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DOI: http://dx.doi.org/10.20534/ESR-16-11.12-134-136
Toshev Sherzod Ergashevich, Tashkent state technical university the senior research associate — the competitor Pirmatov Nurali Berdiyorovich, Tashkent state technical university, Doctor of the technical sciences, professor, department of "Electric machines" Haydarov Safar Djovlievich, Tashkent state technical university, Ph. D., associate professor, department «Electric stations, network and systems»
Duvlonov Jaloliddin Ne'matulla o'g'li, Tashkent state technical university, assistent, department of «<Electric machines» Yakubova Dilifuza Kuanyshovna, Tashkent state technical university, assistent, department of «<Electric machines» E-mail: [email protected]
Analysis of magnetic field in the air gap not expressly pole synchronous generator excitation biaxially at asymmetrical short circuit
Abstract: This article on the developed mathematical model based on the equations of the Park — Gorev considered magnetic field analysis of questions in the air gap is not salient pole synchronous generator with a two-axle drive with asymmetric short circuits.
Keywords: magnetic field, the air gap is not salient-pole synchronous generator, longitudinal — transverse field winding.
The most common accident in electric power systems is a sudden short-circuit on the transmission lines on the tires on the generator station or the terminals, the advent of highly dangerous high currents and other mode parameters [1-3]. The occurrence of electromagnetic transients in electrical systems is largely determined by the behavior of its members and the nature of the process in rotating machines and their design features.
In general, asymmetric modes of the machine — regardless of the choice of the variables that characterize the occurrence of electromagnetic transition process, describing its differential equations will contain periodic coefficients.
To study the electromagnetic processes used traditional schemes "biaxial generator excitation — line — the infinite power of tires", and for this power equation used Park — Gorev takes into account the presence of a transverse field winding [4; 5].
It is known that the analysis of the influence of the magnetic field in the air gap neyavnopolyusnogo biaxial synchronous generator excitation with asymmetric short circuits performed using a mathematical model based on the complete equation Park — Gorev. Given the method of calculation of the magnetic field in the air gap is not salient pole synchronous generator with a two-axle drive with asymmetric short-circuit at the terminals of the generator and the busbar station.
It should be noted that the change in the magnetic field from the perspective of the impact of the displacement of large and small axes of the ellipse shape of the magnetic field in the electromagnetic processes in generators biaxial excitation, which is taken into account through the flux linkage. Here the main influence on the configuration ofthe field excitation currents have transverse rotor winding [5].
For unbalanced short circuit in the electrical system of differential equations of its elements of synchronous generators and generators biaxial excitation describing electromagnetic processes in them, there are periodic coefficients that are a function of time.
Electromagnetic influence of transients in the shorted circuit in the parametric oscillation circuit free phase takes the form of an external disturbance in nature representing elektrodvuzhischeysya forces is a complex periodic function of time, containing an infinite number of odd and even harmonic components. The intensity of the even harmonics shift depends on the angle between the pole axis and the short axis at the time ofwinding asymmetrical short circuit, and its maximum possible value depends on the difference between the longitudinal and transverse responses machine (X'd - X'q ), which acts as the mutual amplitude ratio between the short-circuited and the free phase.
Nature increasing the stator leakage flux associated with the emergence of the free current of the rotor winding to create an ad-
Analysis of magnetic field in the air gap not expressly pole synchronous generator excitation biaxially at asymmetrical short circuit
ditional magnetic flux co-directional flux field winding (T f) and preventing the entry of the stator flux. The greater the voltage drop of the magnetic (i. e., energy dissipation of the magnetic field) in the rotor windings, the less will be inducted elektrodvuzhischeysya forces induced in the phases reduces open magnetic flux [6-8].
By using a common method of bringing the differential equations of the synchronous generator stator windings in the vector
Table
and its conjugated form resulted in and subject to the conditions of asymmetry obtain a system of differential equations taking into account the conditions of the turbogenerator with simultaneous unbalance biaxial excitation expressed in terms of flux linkage are shown in Tables 1 and 2.
The equations of flux linkage synchronous turbogenerator stator windings with biaxial excitation
Kind of short circuit Terms of asymmetry The equations of the stator flux linkage circuits
Single-phase U = 0 a ib = ic = 0 =XaJ (1 + cos2y)(ifJ + ild ) - Xad(ik + ilq ) - 2(Xd + XK )ij V q =-Xad sin2y(tfd + ili )-X„ (1 - cos2Y)(iq + hq ) - 2(X +XK )tq
Two-phase between the phases U - uc = 0 h = ic = *k i = 0 a ^ = Xf-(1 - cos2y)(ifd + ild ) + Xf sin2A(iq + i^ ) - (Xd + XK )id V q = Xf sin2Y(ifd + ild ) + Xf(1 + C0s 2 Y) (iq + ilq ) - (Xq + X
Table 2.
Kind of short circuit Terms of asymmetry The equations of flux linkage stator windings
Single-phase U = 0 a ib = i = 0 b c d ¥ d (2r + 3rK )id = 0 dt q d ¥ —^ + ©r¥d - (2rc + 3rK ) = 0 dt
Two-phase between the phases Uh - U = 0 b c k = i = K ; i = 0 b c K a dW d rnW (r + rK )id = 0 dt q d Y -1 + aYd - (r + rK ) = 0 dt r d c K
The equations of flux linkage stator windings Td and Tq with asymmetric short circuits are determined at each step of integration.
In the case of the absence of complete damper winding formed by another stray field, namely in the space between the poles. This situation entails a decrease of free currents, in connection with which the free magnetic fields associated with the stator, will change much in size due to the fact that they are periodically superimposed a large leakage flux directed along the axis mezhpolosnogo space. This results in strong distortion of the current waveform and magnetic field. In machines with biaxial agitation and full preservation damper system cause the current waveform and the shape of the magnetic field is approaching circular shape due to the presence of a transverse field winding.
From a physical point of view when an asymmetrical switching circuit in asymmetrical stator electric machines appearing pulsating magnetic flux, which is like a combination of two flow systems, one of them is rotated in the direction of rotation of the rotor, and the other in the opposite direction relative to the stator windings. The magnetic field rotating in the opposite direction leads to the damper and excitation windings cross-excitation constituents elektrodvu-
zhischeysya strength and power, which vary with double frequency, which largely inhibit the effect back to the rotating field.
For computational analysis of the magnetic field in the air gap of the generator during asymmetrical short-circuit at the terminals of the phase windings of the equation used in the tables № 1 and № 2.
The figures (Figure 1 and Figure 2) shows the waveform of the pilot study forms a magnetic field in the air gap for single-phase and two-phase short-circuit at the terminals of the traditional model of synchronous generators with performance and biaxial excitation. From comparison of the results shows that the shape of the magnetic field in the air gap of the synchronous generator neyavnopolyusnogo uniaxial and biaxial excitation remains closer to a sine wave with asymmetric short-circuits than the conventional turbine generator synchronous design. Such a difference in the forms of distribution of the magnetic field due to the presence of the transverse field winding synchronous generators biaxial excitation, which will suppress the distortion of the magnetic field due to which field to get closer to the circular, which positively affects the work of the synchronous generator with a two-axle drive with asymmetric modes, often occurring in during operation of the electrical system.
Figure 1. Powered magnetic field in the air gap of the synchronous generator of conventional design (a) and biaxial excitation synchronous generator (b) in a single-phase short circuit
a) b)
Figure 2. Powered magnetic field in the air gap of the synchronous generator of conventional design (a) and biaxial excitation synchronous generator (b) in a two-phase short circuit
Conclusion: In spite of the complexity of the constructive circuit, have a positive impact on the operating conditions of the execution of synchronous generator excitation biaxial they due to electrical system. the suppression of higher harmonics at the unsymmetrical short
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DOI: http://dx.doi.org/10.20534/ESR-16-11.12-136-138
Urinova Sohiba Isroiljonovna, teacher of the Department"Theoretical and applied mechanics" Tashkent Institute of Textile and Light Industry, the Republic of Uzbekistan
Djuraev Anvar Djuraevich, technical sciences associate, professor of the Department "Theoretical and applied mechanics" Tashkent Institute of Textile and Light Industry, the Republic of Uzbekistan
E-mail: [email protected] Madrahimov Shavkat Halimovich, teacher of the Department"Theoretical and applied mechanics" Tashkent Institute of Textile and Light Industry, the Republic of Uzbekistan
E-mail: [email protected]
Reducing method of the redundant links in the kinematic pairs of batten lever mechanism of weaving looms
Abstract: In this article, new scheme of cam and lever battant mechanism with compound hinges, including elastic elements ofweaving looms are investigated. The technique ofliquidation and decrease in superfluous communications in kinematic steams of battant mechanism of the weaving looms are presented.
Keywords: weaving loom, beater, cam, lever, elastic element, inertiaforces, reactionforces, superfluous communications, mobility degree, and kinematic pair.
In practice of weavingindustry, thebattenmechanisms are battenmechanisms are easier on the device and have a high me-divided into two types, crank type and cam type. Crank type chanical efficiency, so on the shuttle weaving looms set mainly
