Abstract

This thesis is about Photovoltaic (PV) cells and its stresses in various directions by calculating the power generated using solar cells under different conditions to improve its efficiency. Our research studies found that using multi-junction cells with larger substrates can increase the efficiency to some extent which in practice is limited to 43 percent. The experiment was conducted using ten solar cells each with an area of 20.9?cm? ^2, where each cell gives 0.5 V and 0.4 A and a 1.25 ? resistor was used. The cells were connected in series. Once, the PV cells were fixed horizontally and the other time tested in tilted position under same outdoor condition. The purpose of testing PV cells was to investigate the efficiency under above mentioned conditions. The data collected from the readings was used in calculation, and we have obtained from the calculations that horizontally fixed cells gave 4.8 percent efficiency whereas tilted cells gave 6.6 percent efficiency. Hence, the ratio showed that fixed cells produced 37.5 percent more power compared to horizontally fixed cells. Our other experiment consisted of testing PV cells under different temperature conditions that was done using a freezer and an oven for temperature variation and a tungsten bulb was used as a light source. The purpose of performing this experiment was to investigate how the efficiency of PV cells is affected under extreme conditions. Part of our thesis was also including studies and analysis of produced energy by the solar panel installed on the roof of “BTH” building in Karlskrona, Sweden. The data consisted of energy produced from February up to August 2014. The investigation also included finding the highest produced energy during these months. We have found that the highest energy was generated on the 1st of July which was 12.86 kWh. Furthermore, we went deep into investigation of the 1st of July to know exactly which hour of that day the highest energy was produced. The data showed that the highest produced energy was at 12:19 and 13:19 which was 2.03 kWh. Ramzi: +46723231353, +966561993488 Zain Document type: Part of book or chapter of book

Abstract

utomation in the mining industry has the potential to increase safety and productivity while improving working conditions. Ore transportation within the mine is a repetitive task which is well suited to be replaced by an autonomous mining vehicle operating around the clock. Scania, a world leader in sustainable transport solutions is investigating this new concept of vehicle. The autonomous operation is enabled by several technologies installed on the vehicle, including a communication system object of this thesis. Connectivity among vehicles is required in order to coordinate paths and exchange mission critical information. In this thesis, after identifying the challenges of wireless propagations in mines, the communication technology is chosen and possible antenna configurations and communication ranges are found. Through numerical link-budget simulations and subsequent range measurements, the potential communication range of this vehicle has been quantified. The results show the effectiveness of height diversity in extending the communication range. Lastly, the performance degradation caused by dust accumulated on the antennas is discussed. Automatiseringen i gruvindustrin har potentialen att öka säkerheten och produktiviteten samtidigt som den förbättrar arbetsvillkoren. Malmtransporten inne i gruvan är en repetitiv uppgift som passar bra att bli utbytt av en autonom gruvtransport som är i drift dygnet runt. Scania, en av de världsledande inom hållbara tranportlösningar, undersöker just nu denna typ av fordon. Den självstyrande driften aktiveras genom att ett flertal teknologier installeras på fordonet, inklusive ett kommunikationssystem som är ämne för denna avhandling. Anslutningen mellan fordonen är nödvändig för att kunna samordna banor och ge information i för uppdraget kritiska lägen. I denna avhandling, efter att ha identifierat svårigheterna med en trådlös utbredning i gruvor, är kommunikationsteknologin vald och möjliga antennkonfigurationer och kommunikationsräckvidder funna. Genom numeriska länkbudgetsimuleringar och efterföljande räckviddsmätningar, har det potentiella kommunikationsområdet för detta fordon kvantifierats. Resultaten visar effektiviteten av mångfald när det gäller höjd när man utvidgar kommunikationsområdet. Slutligen diskuteras prestandaförsämringen orsakad av damm som ackumulerats på antennerna.

Abstract

Network technologies are continuously advancing and attracting ever-growing interests from the industry and society. Network users expect better experience and performance every day. Consequently, network operators need to improve the quality of their services. One way to achieve this goal entails over-provisioning the network resources, which is not economically efficient as it imposes unnecessary costs. Another way is to employ Traffic Engineering (TE) solutions to optimally utilize the current underlying resources by managing traffic distribution in the network. In this thesis, we consider packet-switched Networks (PSN), which allows messages to be split across multiple packets as in today’s Internet. Traffic engineering in PSN is a well-known topic yet current solutions fail to make efficient utilization of the network resources. The goal of the TE process is to compute a traffic distribution in the network that optimizes a given objective function while satisfying the network capacity constraints (e.g., do not overflow the link capacity with an excessive amount of traffic). A critical aspect of TE tools is the ability to capture the impact of routing a certain amount of traffic through a certain link, also referred as the link criticality function. Today’s TE tools rely on simplistic link criticality functions that are inaccurate in capturing the network-wide performance of the computed traffic distribution. A good link criticality function allows the TE tools to distribute the traffic in a way that it achieves close-to-optimal network performance, e.g., in terms of packet loss and possibly packet latencies. In this thesis, we embark upon the study of link criticality functions and introduce four different criticality functions called: 1) LeakyCap, 2) LeakyReLU, 3) SoftCap, and 4) Softplus. We compare and evaluate these four functions with the traditional link criticality function defined by Fortz and Thorup, which aims at capturing the performance degradation of a link given its utilization. To assess the proposed link criticality functions, we designed 57 network scenarios and showed how the link criticality functions affect network performance in terms of packet loss. We used different topologies and considered both constant and bursty types of traffic. Based on our results, the most reliable and effective link criticality function for determining traffic distribution rates is Softplus. Softplus outperformed Fortz function in 79% of experiments and was comparable in the remaining 21% of the cases. Nätverksteknik är ett område under snabb utveckling som röner ett stort och växande intresse från såväl industri som samhälle. Användare av nätverkskommunikation förväntar sig ständigt ökande prestanda och därför behöver nätverksoperatörerna förbättra sina tjänster i motsvarande grad. Ett sätt att möta användarnas ökade krav är att överdimensionera nätverksresurserna, vilket dock leder till onödigt höga kostnader. Ett annat sätt är att använda sig av trafikstyrninglösningar med målet att utnyttjade tillgängliga resurserna så bra som möjligt. I denna avhandling undersöker vi paketswitchade nätverk (PSN) i vilka meddelanden kan delas upp i multipla paket, vilket är den rådande paradigmen för dagens Internet. Ä ven om trafikstyrning (TS) för PSN är ett välkänt ämne så finns det utrymme för förbättringar relativt de lösningar som är kända idag. Målet för TS-processen är att beräkna en trafikfördelning i nätverket som optimerar en given målfunktion, samtidigt som nätverkets kapacitetsbegränsningar inte överskrids. En kritisk aspekt hos TS-verktygen är förmågan att fånga påverkan av att sända en viss mängd trafik genom en specifik länk, vilket vi kallar länkkritikalitetsfunktionen. Dagens TS verktyg använder sig av förenklade länkkritikalitetsfunktioner som inte väl nog beskriver trafikfördelningens påverkan på hela nätverkets prestanda. En bra länkkritikalitetsfunktion möjliggör för TS-verktygen att fördela trafiken på ett sätt som närmar sig optimal nätverksprestanda, till exempel beskrivet som låg paketförlust och låg paketlatens. I denna avhandling undersöker vi länkkritikalitetsfunktioner och föreslår fyra olika funktioner som vi kallar 1) LeakyCap, 2) LeakyReLU, 3) SoftCap, och 4) Softplus. Vi jämför och utvärderar dessa fyra funktioner och inkluderar även klassiska länkkritikalitetsfunktioner som Fortz och Thorup, vilka avser fånga prestandadegraderingen av en länk över graden av utnyttjande.Vi har undersökt 57 olika nätverksscenarier för att bestämma hur de olika länk kritikalitets funktionerna påverkar nätverksprestanda i form av paketförlust. Olika topologier har använts och vi har studerat såväl konstant som stötvis flödande trafik. Enligt våra resultat är Softplus den mest tillförlitliga och effektiva länkkritikalitetsfunktionen för att fördela trafiken i ett nätverk. Softplus presterade bättre än Fortz i 79% av våra tester, och var jämförbar i övriga 21%.

Abstract

Over the past decades, congestion and emission problems has increased remarkablywhich escalates the demands on vehicles. The advancements withinthe eld of information and communication systems gives the opportunity todeal with the aforementioned problems. The concept of platooning shows tobe an attractive way of reducing both congestion and emissions by having ashort inter-vehicle spacing. The ndings in studies show that fuel reductionpotentials of 5-20 % are viable as a result of the lowered air drag by drivingin platoon. This thesis investigates the state of the art within the areaof intelligent transport systems (ITS) along with advanced driver assistancesystems (ADAS). Furthermore, the prosecuted work results in a proposedcontrol design for a longitudinal control in a platoon of vehicles. The platoonconsists of two homogeneous radio controlled vehicles (RCV) which aremodelled by taking advantage of system identication methods. The identi-ed plant models are implemented into a Simulink model where the controlsystem is developed. Moreover, the developed control system is implementedinto a real-time demonstrator for experimental evaluation. The results showsthat the modelled dynamics corresponds reasonably well with the real dynamicsof the system. The developed control system proves to work well andagree with the expectations of its performance obtained from simulations.The performance of the proposed controller has been evaluated by means ofsimulations and real experiments. The resulting control system consists ofPID controllers for both speed and spacing control. Under de senaste decennierna har mangden trakstockningar och problemmed utslapp okat - darmed aven kraven pa vara fordon. Samtidigt skaparframstegen inom informations- och kommunikationssystem mojligheter foratt hantera ovannamnda problem. Kolonnkorning, eller platooning har visatsig vara en eektiv metod for att minska saval trakstockningar som utslappsom en foljd av kortare avstand mellan fordon. Resultat fran studier visarhur en branslereduktion runt 5-20 % ar mojlig till foljd av det sankta luftmotstandet vid kolonnkorning. Avhandlingen undersoker teknikens standpunktinom intelligenta transportsystem (ITS) tillsammans med avancerade drivhjalpsystem(ADAS). Vidare resulterar arbetet i ett forslag till regleringsdesignfor en longitudinell kontroll i en kolonn av fordon. Kolonnen bestar av tvahomogena radiostyrda fordon (RCV) som modelleras genom att utnyttjametoder for systemidentiering. De identierade systemmodellerna implementerasi en Simulink-modell dar styrsystemet utvecklas. Dessutom implementerasdet utvecklade styrsystemet i en realtids-demonstration for experimentellutvardering. Resultaten visar att den modellerade dynamikenstammer bra overens med systemets verkliga dynamik. Det utvecklade styrsystemetvisar sig fungera bra och overensstammer med forvantningarna pa dessprestanda som erhallits genom simuleringar. Den foreslagna regulatorns prestandahar utvarderats med hjalp av simuleringar och verkliga experiment.Det resulterande styrsystemet bestar av PID regulatorer for bade hastighetsochavstandskontroll.

Abstract

Electric vehicles (EV) can be considered as energy storage with availability, energy and capacity constraints that can provide flexibility to the power system in the form of balancing products when aggregated. In this paper, we develop a two-stage stochastic optimization problem that maximizes the profit of a risk-averse EV aggregator for bids on the day ahead in both energy and Frequency Containment Reserve (FCR) markets. Unidirectional charging is examined, while we take into account uncertainty from prices and vehicle availability. Case studies are carried out in different Nordic bidding areas based on historical EV charging data. We identify a strong temporal alignment of EV availability and high FCR-N prices. Results show that consumption is shifted largely towards early hours of the morning. When compared to a reference cost of charging case, up to 50% of the cost of charging can be recovered in Norway, and 100% in Sweden. "p"QC 20190710. QC 20191203

Abstract

In the majority of applications using lithium-ion batteries, batteries are exposed to some harmonic content apart from the main charging/discharging current. The understanding of the effects that alternating currents have on batteries requires specific characterization methods and accurate measurement equipment. The lack of commercial battery testers with high alternating current capability simultaneously to the ability of operating at frequencies above 200 Hz, led to the design of the presented experimental setup. Additionally, the experimental setup expands the state-of-the-art of lithium-ion batteries testers by incorporating relevant lithium-ion battery cell characterization routines, namely hybrid pulse power current, incremental capacity analysis and galvanic intermittent titration technique. In this paper the hardware and the measurement capabilities of the experimental setup are presented. Moreover, the measurements errors due to the setup&rsquo s instruments were analysed to ensure lithium-ion batteries cell characterization quality. Finally, this paper presents preliminary results of capacity fade tests where 28 Ah cells were cycled with and without the injection of 21 A alternating at 1 kHz. Up to 300 cycles, no significant fade in cell capacity may be measured, meaning that alternating currents may not be as harmful for lithium-ion batteries as considered so far. Document type: Article

Abstract

The future smart grids (SGs) consist of considerable amount of renewable energy sources (RESs), electrical vehicles (EVs), and energy storage systems (ESSs). The uncertainties associated with EVs and uncontrollable nature of RESs have magnified voltage stability challenges and the importance of an effective energy management system (EMS) in SGs as a practical solution. This study presents a multi-agent transactive energy management system (TEMS) to control demand and supply in the presence of high levels of RESs and EVs, and maximises profit of each participant in addition to satisfying voltage regulation constraints. For this purpose, a real-time pricing is considered based on Cournot oligopoly competition model for demand and merit order effect for production to compensate RESs' fluctuations in real time by an indirect control method. Simulations are conducted in the modified IEEE 37-bus test system with 1141 customers, 670 EVs, two solar plants, four wind turbines, and one ESS. The results show that the proposed multi-agent TEMS can indirectly control EVs, elastic loads, and ESSs to balance the RESs oscillation, minimise customers cost, and regulate voltage in a real-time manner. "p"QC 20171204