scholarly journals FEATURES OF TRANSIENT RESEARCH IN THREE-PHASE HIGH-VOLTAGE POWER TRANSMISSION CABLE LINES

2021 ◽  
pp. 135-148
Author(s):  
Vadim Lobodzinskiy ◽  
Valeriy Chybelis ◽  
Oleg Petruchenko ◽  
Olga Illina ◽  
Yuliya Chunyak ◽  
...  
Keyword(s):  
Power Transmission ◽  
Initial Conditions ◽  
Current Trend ◽  
Electric Circuit ◽  
Distributed Parameters ◽  
Three Phase ◽  
Cable Lines ◽  
The Impact ◽  
External Connections

The methods of analysis of transients in three-phase circuits with distributed parameters and interphase connections are considered on the basis of representation of such circuits by multipoles, finding their corresponding concentrated parameters and determination of boundary and initial conditions of transients. The formulation of this scientific problem is justified by the current trend in theoretical electrical engineering to consider multiphase circuits as a series-parallel connection of different n-poles, which improves the calculation of transient electromagneticprocesses in multiphase circuits with distributed parameters and interphase connections. Using thetheory of multipoles allows us to represent the elements of the electric circuit by macromodels thatreflect their external connections and the impact on the rest of the circuit. The main difficulty inapplying this principle is to resolve emerging electromagnetic bonds.

Refined Modeling of Projectile Impact Onto Submerged Structure

2008 ◽  
Author(s):  
Justin Onisoru ◽  
Ovidiu Coman ◽  
Paul Wilson ◽  
George Thomas
Keyword(s):  
Strain Rate ◽  
Structural Integrity ◽  
Initial Conditions ◽  
Safety Issue ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Material Behavior ◽  
Spent Fuel ◽  
The Impact

Structural integrity of spent fuel racks is a critical safety issue in nuclear power stations. The standard approach of evaluating the effects of an impact projectile on a submerged structure, which constitute the start point of the current study, involves three main steps: determination of the conditions just prior to the impact (that are considered as initial conditions for the analysis), setting the mechanism of transferring energy from the projectile to the target structure, and determining how that energy is absorbed by the impacted structure. Usually, the dynamics of the projectile are ideally considered, the influence of the fluid presence is restricted to the determination of the impact velocity and strain rate dependency is limited to choosing a true stress vs. strain curve corresponding to some constant strain rate. Starting from the standard engineering approach, the authors have refined the model considering more realistic dynamics of the projectile, extending the influence of the fluid to the entire analysis and using a more accurate strain rate dependant material behavior. Explicit Finite Element analyses are used in order to incorporate the desired effects.

scholarly journals EFFECTS OF STANDARD AND MODIFIED GRAVITY ON INTERPLANETARY RANGES

2011 ◽  
Vol 20 (02) ◽  
pp. 181-232 ◽  
Author(s):  
L. IORIO
Keyword(s):  
Initial Conditions ◽  
A Priori ◽  
Earth Planet ◽  
General Relativistic ◽  
Heliocentric Orbits ◽  
Newtonian Constant ◽  
The Impact ◽  
Very High ◽  
Better Than

We numerically investigate the impact on the two-body range of several Newtonian and non-Newtonian dynamical effects for some Earth-planet (Mercury, Venus, Mars, Jupiter, Saturn) pairs, in view of the expected cm-level accuracy in some future planned or proposed interplanetary ranging operations. The general relativistic gravitomagnetic Lense–Thirring effect should be modeled and solved for in future accurate ranging tests of Newtonian and post-Newtonian gravity, because it falls within their measurability domain. It could a priori "imprint" the determination of some of the target parameters of the tests considered. Moreover, the ring of the minor asteroids, Ceres, Pallas, Vesta (and also many other asteroids if Mars is considered) and the trans-Neptunian objects (TNOs) act as sources of nonnegligible systematic uncertainty on the larger gravitoelectric post-Newtonian signals from which it is intended to determine the parameters γ and β of the parametrized post-Newtonian (PPN) formalism with very high precision (several orders of magnitude better than the current 10-4–10-5levels). Also, other putative, nonconventional gravitational effects, like a violation of the strong equivalence principle (SEP), a secular variation of the Newtonian constant of gravitation G, and the Pioneer anomaly, are considered. The presence of a hypothetical, distant planetary-sized body X could be detectable with future high-accuracy planetary ranging. Our analysis can, in principle, be extended to future interplanetary ranging scenarios in which one or more spacecrafts in heliocentric orbits are involved. The impact of fitting the initial conditions, and of the noise in the observations, on the actual detectability of the dynamical signatures investigated, which may be partly absorbed in the estimation process, should be quantitatively addressed in further studies.

Combined Frequency Equivalent Model for Power Transmission Network Dynamic Behavior Analysis

2018 ◽  
Vol 19 (2) ◽  
Author(s):  
S. Lakrih ◽  
J. Diouri
Keyword(s):  
Frequency Response ◽  
Behavior Analysis ◽  
Dynamic Behavior ◽  
Power Transmission ◽  
Equivalent Model ◽  
Network Dynamic ◽  
Transmission Network ◽  
Lumped Model ◽  
Distributed Parameters ◽  
The Impact

AbstractThis paper presents a dynamic equivalent model for transmission network dynamic behavior analysis in MATLAB SIMULINK. The electromagnetic frequency response and electromechanical response are combined in the model. The dynamic behavior of distributed parameters line modeled by the EMTP equivalent model is compared with that corresponding to lumped parameter line represented by π model. The aim is to define the frequency band in which the lumped model can accurately represent the distributed parameters model on no load conditions but also when the network is loaded. The proposed equivalent model is explored to investigate the impact of topology on the network dynamics. Besides, the influence of load nature and compensation rate on the driving point frequency response are analyzed analytically and simulated via the proposed model.

scholarly journals Determination of the Operating Temperature of the Gas-Insulated Transmission Line

2020 ◽  
Vol 10 (24) ◽  
pp. 8877
Author(s):  
Tomasz Szczegielniak ◽  
Dariusz Kusiak ◽  
Paweł Jabłoński
Keyword(s):  
Power Transmission ◽  
Radiation Heat Transfer ◽  
Proximity Effects ◽  
High Current ◽  
Power Losses ◽  
Factors Affecting ◽  
Three Phase ◽  
Phase Conductors ◽  
High Power Transmission

Gas-insulated lines (GILs) have been increasingly used as high-current busducts for high-power transmission. Temperature is one of the most important factors affecting the performance and ampacity of GILs. In this paper, an analytical method was proposed to determine the temperature of a three-phase high-current busduct in the form of a single pole GIL. First, power losses in the phase conductors and enclosures were determined analytically with the skin, and proximity effects were taken into account. The determined power losses were used as heat sources in thermal analysis. Considering the natural convection and radiation heat transfer effects, the heat balance equations on the surface of the phase conductors and the screens were established, respectively. Subsequently, the temperature of the phase conductors and the enclosures were determined. The validation of the proposed method was carried out using the finite element method and laboratory measurements.

Response of Viscoelastic Plate to Impact

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
D. Ingman ◽  
J. Suzdalnitsky
Keyword(s):  
Initial Conditions ◽  
Viscoelastic Plate ◽  
Servo Control ◽  
Order Function ◽  
Damping Decrement ◽  
Vibration Process ◽  
Alternative Approaches ◽  
The Impact ◽  
Fractional Differentiation Operator

Organization of product tests in the microelectronic and optical-electronic industries by the impact method is considered. Two mathematical models: a circular plate under dynamic loading with predetermined initial conditions, and contact interaction of a falling mass and a barrier, are examined. The deflection function, curvature, and acceleration are determined. As the series for these characteristics may prove divergent, the problem is to secure sufficiently reliable results. The method of impact mechanics permits determination of the duration and force of the impact, estimation of the total energy of each mode in the expansion of the deflection function and preclusion of divergent series when determining the plate acceleration and curvature during the vibration process. In parallel, viscoelasticity is simulated with the aid of a fractional-differentiation operator, certain features of which are discussed. Representation of this operator with time-dependent order by ones with constant orders is considered. Three alternative approaches for determination of the eigenfrequency and damping decrement of a vibration process are examined. In particular, a method for calculating these characteristics under conditions of time-dependence and servo control of the order function is proposed.

scholarly journals A Statistical Methodology for Determination of Safety Systems Actuation Setpoints Based on Extreme Value Statistics

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
D. R. Novog ◽  
P. Sermer
Keyword(s):  
Nuclear Reactor ◽  
Initial Conditions ◽  
General Concept ◽  
Extreme Value Statistics ◽  
Plant Responses ◽  
True Value ◽  
Time Changes ◽  
Safety Systems ◽  
The Impact

This paper provides a novel and robust methodology for determination of nuclear reactor trip setpoints which accounts for uncertainties in input parameters and models, as well as accounting for the variations in operating states that periodically occur. Further it demonstrates that in performing best estimate and uncertainty calculations, it is critical to consider the impact of all fuel channels and instrumentation in the integration of these uncertainties in setpoint determination. This methodology is based on the concept of a true trip setpoint, which is the reactor setpoint that would be required in an ideal situation where all key inputs and plant responses were known, such that during the accident sequence a reactor shutdown will occur which just prevents the acceptance criteria from being exceeded. Since this true value cannot be established, the uncertainties in plant simulations and plant measurements as well as operational variations which lead to time changes in the true value of initial conditions must be considered. This paper presents the general concept used to determine the actuation setpoints considering the uncertainties and changes in initial conditions, and allowing for safety systems instrumentation redundancy. The results demonstrate unique statistical behavior with respect to both fuel and instrumentation uncertainties which has not previously been investigated.

Determination of the power transmission line ageing failure probability due to the impact of forest fire

2018 ◽  
Vol 12 (16) ◽  
pp. 3812-3819 ◽  
Author(s):  
Yufeng Guo ◽  
Runxin Chen ◽  
Jianguo Shi ◽  
Jie Wan ◽  
Hongliang Yi ◽  
...  
Keyword(s):  
Transmission Line ◽  
Forest Fire ◽  
Failure Probability ◽  
Power Transmission ◽  
Power Transmission Line ◽  
The Impact

scholarly journals Математична модель трифазної лінії з розподіленими параметрами при електромагнітних перехідних процесах

2018 ◽  
Vol 124 (4) ◽  
pp. 96-102
Author(s):  
В. Ю. Лободзинський ◽  
В. І. Чибеліс
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Initial Conditions ◽  
Electromagnetic Transients ◽  
Design Stage ◽  
Transient Electromagnetic ◽  
Distributed Parameters ◽  
Electromagnetic Processes ◽  
Three Phase ◽  
Transition Modes

Development of a mathematical model of a three-phase line with distributed parameters at electromagnetic transients, which arise at different commutations for the calculation of transition modes at the design stage. The work is based on differential equations of chain state, limiting and initial conditions for ensuring the solution of practical problems. A mathematical model has been developed for the calculation of electromagnetic transients in three-phase lines, which includes a system of partial differential equations, limit and initial conditions, for the study of a wide class of practical problems related to the calculation of transients in three-phase lines. A mathematical model of a three-phase circuit with distributed parameters has been built, which is suitable for the calculation of transient electromagnetic processes, which take into account possible switching options, both working and emergency ones. Operator images of currents and voltages were obtained taking into account the initial conditions for solving practical problems associated with the calculation of transients in three-phase lines.

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