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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 Oxford NS B3H 4R2 Canada

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.

关键词： line modeling distributed parameters lumped parameters sag lines line wings problem

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Diagnostic Signs of Transient Signals in Power Lines 7

Diagnostic Signs of Transient Signals in Power Lines

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7th International Conference on Engineering and Emerging Technologies (ICEET)

作者： Khuziashev, Rustem Kuzmin, Igor Ircagalieva, Iluza Kazan State Power Engn Univ Kazan Russia

ISBN: (纸本)9781665427142

The results of modeling the transient process on the simplest models of power transmission lines are considered. Linear models with lumped and distributed parameters are investigated. The emergence of various oscillation modes of the transient signal in a multi-circuit model of a power line with lumped parameters is analyzed. The main mechanisms of the formation of the transient process signal during switching in the model of a power transmission line with distributed parameters are considered. On the basis of experimental registrations of the transient process signal, the simplest modal analysis algorithm is proposed, based on the measurement of the values of the half-periods of signal oscillations.

关键词： transient process equivalent circuit lumped parameters distributed parameters diagnostic signs modeling

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A GENERALIZED MATHEMATICAL MODEL OF DC CATENARY LINES

A GENERALIZED MATHEMATICAL MODEL OF DC CATENARY LINES

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作者： MUSTAFA ERDEM SEZGIN MIDDLEAST TECHNICAL UNIVERSITY

学位级别：硕士

Most of the subway systems are powered by electricity around the world. Al- though both AC and DC systems can be employed for energization, DC elec- trified systems are commonly preferred. The DC catenary line voltage can be calculated trivially for stationary systems at steady state. However, accurate modeling of the catenary voltage during the movement of the subway trains is cumbersome, as it requires solution of differential equation systems. This thesis proposes a generalized model for catenary voltage variation of DC powered systems. One of the challenges of modeling problem is calculation of the electrical parameters of the system, because of the non-regular shape of the rails, on which the electric current flows. The thesis firstly develops an analytical method for accurate computation of electrical parameters of the system, and validates it using finite elements analysis. After that, by using the electrical parameters the voltage and current variations through the catenary line are investigated analytically for different mode of operations of the subway trains, such as constant speed and accelerating/decelerating operations. Because of the dynamical behavior of the system, both time and position dependent differential equations are defined during the analytical derivations. The solution of the system based on differential equations is not trivial, and requires significant computational burden, Therefore, this work, proposes a lin- earized method in order to improve the computational performance of the de- rived model. The proposed linear method enables solution of the system with improved computational performance, while maintaining a high accuracy. More- over, the effect of the regenerative braking and the effect of multiple substation and train are investigated. The results of the analytical solution of voltage variation are compared with the real life test results.

关键词： DC Voltage Variation DC Catenary Line distributed parameters DC System Analysis Regenerative Braking

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Development of Efficient and Robust Methods for Estimation of Transmission Line parameters Using Synchronized PMU Data

Development of Efficient and Robust Methods for Estimation o...

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IEEE SoutheastCon Conference

作者： Lahmar, Mustafa Liao, Yuan Univ Kentucky Dept Elect & Comp Engn Lexington KY 40506 USA

ISBN: (纸本)9781538661338

Accurate transmission line parameters are important inputs for power system analysis, operation and planning, and protection and control system design, and are thus essential for safety and reliability of power system networks. The line parameters are affected by several factors and usually change when operating conditions vary. There are a variety of estimation methods, and each estimation method has certain restrictions and advantages. This paper proposes a new online linear method to estimate the positive-sequence line parameters using synchronized PMU data. The series impedance and shunt admittance are linearly estimated using the developed algorithm that is more computationally efficient than non-linear methods. The case study results demonstrate the robustness and effectiveness of the proposed algorithm, and the estimation method is applicable to both long and short transmission lines.

关键词： linear estimation distributed parameters long and short transmission line PMU data

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Měření vlastností tlustovrstvých RC prvků s rozloženými parametry

Měření vlastností tlustovrstvých RC prvků s rozložen...

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作者： Kořínková, Ksenia Brno University of Technology

Předkládaná práce se zabývá analýzou vlastností tlustovrstvých RC prvků s rozloženými parametry. Teoretická část řeší návrh RC prvků, na nějž navazuje ... 详细信息

Předkládaná práce se zabývá analýzou vlastností tlustovrstvých RC prvků s rozloženými parametry. Teoretická část řeší návrh RC prvků, na nějž navazuje jejich realizace. Součástí práce je měření odporů a zjištění závislosti rozptylu daných odporů s různým počtem vrstev struktur v závislosti na jejich vypalovacích režimech. Tato bakalářská práce souvisí s bakalářskou prací "Vlastnosti 3D prvků realizovaných tlustovrstvou technologií".

关键词： RC struktura RC prvky rozložené parametry tlustovrstvé prvky vodivá vrstva dielektrická vrstva odporová vrstva. RC structure RC elements distributed parameters thicklayer elements conductive level dielectric level resistance level. Text

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Características dos parâmetros do condutor equivalente a um feixe de subcondutores de linhas de transmissão: análise inicial

Características dos parâmetros do condutor equivalente a u...

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作者： Carvalho, Carolina Goulart de Universidade Estadual Paulista

O objetivo deste trabalho é desenvolver uma metodologia para definir um condutor equivalente para um condutor múltiplo. O método baseia-se no fato de que os parâmetros dos subcondutores estão distribuídos ao longo do comprimento dos mesmos e, deste modo, cada subcondutor deve ser tratado como uma linha de transmissão. Inicialmente são obtidas as relações entre as correntes e tensões nos dois terminais de cada subcondutor. Em seguida, considera-se que a corrente no condutor múltiplo deve ser igual à corrente no condutor equivalente. Uma vez que as tensões e correntes nos terminais do condutor equivalente são conhecidas, é possível obter a impedância longitudinal e a admitância transversal deste condutor. O método desenvolvido foi aplicado em um condutor múltiplo hipotético constituído de dois subcondutores. Os resultados obtidos com este método são comparados com o método clássico de obtenção do condutor equivalente, que se baseia no raio médio geométrico dos subcondutores do condutor múltiplo. Para isto foi mostrado que quando o raio médio geométrico é usado para definir um condutor equivalente de um condutor múltiplo, os parâmetros longitudinais e transversais do condutor equivalente são *** objective of this work is to improve a methodology to define an equivalent conductor for a bundled conductor. The proposed methodology takes into account that the longitudinal and transversal parameters are distributed along the subconductors. This way, each subconductor of a bundled conductor needs to be considered as being a transmission line. Initially the relationships among currents and voltages at sending and receiving end of each subcondutor are obtained. Then, it is considered that total currents and voltages at sending and receiving end of the bundled conductor is equal to currents and voltages at sending and receiving end of the equivalent conductor. Taking into account that parameters of the equivalent conductor are distributed parameters, it is possible to

关键词： Energia elétrica – Transmissão Condutores eletricos Sistemas de parâmetros distribuídos Analise modal Lines of transmission Multiple conductors distributed parameters Modal domain Frequency domain Dissertação de mestrado

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Minimally Corrective, Approximately Recovering Priors to Correct Expert Judgement in Bayesian Parameter Estimation

Minimally Corrective, Approximately Recovering Priors to Cor...

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作者： May, Thomas Joseph Virginia Tech | University

Bayesian parameter estimation is a popular method to address inverse problems. However, since prior distributions are chosen based on expert judgement, the method can inherently introduce bias into the understanding of the parameters. This can be especially relevant in the case of distributed parameters where it is difficult to check for error. To minimize this bias, we develop the idea of a minimally corrective, approximately recovering prior (MCAR prior) that generates a guide for the prior and corrects the expert supplied prior according to that guide. We demonstrate this approach for the 1D elliptic equation or the elliptic partial differential equation and observe how this method works in cases with significant and without any expert bias. In the case of significant expert bias, the method substantially reduces the bias and, in the case with no expert bias, the method only introduces minor errors. The cost of introducing these small errors for good judgement is worth the benefit of correcting major errors in bad judgement. This is particularly true when the prior is only determined using a heuristic or an assumed distribution.

关键词： Bayesian Parameter Estimation Minimally Corrective Priors distributed parameters Elliptic Equation Karhunen-Loeve Theorem. Thesis

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Mathematical modeling of Brazilian black soybean: Lumped and distributed parameter models

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JOURNAL OF FOOD PROCESS ENGINEERING 2023年第12期46卷 e14487-e14487页

作者： Bissaro, Camila Andressa Defendi, Rafael Oliveira Aranha, Ana Caroline Raimundini Ferrari, Andressa Lopes Matias, Gustavo de Souza Jorge, Luiz Mario de Matos State Univ Maringa UEM Chem Engn Grad Program PEQ 5790 Colombo AveBlock E-46 BR-87020900 Maringa Parana Brazil Fed Technol Univ Parana UTFPR Chem Engn Grad Program PPGEQ AP Apucarana Parana Brazil State Univ Parana UNESPAR Ind Engn Dept Paranagua Parana Brazil

The main objective of the present work was to assess the temperature and the initial moisture content using models of lumped and distributed parameters, in the description of the drying kinetics in the thin layer of the new Brazilian black soybean cultivar. Lumped models (Page, Newton, Approximation of Diffusion, Hii, Law and Cloke, and Midilli) were fitted based on experimental moisture content data for drying experiments carried out in different temperatures. Fractional order model was also performed and it was generalized as a function of temperature. distributed parameter models were also fitted to evaluate the influence of initial moisture content on drying kinetics, in addition to estimating the moisture profile along the position inside the black soybean seed. Results indicated that the best kinetic fitting of drying by the lumped parameter technique was obtained for models with a greater number of parameters. Practical applicationsResults indicated that the best kinetic fitting of drying by the lumped parameter technique was obtained for models with a greater number of parameters. The generalized model showed with first degree function, and the maximum global deviation was 15%, and distributed parameters were predicted with a maximum overall deviation of 10%. This result portrays that the fractional order model can be applied to describe the continuous drying process.

关键词： black soybean distributed parameters drying fractional order lumped parameters

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Research on the Carrier Characteristics of Power Cables Considering the Aging Status of Insulation and Semiconducting Layers

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ENERGIES 2024年第22期17卷 5655-5655页

作者： Yang, Xiaohua Wang, Zixuan Li, Jiahao Wu, Ming Wang, Guanpan Gao, Xueting Gao, Jinghui Measurement Ctr Yunnan Power Grid Co Ltd Kunming 650051 Peoples R China Xi An Jiao Tong Univ Natl Key Lab Elect Mat & Insulat Xian 710049 Peoples R China

The 10 kV XPLE cable is widely used in highly cabled transmission and distribution networks. It is necessary to closely monitor the transient current, harmonic content, and electric field distribution of each layer of the insulation and semiconductive layers of the cable when they age and deteriorate, so as to promptly carry out circuit breaking treatment and prevent safety accidents. Considering the frequency sensitivity and dielectric sensitivity of the distributed Runit, Lunit, Gunit, and Cunit parameters of long cables, this paper quantitatively analyzes the frequency variation of 10 kV cable parameters under different aging states. Reconstructing the frequency variation process of typical electrical quantities through MATLAB PSCAD joint simulation, constructing fault circuits for cable insulation and semiconducting layers, obtaining transient currents in each layer of the cable under aging conditions, and conducting total harmonic distortion (THD) analysis to provide theoretical guidance for the subsequent monitoring and fault diagnosis of distribution cable status.

关键词： aging cable distributed parameters impedance spectrum PSCAD/EMTDC

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Model-based transmission line fault location methods: A review

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INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS 2023年第1期153卷

作者： Liu, Yu Lu, Dayou Vasilev, Stepan Wang, Binglin Lu, Dian Terzija, Vladimir ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Minist Educ Key Lab Control Power Transmiss & Convers SJTU Shanghai 200240 Peoples R China Skolkovo Inst Sci & Technol Ctr Energy Sci & Technol Moscow 121205 Russia

Accurate fault location methods for transmission lines are essential to ensure secure and reliable operation of power systems. Among various fault location approaches, model-based fault location methods are widely adopted in practical power systems since they are compatible with typical data acquisition systems and have clear physical meanings. There are extensive phasor domain and time domain model-based approaches in the existing literature, however, the connections among various line models, as well as corresponding fault location approaches, are not fully investigated. To this end, this paper first systematically reviews transmission line modeling framework for fault location, including time domain and phasor domain matrix/scalar form lumped/ distributed parameter models. The relationships between these models are carefully presented and discussed, with clear assumptions for each model. Next, different phasor domain and time domain model-based fault location methods using various line models are shown in detail. Finally, numerical experiments verify the differences between different model-based methods and the importance to use accurate line models for transmission line fault location. The results also clearly indicate the advantages of time domain model-based methods over phasor domain methods: the time domain approaches can accurately locate faults using a short data window within half a cycle after the fault occurs. Compared to traveling wave based methods, the time domain modelbased methods are compatible with available data acquisition hardware in substations, with a relatively low sampling rates of several kilo-samples/sec.

关键词： distributed parameters Fault location Model-based method Phasor domain Time domain Transmission line

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