUCTION PRINCIPLES AND FUNCTIONALITY OF HIGH-VOLTAGE POWER TRANSFORMER CONDITION MONITORING SYSTEMS

2020 ◽  
pp. 61-70
Author(s):  
O. Ye. Pirotti ◽  
O. I. Balenko ◽  
V. O. Brechko ◽  
M. Yu. Huzin ◽  
Ju. G. Gontar
Keyword(s):  
High Voltage ◽  
Power Transformer ◽  
Short Circuit ◽  
Power Transformers ◽  
Electrical Network ◽  
Characteristic Functions ◽  
Economic Losses ◽  
Monitoring Systems ◽  
Measuring Instruments ◽  
Continuous Control

The article presents the results of analysis of construction principles and functionality of systems used to monitor the condition of high-voltage power transformers. The main functions of modern monitoring systems used to diagnose the condition of electrical network equipment both in Ukraine and abroad were analysed. Based on the analysis it was found that the most characteristic functions of monitoring systems are the detection of rapidly developing defects and continuous control of parameters necessary to predict and assess the state of equipment. It is shown that efficiency of monitoring systems will be determined by both accuracy of measuring instruments and adequacy of prediction and diagnostic models used in the process of measurement results processing. Requirements to the equipment which observance allows providing effective and economically reasonable use of monitoring systems are considered. The typical architecture of modern monitoring systems is analysed, the basic elements of such systems are considered. Basic levels of information flow processing within the systems for monitoring the condition of power transformers have been considered. A detailed description and justification for using diagnostic parameters for monitoring the main components of power transformers such as dissolved gases analysis, partial discharges, current, voltage and power of transformers, oil temperature in different transformer locations, switching and atmospheric overvoltages, short-circuit currents, deformation of windings and others are presented. The output parameters returned by monitoring systems are given. The introduction of modern systems and technical means of monitoring the condition of high-voltage power transformers will reduce the risks of emergencies and, consequently, reduce the economic losses associated with the replacement of damaged transformers and under-release of electrical energy.

scholarly journals DETERMINATION OF “WEAK” BY POWER TRANSFORMERS RELIABILITY OF POWER SYSTEMS ACCORDING TO THE RESULTS OF FAILURE RISK ASSESSMENT UNDER EXTERNAL SHORT CIRCUITS

2021 ◽  
Author(s):  
Eugeniy I. Bardik ◽  
Mykola P. Bolotniy ◽  
Yaroslav S. Koval
Keyword(s):  
Mathematical Model ◽  
Risk Assessment ◽  
Power System ◽  
Electric Power ◽  
Power Transformer ◽  
Short Circuit ◽  
Electric Power System ◽  
Power Transformers ◽  
Electrical Network ◽  
Failure Risk

Background. The increase of technological violation intensity and its consequences severity is caused mainly by objectively existing aging and service life depletion of electrical equipment. The power industry liberalization exacerbates the reliable operation problem of the power system and requires identification of power system operation accompanied by the maximum emergency risk with possible cascade accidents development. Therefore, the model development task for assessment of the equipment failure risk based on the diagnostic results of technical condition in particular under short circuit in the external network is relevant today. Objective. The aim of the work is to develop a fuzzy mathematical model for probability assessment of power transformer failure in the presence of a windings defect, short circuit in external network and emergency risk assessment under power transformers out of service. Methods. The fuzzy set theory and fuzzy logic were used for developing a mathematical model of risk assessment of power trans- former failure. The problems of determining the “weak” in terms of power transformers reliability of power systems based on the results of failure risk assessment due to external short circuits were solved by methods of fuzzy logic and probabilistic-statistical simulation of electric power system modes. Results. The necessity of complex simulation of electric power system modes is substantiated for probability assessment of power transformer failure under electrical network disturbances. The simulation of technical condition of power transformer windings was carried out. The short circuit influence on operability level of power transformers of electric power system was investigated. The quantitative indicators of operational risk of electric power system were determined under power transformers out of service. Conclusions. The linguistic mathematical model for estimating the failure probability of power transformer windings in the presence of defect and short circuit in electrical network has been developed to determine the quantitative indicators of emergency risk in power system.

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 On Simplified Calculations of Leakage Inductances of Power Transformers

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4952 ◽  
Author(s):  
Tadeusz Sobczyk ◽  
Marcin Jaraczewski
Keyword(s):  
Power Transformer ◽  
Short Circuit ◽  
Power Transformers ◽  
Stray Field ◽  
Good Representation ◽  
The Finite Element Method ◽  
Leakage Inductance ◽  
Leakage Flux ◽  
Calculation Results ◽  
Discrete Differential Operator

This paper deals with the problem of the leakage inductance calculations in power transformers. Commonly, the leakage flux in the air zone is represented by short-circuit inductance, which determines the short-circuit voltage, which is a very important factor for power transformers. That inductance is a good representation of the typical power transformer windings, but it is insufficient for multi-winding ones. This paper presents simple formulae for self- and mutual leakage inductance calculations for an arbitrary pair of windings. It follows from a simple 1D approach to analyzing the stray field using a discrete differential operator, and it was verified by the finite element method (FEM) calculation results.

An Innovative Solution for Type Testing of Power Transformers

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Manohar Singh ◽  
Vishnuvarddhan Telukanta ◽  
K S Meera
Keyword(s):  
Power Transformer ◽  
Short Circuit ◽  
Operating Conditions ◽  
Power Transformers ◽  
Test Facility ◽  
Online Testing ◽  
Testing Laboratory ◽  
Power Testing ◽  
Grid Operation ◽  
The Impact

Abstract Type tests are essential to assess the short circuit withstand capabilities of transformer windings. The mechanical durability of power equipment are checked against the mechanical forces developed during making/breaking short circuit operations. These type tests are generally carried out in indoor transformer test laboratories. Testing of Power Transformer for size more than 200 MVA in 765/400 kV voltage class in an indoor laboratory is not economically feasible. Now a days, power transformer manufacturers are fabricating single phase auto- power transformers of size up to 630 megawatt volt ampere (MVA) rating. Type testing of these transformers in indoor laboratories is not feasible. In view of this, strong short circuit fault feeding capabilities of the national grids can be utilized for type testing of these power transformers in an online manner. However, this may affect the grid operation/control during weak grid operating conditions. Recently, National High Power Testing Laboratory is established for testing of power transformer upto of 630 MVA. This is a unique online transformer test facility for testing of 765/400/220/132 kV class power transformers. An offline simulation has been carried out in this article, to assess the impact of online type testing on the Indian National grid. In this article, an online testing scheme has been presented which enables the national grid operator to analysis the prevailing grid condition & subsequently to decide the safe rating of the power transformer for online testing. The simulated results are cross checked with field results and it is found that simulated results are close to actual field results. The concurrence of simulated and field results helped in successfully commissioning of the testing laboratory.

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.

scholarly journals ASSESS THE RISK LEVEL OF POWER TRANSFORMER DUE SHORT-CIRCUIT FAULTS BASED ON ANFIS

SINERGI ◽  
2019 ◽  
Vol 23 (2) ◽  
pp. 99
Author(s):  
Azriyenni Azhari Zakri ◽  
Mohd Wazir Mustafa ◽  
Hari Firdaus ◽  
Ibim Sofimieari
Keyword(s):  
Power Systems ◽  
Power Distribution ◽  
Fuzzy Inference ◽  
Power Transformer ◽  
Short Circuit ◽  
Electrical Power ◽  
Power Transformers ◽  
Risk Level ◽  
Electrical Machine ◽  
Intelligent Technique

A power transformer is an electrical machine that converts electrical power at different voltage levels. Faults, occur in power transformers, inhibit electrical power distribution to the consumer. Protection, therefore, of the power transformers is essential in power systems reliability. The power system can be reliable if the protection devices work well when there is a fault. A hybrid intelligent technique, which is a combination of Artificial Neural Network (ANN) and Fuzzy known as Adaptive Neuro-Fuzzy Inference Systems (ANFIS), was used in this research. The objective of this paper is the simulation of differential relays as a protection device on power transformers using Matlab/Simulink. Performance of differential relays for power transformers protection is carried out with internal and external fault scenarios. The input data were classified into three different input for ANFIS such as internal and external 1, internal and external 2, internal, external 1, and external 2, respectively. The error results of ANFIS training for the type of fault internal and external 1 is 9.46*10-7, and types of fault internal and external 2 is 1.09*10-6 internal, external 1 and external 2 are 8.59*10-7. The results obtained from the simulation were accurate and shows that the ANFIS technique is an efficient method that gives less error and a great value. Finally, the technique can minimize faults with power transformers. Finally, to prove this method can reduce faults in the power transformer, the assess of this model has been carried out through the RMSE that has been generated which is zero.

scholarly journals Diagnosis winding short-circuit faults of power transformer

2018 ◽  
Vol 8 (2) ◽  
pp. 70-78
Author(s):  
Rekik Badri ◽  
Labar Hocine
Keyword(s):  
Power Transformer ◽  
Short Circuit ◽  
Power Transformers ◽  
Vector Diagram ◽  
Distribution Grid ◽  
The Core ◽  
Reliable Detection ◽  
Coupled Circuits ◽  
Base Data ◽  
Diagram Analysis

Diagnostic goal of transformers in service is to detect the winding or the core in fault. Transformers are valuable equipment which makes a major contribution to the supply security of a power system. Consequently, it is of great importance to disequilibria the three phases courant of power transformers. So, vector diagram Analysis is useful tool for reliable detection of incipient mechanical fault in a transformer, by finding winding or core defects. The authors propose this article, the coupled circuits method, because, it gives most possible exhaustive modelling of transformers. Measurement courant homopolaire in order to improve and simplify the response for à faults transformer.This study can be useful as a base data for the other transformers of the same categories intended for distribution grid.  Keywords—Diagnostic; Short-Circuit; Transformer Faults; unbalanced current.

scholarly journals Protection of power transformers against the effect of magnetic storms

2021 ◽  
Vol 72 (4) ◽  
pp. 249-255
Author(s):  
Daniel Mayer
Keyword(s):  
Power Systems ◽  
High Voltage ◽  
Large Scale ◽  
Geomagnetic Storms ◽  
Power Transformer ◽  
Physical Nature ◽  
Magnetic Storms ◽  
Power Transformers ◽  
Long Distance ◽  
New Device

Abstract In the operation of large-scale power systems for the long-distance transmission of large amounts of electricity, a number of cases have been reported in which anomalies in the Earth’s magnetosphere, referred to as geomagnetic storms, have caused a severe system collapse. Changes in the geomagnetic field cause a semi-saturating phenomenon, in which the high-voltage lines and especially the high-voltage windings of the power transformers of the system are overloaded with current and subsequently also thermally. The present article briefly explains the physical nature of magnetic storms and then describes a new device that either eliminates the possibility of a step-down power transformer accident or significantly reduces its effects on the system. The essence of this device are frequency filters, which are connected in parallel to the high-voltage windings of power transformers. At the beginning of a geomagnetic storm, the frequency filter is automatically connected to the system and is automatically disconnected when it subsides. The operation of frequency filters does not require human intervention, acquisition and operating costs are low and their integration into existing power systems is easy.

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