IMPLEMENTATION OF MAGNETIC CORE FREQUENCY CHARACTERISTICS IN MODELLING OF POWER TRANSFORMERS

2016 ◽  
Vol 63 (273) ◽  
pp. 35-44
Author(s):  
Tadeusz DASZCZYŃSKI ◽  
Zbigniew POCHANKE
Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 803-808
Author(s):  
Janis Marks ◽  
Sandra Vitolina

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.


2017 ◽  
Vol 25 ◽  
pp. 113-117
Author(s):  
Pavlo Krasovskyi

Developed and released recommendations to clarify the calculation of idle power losses in power transformers of distribution networks. It takes into account the dynamics of magnetic properties changes in transformer cores, depending on the operation term and conditions, and major overhaul of the transformers with the magnetic core unburdening. It will improve the accuracy of normative losses calculation in power transformers and determine the most accurate structure of losses in electric networks.


2021 ◽  
Vol 2131 (4) ◽  
pp. 042097
Author(s):  
S Ivankov ◽  
S Zagulyaev ◽  
D Gukov

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.


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