Long resistive cables used in the operation of remote instrumentation impose fundamental limits on the amount of power delivered and create difficulties in voltage regulation at the remote-end (voltage at the end of the cable) with changing load conditions. This type of power delivery is used in many engineering systems such as in the operation of underwater remotely-operated vehicles, in oil drilling and mining industries, and in highly distributed systems (aircraft, submarines, and space stations, etc.). The focus of this research is to develop new approaches for power delivery in systems that have considerable voltage drops between the local and remote-ends.Two novel methods of power delivery based on state feedback control and parallel operation of switching and linear regulators to enhance stability and increase the power delivered at the remote-end are developed and validated experimentally.A system-level approach is developed to control the remote-end voltage for changing load conditions through the usage of a model inversion technique at the local-end along with a feedback of the local-end variables.

The advancement in integrated circuit (IC) technology has resulted in scaling down of device sizes and supply voltages without proportionally scaling down the threshold voltage of the MOS transistor. This, coupled with the increasing demand for low power, portable, battery-operated electronic devices, like mobile phones, and laptops provides the impetus for further research towards achieving higher integration on chip and low power consumption. High gain, wide bandwidth amplifiers driving large capacitive loads serve as error amplifiers in low-voltage low drop out regulators in portable devices. This demands low power, low area, and frequency-compensated multistage amplifiers capable of driving large capacitive loads. The first part of the research proposes two power and area efficient frequency compensation schemes: Single Miller Capacitor Compensation (SMC) and Single Miller Capacitor Feedforward Compensation (SMFFC), for multistage amplifiers driving large capacitive loads. The designs have been implemented in a 0.5??m CMOS process. Experimental results show that the SMC and SMFFC amplifiers achieve gain-bandwidth products of 4.6MHz and 9MHz, respectively, when driving a load of 25Kδ/120pF. Each amplifier operates from a ??1V supply, dissipates less than 0.42mW of power and occupies less than 0.02mm2 of silicon area. The inception of the latest IEEE standard like IEEE 802.16 wireless metropolitan area network (WMAN) for 10 -66 GHz range demands wide band amplifiers operating at high frequencies to serve as front-end circuits (e.g. low noise amplifier) in such receiver architectures. Devices used in cascade (multistage amplifiers) can be used to increase the gain but it is achieved at an expense of bandwidth. Distributing the capacitance associated with the input and the output of the device over a ladder structure (which is periodic), rather than considering it to be lumped can achieve an extension of bandwidth without sacrificing gain. This concept which is also known as distributed amplification has been explored in the second part of the research. This work proposes certain guidelines for the design of distributed low noise amplifiers operating at very high frequencies. Noise analysis of the distributed amplifier with real transmission lines is introduced. The analysis for gain and noise figure is verified with simulation results from a 5-stage distributed amplifier implemented in a 0.18??m CMOS process.

In this dissertation, a new signaling scheme known as Constant Voltage Power Transmission Line (CV-PTL) is presented to supply power to a digital I/O circuit. This signaling scheme provides power through a transmission line in place of a power plane while dynamically changing the impedance of the power delivery network to keep a constant voltage at the power pin of the IC. Consequently, this reduces the effects of return path discontinuities and can improve the quality of output signal by reducing power and ground bounce. Through theory, simulation, and measurements, we show that this new method can be used to reduce jitter and eye height with the proposed PDN methodology. In addition, the signaling scheme was extended to vertically-stacked 3D integrated circuits (3D ICs). It is known that power supply noise worsens as one goes higher up in the stack of dies due to increased interconnect inductance. However, by utilizing the CV-PTL concept in the PDN design of a 3-layer 3DIC system, the circuit showed considerable improvement in power supply noise and peak-to-peak jitter as compared to the conventional design approach. In addition to signal and power integrity of these signaling schemes, the noise coupling between digital and RF components is also investigated. A simple design for mitigating the coupling of power supply noise in mixed-signal electronics is presented. Currently used methods, such as electromagnetic bandgap structures have been shown to exhibit excellent noise isolation characteristics, and are a popular area of research in this area. However, these structures can pose difficulties for signal integrity. The proposed method extends the previous power transmission line work to address both the power supply noise generation and isolation. Test vehicles using these proposed methods, as well as using an EBG structure were fabricated and tested with regards to power supply noise, jitter, and noise isolation. The proposed methods show significant improvements in almost all performance metrics as compared to EBG. Finally, this dissertation discusses the effect of implementing a power transmission line in a power distribution network composed of a switching regulator and a voltage regulator module. The DC conductor losses of the PTL can not only affect power efficiency of the entire system, but can also affect the proper operation of the linear regulator module when supporting large currents. Consequently, recommendations are made on the design of the PTL to ensure proper operation and efficiency.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη της λειτουργίας των καθοδικών αλεξικεραύνων κατά την προστασία γραμμών μεταφοράς υψηλής τάσης. Ειδικότερα, λόγω της ιδιαίτερης φύσης των κεραυνών και των πληγμάτων που αυτοί επιφέρουν, γίνεται μελέτη μοντέλων που έχουν προταθεί για την προσομείωση των αλεξικεραύνων κατά την λειτουργία τους. / The purpose of this paper is to study the function of surge arresters protecting high voltage transmission lines. Specifically, given the particular nature of lightning strikes and the blows they bring, models that have been proposed for the simulation of surge arrestes during operation are being studied.

Σκοπός της παρούσας διπλωματικής είναι η μελέτη των αναπτυσσόμενων υπερτάσεων στις γραμμές μεταφοράς υψηλής τάσης (132kV) του δικτύου της Αρχής Ηλεκτρισμού Κύπρου. Γίνεται μια παρουσίαση του κάθε στοιχείου του δικτύου ξεχωριστά, με ποιο τρόπο μπορεί να μοντελοποιηθεί και πως συμπεριφέρεται σε κεραυνικό πλήγμα εύρους 100kA με τρία διαφορετικά σήματα. Τέλος παρουσιάζονται τα αποτελέσματα της προσομοίωσης στο λογισμικό ATP-EMTP και εξάγονται παρατηρήσεις και συμπεράσματα. Αρχικά στο πρώτο κεφάλαιο γίνεται μια εισαγωγική παρουσίαση της διπλωματικής εργασίας, μια ιστορική αναδρομή για τα συστήματα ηλεκτρικής ενέργειας και την επανάσταση που έφερε η ανάπτυξη τους. Στη συνέχεια παρουσιάζεται η πορεία του ηλεκτρισμού στη Κύπρο κάτω από το φορέα διαχείρισης του, την Αρχή Ηλεκτρισμού Κύπρου. Στο δεύτερο κεφάλαιο παρατίθενται λεπτομερώς τα στοιχεία που συνθέτουν σήμερα το δίκτυο της Α.Η.Κ από την παραγωγή, τη μεταφορά και τη διανομή της ηλεκτρικής ενέργειας στο νησί. Ακόμη γίνεται μία σύντομη αναφορά στο κλίμα της Κύπρου και πως αυτό ευνοεί τη δημιουργία κεραυνών. Στο τρίτο κεφάλαιο παρουσιάζεται και περιγράφεται αναλυτικά η αιτία της δημιουργίας των εξωτερικών υπερτάσεων, δηλαδή ο κεραυνός και πως λειτουργεί αυτός ως φυσικό φαινόμενο. Επίσης περιγράφονται οι διάφοροι μηχανισμοί δημιουργίας υπερτάσεων από τους κεραυνούς. Στα επόμενα τρία κεφάλαια παρουσιάζονται ενδελεχώς τα τρία βασικά στοιχεία του δικτύου το οποίο τυγχάνει προσομοίωσης, δηλαδή οι γραμμές μεταφοράς, οι πυλώνες και οι αλυσοειδείς μονωτήρες ανάρτησης. Συγκεκριμένα, για τις μεταφοράς γίνεται αναφορά στα γενικά τους στοιχεία, στα χαρακτηριστικά τους αλλά και στις καταπονήσεις που υφίστανται. Στους πυλώνες παρουσιάζεται η καταπόνηση τους από κεραυνούς με απότομο μέτωπο, το πως εκτιμάται η αντίσταση γείωσης τους και τι ρόλο παίζει η ειδική αντίσταση εδάφους. Όσο αφορά τους μονωτήρες ανάρτησης προβάλλονται γενικά κατασκευαστικά τους στοιχεία, οι συνθήκες στις οποίες λαμβάνει χώρα η υπερπήδηση(διάσπαση) τους και οι μέθοδοι υπολογισμού του χρόνου επιφανειακής διάσπασης των. Στο έβδομο κεφάλαιο παρουσιάζεται το λογισμικό ATP- EMTP μέσω του οποίου γίνεται η μοντελοποίηση των στοιχείων του δικτύου και η προσομοίωση τους. Γίνεται αναφορά στη δομή του προγράμματος, τα ιστορικά του στοιχεία, τις διάφορες βιβλιοθήκες μοντέλων που εμπεριέχονται σε αυτό, τα διάφορα προγράμματα υποστήριξης του και περισσότερο το ATP – Draw όπου παρέχεται η δυνατότητα για σχεδίαση των στοιχείων και εισαγωγή των παραμέτρων τους. Στο όγδοο κεφάλαιο παρουσιάζεται η μοντελοποίηση των προαναφερθέντων στοιχείων της διάταξης και ενσωμάτωση τους στο ATP – EMTP. Τέλος, στο ένατο και τελευταίο κεφάλαιο παρατίθενται τα αποτελέσματα της προσομοίωσης, η εξαγωγή των αποτελεσμάτων, οι παρατηρήσεις και τα συμπεράσματα. / The aim of the work described in this thesis is the study of the induced overvoltages on high voltage transmission lines (132kV) of the network of the Electricity Authority of Cyprus. Every network element is separately described, ways for the modeling of each element are explored and the behavior of each element during a 100kA lightning strike using three different signals is observed. Lastly, the results of the simulation are presented by using ATP/EMTP software, observations are made and findings are determined. The first chapter introduces the thesis and consists of a historical overview of electrical power systems and an overview of the revolution brought through their development. Thereafter the development of electricity in Cyprus as part of the electricity supplier “Electricity Authority of Cyprus” is analyzed. A detailed review of the system used by the “Electricity Authority of Cyprus” (Generation, Transmission, Distribution, Supply) constitutes the second chapter. Further, a brief reference to the climate of Cyprus is made and on how it favors the formation of lightning. The third chapter presents and describes in detail what might cause extraneous voltages, i.e. lightning and how it works as a natural phenomenon. Plus the different generation mechanisms of lightning overvoltages are described. In the next three chapters the main three elements of the network being simulated are presented in detail, i.e. transmission lines, pylons and catenary suspension insulators. Namely, with regard to transmission lines general information is given, their characteristics are described along with the stresses they face. As long as the pylons are concerned, the stresses they face by steep-front lightning are described, information on how to assess their grounding system resistance is given and it is also discussed whether Soil Resistivity plays a dominant role. Regarding suspension insulators their parts are described, the circumstances under which their disruptive discharge takes place and the methods of calculating surface discharges. In the seventh chapter the ATP/EMTP software used for network modeling and simulation is presented. Reference is made to the program structure, the historical data, the various model- libraries included in it, the various supporting programs and more specifically ATPDraw which creates/draws the elements and which does the parameter fitting. The eighth chapter contains the analysis of the modeling of the aforementioned parts of the assembly and their integration in the ATP/EMTP. Lastly, in the ninth and final chapter the results of the simulation are presented, observations are made and findings are determined.

No description available.

No description available.

This thesis explores and implements techniques for frequency domain modelling and time domain simulation of overhead transmission lines. The popular Vector Fitting algorithm is employed to approximate the frequency domain model using rational functions, and the recursive convolution technique is applied to the rational approximation to generate a time domain form. The frequency domain model is translated into the time domain using delay extraction, modal decomposition, passivity enforcement, and rational approximation. Several approaches to each of these procedures are investigated. The thesis also discusses several choices for the integration method used within the recursive convolution procedure. In order to make the transmission line modeller and simulator easy to use, a Java-based library and partial graphical interface were developed. Specifically, the goal was to develop a platform-independent program that can run either stand-alone or as an applet inside a web page.

This thesis explores and implements techniques for frequency domain modelling and time domain simulation of overhead transmission lines. The popular Vector Fitting algorithm is employed to approximate the frequency domain model using rational functions, and the recursive convolution technique is applied to the rational approximation to generate a time domain form. The frequency domain model is translated into the time domain using delay extraction, modal decomposition, passivity enforcement, and rational approximation. Several approaches to each of these procedures are investigated. The thesis also discusses several choices for the integration method used within the recursive convolution procedure. In order to make the transmission line modeller and simulator easy to use, a Java-based library and partial graphical interface were developed. Specifically, the goal was to develop a platform-independent program that can run either stand-alone or as an applet inside a web page.

This thesis investigates the presence of multiple (quasi-TEM) modes in inverted embedded microstrip lines. It has already been shown that parasitic modes do exist in inverted embedded microstrips due to field leakage inside the dielectric substrate, especially for high dielectric constants (like Silicon). This thesis expands upon that work and characterizes those modes for a variety of geometrical dimensions. Chapter 1 focuses on the theory behind the different transmission line modes, which may be present in inverted embedded microstrips. Based on the structure of the inverted embedded microstrip, the conventional microstrip mode, the quasi-conventional microstrip mode, and the stripline mode are expected. Chapter 2 discusses in detail the techniques used to decompose the total probed field into the various modes present in the inverted embedded microstrip lines. Firstly, a short explanation of the finite-difference time-domain method, that is used for the simulation and modeling of inverted microstrips up to 50 GHz is provided. Next, a flowchart of the process involved in decomposing the modes is laid out. Lastly, the challenges of this approach are also highlighted to give an appreciation of the difficulty in obtaining accurate results. Chapter 3 shows the results (dispersion diagrams, values/percentage of the individual mode energies ) obtained after running time-domain simulations for a variety of geometrical dimensions. Chapter 4 concludes the thesis by explaining the results in terms of the transmission line theory presented in Chapter 1. Next, possible future work is mentioned.