Self-oscillations at the frequency of subharmonics in nonlinear electric chains and systems

It is known that the occurrence and existence of autoparametric oscillations (AIC) at the subharmonic frequency (GHC) in power lines (power lines) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is an extensive class of nonlinear electric circuits in which the excitation of the AIC at the frequency of the SGC forms the basis of frequency-converting devices serving as secondary power sources. It is shown that single-phase-three-phase nonlinear systems are, to one degree or another, equivalent circuits of power lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with non-linear characteristics. The regularities of the excitation of the GCC at the frequency (ω / 3) of the power lines were studied, theoretical and experimental studies of the equivalent model of single-phase-three-phase circuits with nonlinear inductance were carried out. For a theoretical analysis of the steady-state mode of SGK at a frequency (ω / 3) with inductive coupling, the frequency- energy approach is used. The conditions of existence and critical parameters of the circuit are determined, and the mechanism of the appearance of the SGC at the frequency (ω / 3) is also studied.

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On the General Theory for Analysis of Subharmonic Oscillations in Three-Phase Ferroresonance Circuits and Systems

Elektrichestvo ◽

10.24160/0013-5380-2021-12-35-44 ◽

2021 ◽

pp. 35-44

Author(s):

Muhtarhan IBADULLAEV ◽

◽

Akrom N. TOVBAEV ◽

Azamat Zh. ESENBEKOV ◽

◽

...

Keyword(s):

General Theory ◽

Initial Conditions ◽

Experimental Studies ◽

Input Voltage ◽

Equivalent Model ◽

Critical Parameters ◽

Steady State Mode ◽

Power Sources ◽

Three Phase ◽

Study Results

The general theory for analysis of subharmonic oscillations at a frequency of ω/3 in three-phase ferroresonance circuits is presented. The occurrence and existence of ferroresonance oscillations at subharmonic frequencies in power transmission lines and power supply systems is highly undesirable, since they cause overvoltages at various frequencies. At the same time, there is an extensive class of nonlinear electrical circuits in which the excitation of autoparametric oscillations at the frequency of subharmonics forms the basis of phase-discrete frequency converting devices serving as secondary power sources. To study the regularities of excitation and maintaining of subharmonic oscillations at a frequency of ω/3 in three-phase ferroresonance circuits, theoretical and experimental studies of an equivalent model of a three-phase circuit with nonlinear inductance were carried out. A generalized nonlinear differential equation for a three-phase circuit with mixed connection of its elements is derived. The steady-state mode of subharmonic oscillations at a frequency of ω/3 is analyzed using the small parameter (averaging) method, which made it possible to determine their existence domains and circuit critical parameters. A mathematical model and algorithm for calculating autoparametric oscillations have been developed to study the subharmonic oscillation excitation processes at a frequency of ω/3 in three-phase ferroresonance circuits depending on the initial conditions, circuit parameters and input voltage. The theoretical study results have been confirmed experimentally.

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Research of Ferr-Resonance Oscillations at the Frequency of Subharmonics in Three-Phase Non-Linear Electric Circuits and Systems

E3S Web of Conferences ◽

10.1051/e3sconf/202021601113 ◽

2020 ◽

Vol 216 ◽

pp. 01113

Author(s):

M. Ibadullaev ◽

A. N. Tovbaev

Keyword(s):

Transmission Lines ◽

Power Transmission ◽

Experimental Studies ◽

Theoretical Research ◽

Equivalent Model ◽

Critical Parameters ◽

Power Transmission Lines ◽

Power Sources ◽

Electric Circuits ◽

Three Phase

It is known that the occurrence and existence of ferroresonant oscillations at the subharmonic frequency (SHC) in power transmission lines (TL) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is a wide class of nonlinear electrical circuits, in which the excitation of autoparametric oscillations (AIC) at the frequency of the SHC forms the basis of frequency converting devices serving as secondary power sources. It is shown that three-phase nonlinear systems are in one way or another equivalent circuits for power transmission lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with a nonlinear characteristic. To study the regularities of the excitation and maintenance of SHC at a frequency in three-phase electro-ferromagnetic circuits (EFMC), theoretical and experimental studies of an equivalent model of a three-phase circuit with nonlinear inductance were carried out. For the analysis of the steady-state mode of the SHC at the frequency, the method of a small parameter (averaging) was applied. A shortened differential equation of motion for a three-phase nonlinear circuit is obtained. By solving them, the regions of existence of the SHC and the critical parameters of the chain were determined. The obtained results of theoretical research are confirmed by experimental studies.

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Identification power line sections with increased electricity losses using sensors with Wi-Fi technology for data transmission

E3S Web of Conferences ◽

10.1051/e3sconf/202017801053 ◽

2020 ◽

Vol 178 ◽

pp. 01053

Author(s):

A.V. Vinogradov ◽

A.V. Bukreev ◽

V.E. Bolshev ◽

A.V. Vinogradova ◽

M.O. Ward ◽

...

Keyword(s):

Transmission Line ◽

Data Transmission ◽

Single Phase ◽

Power Transmission ◽

Power Line ◽

Measured Data ◽

Power Lines ◽

Power Transmission Line ◽

Central Unit ◽

Three Phase

The article presents portable timers-electricity meters (PTEM) which are devices for examining 0.4 kV power lines. There are two developed several versions of the devices: single-phase PTEM used to examine single-phase branch lines to consumers, and three-phase PTEM used for any power line sections. Also, the method to identify sections of power lines with increased electricity losses by means of these devices is presented. The paper considers the application of the three-phase PTEM with Wi-Fi technology to transmit data. Up to six independent three-phase PTEMs with Wi-Fi technology can be installed at different points of the power transmission line and transmit measured data in real time to the central unit. The use of these devices allows determining both technological and commercial losses of electricity in different power line sections and draw conclusions about whether these losses are overestimated. On the basis of this, measures are taken to reduce losses.

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WAY OF CONNECTION OF A THREE-PHASE MOTOR TO A SINGLE-PHASE NETWORK VIA RESONANCE EFFECT

CBU International Conference Proceedings ◽

10.12955/cbup.v7.1475 ◽

2019 ◽

Vol 7 ◽

pp. 920-927

Author(s):

Zharilkassin Iskakov ◽

Vladimir Kossov

Keyword(s):

Single Phase ◽

Reactive Power ◽

Theoretical Calculations ◽

Resonance Effect ◽

Experimental Studies ◽

Educational Process ◽

Resonance Phenomenon ◽

Power Coefficient ◽

Motor Circuit ◽

Three Phase

In this paper, we propose a method to connect a three-phase motor, with windings connected by a star and a phase-shifting capacitor as the third contact, to a single-phase network, with efficient use of electrical energy due to compensation of reactive power and due to effective distribution of the voltage in front of the motor’s oscillating circuit. A resonance phenomenon in an oscillating circuit of the motor is used to compensate for reactive power, i.e. to increase the active power coefficient to the maximum value. A capacitor bank in front of the circuit is used to effectively distribute the voltage at the input of the motor circuit in order to increase the motor voltage from the mains value of 220 V to the nominal value of a three-phase motor of 380 V. A special installation was created for experimental studies. The results of experimental studies, theoretical calculations of the electrical circuit of the installation, as well as the voltage vector diagram of the motor circuit show that the case when voltages on the motor are U = 380 B (UL= UC5= 325.4 B) and U = 392 B (UL= UC5= 375.6 B) most closely corresponds to the resonant state of the motor oscillating circuit. The proposed method was introduced into the educational process as a laboratory work for students of technical specialties of the Almaty University of Energy and Communications, and can be used by designers, inventors, scientists and specialists interested in similar issues to create devices that connect a three-phase star-connected motor to a single-phase network.

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