A constructive heuristic algorithm to Short Term Transmission Network Expansion Planning

In this paper a method for solving the Short Term Transmission Network Expansion Planning (STTNEP) problem is presented. The STTNEP is a very complex mixed integer nonlinear programming problem that presents a combinatorial explosion in the search space. In this work we present a constructive heuristic algorithm to find a solution of the STTNEP of excellent quality. In each step of the algorithm a sensitivity index is used to add a circuit (transmission line or transformer) to the system. This sensitivity index is obtained solving the STTNEP problem considering as a continuous variable the number of circuits to be added (relaxed problem). The relaxed problem is a large and complex nonlinear programming and was solved through an interior points method that uses a combination of the multiple predictor corrector and multiple centrality corrections methods, both belonging to the family of higher order interior points method (HOIPM). Tests were carried out using a modified Carver system and the results presented show the good performance of both the constructive heuristic algorithm to solve the STTNEP problem and the HOIPM used in each step.

Heuristic algorithm to solve the short term transmission network expansion planning

In this paper, a method for solving the short term transmission network expansion planning problem is presented. This is a very complex mixed integer nonlinear programming problem that presents a combinatorial explosion in the search space. In order to And a solution of excellent quality for this problem, a constructive heuristic algorithm is presented in this paper. In each step of the algorithm, a sensitivity index is used to add a circuit (transmission line or transformer) or a capacitor bank (fixed or variable) to the system. This sensitivity index is obtained solving the problem considering the numbers of circuits and capacitors banks to be added (relaxed problem), as continuous variables. The relaxed problem is a large and complex nonlinear programming and was solved through a higher order interior point method. The paper shows results of several tests that were performed using three well-known electric energy systems in order to show the possibility and the advantages of using the AC model. ©2007 IEEE.

Simplified procedure to estimate the resistance parameters of transmission lines

An alternative and simplified procedure is described to estimate the longitudinal resistances of transmission lines based on the real-time load profile. This method proposes to estimate the resistance parameters from the synchronized measurements of complex currents and complex voltages at the sending and receiving ends of transmission systems. The synchronized measurements can be in practice obtained using phasor measurement units (PMUs). © 2012 Springer-Verlag Berlin Heidelberg.

Assessment of branch outage contingencies using the continuation method

This paper provides a contribution to the contingency analysis of electric power systems under steady state conditions. An alternative methodology is presented for static contingency analyses that only use continuation methods and thus provides an accurate determination of the loading margin. Rather than starting from the base case operating point, the proposed continuation power flow obtains the post-contingency loading margins starting from the maximum loading and using a bus voltage magnitude as a parameter. The branch selected for the contingency evaluation is parameterised using a scaling factor, which allows its gradual removal and assures the continuation power flow convergence for the cases where the method would diverge for the complete transmission line or transformer removal. The applicability and effectiveness of the proposed methodology have been investigated on IEEE test systems (14, 57 and 118 buses) and compared with the continuation power flow, which obtains the post-contingency loading margin starting from the base case solution. In general, for most of the analysed contingencies, few iterations are necessary to determine the post-contingency maximum loading point. Thus, a significant reduction in the global number of iterations is achieved. Therefore, the proposed methodology can be used as an alternative technique to verify and even to obtain the list of critical contingencies supplied by the electric power systems security analysis function. © 2013 Elsevier Ltd. All rights reserved.

Analysis of the electrical characteristics and surge protection of EHV transmission lines supported by tall towers

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fitting the frequency-dependent parameters in the Bergeron line model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Representation of transmission lines: comparison of models and parameters distributed discrete parameters

A transmission line is characterized by the fact that its parameters are distributed along its length. This fact makes the voltages and currents along the line to behave like waves and these are described by differential equations. In general, the differential equations mentioned are difficult to solve in the time domain, due to the convolution integral, but in the frequency domain these equations become simpler and their solutions are known. The transmission line can be represented by a cascade of π circuits. This model has the advantage of being developed directly in the time domain, but there is a need to apply numerical integration methods. In this work a comparison of the model that considers the fact that the parameters are distributed (Universal Line Model) and the fact that the parameters considered concentrated along the line (π circuit model) using the trapezoidal integration method, and Simpson's rule Runge-Kutta in a single-phase transmission line length of 100 km subjected to an operation power. © 2003-2012 IEEE.

Reduced-order modelling, circuit-level design and SOI fabrication of microelectromechanical resonators

This thesis deals with two important research aspects concerning radio frequency (RF) microresonators and switches. First, a new approach for compact modeling and simulation of these devices is presented. Then, a combined process flow for their simultaneous fabrication on a SOI substrate is proposed. Compact models for microresonators and switches are extracted by applying mathematical model order reduction (MOR) to the devices finite element (FE) description in ANSYS c° . The behaviour of these devices includes forms of nonlinearities. However, an approximation in the creation of the FE model is introduced, which enables the use of linear model order reduction. Microresonators are modeled with the introduction of transducer elements, which allow for direct coupling of the electrical and mechanical domain. The coupled system element matrices are linearized around an operating point and reduced. The resulting macromodel is valid for small signal analysis around the bias point, such as harmonic pre-stressed analysis. This is extremely useful for characterizing the frequency response of resonators. Compact modelling of switches preserves the nonlinearity of the device behaviour. Nonlinear reduced order models are obtained by reducing the number of nonlinearities in the system and handling them as input to the system. In this way, the system can be reduced using linear MOR techniques and nonlinearities are introduced directly in the reduced order model. The reduction of the number of system nonlinearities implies the approximation of all distributed forces in the model with lumped forces. Both for microresonators and switches, a procedure for matrices extraction has been developed so that reduced order models include the effects of electrical and mechanical pre-stress. The extraction process is fast and can be done automatically from ANSYS binary files. The method has been applied for the simulation of several devices both at devices and circuit level. Simulation results have been compared with full model simulations, and, when available, experimental data. Reduced order models have proven to conserve the accuracy of finite element method and to give a good description of the overall device behaviour, despite the introduced approximations. In addition, simulation is very fast, both at device and circuit level. A combined process-flow for the integrated fabrication of microresonators and switches has been defined. For this purpose, two processes that are optimized for the independent fabrication of these devices are merged. The major advantage of this process is the possibility to create on-chip circuit blocks that include both microresonators and switches. An application is, for example, aswitched filter bank for wireless transceiver. The process for microresonators fabrication is characterized by the use of silicon on insulator (SOI) wafers and on a deep reactive ion etching (DRIE) step for the creation of the vibrating structures in single-crystal silicon and the use of a sacrificial oxide layer for the definition of resonator to electrode distance. The fabrication of switches is characterized by the use of two different conductive layers for the definition of the actuation electrodes and by the use of a photoresist as a sacrificial layer for the creation of the suspended structure. Both processes have a gold electroplating step, for the creation of the resonators electrodes, transmission lines and suspended structures. The combined process flow is designed such that it conserves the basic properties of the original processes. Neither the performance of the resonators nor the performance of the switches results affected by the simultaneous fabrication. Moreover, common fabrication steps are shared, which allows for cheaper and faster fabrication.

Análisis y diseño de un patrón de ruido térmico de 10 MHz a 26,5 GHz en tecnología coaxial

Esta Tesis Doctoral presenta las investigaciones y los trabajos desarrollados durante los años 2008 a 2012 para el análisis y diseño de un patrón primario de ruido térmico de banda ancha en tecnología coaxial. Para ubicar esta Tesis en su campo científico es necesario tomar conciencia de que la realización de mediciones fiables y trazables forma parte del sostenimiento del bienestar de una sociedad moderna y juega un papel crítico en apoyo de la competitividad económica, la fabricación y el comercio, así como de la calidad de vida. En el mundo moderno actual, una infraestructura de medición bien desarrollada genera confianza en muchas facetas de nuestra vida diaria, porque nos permite el desarrollo y fabricación de productos fiables, innovadores y de alta calidad; porque sustenta la competitividad de las industrias y su producción sostenible; además de contribuir a la eliminación de barreras técnicas y de dar soporte a un comercio justo, garantizar la seguridad y eficacia de la asistencia sanitaria, y por supuesto, dar respuesta a los grandes retos de la sociedad moderna en temas tan complicados como la energía y el medio ambiente. Con todo esto en mente se ha desarrollado un patrón primario de ruido térmico con el fin de aportar al sistema metrológico español un nuevo patrón primario de referencia capaz de ser usado para desarrollar mediciones fiables y trazables en el campo de la medida y calibración de dispositivos de ruido electromagnético de radiofrecuencia y microondas. Este patrón se ha planteado para que cumpla en el rango de 10 MHz a 26,5 GHz con las siguientes especificaciones: Salida nominal de temperatura de ruido aproximada de ~ 83 K. Incertidumbre de temperatura de ruido menor que ± 1 K en todo su rango de frecuencias. Coeficiente de reflexión en todo su ancho de banda de 0,01 a 26,5 GHz lo más bajo posible. Se ha divido esta Tesis Doctoral en tres partes claramente diferenciadas. La primera de ellas, que comprende los capítulos 1, 2, 3, 4 y 5, presenta todo el proceso de simulaciones y ajustes de los parámetros principales del dispositivo con el fin de dejar definidos los que resultan críticos en su construcción. A continuación viene una segunda parte compuesta por el capítulo 6 en donde se desarrollan los cálculos necesarios para obtener la temperatura de ruido a la salida del dispositivo. La tercera y última parte, capítulo 7, se dedica a la estimación de la incertidumbre de la temperatura de ruido del nuevo patrón primario de ruido obtenida en el capítulo anterior. Más concretamente tenemos que en el capítulo 1 se hace una exhaustiva introducción del entorno científico en donde se desarrolla este trabajo de investigación. Además se detallan los objetivos que se persiguen y se presenta la metodología utilizada para conseguirlos. El capítulo 2 describe la caracterización y selección del material dieléctrico para el anillo del interior de la línea de transmisión del patrón que ponga en contacto térmico los dos conductores del coaxial para igualar las temperaturas entre ambos y mantener la impedancia característica de todo el patrón primario de ruido. Además se estudian las propiedades dieléctricas del nitrógeno líquido para evaluar su influencia en la impedancia final de la línea de transmisión. En el capítulo 3 se analiza el comportamiento de dos cargas y una línea de aire comerciales trabajando en condiciones criogénicas. Se pretende con este estudio obtener la variación que se produce en el coeficiente de reflexión al pasar de temperatura ambiente a criogénica y comprobar si estos dispositivos resultan dañados por trabajar a temperaturas criogénicas; además se estudia si se modifica su comportamiento tras sucesivos ciclos de enfriamiento – calentamiento, obteniendo una cota de la variación para poder así seleccionar la carga que proporcione un menor coeficiente de reflexión y una menor variabilidad. En el capítulo 4 se parte del análisis de la estructura del anillo de material dieléctrico utilizada en la nota técnica NBS 1074 del NIST con el fin de obtener sus parámetros de dispersión que nos servirán para calcular el efecto que produce sobre el coeficiente de reflexión de la estructura coaxial completa. Además se realiza un estudio posterior con el fin de mejorar el diseño de la nota técnica NBS 1074 del NIST, donde se analiza el anillo de material dieléctrico, para posteriormente realizar modificaciones en la geometría de la zona donde se encuentra éste con el fin de reducir la reflexión que produce. Concretamente se estudia el ajuste del radio del conductor interior en la zona del anillo para que presente la misma impedancia característica que la línea. Y para finalizar se obtiene analíticamente la relación entre el radio del conductor interior y el radio de la transición de anillo térmico para garantizar en todo punto de esa transición la misma impedancia característica, manteniendo además criterios de robustez del dispositivo y de fabricación realistas. En el capítulo 5 se analiza el comportamiento térmico del patrón de ruido y su influencia en la conductividad de los materiales metálicos. Se plantean las posibilidades de que el nitrógeno líquido sea exterior a la línea o que éste penetre en su interior. En ambos casos, dada la simetría rotacional del problema, se ha simulado térmicamente una sección de la línea coaxial, es decir, se ha resuelto un problema bidimensional, aunque los resultados son aplicables a la estructura real tridimensional. Para la simulación térmica se ha empleado la herramienta PDE Toolbox de Matlab®. En el capítulo 6 se calcula la temperatura de ruido a la salida del dispositivo. Se parte del estudio de la aportación a la temperatura de ruido final de cada sección que compone el patrón. Además se estudia la influencia de las variaciones de determinados parámetros de los elementos que conforman el patrón de ruido sobre las características fundamentales de éste, esto es, el coeficiente de reflexión a lo largo de todo el dispositivo. Una vez descrito el patrón de ruido electromagnético se procede, en el capítulo 7, a describir los pasos seguidos para estimar la incertidumbre de la temperatura de ruido electromagnético a su salida. Para ello se utilizan dos métodos, el clásico de la guía para la estimación de la incertidumbre [GUM95] y el método de simulación de Monte Carlo. En el capítulo 8 se describen las conclusiones y lo logros conseguidos. Durante el desarrollo de esta Tesis Doctoral se ha obtenido un dispositivo novedoso susceptible de ser patentado, que ha sido registrado en la Oficina Española de Patentes y Marcas (O.E.P.M.) en Madrid, de conformidad con lo establecido en el artículo 20 de la Ley 11/1986, de 20 de Marzo, de Patentes, con el título Patrón Primario de Ruido Térmico de Banda Ancha (Referencia P-101061) con fecha 7 de febrero de 2011. ABSTRACT This Ph. D. work describes a number of investigations that were performed along the years 2008 to 2011, as a preparation for the study and design of a coaxial cryogenic reference noise standard. Reliable and traceable measurement underpins the welfare of a modern society and plays a critical role in supporting economic competitiveness, manufacturing and trade as well as quality of life. In our modern world, a well developed measurement infrastructure gives confidence in many aspects of our daily life, for example by enabling the development and manufacturing of reliable, high quality and innovative products; by supporting industry to be competitive and sustainable in its production; by removing technical barriers to trade and supporting fair trade; by ensuring safety and effectiveness of healthcare; by giving response to the major challenges in key sectors such energy and environment, etc. With all this in mind we have developed a primary standard thermal noise with the aim of providing the Spanish metrology system with a new primary standard for noise reference. This standard will allow development of reliable and traceable measurements in the field of calibration and measurement of electromagnetic noise RF and microwave devices. This standard has been designed to work in the frequency range from 10 MHz to 26.5 GHz, meeting the following specifications: 1. Noise temperature output is to be nominally ~ 83 K. 2. Noise temperature uncertainty less than ± 1 K in the frequency range from 0.01 to 26.5 GHz. 3. Broadband performance requires as low a reflection coefficient as possible from 0.01 to 26.5 GHz. The present Ph. D. work is divided into three clearly differentiated parts. The first one, which comprises Chapters 1 to 5, presents the whole process of simulation and adjustment of the main parameters of the device in order to define those of them which are critical for the manufacturing of the device. Next, the second part consists of Chapter 6 where the necessary computations to obtain the output noise temperature of the device are carried out. The third and last part, Chapter 7, is devoted to the estimation of the uncertainty related to the noise temperature of the noise primary standard as obtained in the preceding chapter. More specifically, Chapter 1 provides a thorough introduction to the scientific and technological environment where this research takes place. It also details the objectives to be achieved and presents the methodology used to achieve them. Chapter 2 describes the characterization and selection of the bead dielectric material inside the transmission line, intended to connect the two coaxial conductors equalizing the temperature between the two of them and thus keeping the characteristic impedance constant for the whole standard. In addition the dielectric properties of liquid nitrogen are analyzed in order to assess their influence on the impedance of the transmission line. Chapter 3 analyzes the behavior of two different loads and of a commercial airline when subjected to cryogenic working conditions. This study is intended to obtain the variation in the reflection coefficient when the temperature changes from room to cryogenic temperature, and to check whether these devices can be damaged as a result of working at cryogenic temperatures. Also we try to see whether the load changes its behavior after successive cycles of cooling / heating, in order to obtain a bound for the allowed variation of the reflection coefficient of the load. Chapter 4 analyzes the ring structure of the dielectric material used in the NBS technical note 1074 of NIST, in order to obtain its scattering parameters that will be used for computation of its effect upon the reflection coefficient of the whole coaxial structure. Subsequently, we perform a further investigation with the aim of improving the design of NBS technical note 1074 of NIST, and modifications are introduced in the geometry of the transition area in order to reduce the reflection it produces. We first analyze the ring, specifically the influence of the radius of inner conductor of the bead, and then make changes in its geometry so that it presents the same characteristic impedance as that of the line. Finally we analytically obtain the relationship between the inner conductor radius and the radius of the transition from ring, in order to ensure the heat flow through the transition thus keeping the same reflection coefficient, and at the same time meeting the robustness requirements and the feasibility of manufacturing. Chapter 5 analyzes the thermal behavior of the noise standard and its influence on the conductivity of metallic materials. Both possibilities are raised that the liquid nitrogen is kept outside the line or that it penetrates inside. In both cases, given the rotational symmetry of the structure, we have simulated a section of coaxial line, i.e. the equivalent two-dimensional problem has been resolved, although the results are applicable to the actual three-dimensional structure. For thermal simulation Matlab™ PDE Toolbox has been used. In Chapter 6 we compute the output noise temperature of the device. The starting point is the analysis of the contribution to the overall noise temperature of each section making up the standard. Moreover the influence of the variations in the parameters of all elements of the standard is analyzed, specifically the variation of the reflection coefficient along the entire device. Once the electromagnetic noise standard has been described and analyzed, in Chapter 7 we describe the steps followed to estimate the uncertainty of the output electromagnetic noise temperature. This is done using two methods, the classic analytical approach following the Guide to the Estimation of Uncertainty [GUM95] and numerical simulations made with the Monte Carlo method. Chapter 8 discusses the conclusions and achievements. During the development of this thesis, a novel device was obtained which was potentially patentable, and which was finally registered through the Spanish Patent and Trademark Office (SPTO) in Madrid, in accordance with the provisions of Article 20 of Law 11/1986 about Patents, dated March 20th, 1986. It was registered under the denomination Broadband Thermal Noise Primary Standard (Reference P-101061) dated February 7th, 2011.

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission

Optical regeneration at 40 Gb/s in dispersion-managed transmission lines with in-line synchronous modulators

Numerical optimization is performed of the 40-Gb/s dispersion-managed (DM) soliton transmission system with in-line synchronous intensity modulation. Stability of DM soliton transmission results from a combined action of dispersion, nonlinearity, in-line filtering, and modulation through effective periodic bandwidth management of carrier pulses. Therefore, analysis of the multiparametric problem is typically required. A two-stage time-saving numerical optimization procedure is applied. At the first step, the regions of the stable carrier propagation are determined using theoretical models available for DM solitons, and system parameters are optimized. At the second stage, full numerical simulations are undertaken in order to verify the tolerance of optimal transmission regimes. An approach developed demonstrates feasibility of error-free transmission over 20 000 km in a transmission line composed of standard fiber and dispersion compensation fiber at 40 Gb/s.

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. © 2013 Optical Society of America.

Application of meta-analytical probabilistic approach for reliability benefits reflective optimal transmission costing – the case of India

In the deregulated Power markets it is necessary to have a appropriate Transmission Pricing methodology that also takes into account “Congestion and Reliability”, in order to ensure an economically viable, equitable, and congestion free power transfer capability, with high reliability and security. This thesis presents results of research conducted on the development of a Decision Making Framework (DMF) of concepts and data analytic and modelling methods for the Reliability benefits Reflective Optimal “cost evaluation for the calculation of Transmission Cost” for composite power systems, using probabilistic methods. The methodology within the DMF devised and reported in this thesis, utilises a full AC Newton-Raphson load flow and a Monte-Carlo approach to determine, Reliability Indices which are then used for the proposed Meta-Analytical Probabilistic Approach (MAPA) for the evaluation and calculation of the Reliability benefit Reflective Optimal Transmission Cost (ROTC), of a transmission system. This DMF includes methods for transmission line embedded cost allocation among transmission transactions, accounting for line capacity-use as well as congestion costing that can be used for pricing using application of Power Transfer Distribution Factor (PTDF) as well as Bialek’s method to determine a methodology which consists of a series of methods and procedures as explained in detail in the thesis for the proposed MAPA for ROTC. The MAPA utilises the Bus Data, Generator Data, Line Data, Reliability Data and Customer Damage Function (CDF) Data for the evaluation of Congestion, Transmission and Reliability costing studies using proposed application of PTDF and other established/proven methods which are then compared, analysed and selected according to the area/state requirements and then integrated to develop ROTC. Case studies involving standard 7-Bus, IEEE 30-Bus and 146-Bus Indian utility test systems are conducted and reported throughout in the relevant sections of the dissertation. There are close correlation between results obtained through proposed application of PTDF method with the Bialek’s and different MW-Mile methods. The novel contributions of this research work are: firstly the application of PTDF method developed for determination of Transmission and Congestion costing, which are further compared with other proved methods. The viability of developed method is explained in the methodology, discussion and conclusion chapters. Secondly the development of comprehensive DMF which helps the decision makers to analyse and decide the selection of a costing approaches according to their requirements. As in the DMF all the costing approaches have been integrated to achieve ROTC. Thirdly the composite methodology for calculating ROTC has been formed into suits of algorithms and MATLAB programs for each part of the DMF, which are further described in the methodology section. Finally the dissertation concludes with suggestions for Future work.

Fault-Location System for Multiterminal Transmission Lines

This research presents the development and implementation in a computational routine of algorithms for fault location in multiterminal transmission lines. These algorithms are part of a fault-location system, which is capable of correctly identifying the fault point based on voltage and current phasor quantities, calculated by using measurements of voltage and current signals from intelligent electronic devices, located on the transmission-line terminals. The algorithms have access to the electrical parameters of the transmission lines and to information about the transformers loading and their connection type. This paper also presents the development of phase component models for the power system elements used by the fault-location algorithms.

Transmission lines distance protection using artificial neural networks

This work presents the development and implementation of an artificial neural network based algorithm for transmission lines distance protection. This algorithm was developed to be used in any transmission line regardless of its configuration or voltage level. The described ANN-based algorithm does not need any topology adaptation or ANN parameters adjustment when applied to different electrical systems. This feature makes this solution unique since all ANN-based solutions presented until now were developed for particular transmission lines, which means that those solutions cannot be implemented in commercial relays. (c) 2011 Elsevier Ltd. All rights reserved.