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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Techno-economic analysis of retrofitting existing fuel stations with DC fast chargers along with solar PV and energy storage with load flow analysis

Ghosh, Nilanshu January 2020 (has links)
The increasing number of electric vehicles (EVs) in the transport sector has rendered the conventional fuel-based vehicles obsolete along with the fuel filling stations. With the growth in EVs, there has been an increase in the public charging infrastructure with fast charging equipment being used to charge the EVs in least possible time and also address the issue of ‘range anxiety’ among the EV owners. Many countries like South Korea and Germany has seen policies being implemented to install fast chargers for EVs in existing fuel filling stations. This study aims conduct a techno-economic feasibility to analyse the potential of implementing Electric Vehicle Supply Equipment (EVSE) with fast charging capacity into existing fuel filling stations. The potential of using solar photovoltaic system (PV) and battery storage systems (BESS) to reduce the load from the grid is also explored. Scenarios are developed considering different configurations of the EVSE, PV and BESS and an in-depth economic analysis is conducted to analyse the economic feasibility of the configurations. The impact on the electricity grid is also analysed in this thesis by conducting a load flow analysis on the CIGRE Low voltage network for Europe using Python.The proposed design enables selection of techno-economically feasible configurations of EVSE, BESS and PV. The results of the design are explained with the UK as a case study. It is observed that the configurations with 3 EVSE, BESS and 8 hours and the configuration with 3 EVSE, 1 BESS and 1 PV system for 8 hours of operation are economically viable. The proposed design shows that though the connection cost is the dominant factor affecting the feasibility, use of BESS with or without PV can reduce the connection cost by almost 90% depending on the number of BESS. Load flow analysis is conducted for the different configurations of EVSE, BESS and PV on the CIGRE LV network on Pandapower in Python. The results indicate that the existing network needs to be reinforced to facilitate the connection of EV fast chargers into the grid. Upgrading the network cables and increasing the slack voltage to a value of 1.05 or 1.1 Volts per unit, are the two strategies that have been suggested in this study to prevent any undervoltage that may occur as a result of connecting the EVSE to the electricity grid. The simulations conducted for the two strategies highlight that by implementing these strategies into the electricity grid network, the undervoltage issues in the transmission network can be mitigated. / Det ökande antalet elfordon inom transportsektorn har gjort de konventionella bränslebaserade fordonen föråldrade tillsammans med bränslepåfyllningsstationerna. Med ökningen av elbilar har det skett en ökning av den offentliga laddningsinfrastrukturen med snabbladdningsutrustning som används för att ladda elbilarna på åtminstone möjlig tid och också ta itu med frågan om ’range anxiety’ bland elägare. Många länder som Sydkorea och Tyskland har sett politik införas för att installera snabbladdare för elbilar i befintliga bensinstationer. Denna studie syftar till att genomföra en teknisk-ekonomisk genomförbarhet för att analysera potentialen för att implementera elfordonstillförselutrustning (EVSE) med snabb laddningskapacitet i befintliga bensinstationer. Potentialen med att använda solcellssystem (PV) och batterilagringssystem (BESS) för att minska belastningen från nätet undersöks också. Scenarier utvecklas med beaktande av olika konfigurationer av EVSE, PV och BESS och en djupgående ekonomisk analys genomförs för att analysera konfigurationernas ekonomiska genomförbarhet. Effekten på elnätet analyseras också i denna avhandling genom att genomföra en belastningsflödesanalys på CIGRE lågspänningsnät för Europa med Python.Den föreslagna designen möjliggör val av tekno-ekonomiskt genomförbara konfigurationer av EVSE, BESS och PV. Resultaten av designen förklaras med Storbritannien som en fallstudie. Det observeras att konfigurationerna med 3 EVSE, BESS och 8 timmar och konfigurationen med 3 EVSE, 1 BESS och 1 PV-system för 8 timmars drift är ekonomiskt lönsamma. Den föreslagna designen visar att även om anslutningskostnaden är den dominerande faktorn som påverkar genomförbarheten, kan användning av BESS med eller utan solceller minska anslutningskostnaden med nästan 90% beroende på antalet BESS. Lastflödesanalys utförs för de olika konfigurationerna av EVSE, BESS och PV på CIGRE LV-nätverket på Pandapower i Python. Resultaten visar att det befintliga nätverket måste förstärkas för att underlätta anslutningen av EV-snabbladdare till nätet. Uppgradering av nätverkskablarna och ökning av spänningen till 1,05 eller 1,1 volt per enhet är de två strategier som har föreslagits i denna studie för att förhindra underspänning som kan uppstå till följd av att EVSE ansluts till elnätet. Simuleringarna för de två strategierna lyfter fram att genom att implementera dessa strategier i elnätet kan underspänningsfrågorna i överföringsnätet mildras.
52

CELLULAR BROADBAND TELEMETRY OPTIONS FOR THE 21st CENTURY: Looking at broadband cellular from a telemetry perspective

Smith, Brian J. 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / With the recent broadband upgrades to various cellular infrastructures and the myriad new emerging wireless broadband standards and services offered by carriers, it is often difficult to navigate this sea of technology. In deciding the best choice for broadband telemetry applications, one must look not only at the technology, but also at the economics, market timing, bandwidths, legacy issues, future expandability and coverage, security, protocols, and the requirements of the specific application. This paper reviews the technology roadmap of cellular providers keeping these issues in perspective as they apply to TCP/IP data for images, audio, video, and other broadband telemetry data using CDMA 1xRTT, EV-DO, and EV-DO Rev A systems as well as GSM GPRS/EDGE, UMTS/W-CDMA, HSDPA, and HSUPA networks. Lastly, issues seen by system integrators when using cellular channels for telemetry applications are examined, and a case is presented for overcoming many of these issues through the use of cellular routers.
53

Workplace Electric Vehicle Solar Smart Charging based on Solar Irradiance Forecasting

Almquist, Isabelle, Lindblom, Ellen, Birging, Alfred January 2017 (has links)
The purpose of this bachelor thesis is to investigate different outcomes of the usage of photovoltaic (PV) power for electric vehicle (EV) charging adjacent to workplaces. In the investigated case, EV charging stations are assumed to be connected to photovoltaic systems as well as the electricity grid. The model used to simulate different scenarios is based on a goal of achieving constant power exchange with the grid by adjusting EV charging to a solar irradiance forecast. The model is implemented in MATLAB. This enables multiple simulations for varying input parameters. Data on solar irradiance are used to simulate the expected PV power generation. Data on driving distances are used to simulate hourly electricity demands of the EVs at the charging stations. A sensitivity analysis, based on PV irradiance that deviates from the forecast, is carried out. The results show what power the grid needs to have installed capacity for if no PV power system is installed. Furthermore, appropriate PV power installation sizes are suggested. The suggestions depend on whether the aim is to achieve 100 percent self-consumption of PV generated power or full PV power coverage of charging demands. For different scenarios, PV power installations appropriate for reducing peak powers on the grid are suggested. The sensitivity analysis highlights deviations caused by interference in solar irradiance.
54

Modeling of Battery Degradation in Electrified Vehicles

Juhlin, Olof January 2016 (has links)
This thesis provides an insight into battery modeling in electric vehicles which includes degradation mechanisms as in automotive operation in electric vehicles. As electric vehicles with lithium ion batteries increase in popularity there is an increased need to study and model the capacity losses in such batteries. If there is a good understanding of the phenomena involved and an ability to predict these losses there is also a foundation to take measures to minimize these losses. In this thesis a battery model for lithium ion batteries which includes heat dissipation is used as groundwork. This model is expanded with the addition of capacity losses due to usage as well as storage. By combining this with a simple vehicle model one can use these models to achieve an understanding as to how a battery or pack of several batteries would behave in a specific driving scenario. Much of the focus in the thesis is put into comparing the different factors of degradation to highlight what the major contributors are. The conclusion is drawn that heat is the main cause for degradation for batteries in electric vehicles. This applies for driving usage as well as during storage. As heat is generated when a battery is used, the level of current is also a factor, as well as in which state of charge region the battery is used.
55

The Gladiators of the OMXSPI : What are the key drivers trailing the durable performance?

Cullhed, Jakob, Olsson, Fredrik January 2019 (has links)
Background and problem: The impact on the stock market of macroeconomic factors have been analyzed in several earlier studies. These are forces constantly changing and thereby they contribute to changing the supply and demand of stocks. The fact that macroeconomic variables have affected the top performing stocks of the OMXSPI during 2004 – 2018, in terms of performance, plays an important part of the study. Different authors have recognized different factors to affect the stock price development and there has not yet been established an explanation of the determinants of stock prices. Purpose: The purpose of the study was to identify the stocks that continuously have had a development superior to the OMXSPI, and therefore have contributed the most to the development of the OMXSPI during 2004 – 2018. Moreover, the study analyzes the drivers that have contributed to the performance of these stocks. Furthermore, the study clarifies which factors that have contributed to the development of the P/E and the EV/EBITDA of the top performers. Methodology: The study followed a quantitative and deductive approach. The Swedish stock market was analyzed with a focus on the OMXSPI were the top performing stocks of this index were identified through a screening process. Moreover, the top performers were put against the OMXSPI in different time periods to compare the performance. Furthermore, multiples of these top performers and the sectors which they trade in were calculated in order to compare the multiples to each other, with the purpose of analyzing them relative to each other in different time periods. Conclusion: From the findings it could be established very similar patterns between the top performers and the OMXSPI. The difference mainly being that the top performers in every sequence experienced a superior development than the OMXSPI, but also greater declines during short sequences. Moreover, the tables displayed remarkable returns of the top performers and the aggregated top performers traded at premium levels in all analyzed time periods.
56

Design and construction of a bidirectional DCDC converter for an EV application

Hedlund, Magnus January 2010 (has links)
<p>A Sliding Mode Control System for a Bidirectional DCDC Converter was designed and a low voltage prototype was constructed. The control system based its decisions solely on the latest available measurements, which improves performance when changing operative quadrant, since no memory needs reinitializing (such as for PI and state prediction methods). A boost control philosophy was presented, based on a current source approximation. The control was found to be stable without steady-state errors when the variance of the input/output dynamics was high.</p><p>The target application for the DCDC Converter is an EV (Electric Vehicle) with a flywheel driveline, which puts additional requirements of the converter. Among these are current and voltage control, bidirectionality, and a broad input voltage range.</p><p>Simulations were performed in Simulink prior to physical implementation, proving functionality of the proposed control system. The physical implementation of the control was done on a digital signal processor with code compiled from C. A median filter was designed to increase measurement efficiency for the current sensors which had shot-like noise distortions.</p>
57

Powertrain technology and cost assessment of battery electric vehicles

Qin, Helen 01 April 2010 (has links)
This thesis takes EV from the late 90’s as a baseline, assess the capability of today’s EV technology, and establishes its near-term and long-term prospects. Simulations are performed to evaluate EVs with different combinations of new electric machines and battery chemistries. Cost assessment is also presented to address the major challenge of EV commercialization. This assessment is based on two popular vehicle classes: subcompact and mid-size. Fuel, electricity and battery costs are taken into consideration for this study. Despite remaining challenges and concerns, this study shows that with production level increases and battery price-drops, full function EVs could dominate the market in the longer term. The modeling shows that from a technical and performance standpoint both range and recharge times already fall into a window of practicality, with few if any compromises relative to conventional vehicles. Electric vehicles are the most sustainable alternative personal transportation technology available to-date. With continuing breakthroughs, minimal change to the power grid, and optimal GHG reductions, emerging electric vehicle performance is unexpectedly high.
58

Design and construction of a bidirectional DCDC converter for an EV application

Hedlund, Magnus January 2010 (has links)
A Sliding Mode Control System for a Bidirectional DCDC Converter was designed and a low voltage prototype was constructed. The control system based its decisions solely on the latest available measurements, which improves performance when changing operative quadrant, since no memory needs reinitializing (such as for PI and state prediction methods). A boost control philosophy was presented, based on a current source approximation. The control was found to be stable without steady-state errors when the variance of the input/output dynamics was high. The target application for the DCDC Converter is an EV (Electric Vehicle) with a flywheel driveline, which puts additional requirements of the converter. Among these are current and voltage control, bidirectionality, and a broad input voltage range. Simulations were performed in Simulink prior to physical implementation, proving functionality of the proposed control system. The physical implementation of the control was done on a digital signal processor with code compiled from C. A median filter was designed to increase measurement efficiency for the current sensors which had shot-like noise distortions.
59

Finns det ett samband mellan börsnoterade företags resultat och dess värdering?

Oguz, Caroline, Tunc, Lena January 2012 (has links)
Background: What is a share and what determines the value of a company? This is a constant issue that many in the financial world are facing. Many argue that there has been some decoupling between stock valuation and how the company in question is developing operationally after the financial crisis that the world faced during 2008-2009. Problem: It is important to distinguish between the company and the share. A company that is good and well maintained may not be worth buying only because of it. The share is judged by other elements also. It can be a problem when people doesn´t make this distinction. Purpose: The purpose of this paper is to test the following hypothesis: The higher operating profit (performance) a company has, the higher will the valuation for the share on the market be. Question: Is there a relationship between a listed company's operating performance and its share valuation? Method: In our study we will focus on figures from annual reports, called "hard" data and therefore it is most natural to make use of the quantitative research approach. One reason that we chose the deductive approach is that it usually forms the basis for our research strategy. Theory: We use key performance indicators that measure the operational development of the business and sets them against the key indicators for the stock valuation. The following ratios are used for operational activities; Solidity, revenue growth, return on equity and return on capital employed. The figures for stock valuation is EV/EBIT and P/E-ratio. Conclusion: There is a weak positive correlation between a company's operational development and its share valuation, but it is very weak when looking at a sample group as a whole. In individual cases, there is relatively strong correlation.
60

A Study on Electrical Vehicle Charging Station DC Microgrid Operations

Liao, Yung-tang 11 September 2012 (has links)
Power converters are used in many distributed energy resources (DER) applications. With proper controls, DER systems can reduce losses and achieve higher energy efficiency if various power sources and loads are integrated through DC bus. High voltage electric vehicle (EV) DC charging station is becoming popular in order to reduce charging time and improve energy efficiency. A DC EV charging station model involving photovoltaic, energy storage system (ESS), fuel cell and DC loads is studied in this work. A dynamic programming technique that considers various uncertainties involved in the system is adopted to obtain optimal dispatch of ESS and fuel cell system. The effects of different tariffs, demand response programs and contract capacities of demand in the power scheduling are investigated and the results are presented.

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