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Principles of modular harmonic power flow methodology

IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION 2000年第1期147卷 1-6页

作者： Semlyen, A Shlash, M Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada Stone & Webster Engn Corp Toronto ON M4P 2W6 Canada

The generalisation and refinement of a very efficient modular harmonic power flow (MHPF) methodology, initially available for simple components only, is presented. Its capabilities have been extended to three-phase systems that may include: nonlinear elements, such as generators;components with distributed and frequency-dependent parameters, as in the case of transmission lines;and switched components, exemplified by a thyristor controlled series capacitance (TCSC). The exact modelling of complex components is carried out individually in the time domain using Poincare acceleration for the fast and accurate calculation of the steady state. An incremental harmonic domain admittance matrix for the whole system is then used in an iterative process to obtain a system-wide solution. Numerical results for a small system serve to illustrate some details of the MHPF.

关键词： thyristor controlled series capacitance power capacitors Power transmission lines and cables frequency-dependent parameters synchronous generators three-phase systems time domain modelling power transmission lines incremental harmonic domain admittance matrix switched components nonlinear elements Other power apparatus and electric machines iterative process modular harmonic power flow methodology generators time-domain analysis Power supply quality and harmonics Synchronous machines steady state calculation distributed parameters power system harmonics thyristor applications transmission lines load flow electric admittance Poincare acceleration Integral transforms

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Reducing the Spurious Oscillations in the Lumped parameters Model Using Low-Pass Filter

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IEEE LATIN AMERICA TRANSACTIONS 2015年第4期13卷 1029-1034页

作者： de Araujo, A. R. J. da Silva, R. C. Kurokawa, S. Univ Estadual Paulista UNESP Ilha Solteira SP Brazil

Voltages and currents in the transmission line are described by differential equations that are difficult to solve due soil and skin effect that has to be considered for accurate results, but it increases their complexity. Therefore there are some models to study the voltages and currents along in transmission line. The distributed parameters model that transforms the equations in time domain to the frequency domain and once the solutions are obtained, they are converted to time domain using the Inverse Laplace Transform using numerical methods. Another model is named lumped parameters model and it considers the transmission line represented by a pi-circuit cascade and the currents and voltages are described by state equations. In the simulations using the lumped parameters model, it can be observed the presence of spurious oscillations that are independent of the quantity of pi-circuits used and do not represent the real value of the transient. In this work will be projected a passive low-pass filter directly inserted in the lumped parameters model to reduce the spurious oscillations in the simulations, making this model more accurate and reliable for studying the electromagnetic transients in power systems.

关键词： Electromagnetic transients transmission lines distributed parameters lumped parameters low-pass filter

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The limitations of assessing impacts of land use changes on runoff with a distributed hydrological model: case study of the Hron River

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BIOLOGIA 2009年第3期64卷 589-593页

作者： Hlavcova, Kamila Szolgay, Jan Kohnova, Silvia Horvat, Oliver Slovak Tech Univ Dept Land & Water Resources Management SK-81368 Bratislava Slovakia

A distributed hydrological model was applied for estimating changes in a runoff regime due to land use changes. The upper Hron river basin, which has an area of 1766 km(2) and is located in central Slovakia, was selected as the pilot basin. A physically-based rainfall-runoff model with distributed parameters was used for modelling runoff from rainfall and melting snow. The parameters of the model were estimated using climate data from 1981-2000 and from three digital map layers: a land-use map, soil map and digital elevation model. Several scenarios of changes in land use were prepared, and the runoff under the new land use conditions was simulated. Long-term mean annual runoff components and the design maximal mean daily discharges with a return period from 5 to 100 years under the previous and changed land uses were estimated and compared. The simulated runoff changes were confronted with expert judgments and estimates from the literature. Limitations of the use of distributed models for estimating land use changes are discussed.

关键词： distributed parameters land use change rainfall-runoff model

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Digital Simulation and Control of Electromagnetic Field Effects in Heterogeneous Organic Tissues

Digital Simulation and Control of Electromagnetic Field Effe...

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IEEE International Conference on Automation, Quality and Testing, Robotics (AQTR)

作者： Colosi, H. A. Roman, M. N. Univ Med & Pharm Iuliu Hatieganu Cluj Napoca Romania Tech Univ Cluj Napoca Romania

ISBN: (纸本)9781424467259

The paper presents an original modeling method and its computer simulation results regarding effects of radiation conduction through different layers of organic tissue. 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 propagation through different layers of organic tissue of an electromagnetic field generated by a medical device. The paper offers premises for future developments regarding computer controlled fine-tuning of medical electromagnetic devices.

关键词： electromagnetic field conduction distributed parameters partial derivatives medical equipment

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A Mathematical Model of a Single-Mass Electromechanical System taking into Account the Temperature Effect on System parameters on the Example of Mill Stand

A Mathematical Model of a Single-Mass Electromechanical Syst...

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ELEKTRO 10th International Conference

作者： Lis, Marek Patro, Marek Nowak, Marcjan Rusek, Andrzej Czestochowa Tech Univ Fac Elect Engn Czestochowa Poland

ISBN: (纸本)9781479937219

In the paper a general form of a mechanical system of a single mill stand cooperating with a rolling transportation line with electro-rolls is presented. The dependencies of the influence of temperature on Young elasticity modulus and the dependencies of steel density on temperature of components being transported, as well as the dependencies of the plasticity of the transported piece of metal on temperature. A generalized mathematical model of a single-mass mechanical system is formulated. The generalized model has been transformed and supplemented with the relationships influencing the values of forces occurring in the rotation transmission system that result from the dependencies of the transported material on temperature.

关键词： transient states electro-mechanical systems distributed parameters rolling transportation line electro-rolls

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Universal Mathematical Model of Three-phase Electrical Transmission Lines 11

Universal Mathematical Model of Three-phase Electrical Trans...

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11th International Forum on Strategic Technology (IFOST)

作者： Andreev, Mikhail Suvorov, Aleksey Sulaymanov, Almaz Natl Res Tomsk Polytech Univ Inst Power Engn Tomsk Russia

Basis and synthesis of electrical transmission lines mathematical model, which allows reproducing the whole range of both normal processes and fault within three-phase electrical transmission lines of different length... 详细信息

ISBN: (纸本)9781509008551

关键词： power system simulation mathematical model of electrical transmission lines distributed parameters skin effect corona effect hybrid simulation verification

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Modeling Approach for Short-Transmission Lines on the same Tower with Different Wire parameters and Tower Structure

Modeling Approach for Short-Transmission Lines on the same T...

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International Conference on Power System Technology (POWERCON)

作者： Li, Xiaohua Li, Fan Liu, Piao Cai, Wangyan Cai, Zexiang South China Univ Technol Sch Elect Power Guangzhou Guangdong Peoples R China

ISBN: (纸本)9781538664612

The transmission corridor is scarcity in many areas. Therefore, tower with multi-circuit transmission lines has a high proportion in the power grid. Moreover, it is common that there are short and ultrashort line, diverse tower structure and different wire parameters in multi-circuit lines. Most of the normal modeling methods for multi-circuit lines on the same tower are based on the distributed parameter model. However, they focus basically in the long lines, single type of tower structure and one kind of wire parameter. The present modeling methods cannot deal with the problem in short lines, diverse tower structure and different wire parameters. Hence, this paper proposes an approach to process this problem is proposed through studying the influence of the change of the wire parameters on the impedance/admittance matrix. The modeling approach combines the distribution parameter characteristics of tower structure and the good adaptability for short lines of the lumped parameter model. It can be applied to short lines with different tower structure and wire parameters. High accuracy of the modeling approach in this paper is verified with the measured parameters.

关键词： Multi-circuit lines on the same tower different voltage class short and ultrashort line lumped parameters distributed parameters

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The stability postulate of N. G. Cetaev and the augmented model validation

The stability postulate of N. G. Cetaev and the augmented mo...

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20th World Congress of the International-Federation-of-Automatic-Control (IFAC)

作者： Rasvan, Vladimir Univ Craiova Dept Automat & Elect AI Cuza 13 RO-200585 Craiova Romania

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. Cetaev states that only those trajectories and equilibria which are at least stable in the sense of Lyapunov are observable and measurable. On the other hand any mathematical model of some real (physical) process requires validation in order to be self consistent as a mathematical object, also to fit to data obtained from experiments (at least basically). Combining standard validation criteria for self consistency (existence, uniqueness, data dependence) with the Stability Postulate, also with other requirements will lead to the so-called augmented model validation for self consistency i.e. as a mathematical object. Since these new concepts (like the Stability Postulate) define a methodology they have to be checked on applications (as Cetaev did). Therefore, there will be considered a case of energy co-generation described by conservation laws. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： distributed parameters Stability Postulate Model validation Energy control

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How to Estimate Temperature Coefficients of Series and Shunt parameters of Transmission Lines with Sag

How to Estimate Temperature Coefficients of Series and Shunt...

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IEEE Electric Power and Energy Conference (EPEC)

作者： Al-Roomi, Ali R. El-Hawary, Mohamed E. Dalhousie Univ Dept Elect & Comp Engn 1459 Oxford St Halifax NS B3H 4R2 Canada

ISBN: (纸本)9781728164892

For line distributed resistance, it is easy to know its temperature coefficient. The literature has different approaches to express that distributed parameter as a temperature-dependent quantity. For line distributed inductance, capacitance, and conductance, the literature still lacks any methodology to express them as temperature-dependent quantities. This study is the first trial to express these temperature coefficients. Two possible approaches are provided. The first one assumes that the conductor temperature is known, while the other offers temperature-free estimations by regressing some variables correlated with the conductor temperature. The formulas provided in this study can be considered as a foundation to develop more advanced methods.

关键词： line modeling distributed parameters lumped parameters sag conductors temperature-dependent

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Optimal Control Problem for Linear Fractional-Order Systems

Optimal Control Problem for Linear Fractional-Order Systems

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International Conference on Fractional Differentiation and its Applications (ICFDA)

作者： Kubyshkin, Victor Postnov, Sergey Russian Acad Sci VA Trapeznikov Inst Control Sci Moscow Russia

ISBN: (纸本)9781479925919

The optimal control problem for linear dynamic systems of fractional order is investigated. This problem is reduced to the classical moment problem. This paper validates the conditions making possible to formulate and resolve the obtained moment problem. Some particular cases of one- and two-dimensional fractional-order systems are discussed and the explicit solutions for the problems of optimal control were obtained. In particular, this paper studies the problem to minimize the norm of control for the assigned time interval and the problem of control with the minimal time of the object transition into the desirable state with the given limitation of the norm of control. It is also shown that the moment method may be also applied to the systems of fractional order with distributed parameters. The problem of optimal control for the transfer-type equation with a fractional derivative in time is formulated and the respective moment problem is analyzed.

关键词： distributed parameter systems linear systems method of moments optimal control 1D fractional-order systems 2D fractional-order systems distributed parameters fractional derivative linear fractional-order dynamic systems moment method optimal control problem transfer-type equation Equations Indexes Integral equations Mathematical model Method of moments Optimal control Oscillators METHOD OF MOMENTS Optimal control distributed parameter fractional order distributed parameter systems Integral equations Oscillators Linear system Mathematical Model Explicit Solution

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