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22Растягивающее воздействие на водопоглощен-ный материал со скоростью большей Кэввл разрушает материал.
15. Увл - вектор Умова при растяжении водопо-глощенного материала, Вт/м2:
У = Р V = Р •
^ вл ' вл пр при растяж * эввл ' пр при растяж
пр прирастяж дт/м2 Рв '
Увл- Растягивающее воздействие на водопо-глощенный материал с поверхностной плотностью мощности большей Увл разрушает материал.
1.4. Полевые электромагнитные воздействия на материал
1.4.2. Электромагнитное воздействие постоянного тока (р^, Ом • м; £пр, кВдейств/мм)
Интервенты: £,пр - пробойная электрическая напряженность электростатического поля в материале, В/м; /пр - длина пробойного промежутка в материале, м;
Реактор:
16. Упр - вектор Умова в канале пробоя, Вт/м2:
V -Упр s
^пр
2
32еб
1е+14 пр
¿пр, Вт/м2, где р^ -
удельное электрическое сопротивление материала, Ом • м.
Упр —минимальная поверхностная плотность мощности электростатического воздействия на материал, при которой происходит электрический пробой образца материала, Вт/м2
При поверхностной плотности мощности электростатического воздействия на материал меньшей Упр электростатического пробоя образца материала не происходит.
Выводы и предложения.
Предложенные векторно-энергетические реакторы синтетических высокополимерных диэлектриков являются справочными материалами для проведения 3Б аудита и динамического конструирования реальных технических устройств и сооружений.
Литература
1. Электротехнический справочник (под общей редакцией профессоров МЭИ). Том.1. Книга первая. М.: Энергия, 1971. 880 с.
MODELING THE SATURATION EFFECT OF THE MAGNETIC CORE OF A POWER TRANSFORMER AND ITS EFFECT ON THE CHARACTERISTICS OF CONSUMER
ELECTRICITY
Dorofeev D.
Kazan State Power Engineering University, Russia
2
E
пр
ABSTRACT
Overvoltage encountered in loads connected to power transformers can be a consequence of nonlinear core magnetization. In order to identify the impact on the quality of electricity consumer, we conducted a computer experiment in the "Multisim" program. To form the research, it was created a T-shaped transformer substitution circuit, to which the load was connected in turn: active, inductive and capacitive with different values of parameters. The purpose of the experiment is to pinpoint the cause of overvoltage, to verify that the transformer is capable of producing an effect and to show how severe it can be.
Keywords: transformer, core, magnetization, ferroresonance, current, voltage, consumer, simulation, experiment, influence of magnetization, circuit.
Multisim simulation of saturation processes was performed on a 125 MVA power transformer installed at Kazan CHP-2, Russia. In the simulation, the transformer was replaced by a T-shape substitution circuit with circuit elements calculated from the results of measurements in the no-load and short-circuit experiments. These calculations were made on the basis of the transformer nameplate data. The T-shape substitution circuit is used for two-winding single-phase or three-phase transformers with magnetic coupling, replacing
it with electrical coupling. The substitution scheme allows to calculate the primary and secondary circuits separately, bringing them to a transformation ratio of 1, in which case the equality of winding potentials is achieved. In this model experiment, the calculation will be based on one phase of a three-phase transformer, since the calculation for each phase will be equivalent to the other. Thereby, after calculating the parameters, the scheme has acquired the following view:
Lkz2
JWV1_
0.02H
Fig.1. T-shape circuit with parameters
To form the core magnetization process, it was made the hysteresis loop simulating circuit and implemented in the T-shaped circuit hereinafter.
Fig.2. Conditional magnetization circuit.
The oscilloscope diagram shows the process of the circuit. After analysis, it was concluded that the scheme works.
Fig.3. Oscilloscope diagram.
In this model experiment it was achieved on/off switches in the positive and negative half-period. The deviation of the on/off line also corresponds to 647 microseconds, which is acceptable, considering the errors.
After implementing the magnetization circuit in the main circuit, we prepared for the main work - the experiment with loads.
Fig. 4. Circuit without loads.
The main scheme has the following parameters: source voltage is 10,5 kV; switches ON/OFF voltages are 8,5 kV; the core inductance varies from 0.02 H to 150 H; the active resistance of the core is 9178 Ohm; active and inductive resistances of both windings are respectively equal 0.41 Ohm and 0.02 H.
The oscilloscope is connected in such a way that the red wire receives a voltage signal from the source and the blue wire is getting signal from the core. The R3 resistance is using as a shunt.
Fig.5. Oscilloscope diagram.
So the scale for the red wire is 10 kV/Div and for the blue is 10 V/Div accordingly.
To determine the effect of saturation on loads, five experiments were performed. The first one is an
unloaded line, transformer.
which is connected to the bus with
Parameters: R line (RL) = 0,16 Ohm/km; C line (CL1) = 8 nF/km; C bus (C_BUS) = 6 nF.
Fig. 6. The first experiment. Unloaded line.
The task is to change the distance from 1 km to
Table 1.
100 km and assess the line voltage.
L (km) R (Ohm) C(F) Uloads(kV)
1 0,16 0,000000008 136,2
10 1,6 0,00000008 115,3
30 4,8 0,00000024 106,8
50 8 0,0000004 102,2
80 12,8 0,00000064 101,8
100 16 0,0000008 101,6
Fig. 7. Voltage vs. line length graph.
The second experiment is an active loads, connected to a 1 km line, bus and transformer.
Fig.8. The second experiment. Active loads.
This experiment evaluated the effect of saturation on the active load. High-power loads ranging from 10 ohms to a low-power 200 kilohms were installed. On their basis, the following data were obtained, where in
yellow marked overvoltages, which correspond to greater values than the amplitude of the source of 98.6 kV.
R (Ohm)
U loads (kV)
R loads parameters.
P(kW) îiofZtr
% of Z line % of Etr
ISO 140 120
£ D
Table 2.
ID 50 174555 159 2 413,93
100 96,7 47147 1592 25 113,15
1000 93,4 4373 15924 24B 11,70
5000 9B,5 975 7961B 123B 2,34
10000 9B,1 4BB 159236 2475 1,17
20000 99 244 31B471 4951 0.59
30000 101 162 477707 7426 0.39
40000 110 122 636943 9901 0.29
50000 112,7 97 796173 12376 0,23
60000 123 B2 955414 14B52 0,20
30000 151 61 1273335 19302 0,15
100000 139 50 1592357 24753 0,12
130000 134 38 2070054 32179 0,09
150000 140 33 2333535 37129 0,03
200000 123 24 31B4713 49505 0,06
-Ü loads
-Amplitude source voltage
Jf J> ^ & 4> tf & <S> # #
P loads, kW
Fig.9. Voltage vs. power graph.
The third experiment is almost as the second, but without line. The active load is connected to the bus directly.
R (Ohm)
Fig.10. The third experiment. Active loads.
U loads (kV)
R loads parameters.
P (kW)
10 60 176878 159 2 424,51
100 96,7 47288 1592 25 113,49
1000 98,4 4875 15924 248 11,70
5000 98,5 976 79618 1238 2,34
10000 99 488 159236 2475 1,17
20000 98,8 244 318471 4951 0,59
30000 97,6 163 477707 7426 0,39
40000 99,8 122 636943 9901 0,29
50000 100 97 796178 12376 0,23
60000 106 82 955414 14852 0,20
80000 150 61 1273885 19802 0,15
100000 156 50 1592357 24753 0,12
130000 152 38 2070064 32179 0,09
150000 158 33 2388535 37129 0,08
200000 109 24 3184713 49505 0,06
Table 3.
Fig.11. Voltage vs. power graph. In this experiment, there is a significant difference from the previous one, as can be seen in Figure 12.
150 156 152 153
96,7 98,4 98,5 99 98,3 97£, •"lOff 109
98,6 A 98,6 93, £ 98, 6
60/
— U loads. 3 experiment -Amplitude source voltage -U loads. 2 experiment
^ ¿f & $ & & * *
P loads, kw
Fig.12. Voltage vs. power graph of the second and the third experiments.
The fourth and fifth experiments are the same and refer to the second and third experiments, but without the vertical part of the substitution scheme. In these experiments we turned off the nonlinearity of the magnet-
ization of the transformer and showed that there is indeed an effect on the loads. By removing the vertical part, there were no overvoltage in the loads, which you can see in Figure 15.
Table 4.
R loads parameters. 4th and 5th experiment.
R (Ohm) U loads (kV) P (kW)
10 60 174556
100 96,7 47147
100D 98,6 4873
5000 98,6 975
10000 98,6 488
20000 98,6 244
30000 98,6 162
4D00D 98,6 122
50000 98,6 97
60000 98,6 82
80000 98,6 61
10D00D 98,6 50
130000 98,6 38
150000 98,6 33
2D00DD 98,6 24
Fig.13. The 4th experiment. Active loads.
Fig.14. The 5th experiment. Active loads.
96,7 'M-6 98,6 98,6 98,6 98,6 98,6 98,6 98,6 98,6 98,6 98,6 98,6 98,6
/
/
174556 47147 4873 975 4SS 244 162 122 37 82 61 50 38 33 24 P loads, fcW
Fig.15. Voltage vs. power graph of the 4th and 5th experiment.
Based on these experiments, we can conclude that if the load is correctly installed in the transformer substitution circuit, we can see the influence of the nonlinear saturation of the magnetic core, namely voltage spikes above the amplitude value of the source. And also, when the vertical part is removed from the circuit.
this influence is not detected. The traditional literature has done these experiments differently. The load was placed in the circuit in the way shown in Figure17. In this case, phase reversal and ferroresonance were observed at certain load parameters.
Fig.16. The traditional ferroresonance experiment.
Ostiiwscoi*-*SC2 IX
та 1* Sim? ÍT¡Üít!i IWlO): 0 »«.J».): 1 Sa* |ШИЦИ» ~ П~1, г [Ö VH«Mi T° о —
Fig.16. Load oscilloscope (Ckz1).
To summarize, with the correct transformer substitution scheme with the transformer core magnetization nonlinearity implemented in it, it was possible to clearly demonstrate the dynamic effect of magnetization on loads of different nature and value. This article presents a comparison with the traditional understanding of the effect, in which shortcomings have been identified.
References
1. Knowledge base of NI Multisim. https://search.ni.com/ni-
search/app/main/p/ap/tech/lang/ru/pg/1/sn/catnav:kb
2. Bräunlich R., Däumling H., Hofstetter M. et al. Ferroresonanzschwingungen in Hochund Mittelspannungsnetzen, Teil 4. - Bulletin SEV/VSE, 2009, №1.
3. Зилес Л.Д. О подавлении феррорезонанса трансформаторов напряжения 110 500 кВ. - Электричество, 1986, №12.
4. Ziles L.D. Elektrichestvo (Electricity), 2012, № 1, рр. 59-62.
5. Dement'yev Yu. A., Goryushin Yu.A., Dar'yan L.A., Arkhipov I.L., Akopyan A.G., Berlin B.Ye., Agofonov G.E., Kadomskaya K.P., Laptev O.I., Gaivoronskii A.S. ELEKTRO (Electro), 2007, № 4, рр. 10 -14
ИННОВАЦИОННОЕ РАСТЕНИЕ ТОПИНАМБУР МЕСТНОГО ПРОИСХОЖДЕНИЯ ДЛЯ ИСПОЛЬЗОВАНИЯ В СОСТАВЕ ПИЩЕВЫХ ПРОДУКТОВ
Фатхуллаев А.
Кандидат технических наук, доцент Ташкентский государственный аграрный университет,
Искандаров З.С. Доктор технических наук, профессор, Ташкентский государственный аграрный университет,
Абдумаликов И.Р. докторант
Ташкентский государственный аграрный университет,
Гафуров Ж.М. магистрант
Ташкентский государственный аграрный университет
AN INNOVATIVE LOCAL TOPINAMBUR PLANT FOR USE IN FOOD
Fatkhullaev A.
Candidate of Technical Sciences, Associate Professor Tashkent State Agrarian University, Iskandarov Z. Doctor of Technical Sciences, Professor, Tashkent State Agrarian University,
Abdumalikov I.
doctoral student Tashkent State Agrarian University, G'afurov J. undergraduate Tashkent State Agrarian University
