Software product line for power converters

Työn tilaajana toimi Visedo Oy. Työn tavoitteina oli tutkia Visedo Oy:n ohjelmistokehityksen nykytila, tunnistaa seuraavat parannuskohteet ja antaa ohjeita havaittujen parannuskohteiden korjaamiseksi. Visedo Oy:n tehonmuokkain ohjelmistokehityksen nykytilaa käsiteltiin neljän valitun osa-alueen näkökulmasta: ohjelmistoarkkitehtuurityyli, komponenttipohjainen ohjelmistokehitys, ohjelmistotuotelinjojen kehitysmenetelmät ja ohjelmistovariaatioiden hallinta. Valituilla osa-alueilla havaittujen parannuskohteiden perusteella annettiin korjausehdotuksia: ohjelmistoarkkitehtuurin rakenteeseen, komponenttien jakautumiselle, komponenttien koostamiselle ja komponenttien versioinnille. Lisäksi ehdotettiin uudenlaista ohjelmistotuotelinja rakennetta, joka yhdistää kerros- ja komponenttipohjaiset arkkitehtuurityylit mahdollistaen ominaisuuksiltaan eroavien tehonmuokkain ohjelmistojen hallinnan.

LVDC power distribution system: computational modelling

In the doctoral dissertation, low-voltage direct current (LVDC) distribution system stability, supply security and power quality are evaluated by computational modelling and measurements on an LVDC research platform. Computational models for the LVDC network analysis are developed. Time-domain simulation models are implemented in the time-domain simulation environment PSCAD/EMTDC. The PSCAD/EMTDC models of the LVDC network are applied to the transient behaviour and power quality studies. The LVDC network power loss model is developed in a MATLAB environment and is capable of fast estimation of the network and component power losses. The model integrates analytical equations that describe the power loss mechanism of the network components with power flow calculations. For an LVDC network research platform, a monitoring and control software solution is developed. The solution is used to deliver measurement data for verification of the developed models and analysis of the modelling results. In the work, the power loss mechanism of the LVDC network components and its main dependencies are described. Energy loss distribution of the LVDC network components is presented. Power quality measurements and current spectra are provided and harmonic pollution on the DC network is analysed. The transient behaviour of the network is verified through time-domain simulations. DC capacitor guidelines for an LVDC power distribution network are introduced. The power loss analysis results show that one of the main optimisation targets for an LVDC power distribution network should be reduction of the no-load losses and efficiency improvement of converters at partial loads. Low-frequency spectra of the network voltages and currents are shown, and harmonic propagation is analysed. Power quality in the LVDC network point of common coupling (PCC) is discussed. Power quality standard requirements are shown to be met by the LVDC network. The network behaviour during transients is analysed by time-domain simulations. The network is shown to be transient stable during large-scale disturbances. Measurement results on the LVDC research platform proving this are presented in the work.

Comparison study of two competing models of an all mechanical power transmission system

A comparison between two competing models of an all mechanical power transmission system is studied by using Dymola –software as the simulation tool. This tool is compared with Matlab/ Simulink –software by using functionality, user-friendliness and price as comparison criteria. In this research we assume that the torque is balanceable and transmission ratios are calculated. Using kinematic connection sketches of the two transmission models, simulation models are built into the Dymola simulation environment. Models of transmission systems are modified according to simulation results to achieve a continuous variable transmission ratio. Simulation results are compared between the two transmission systems. The main features of Dymola and MATLAB/ Simulink are compared. Advantages and disadvantages of the two softwares are analyzed and compared.

The role of nuclear power in the future energy system

Currently widely accepted consensus is that greenhouse gas emissions produced by the mankind have to be reduced in order to avoid further global warming. The European Union has set a variety of CO2 reduction and renewable generation targets for its member states. The current energy system in the Nordic countries is one of the most carbon free in the world, but the aim is to achieve a fully carbon neutral energy system. The objective of this thesis is to consider the role of nuclear power in the future energy system. Nuclear power is a low carbon energy technology because it produces virtually no air pollutants during operation. In this respect, nuclear power is suitable for a carbon free energy system. In this master's thesis, the basic characteristics of nuclear power are presented and compared to fossil fuelled and renewable generation. Nordic energy systems and different scenarios in 2050 are modelled. Using models and information about the basic characteristics of nuclear power, an opinion is formed about its role in the future energy system in Nordic countries. The model shows that it is possible to form a carbon free Nordic energy system. Nordic countries benefit from large hydropower capacity which helps to offset fluctuating nature of wind power. Biomass fuelled generation and nuclear power provide stable and predictable electricity throughout the year. Nuclear power offers better energy security and security of supply than fossil fuelled generation and it is competitive with other low carbon technologies.

Carbon sources for Power-to-Gas applications in the Finnish energy system

This thesis is done as a part of the NEOCARBON project. The aim of NEOCARBON project is to study a fully renewable energy system utilizing Power-to-Gas or Power-to-Liquid technology for energy storage. Power-to-Gas consists of two main operations: Hydrogen production via electrolysis and methane production via methanation. Methanation requires carbon dioxide and hydrogen as a raw material. This thesis studies the potential carbon dioxide sources within Finland. The different sources are ranked using the cost and energy penalty of the carbon capture, carbon biogenity and compatibility with Power-to-Gas. It can be concluded that in Finland there exists enough CO2 point sources to provide national PtG system with sufficient amounts of carbon. Pulp and paper industry is single largest producer of biogenic CO2 in Finland. It is possible to obtain single unit capable of grid balancing operations and energy transformations via Power-to-Gas and Gas-to-Power by coupling biogas plants with biomethanation and CHP units.

Impacts of increased levels of wind penetration on the Electric Power System of the Åland Islands

The application of VSC-HVDC technology throughout the world has turned out to be an efficient solution regarding a large share of wind power in different power systems. This technology enhances the overall reliability of the grid by utilization of the active and reactive power control schemes which allows to maintain frequency and voltage on busbars of the end-consumers at the required level stated by the network operator. This master’s thesis is focused on the existing and planned wind farms as well as electric power system of the Åland Islands. The goal is to analyze the wind conditions of the islands and appropriately predict a possible production of the existing and planned wind farms with a help of WAsP software program. Further, to investigate the influence of increased wind power it is necessary to develop a simulation model of the electric grid and VSC-HVDC system in PSCAD and examine grid response to different wind power production cases with respect to the grid code requirements and ensure the stability of the power system.

The role of nuclear and other conventional power plants in the flexible energy system

This thesis reviews the role of nuclear and conventional power plants in the future energy system. The review is done by utilizing freely accesible publications in addition to generating load duration and ramping curves for Nordic energy system. As the aim of the future energy system is to reduce GHG-emissions and avoid further global warming, the need for flexible power generation increases with the increased share of intermittent renewables. The goal of this thesis is to offer extensive understanding of possibilities and restrictions that nuclear power and conventional power plants have regarding flexible and sustainable generation. As a conclusion, nuclear power is the only technology that is able to provide large scale GHG-free power output variations with good ramping values. Most of the currently operating plants are able to take part in load following as the requirement to do so is already required to be included in the plant design. Load duration and ramping curves produced prove that nuclear power is able to cover most of the annual generation variation and ramping needs in the Nordic energy system. From the conventional power generation methods, only biomass combustion can be considered GHG-free because biomass is considered carbon neutral. CFB combusted biomass has good load follow capabilities in good ramping and turndown ratios. All the other conventional power generation technologies generate GHG-emissions and therefore the use of these technologies should be reduced.

The Discourse of Home Recording : Accessibility, Exclusion and Power

Ce mémoire propose une analyse critique du discours de l’enregistrement sonore à domicile (home recording). Dans la foulée des propos mettant de l’avant l’ «accessibilité» et la «démocratisation» de l’enregistrement sonore, ce mémoire analyse les relations de savoir/pouvoir produites et légitimées par le discours, ce qu’elles permettent et contraignent, autorisent et excluent. Le corpus à l’étude est issu de la presse musicale ainsi que de forums de discussion en ligne relevant de sites spécialisés. Les méthodes utilisées sont inspirées de l’approche du discours développées par Michel Foucault et de ce que Johnson et. al. (2004) appellent l’interprétation critique. L’analyse met en évidence les deux principaux sujets du discours de l’enregistrement sonore à la maison : les professionnels de l’enregistrement et les «pros» de l’enregistrement à domicile, deux groupes constitués d’hommes financièrement aisés. Les règles qui régissent l’enregistrement à domicile semblent reprendre, en les adaptant, celles régissant les studios professionnels. Ce mémoire suggère que la «démocratisation» telle qu'énoncée dans ce discours articule l'«accessibilité contemporaine» à certains savoirs et certaines technologies à des exclusions singulières – comme des femmes et des personnes de moyens limités – qui rendent ce discours possible. Être dans le vrai, dans ce discours, c’est échanger, argumenter, discuter et prescrire des façons de faire et de dire qui font des studios professionnels l’espace des normes et des légitimités. Mots clés: enregistrement, musique, maison, domicile, studio, démocratisation, technologie, l'analyse du discours, relations de pouvoir/savoir, Michel Foucault.

High power N2 laser with a modified gas flow system and discharge geometry

A high power Nz laser of the double-Blumlein type having a modified gas flow system, electrode configuration, and discharge geometry with minimum inductance is described. By incorporating a triggere’d-pressurized spark gap switch, arc-free operation was achieved for a wide E/P range. The device gives a peak power in excess of 700 kW with a FWHM of 3 ns and an efficiency of 0.51%, which is remarkably high for a pulsed nitrogen laser system. The dependence of output power on parameters such as operating pressure, voltage, and repetition rate are discussed.

Studies on some generalizations of line graph and the power domination problem in graphs

Department of Mathematics, Cochin University of Science and Technology

k-NN based On-Line Handwritten Character recognition system

On-line handwriting recognition has been a frontier area of research for the last few decades under the purview of pattern recognition. Word processing turns to be a vexing experience even if it is with the assistance of an alphanumeric keyboard in Indian languages. A natural solution for this problem is offered through online character recognition. There is abundant literature on the handwriting recognition of western, Chinese and Japanese scripts, but there are very few related to the recognition of Indic script such as Malayalam. This paper presents an efficient Online Handwritten character Recognition System for Malayalam Characters (OHR-M) using K-NN algorithm. It would help in recognizing Malayalam text entered using pen-like devices. A novel feature extraction method, a combination of time domain features and dynamic representation of writing direction along with its curvature is used for recognizing Malayalam characters. This writer independent system gives an excellent accuracy of 98.125% with recognition time of 15-30 milliseconds

Short-Term Load Forecast Of A Low Loadfactor Power System For Optimization Of Merit Order Dispatch Using Adaptive Learning Algorithm

Short term load forecasting is one of the key inputs to optimize the management of power system. Almost 60-65% of revenue expenditure of a distribution company is against power purchase. Cost of power depends on source of power. Hence any optimization strategy involves optimization in scheduling power from various sources. As the scheduling involves many technical and commercial considerations and constraints, the efficiency in scheduling depends on the accuracy of load forecast. Load forecasting is a topic much visited in research world and a number of papers using different techniques are already presented. The accuracy of forecast for the purpose of merit order dispatch decisions depends on the extent of the permissible variation in generation limits. For a system with low load factor, the peak and the off peak trough are prominent and the forecast should be able to identify these points to more accuracy rather than minimizing the error in the energy content. In this paper an attempt is made to apply Artificial Neural Network (ANN) with supervised learning based approach to make short term load forecasting for a power system with comparatively low load factor. Such power systems are usual in tropical areas with concentrated rainy season for a considerable period of the year

Hybrid Power System Modelling - Simulation and Energy Management Unit Development

Weltweit leben mehr als 2 Milliarden Menschen in ländlichen Gebieten. Als Konzept für die elektrische Energieversorgung solcher Gebiete kommen dezentrale elektrische Energieversorgungseinheiten zum Einsatz, die lokal verfügbare erneuerbare Ressourcen nutzen. Stand der Technik bilden Einheiten, die auf PV-Diesel-Batterie System basieren. Die verwendeten Versorgungsskonzepte in Hybridsystemen sind durch den Einsatz von Batterien als Energiespeicher meist wenig zuverlässig und teuer. Diese Energiespeicher sind sehr aufwendig zu überwachen und schwerig zu entsorgen. Den Schwerpunkt dieser Arbeit bildet die Entwicklung eines neuen Hybridsystems mit einem Wasserreservoir als Energiespeicher. Dieses Konzept eignet sich für Bergregionen in Entwicklungsländern wie Nepal, wo z.B. neben der solaren Strahlung kleine Flüsse in großer Anzahl vorhanden sind. Das Hybridsystem verfügt über einen Synchrongenerator, der die Netzgrößen Frequenz und Spannung vorgibt und zusätzlich unterstützen PV und Windkraftanlage die Versorgung. Die Wasserkraftanlage soll den Anteil der erneuerbaren Energienutzung erhöhen. Die Erweiterung des Systems um ein Dieselaggregat soll die Zuverlässigkeit der Versorgung erhöhen. Das Hybridsystem inkl. der Batterien wird modelliert und simuliert. Anschließend werden die Simulations- und Messergebnisse verglichen, um eine Validierung des Modells zu erreichen. Die Regelungsstruktur ist aufgrund der hohen Anzahl an Systemen und Parametern sehr komplex. Sie wird mit dem Simulationstool Matlab/Simulink nachgebildet. Das Verhalten des Gesamtsystems wird unter verschiedene Lasten und unterschiedlichen meteorologischen Gegebenheiten untersucht. Ein weiterer Schwerpunkt dieser Arbeit ist die Entwicklung einer modularen Energiemanagementeinheit, die auf Basis der erneuerbaren Energieversorgung aufgebaut wird. Dabei stellt die Netzfrequenz eine wichtige Eingangsgröße für die Regelung dar. Sie gibt über die Wirkleistungsstatik die Leistungsänderung im Netz wider. Über diese Angabe und die meteorologischen Daten kann eine optimale wirtschaftliche Aufteilung der Energieversorgung berechnet und eine zuverlässige Versorgung gewährleistet werden. Abschließend wurde die entwickelte Energiemanagementeinheit hardwaretechnisch aufgebaut, sowie Sensoren, Anzeige- und Eingabeeinheit in die Hardware integriert. Die Algorithmen werden in einer höheren Programmiersprache umgesetzt. Die Simulationen unter verschiedenen meteorologischen und netztechnischen Gegebenheiten mit dem entwickelten Model eines Hybridsystems für die elektrische Energieversorgung haben gezeigt, dass das verwendete Konzept mit einem Wasserreservoir als Energiespeicher ökologisch und ökonomisch eine geeignete Lösung für Entwicklungsländer sein kann. Die hardwaretechnische Umsetzung des entwickelten Modells einer Energiemanagementeinheit hat seine sichere Funktion bei der praktischen Anwendung in einem Hybridsystem bestätigen können.

Mission control system for dam inspection with an AUV

This paper presents a complete control architecture that has been designed to fulfill predefined missions with an autonomous underwater vehicle (AUV). The control architecture has three levels of control: mission level, task level and vehicle level. The novelty of the work resides in the mission level, which is built with a Petri network that defines the sequence of tasks that are executed depending on the unpredictable situations that may occur. The task control system is composed of a set of active behaviours and a coordinator that selects the most appropriate vehicle action at each moment. The paper focuses on the design of the mission controller and its interaction with the task controller. Simulations, inspired on an industrial underwater inspection of a dam grate, show the effectiveness of the control architecture

Application for fault location in electrical power distribution systems

Fault location has been studied deeply for transmission lines due to its importance in power systems. Nowadays the problem of fault location on distribution systems is receiving special attention mainly because of the power quality regulations. In this context, this paper presents an application software developed in Matlabtrade that automatically calculates the location of a fault in a distribution power system, starting from voltages and currents measured at the line terminal and the model of the distribution power system data. The application is based on a N-ary tree structure, which is suitable to be used in this application due to the highly branched and the non- homogeneity nature of the distribution systems, and has been developed for single-phase, two-phase, two-phase-to-ground, and three-phase faults. The implemented application is tested by using fault data in a real electrical distribution power system