This paper presents the methods and the results obtained during the project conducted by Sylvain Kerouanton for the French transmission system operator RTE. The objective of the project is to define methods to estimate the electric consumption of the substations of the high voltage network. The developed methods are based on the analysis of the past consumption of the substations to predict the load repartition of area consumption forecast over the substations of this area. This project does not deal with the consumption forecast but only with the repartition of it. Methods are presented in this report; the first one, the two floors method, classifies the substations with respect to their active power consumption in order to ease the repartition. The great issue of this method is the load transfers: the load of one substation that is transiently transferred to another substation. The second one aims to adapt the reactive power of substations from the variation of the active power. The third method finds a historical network situation which is as close as possible from the one that must be estimated. A study case on one of the seven regions of France defined by RTE is presented. The conclusion of the study case is that the two floors method can be used to clean up the load transfers of a well-chosen reference situation. This gives the best consumption repartition. / I detta examensarbete presenteras metoder och resultat som erhållits i ett projekt utfört av Sylvain Kerouanton för den franska systemoperatören RTE. Syftet med projektet var att utveckla metoder för att skatta lasten i olika ställverk i högspänningsnätet. De metoder som utvecklats är baserade på analys av den historiska lasten i ställverken för att fördela ut den prognostiserade elförbrukningen i ett område över ställverken. Projektet har inte studerat förbrukningsprognoserna i sig, utan endast hur lasten fördelas inom ett område. Den första metoden som behandlas i rapporten är "two floors"-metoden, som för att underlätta fördelningen av lasten klassificerar ställverk utifrån deras aktiva effektförbrukning. Den andra metoden syftar till att anpassa den reaktiva effektförbrukningen i ställverken till variationerna i den aktiva effektförbrukningen. Den tredje metoden används för att söka en historisk nätsituation som ligger så nära som möjligt den situation som studeras. En fallstudie från en av RTE:s sju regioner i Frankrike presenteras. Slutsatsen från fallstudien är att "two floors"- metoden kan användas för att rensa bort lasttransfereringar i en väl vald referenssituation. Detta ger den bästa skattade fördelningen av lasten.

The Swedish parliament has passed a planning framework to increase wind power production and have the annual production of 30 TWh wind power in 2020. The expansion of a continuously varying generation would result in an increased need for the capability of power system to keep the balance between generation and consumption. Therefore, it is important to study the flexibility of Swedish power system. Two models of Swedish power system are studied in this thesis work. The first model is a model of Swedish hydro power system which has been developed at KTH. The KTH model is formulated as a large linear optimization problem simulated in GAMS platform. It has a detailed representation of large hydro power plants but presents a simple model of electricity market and trading to other areas. The other model is Apollo which is developed by Sweco Company. Apollo is also formulated as an optimization problem and is a market model which uses a simplified model of hydro power system. The objective of this thesis work is to exchange data between the two models in order to compare, validate and if possible improve the models. To exchange data, the inputs and some outputs of Apollo are used as the inputs of KTH model and finally the outputs of KTH model is compared with the corresponding outputs of Apollo. There are some differences between the two models that must be removed in order to exchange data. All of differences except one of them are removed by data adjustment. The different methods that are used to remove those differences are discussed in the report. Due to the remaining difference and different efficiencies in the two models, scenarios cannot be directly transformed from Apollo to the KTH model. Therefore, three methods are introduced as compensation for the remaining differences. After applying those methods the same results can be obtained in the two models. As a result of the work on the data exchange some improvements are implemented in the KTH model and some improvements are identified and proposed for future work. The improvements are toward removing all the differences between the two models and make the models more similar to the real Swedish hydro power system. It is also concluded from the results that the Apollo hydro power schedules are feasible according to KTH model of hydro power system. This shows that Apollo does not overestimate the flexibility of Swedish hydro power system in the tested scenarios. / Riksdagen har beslutat om ett planeringsmål för ökad vindkraftproduktion upp till 30 TWh vindkraft år 2020. En utbygnnad av kontinuerligt varierande produktion skulle medföra ett ökat behov för elsystemets förmåga att balansera produktion och konsumtion. Därför är det viktigt att studera flexibiliteten i det svenska elsystemet. Två modeller av det svenska elsystemet studeras i detta examensarbete. Den första modellen, som är utvecklad på KTH, är en modell av det svenska vattenkraftsystemet. KTH-modellen är formulerad som ett stort linjärt optimeringsproblem som simuleras i GAMS-plattformen. Modellen har en detaljerad representation av större vattenkraftverk, medan modellen av elmarknaden och handeln med andra områden är mycket förenklad. Den andra modellen heter Apollo och är utvecklad av konsultföretaget Sweco. Apollo är också formulerad som ett optimeringsproblem, och är en marknadsmodell som använder en förenklad modell av vattenkraftsystemet. Målsättningen med detta arbete är att utbyta data mellan de två modellerna för att jämföra, validera och om möjligt förbättra de två modellerna. För att utbyta data används indata och vissa utdata från Apollo som indata till KTH-modellen och slutligen jämförs utdata från KTH-modellen med motsvarande utdata från Apollo. Det finns en del skillnader mellan de två modellerna som måste hanteras för att datautbytet ska vara möjligt. Alla skillnader utom en hanteras genom att modifiera data. De olika metoder som används för att hantera dessa skillnader diskuteras i rapporten. På grund av den återstående skillnaden och olika verkningsgrader i de två modellerna så kan inte scenarier överföras direkt från Apollo till KTH-modellen. Därför föreslås tre metoder för att kompensera de återstående skillnaderna. Med hjälp av dessa metoder kan samma resultat erhållas från de två modellerna. Till följd av arbetet med datautbytet har några förbättringar av KTH-modellen implementerats och ytterligare förbättringar har identifierats och föreslagits som framtida arbete. Dessa förbättringar syftar till att ta bort skillnaderna mellan de två modellerna och att göra de modellerna mer lika det verkliga svenska vattenkraftsystemet. En slutsats från projektet är också att de produktionsplaner för vattenkraften som erhålls från Apollo är genomförbara enligt KTH:s modell av vattenkraften. Detta visar att Apollo i de testade scenarierna inte överskattar flexibiliteten i det svenska vattenkraftsystemet.

As the global energy demand is rising, issues of emissions and security of supply arise and become increasingly acute as more energy is being consumed. Schemes of emission reductions and energy efficiency improvements have been introduced to deal with these issues. The answer to part of these efficiency improvements lies within the electricity grid's development towards a so-called smart grid. One integral part of the smart grid is the demand response program which strives to change consumer consumption patterns to further increase grid efficiency. Demand response (DR) has been widely studied in terms of effects and design. Even though much research has been performed, there is still very little knowledge about the economic impact of implementation. This study focuses on uncovering the economic effects DR implementation may have on Distribution System Operators (DSOs) in Sweden. A model has been developed which estimates the possible positive economic effects following a DR implementation for a Swedish DSO. The model is generally applicable to most Swedish DSOs, and their counterparts in other European power markets with similar market design, since it uses universally available data. This is done by investigating the factors driving the DSO's business in terms of impact of DR and generality. Factors identified and used in the model are power losses, grid fee to feeding grid and postponed future investments. These factors were chosen for their economic impact, the rate of effect which DR has on them and on the ability to model them with generally available data. A model implementation is performed to show the possible results which the model can yield. Data from a Swedish DSO is used along with a fictional DR program designed for this purpose. The results show a potential for significant positive effects on DSO economy. An analysis is made on the maximum potential for DR. It is estimated that a reduction in power losses of 19% could be realized, this corresponds to 36% of the annual cost of losses for the DSO. For the grid fee to feeding grid, an estimation of a 46% reduction of the level of subscribed maximum power and 47% of its cost is realized; the subscribed maximum power is the only part of the grid fee to feeding grid affected by peak load shift. For postponed investments, a present value of 45,8 million SEK is realizable over a period of 40 years; this figure is uncertain because of model restraints and long time frames. The current regulation limits the benefits for the DSO however, as many of these costs are passed through to the customer. The customer is thus the current winner when DR is implemented by Swedish DSOs, leaving the DSO with little financial incentive. / Då världens energianvändning ökar framträder problem med utsläpp samt tillgång till energiresurser. Dessa problem ökar i omfattning då allt större mängd energi används. Olika planer för att minska utsläpp och öka energieffektiviteten har satts i verket av världens ledare för att hantera problemen. En del av svaret på en del av dessa energieffektiviseringar finns inom elnätens omställning mot smarta nät. En viktig del inom detta är Demand Response (DR) programmen vilka syftar till att ändra konsumenternas konsumtionsbeteende för att öka effektiviteten inom elnätet. Det existerar mycket forskning inom DR med avseende på dess effekter och design. Då mycket forskning genomförts finns det fortfarande väldigt lite information om den ekonomiska påverkan efter en implementering av DR. Den här studien syftar till att undersöka och belysa den ekonomiska påverkan som en DR implementering hos en svensk distributionsnätägare kan ha. En modell har tagits fram vilken uppskattar det möjliga positiva effekterna följande en DR implementering för en svensk distributionsnätägare. Modellen är generellt applicerbar för de flesta svenska distributionsnätägarna, samt dessas motsvarigheter på andra europeiska marknader med liknande marknadsdesign, då den använder sig av allmänt tillgänglig data. Modellen togs fram genom att undersöka de faktorer som driver distributionsnätägarens affärer med avseende på DR effekt och hur generella dessa faktorer var. De faktorer som identifierades och som utgör modellen är kraftförluster, kostnad mot överliggande nät samt uppskjutna framtida investeringar. Dessa faktorer valdes ut för deras ekonomiska påverkan, den grad DR har möjlighet att påverka varje faktor samt möjligheten att modellera dem med hjälp av allmänt tillgänglig data. En modellimplementering gjordes för att visa de resultat som modellen kan användas för att beräkna. Data från en svensk distributionsnätägare användes samt ett fabricerat DR program designat för detta syfte. Resultatet visar positiva resultat för distributionsnätägarens ekonomi. En analys är utförd över den maximala effekten av demand response för distributionsnätägaren. Det uppskattas att en sänkning av kraftförluster på 19% kan realiseras genom demand response, detta motsvarar 36% av kostnaden för dessa kraftförluster. För kostnaden mot överliggande nät uppskattas en reducering på 46% för nivån av den abonnerade effekten mot regionnätägaren samt 47% av dess kostnad; den abonnerade effekten mot regionnätägaren är den enda kostnaden mot överliggande nät som påverkas av peak load-förflyttning. För förskjutna investeringar beräknas att en besparing motsvarande ett nuvärde på 45,8 miljoner SEK kan realiseras över en period på 40 år; denna siffra har osäkerhet på grund av modellens begränsningar samt långa investeringstider.

As the formation of nearly abrupt p-n junctions in aggressively scaled transistors has become a complex task, a novel type of device in which there are no junctions has recently been suggested (J. P. Colinge et al., Nature 2010). The device of interest is referred to as the junctionless transistor, and it has demonstrated excellent functionality, with the advantage of a simpler fabrication process than conventional FETs. Despite the remarkable performances exhibited by the junctionless transistor, this device has to be tested against variability before it may be produced in large scale. Hence, the study of how the fluctuations in the number and in the position of the dopant atoms affects a large number of devices has been developed in this work. Such variability source is referred to as Random Dopant Fluctuations (RDF) and it is among the most critical ones for conventional MOSFETs. Our view is that RDF ought to largely affect the junctionless transistors. Hence, in this work we mainly aim at investigating the impact of RDF in these type of devices. Firstly, we provide a detailed analysis on the performance of an ideal junctionless transistor with a uniform non-random doping concentration, by mean of simulations developed using a TCAD software. Secondly, we investigate the effects of RDF in the junctionless transistor, as the principal aim of our study. Here, we determine how the I-V characteristics are affected by the random dopants and we illustrate fundamental the causes of the variations. A first estimation of the impact of RDF is provided by the illustration of the threshold voltage and beta [1] distributions, and by the computation of the fundamental statistical quantities relating to the two parameters. A further and last estimation is provided by the comparison obtained studying RDF on the inversion mode FET.

The rapid development of wind power technology is reshaping conventional power grids in many countries across the world. As the installed capacity of wind power increases, its impact on power grids is becoming more important. To ensure the reliable operation of a power system which is significantly fed by wind power, the dynamics of the power system must be understood, and the purpose of this study is to develop suitable analytical tools for analysing the dynamic impact of large-scale wind parks on the stability of a power grid, and to investigate the possibility of improving the stabilisation and damping of the grid by smart control strategies for wind turbines.Many of the newer, larger turbines now being produced are variable speed turbines, which use doubly fed induction generators (DFIGs). These are induction generators which have their stator and rotor independently excited. When unconventional generators of this type are used in a power system, the system behaves differently under abnormal dynamic events.  For example, new types of generators cause different modes of oscillation in the power system, not only because of their dynamic characteristics, but also because they load the system differently.Very large power oscillations can occur in a power system as a result of internal disturbances.  Ordinarily these oscillations are slow and, in principle, it is possible to damp them with the help of wind power.  This leads to the idea of using a power system stabiliser (PSS) for a DFIG.  In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods to optimally damp the oscillations.Voltage stability is another important aspect of the safe operation of a power system. It has been shown that the voltage stability of a power system is affected by induction generators.  The voltage stability must therefore be carefully analysed in order to guard against a power system collapse.By using modal analysis and dynamic simulations, we show that the presence of a wind farm in the vicinity of a power system will improve the angular behaviour of the power system under small disturbances, but may decrease voltage stability under larger disturbances. We compare the performance of wind turbines to that of conventional synchronous generator power plants, and we show that a wind park consisting of DFIGs, which are equipped with PSSs, may be used as a positive contribution to power system damping.

No description available.

Effektförstärkare för radiofrekvensapplikationer utgör fortfarande ett av de största problemen i trådlösa kommunikationssystem. Detta beror på att dessa förstärkare är ickelinjära, har låg energieffektivitet och ger mycket distortioner. Bättre verktyg för att förstå och korrigera dessa beteenden är nödvändiga. Ett sådant verktyg är beteendemodellering. En beteendemodell kan ses som en svart låda med insignal(er) och utsignal(er). In detta fall är dessa signaler samplade basbandssignaler och den svarta lådan är en matematisk relation mellan en insignal och en utsignal. Avhandlingen behandlar några krav för beteendemodellering av nämnda system genom att presentera metoder för utvärdering och förbättring av modellernas prestanda. Detta åstadkoms genom att betrakta ett frekvensviktat felkriterium. Ett högpresterande mätsystem är också nödvändigt för experimenten. Prestandan hos det tillgängliga systemet jämförs med prestandan hos ett allmänt erkänt mätsystem, en s.k. storsignalsnätverksanalysator, genom att betrakta prestandan hos beteendemodellerna som extraheras och valideras med data från respektive mätsystem. Resultatet visar att det existerande mätsystemet har god prestanda. Ett stort problem vid beteendemodellering är att kunna sampla med tillräckligt hög hastighet. Genom att använda Zhu-Franks generaliserade samplingsteorem vid beteendemodellering kan en del av detta problem undvikas. Teoremet medför att man kan sampla med en väsentligt lägre samlingsfrekvens än vad Nyquistteoremet säger. Modeller extraheras och prestandan utvärderas genom att använda kriteriet normalized mean square error (NMSE). För stabil prediktion och korrektion av utsignalen måste robustheten hos de använda modellerna verifieras. En sådan studie som berör robustheten mot variationer i lastimpedansen har genomförts. Prestandan på direkta modeller försämras med 7 dB mätt som adjacent channel error power ratio (ACEPR). Prestanda på inversmodellen, implementerad som digital predistortion, försämras med upp till 13 dB mätt som adjacent channel power ratio (ACPR). / Radio frequency (RF) power amplifiers (PA) are still the most troublesomepart of a wireless system due to their inherent nonlinearity, low powerefficiency and high distortions. Better tools are needed to understand and correct the undesirable behavior. Some of these tools are behavioral models. A behavioral model is often thought of as a black box with some inputs andsome outputs. In the case here these inputs are sampled signals which meansthat the modeling amounts to finding a mathematical relationship betweenthe input signal(s) and the output signal(s). This thesis considers some requirements for behavioral modeling of said systems by presenting methods for general performance evaluation and improvement by considering a frequency weighted error criterion. A high performance measurement system is also needed. The performance of the available system is compared to the performance of a well recognized system, the largesignal network analyzer (LSNA). The results show that the existing measurementsystem can extract behavioral models with the same performance as the LSNA and can give lower performance validation errors. Still the need for higher bandwidths drives the measurement systems to the limits, especially the digital parts. By utilizing the so called Zhu-Frank generalized sampling theorem, behavioral modeling of a PA is done by using data acquired at a sampling rate lower than the Nyquist rate. Models of a PA are extracted and the performance is evaluated using the normalized meansquare error (NMSE) criterion. For prediction and correction of the output signals the stability of the models regarding changes must be investigated. One such study considering controlled variations on the output load of the PA is done and both the predictive and corrective capabilities of the models are evaluated. The predictive capability gets up to 7 dB worse measured as adjacent channel error powerratio (ACEPR) and the corrective, as digital predistortion, gets up to 13 dB worse measured as adjacent channel power ratio (ACPR).

The rapid development of the global economics has made power systems allover the world become large-scale interconnected grids. This increases the capabilityof power grids to transfer power over the long distance to serve the desiredpower demand with the minimum cost of operation. Unfortunately, it alsoenables the propagation of local failures into global networks. In other words,if a blackout happens in a power system, the size and the damage may significantlyincrease. One of the main ways in which blackouts become widespread is cascadingfailures. This type of failure originates after a critical component of the systemhas been removed fromthe service by protective relaying. As a consequence, theload handled by the failed component needs to be redistributed which mightcause an overloading on other components in the system. On the other hand, the high power electronics controllable devices suchas Voltage Source Converters-based High Voltage Direct Current (VSC-HVDC)transmission are recently developed. These electronics devices have the potentialadvantages such as the ability to independently control active and reactivepower, and maintain voltage to be at acceptable level. Therefore, they are consideredto be the promising devices that with an appropriately designed controlstrategy, they can substantially improve the performance and reliability of thepower system. This thesis presents the possibility to consider protection system status inthe control of VSC-HVDC link. A great deal of this research is development ofcoordination between this power electronic device and protection system which normally are considered separately. The derivation of protection system has been selected to determine the operation of VSC-HVDC. The methodology isbased on utilizing the signal created from a logical evaluation of relay and simplificationsof certain parameters. By introducing information from the relays tothe VSC-HVDC link via Central Control Unit (CCU), the modulation of transmitted power is devised in order to reduce the risk of system-wide failures. In turn,this means an avoided blackout.Furthermore, this thesis also includes the preliminary suggestion to selectthe location of VSC-HVDC. The methodology is based on predicting voltage instabilityusing voltage stability indices and related parameterswhich are derivedby using Singular ValueDecomposition method. The solutions indicate an effectivelocation for applying corrective action such as load shedding. This optimallocation is selected to reinforce the control strategy of VSC-HVDC in order toprevent cascading failures in the more encompassing systems. / QC20100615

Given the potential benefits offered by wireless sensor networks(WSNs), they are becoming an appealing technology for process,manufacturing, and industrial control applications. In thisthesis, we propose a novel approach to WSN protocol design forcontrol applications. The protocols are designed to minimize theenergy consumption of the network, while meeting reliability andpacket delay requirements. The parameters of the protocol areselected by solving a constrained optimization problem, where theobjective is to minimize the energy consumption and theconstraints are the probability of successful packet reception andthe communication delay. The proposed design methodology allowsone to perform a systematic tradeoff between the controlrequirements of the application and the network energyconsumption. An important step in the design process is thedevelopment of analytical expressions of the performanceindicators. We apply the proposed approach to optimize the networkfor various communication protocols. In Paper A, we present an adaptive IEEE 802.15.4 for energyefficient, reliable, and low latency packet transmission. Thebackoff mechanisms and retry limits of the standard are adapted tothe estimated channel conditions. Numerical results show that theproposed protocol enhancement is efficient and ensures a longerlifetime of the network under different conditions. Furthermore,we investigate the robustness and sensitivity of the protocol topossible errors during the estimation process.   In Paper B, we investigate the design and optimization ofduty-cycled WSNs with preamble sampling over IEEE 802.15.4. Theanalytical expressions of performance indicators are developed andused to optimize the duty-cycle of the nodes to minimize energyconsumption while ensuring low latency and reliable packettransmissions. The optimization results in a significant reductionof the energy consumption compared to existing solutions. The cross-layer protocol called Breath is proposed in Paper C. Theprotocol is suitable for control applications by using theconstrained optimization framework proposed in the thesis. It isbased on randomized routing, CSMA/CA MAC, and duty-cycling. Theprotocol is implemented and experimentally evaluated on a testbed,and it is compared with a standard IEEE 802.15.4 solution. Breathexhibits a good distribution of the work load among the networknodes, and ensures a long network lifetime. / <p>Korr av felaktigt ISBN; 978-91-7415-441-5</p>

The solar wind interaction with the magnetosphere-ionosphere system continuously drives plasma convection in the polar regions of the ionosphere. The flow velocity and the shape of the convection pattern are closely dependent on the interplanetary conditions, in particular the direction of the interplanetary magnetic field (IMF). The main driver of the system is considered to be magnetic reconnection between the IMF and the terrestrial field, a process that is most efficient during southward IMF when the magnetic fields at the dayside magnetopause are anti-parallell, and less efficient but still present when the IMF is northward. Additional driving may be caused by waves at the magnetopause flanks, where viscous effects can lead to an energy, momentum and plasma exchange across the boundary. In this work, we make use of the characteristics of the ionospheric convection and particle precipitation to investigate the nature of the driving dynamos, and large statistical data sets for steady solar wind conditions are used to derive the general behavior of the driving processes and their dependence on interplanetary conditions. The results show that the primary dynamo responsible for the convection in the boundary layer is closely dependent on the sign of the IMF Bz component, the average potential over the boundary layer region increases from &lt;1 kV for steady southward IMF up to the order of 10kV for strictly northward conditions with reconnection poleward of the cusps, whereas the magnitude of magnetic field only has a minor influence at most. This could for example indicate that the magnetopause is more unstable to Kelvin-Helmholtz waves for parallel rather than anti-parallel magnetic fields, or that magnetic reconnection on the dayside suppresses other processes. It is well known that the ionospheric potential drop saturates during strong driving conditions and southward IMF. The results presented here also show that the same phenomenon occurs when the IMF is northward. This gives additional information on the physics governing the solar wind-magnetosphere-ionosphere interaction, and may impose new restrictions on the theories explaining the saturation.