The stability in the sense of Lyapunov turned to be a most important property for equilibria and global trajectories of the dynamical systems. The so-called Stability Postulate of N.G. Četaev states that only those tr...
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This paper proposes three single-ended time-domain fault location methods for AC transmission lines. The traditional impedance based single-ended fault location methods usually assume that the system is homogeneous or...
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ISBN:
(纸本)9781665464413
This paper proposes three single-ended time-domain fault location methods for AC transmission lines. The traditional impedance based single-ended fault location methods usually assume that the system is homogeneous or the remote source parameters are known, which are not always satisfied. In addition, the phasor measurements are required, which need a relatively long measurement time window (typically more than one cycle). The proposed methods utilize the additional information brought by the operation modes of circuit breakers. The proposed methods only require instantaneous voltage and current measurements at the local end, and do not need any remote side information. Specifically, the line models considering lumped or distributed parameters are utilized, formulating three fault location methods. The effectiveness of the proposed methods is verified via numerous case studies in PSCAD/EMTDC, with different fault types, locations and resistances, and the results prove that the method with full consideration of distributed parameters presents the best accuracy. The methods only require a short data window within half a cycle (10 ms) and a relatively low sampling rate of 4kHz.
In this work, we consider the estimation of temperature profiles along the pipes of a plate heat exchanger. The transport phenomena through the heat exchanger are modeled by hyperbolic partial differential equations (...
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The paper presents an original method and its computer simulation results connected to specific details of radiation conduction from medical imaging or radiation therapy devices. The study is based on analogical model...
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ISBN:
(纸本)9783642042911
The paper presents an original method and its computer simulation results connected to specific details of radiation conduction from medical imaging or radiation therapy devices. The study is based on analogical modeling and digital simulation of processes with distributed parameters, described by equations with partial derivatives. A case study presented in this work simulates the process of radiation propagation from a medical device, offering the premises for future developments regarding computer controlled fine-tuning of radiological equipment.
Real transmission lines are translated into mathematical models using either the lumped parameter approach or the distributed parameter approach. The first one is used for short- and medium-length transmission lines, ...
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ISBN:
(纸本)9781728154428
Real transmission lines are translated into mathematical models using either the lumped parameter approach or the distributed parameter approach. The first one is used for short- and medium-length transmission lines, while the other is used for long-length transmission lines where the accuracy and precision are required. For medium transmission lines, the lumped parameter approach can be applied using one of four popular circuit representations known as gamma (Gamma), opposite-gamma (Gamma), tee (T), and pi (Pi). This study presents a new circuit representation called em (M). This model is inspired by the sagging phenomenon where, at the sag point, the distributed series impedance of the Pi-model is divided into two equal/unequal parts and the distributed shunt admittance at the center is bigger than that at both ends. For some numerical experiments, the M-model shows a stunning performance in estimating transmission line readings. It wins in most cases and, for the few remaining cases, the M-model shows very competitive results.
This work presents a new approach for statespace modeling of distributed parameter transmission tine for transient analysis. The lossless line model based on the method of characteristics is used and the state equatio...
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ISBN:
(纸本)9781424408122
This work presents a new approach for statespace modeling of distributed parameter transmission tine for transient analysis. The lossless line model based on the method of characteristics is used and the state equations are derived. These equations are converted to a set of difference equations using the trapezoidal rule of integration. By solving these equations, the state of system at discrete time points is obtained. An illustrative example is given and the obtained results are compared with those obtained using conventional methods based on s-domain and fast inverse Laplace transform (FILT). The study also investigates the effects caused by lumped parameter approximation of tine losses.
Based on the distributed parameters circuit model of motor windings, time domain analysis is applied to get the function of the winding voltage that depends on time, voltage input and location of each turn. The softwa...
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ISBN:
(纸本)0780374592
Based on the distributed parameters circuit model of motor windings, time domain analysis is applied to get the function of the winding voltage that depends on time, voltage input and location of each turn. The software ANSYS for Finite Element Analysis (FEA) is used to analyze the electromagnetic field in stator slots of the motor. A model of a single slot is constructed;from which distributed inductance and distributed capacitance of each turn in the slot can be obtained. The results show the rules of distributed parameters of windings in different location of each turn. Lastly, using MATLAB simulation, this paper probes into the voltage distribution laws in turns and windings when the motor is driven by PWM pulse voltage, which founds the theoretical basis of premature failure of winding insulation.
In this work, we consider the estimation of temperature profiles along the pipes of a plate heat exchanger. The transport phenomena through the heat exchanger are modeled by hyperbolic partial differential equations (...
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In this work, we consider the estimation of temperature profiles along the pipes of a plate heat exchanger. The transport phenomena through the heat exchanger are modeled by hyperbolic partial differential equations (PDE) of first order in time and space. The counter flow heat exchange implies that the system is comprised of rightward (where the hot fluid circulates) and leftward (cold fluid pipes) hyperbolic PDE. The heat exchanged between the pipes of hot and cold fluid induces a coupling between the rightward and leftward equations, which increases the difficulty of solving the PDE system. The estimation objective is addressed by the design of an observer using a PDE approach, which uses boundary measurements to estimate the distributed profiles. The convergence of the observation error is established using Lyapunov analysis. Simulation results illustrate the efficiency of our method using a simulator with time-varying parameters validated on experimental data. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
It is considered a mechanical system composed of a string in cantilever having a pointwise damping. The discontinuous B(oundary) V(alue) P(roblem) is split in two coupled BVPs. Introducing the Riemann invariants and t...
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It is considered a mechanical system composed of a string in cantilever having a pointwise damping. The discontinuous B(oundary) V(alue) P(roblem) is split in two coupled BVPs. Introducing the Riemann invariants and taking into account their invariance along the characteristics, a system of continuous time difference equations with two delays is associated to the coupled BVPs and a one-to-one correspondence between the solutions of the two mathematical objects is proven. Then a theorem on exponential stability for the difference system is obtained. The stability depends on the arithmetic properties of the delay ratio. The aforementioned one-to-one correspondence is then used to establish exponential stability of the classical solutions of the coupled BVPs. Some conclusions and a sketch of open and future research subjects end the paper. Copyright (c) 2024 The Authors.
Real transmission lines are exposed to dynamic weather conditions and operated under different system states. These changes force power cables to sag, and thus the values of their distributed series and shunt paramete...
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ISBN:
(纸本)9781728164892
Real transmission lines are exposed to dynamic weather conditions and operated under different system states. These changes force power cables to sag, and thus the values of their distributed series and shunt parameters vary as well. This study is an attempt to account for the variations in these parameters by using a new highly precise medium-length transmission line model called the M-model. This lumped circuit represents the changes in the shunt parameters by a variable slack admittance placed in the middle of the circuit and the changes in the series parameters by two variable series impedances. Two approaches are proposed in this paper to realize the lumped shunt admittance. The first one divides the line into three ideal parts and then calculates the shunt admittance of the middle part at an equivalent height. The second one takes the ratio of the area below the line before and after sag. These methods can directly solve the inherent weaknesses associated with temperature-dependent studies without the necessity to know any temperature coefficient.
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