Testing of Dynamic Models for Stability Studies

This paper deals with turbine-governor and excitation system dynamic models which are suitable for dynamic stability assessment of a transmission system. ENTSO-E uses the Common Grid Model Exchange Specification (CGMES) to facilitate the exchange of operational and grid planning data among transmission system operators. CGMES also includes a detailed description of the models needed to perform dynamic stability studies. These models are compared with the models implemented in the network simulator MODES

Disseny microelectrnic de circuits discriminadors de polsos pel detector LHCb

The aim of this thesis is to present a solution for implementing the front end system of the Scintillator Pad Detector (SPD) of the calorimeter system of the LHCb experiment that will start in 2008 at the Large Hadron Collider (LHC) at CERN. The requirements of this specific system are discussed and an integrated solution is presented, both at system and circuit level. We also report some methodological achievements. In first place, a method to study the PSRR (and any transfer function) in fully differential circuits taking into account the effect of parameter mismatch is proposed. Concerning noise analysis, a method to study time variant circuits in the frequency domain is presented and justified. This would open the possibility to study the effect of 1/f noise in time variants circuits. In addition, it will be shown that the architecture developed for this system is a general solution for front ends in high luminosity experiments that must be operated with no dead time and must be robust against ballistic deficit

Experimental investigation on the performances of a multilevel inverter using a field programmable gate array-based control system

The Field Programmable Gate Array (FPGA) represents a valid solution for the design of control systems for inverters adopted in many industry applications, because of both its high flexibility of use and its high-performance with respect to other types of digital controllers. In this context, this paper presents an experimental investigation on the harmonic content of the voltages produced by a three-phase, five level cascaded H-Bridge Multilevel inverter with an FPGA-based control board, aiming also to evaluate the performance of the FPGA through the implementation of the main common modulation techniques and the comparison between simulation and experimental results. The control algorithms are implemented by means of the VHDL programming language. The output voltage waveforms, which have been obtained by applying to the inverter the main PWM techniques, are compared in terms of THD%. Simulation and experimental results are analyzed, compared and finally discussed

Lifetime prediction for power converters

Renewable energy is developing rapidly and gaining more and more commercial viability. High reliability of the generation system is essential to maximize the output power. The power inverter is an important unit in this system and is believed to be one of the most unreliable parts. In the case of wind power generation, especially in off-shore wind, when the system reliability requirement is high, a technique to predict the inverter lifetime is invaluable as it would help the inverter designer optimize his design for minimal maintenance. Previous researchers studying inverter lifetime prediction, focus either at device level such as device fatigue damage models, or at system level which require experimental data for their selected device. This work presents a new method to estimate the inverter lifetime from a given mission profile within a reasonable simulation time. Such model can be used as a converter design tool or an on-line lifetime estimation tool after being configured to a real converter system. The key contribution of this work is to link the physics of the power devices to a large scale system simulation within a reasonable framework of time. With this technique, the system down time can be reduced and therefore more power can be generated. Also, the failure damage to the system is avoided which reduces the maintenance cost. A power cycling test is designed to gather the lifetime data of a selected IGBT module. Die-attach solder fatigue is found out to be the dominant failure mode of this IGBT module. The accuracy of widely accepted Miner’s rule, which accumulates damage linearly, is discussed and a nonlinear accumulation method is promoted to predict the lifetime of power inverters

Electronics in the on-line control of railway movements: quantitative aspects

The present thesis is concerned with a quantitative examination of the on-line control of railway movements and develops a mathematical technique for the evaluation of safety based on the use of Markov processes, illustrated with examples. In addition, the thesis presents a design methodology applicable to electronic safety systems. These systems are shown to be an essential element in the development of fully electronic railway signalling systems, as well as in the increased automation of railway movements. An analysis of the limits of automation of railway movements is described and discussed together with a possible system configuration for the achievement of crewless train operation. The research described herein has been carried out at the British Railways R & D division and the methods described have been successfully applied to real engineering problems. The industrial R & D background of the present thesis is also reflected in the inclusion of a section on the socio-economic consequences of major innovation, particularly in the field of automation and in the consideration of costs and benefits. Section 2 contains an approach evolved jointly with Mr. W.T. Parkman, also at the R & D Division of British Railways, and has been published as Reference 16. Section 5 is a short description or the work carried out by the group under the direct responsibility of the author at the R & D Division of British Railways

Notional System Report

The objective of this report is to set forth a group of time-domain models for the early-stage design study of shipboard power systems, and to demonstrate their use on various system architectures. The effort stemmed out of an earlier effort in which waveform-level models of three notional architectures – a Medium Voltage AC System, a High-Frequency AC System, and a Medium Voltage DC System were partially developed. Unfortunately, these codes were extremely computationally intense, limiting their usefulness for early design studies in which large numbers of runs, and a degree of user interactiveness, is required.Center for Electromechanic