Transient processes in primary winding of voltage transformers under single-phase short circuits in 110 kV power grids with cable fixings

2008 ◽  
Author(s):  
Khlopova Anastasiya ◽  
Sarin Leonid
Keyword(s):  
Single Phase ◽  
Power Grids ◽  
Transient Processes ◽  
Short Circuits

scholarly journals Research of transient processes in case of single-phase insulation faults in low-voltage ship power grids, taking into account the resistance at the fault point

2020 ◽  
pp. 49-54
Author(s):  
И.Е. Кажекин
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Experimental Studies ◽  
Power Grids ◽  
Transient Processes ◽  
Safety Issues ◽  
Physical Experiments ◽  
Marine Industry ◽  
Calculation Results ◽  
Constant Potential

В работе рассмотрены вопросы безопасности бортовых электросетей объектов морской индустрии, показано влияние перенапряжений на их основные показатели, которыми определяются опасности смертельных электротравм, опасности возникновения пожаров и взрывов. Представлены результаты математического моделирования электрического разряда по уравнению Майра с учетом особенностей переходного процесса при однофазных замыканиях на корпус. Показана роль напряжения смещения нейтрали по постоянному потенциалу, наибольшие значения которого формируются при неустойчивом контакте фазы с корпусом судна. Описаны результаты экспериментальных исследований переходных процессов, сопровождающихся возникновением неустойчивыми искровыми разрядами. Сравнение результатов расчета по предложенной методике с результатами физических экспериментов показало весьма удовлетворительную сходимость. Предложенная модель может быть использована для уточнения показателей, характеризующих безопасность судовых электросетей. The paper deals with the safety issues of on-board power grids of the marine industry facilities, shows the influence of overvoltages on their main indicators, which determine the dangers of fatal electrical injuries, the risk of fires and explosions. The results of mathematical modeling of an electric discharge according to the Mayr equation, taking into account the features of the transient process in single-phase short circuits to the case, are presented. The role of the bias voltage of the neutral at a constant potential is shown, the highest values ​​of which are formed during unstable contact of the phase with the ship's hull. The results of experimental studies of transient processes accompanied by the appearance of unstable spark discharges are described. Comparison of the calculation results by the proposed method with the results of physical experiments showed a very satisfactory convergence. The proposed model can be used to refine the indicators characterizing the safety of ship power grids.

scholarly journals Voltages Induced in Overhead Ground-Wire Cable as Risk Factor. Part 1

2016 ◽  
Vol 5 (1) ◽  
pp. 28-40 ◽  
Author(s):  
Токарский ◽  
A. Tokarskiy ◽  
Рубцова ◽  
Nina Rubtsova ◽  
Рябченко ◽  
...  
Keyword(s):  
Risk Factor ◽  
Single Phase ◽  
Interval Length ◽  
Maximum Permissible Level ◽  
Overhead Transmission Line ◽  
Spark Gap ◽  
Three Phase ◽  
Electric And Magnetic Fields ◽  
Short Circuits ◽  
Selection Of

To ensure the staff safety under hot-line overhead transmission line (OTL) maintenance, as well as overhead ground-wire cable (OGWC) insulation integrity maintaining, by the example of three-phase 750 kV OTL has been presented an algorithm for calculation of voltages and electromotive forces (EMF) induced in this line’s OGWC by electric and magnetic fields (EF and MF) generated by OTL phases’ voltages and currents. Algorithms for calculation of line-to-earth voltages distribution along grounded at one end OGWC’ intervals have been given. It has been shown that the voltage induced at OGWC by EF of 750 kV OTL is much less than the voltage induced by this OTL’s MF. For single-phase short circuits modes has been presented an algorithm for selection of grounded at one end OGWC’ interval length by condition of respecting of voltage’s maximum permissible level on a spark gap shunting OGWC’s insulator set.

The Poynting Vector and the New Theory of a Transformer. Part 11. Three-Phase Three-Core Transformers without a Neutral Wire

2021 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Mansur A. SHAKIROV ◽  
Keyword(s):  
Equivalent Circuit ◽  
Single Phase ◽  
Poynting Vector ◽  
Magnetic Circuit ◽  
Phase Zone ◽  
Field Patterns ◽  
Three Phase ◽  
Short Circuits ◽  
The Difference ◽  
Mathematical Relations

A topological equivalent circuit for a three-phase three-core transformer reflecting the spatial structure of its magnetic system is developed. Owing to this approach, it became possible to represent the magnetic fluxes of the magnetic circuit’s all main sections and the apertures for each of three phases directly in the circuit in the absence of the windings’ neutral wires. The circuit is constructed by stitching together the anatomical circuit models of single-phase transformers obtained in the previous parts with taking into account the relationships between the fluxes at the junctions of the phase zones in iron. Its validity is confirmed by the rigor nature of the physical and mathematical relations for idealized transformers with infinite magnetic permeability of iron and simplified magnetic field patterns, which corresponds to the generally accepted approach with neglecting the magnetization currents. The difference lies in the fact that the developed model takes into account the heterogeneity of magnetization in different parts of the magnetic circuit with allocating more than 30 sections in the iron and apertures. The transition to the model of a real three-core transformer is carried out by adding four nonlinear transverse magnetization branches in each extreme phase zone and eight branches in the central phase zone to the idealized equivalent circuit. It is shown that in cases of winding connections without neutral wires, there is no flux of the Poynting vector in interphase zones in any unbalanced mode. In this case, the problems connected with the occurrence of fluxes exceeding the no-load fluxes under the conditions of symmetric and asymmetric short circuits, as well as the occurrence of buckling fluxes in these modes in the region outside the transformer iron, are solved.

Computer simulation and experimental study of transient processes in a single-phase voltage transformer

2015 ◽  
Vol 60 (2) ◽  
pp. 188-195
Author(s):  
A. V. Kruzhaev ◽  
I. A. Elagin ◽  
M. A. Pavleino ◽  
V. A. Dmitriev ◽  
A. M. Chaly
Keyword(s):  
Experimental Study ◽  
Computer Simulation ◽  
Single Phase ◽  
Transient Processes ◽  
Phase Voltage ◽  
Voltage Transformer

scholarly journals Simulation of Transient Processes in a Generator-Transformer-Load System with Non-Symmetry of Phase Windings of the Stator and Saturation of the Magnetic System

2019 ◽  
pp. 939-951
Author(s):  
Gleb V. Glazyrin ◽  
Nikolay A. Mitrofanov
Keyword(s):  
Magnetic System ◽  
Synchronous Machine ◽  
Transient Processes ◽  
Stator Winding ◽  
System A ◽  
Voltage Drops ◽  
Phase Coordinates ◽  
Calculation Results ◽  
Unequal Number ◽  
Short Circuits

Transient processes of a generator-transformer-load system are considered taking into account the saturation of its magnetic system. A method is proposed for numerical simulation of the transient processes of a synchronous machine with the possibility of taking into account the asymmetry of the stator winding and the saturation of the magnetic system. The appearance of asymmetry is possible if the synchronous machine is damaged, in particular, during inter-turn short circuits in the stator winding. It is based on the direct solution of the differential equations of equilibrium of the emf and voltage drops in the windings in phase coordinates together with the equation of motion of the rotor. In this case, the contour of each phase winding of the stator is described by a separate equation, and different phase parameters can be taken into account. The mathematical model of the system is realized in the software package MATLAB. The model takes into account one of the possible types of nonsymmetry – an unequal number of turns in phase windings, which makes it possible to simulate interturn short circuits without taking into account the appearance of additional short-circuited circuits. The model was verified by comparing the transient calculation results obtained using the developed model and using the MATLAB Simulink tools. The simulation results for the idle and load modes are analyzed. The obtained results allowed to draw a conclusion about the adequacy of the realized model

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