Safe operation of a large synchronous power system as Nordel is not an easy task. There are several aspects to take into consideration. This thesis focuses on the problems due to voltage collapses in a transmission system. The ability to foresee an upcoming collapse is vital to maintain stable operation of the grid. The grid operator at Svenska Kraftnät (SvK) uses the computer program SPICA to predict the maximum transfer limit at specified transfer sections. SPICA uses actual states from the grid to predict the transfer limitation, and a quarter later a renewed estimate is produced and so on. This means that the operator can se his transfer limits vary every fifteen minutes. Our task in this project is to validate the accuracy of the limitations obtained by SPICA. The validation process was carried out as a comparison with another power system analyser, ARISTO. The latter program simulates transient stability as a function of time, and is a versatile tool in many aspects. Another objective of this project is to develop the two programs as we discover disparity. Our investigations carried out in the CIGRÉ Nordic 32 test system show that, the method of repeatedly updated load flows can in some extent be used to predict the limit of stable operation, in a transfer limiting point of view. Repeatedly investigations show that the prediction seems to be more accurate, the closer the actual point of operation, is to the physical transfer limit. Further investigations with ARISTO as a guide, we discovered that this behaviour depended on the way to express the reactance in the generator model, which in case of a net failure causes SPICA to produce a value some few percent too high. During the process we also discovered a couple of improvements of the software involved, which were immediately implemented by the system administrator. The continuous upgrades have led to an iterative process of the analysis. The project also involved production of a tool for converting network-databases between ARISTO-SPICA, This has been made by ordinary staff at SvK by our requirements.

The ongoing environmental debate emphasizes the need for reducing CO2 emissions in order to counteract rapid climate change. The transportation industry is growing and is already today a signicant contributor to green house gas emissions. Information and Communication Technology (ICT) can be utilized to create intelligent transportation systems which have proven to be able to reduce fuel consumption signicantly. The concept of vehicle platooning involves vehicles traveling in a longitudinal convoy with a short intermediate distance. By introducing ICT to a vehicle platoon the intermediate distance can be even shorter without compromising trac safety. The shorter distance also allows for reduced drag, thus reduced fuel consumption. A research group from KTH Royal Institute of Technology and Scania CV AB competed successfully with an autonomous platooning system in the Grand Cooperative Driving Challenge in 2011. In 2012 the cooperation continued and a new platooning system including lateral maneuvers, i.e. lane changing, was implemented. This master thesis presents the design and implementation of a new hardware and software architecture for the platooning system. For exibility and control prototyping issues a new real-time platform supporting the system was tested. The choice was to evaluate and test the xPC Target TM system developed by MathWorks. The xPC Target platform supports real-time code generation from Simulink Rand also provides an extensive I/O library needed for communication with external physical systems. In order to adapt to the xPC Target platform and lateral platooning scenarios a new system architectural framework was suggested. The architecture emphasized the need for separated components each with clearly delimited tasks. Another important requirement was to provide a system with a short learning curve for new master students that will work with the system in the future. A new system architecture approach was presented and implemented in two real-time computer systems. The rst computer executed a real-time software created in C++ which primarily handled wireless transmission. The second unit utilized a real-time software created in Simulink Rand executed on the xPC Target platform. Successful vehicle platooning experiments, including lateral maneuvers, were performed with the new system in November 2012.

In diesel engines throttle valves are used for various purposes. One of these is to control the amount of air which is let into the cylinders. A precise amount of air is needed for optimal combustion, and for that reason a throttle is used to regulate air intake. As technology has advanced, it has become more common to control these throttles with electrical actuators as opposed to pneumatic ones as electric actuators are faster and more accurate. In this thesis, two methods to position control a brush-less direct current motor are proposed. One consists of a linear quadratic controller which is evaluated with simulations and one consists of a single PI-controller which is evaluated both with simulations and with experiments. The motor is controlled with three pulse width modulated signals generated with six transistors mounted on half-bridges. It is shown that good control performance can be achieved with both controllers.

A signicant growth was witnessed in the led of Wireless Sensor Networks (WSNs), the previous decade. Advances in hardware miniaturization coupled with increased processing capabilities and memory capacity have extended the application domains of WSNs. In light of this, standardization organizations led by academia and industries initiated activities for the design of protocols such as IEEE 802.15.4 and IETF RPL (Routing Protocol for Low power and Lossy Networks). IEEE 802.15.4 denes physical and media access layers for WSNs while IETF RPL denes the functionality of the routing layer. This thesis investigates research issues in wireless sensor networks and network controlled systems that control micro-biological processes for water treatment plants. By choosing a process model that can relate to an industrial process, feasibility of control over IEEE 802.15.4 and RPL protocols is evaluated for stability with regards to network delay and packet loss. Settling time and overshoot are measured to indicate control performance. Control messages related to routing and routing table lengths are measured to indicate network stability and scalability. The system model used is a centralized discrete controller controlling a thermal processes running on the sensors. This model is chosen for representing wide industrial networked control systems while adding a WSN dimension based on IEEE 802.15.4 and RPL. The main contribution of this thesis is an experimental study where both the network and controller performance is validated while utilizing commercial o-theshelf sensor platforms. The results from this experimental work include rst the use of established theorems for analyzing control using WSNs. Moreover, the ability of IEEE 802.15.4 and RPL to provide stable communication that is reliable enough for actual industrial control implementation is validated.

Road freight transport is a growing business and serves as a centerpiece of modern economics. Traffic congestions due to the increasing amount of vehicles, growing environmental problems due to CO2 emissions and rising fuel prizes create a vast demand for solutions to these global issues. Look ahead cruise control and vehicle platooning can be part of a future transport concept. By using GPS localization and considering road topography data (map data), a Look Ahead Cruise Controller LAC optimizes the velocity profile of a single vehicle when facing steep up- or downhills in order to save fuel. Platooning describes the concept of driving vehicles in a convoy with short intermediate distance to reduce the aerodynamic drag and achieve considerable fuel consumption reductions for all vehicles in the platoon. However, research on platooning with road topography preview information is a novel topic. In this thesis, look ahead cruise control and platooning are analyzed and results are combined in order to develop a platoon look ahead controller (PLAC). The PLAC features low computational complexity due to a simple parametric optimization method and reaches simulated energy consumption reductions of up to 20% for a vehicle in the platoon compared to its single drive on the same road. When velocity limits are considered, the fuel saving potential is even higher. It can be shown that the reached energy consumption with a PLAC lies slightly (1.3%-1.9%) over a minimum energy consumption needed to traverse the road section. Results reveal that in practical situations, a platoon should be maintained whenever possible. Errors in parameters of the vehicle, road parameters and localization errors are analyzed in terms of their influence on the energy consumption. Strategies are presented to reduce the influence of parameter errors on the fuel consumption and especially reduce the chance of a separate of the platoon.

In the north of Sweden, there are some wealthy mines that have being actively explored. To transport the metals from the mines to its destination there are being used Heavy Duty Vehicles (HDV). This setup has two main restrictions: the HDVs must travel 4 minutes apart; and due to the roughness of the terrain there are some areas where only one vehicle can go through at a time. The project was developed in the Smart Mobility Lab (SML), in KTH, Stockholm. It was created a test platform that simulates the behavior of HDVs in scaled trucks. The scaled trucks are controlled with PID controllers to follow paths in a road network that was also created during this project and also keep a formation with a fixed distance between vehicles. To track the position of the trucks it was used a motion capture system. Basically, it was created a system that allows to test several features of platooning and at the same time apply traffic control with virtual traffic lights. On top of the system it was applied an instantaneous fuel consumption model that makes possible a fuel consumption analysis. Several scenarios were designed in order to showcase some features of the system and at the same time analyze its benefits. In the end of the thesis it was possible to see the benefits of using traffic control in the situation described. Also a big contribution of the thesis was the construction of the testbed that has been proven to be an effective showcase tool of platooning techniques and simple traffic control. The application developed was created in a generic way in order to serve as a base resource of knowledge for future works.

With the rapid growth of usage of mobile devices and their applications and the ever increasing use of these technologies, optimizing the performance of cellular networks becomes inevitable. Considering the fact that mobile devices are carried by humans, we can conclude that the performance of cellular networks depends on the characteristics of human mobility. Therefore, understanding the basic characteristics of human mobility and designing realistic models based on this understanding can help in optimizing the performance of cellular networks in terms of managing node or base station capacity, handling handoffs, paging, location updating, etc. In this work, we review the most important human mobility characteristics that are extracted from real human mobility traces. We then propose asynthetic model that can produce human traces; we verify the model to examine if it cancapture all the introduced characteristics. The model is designed as a graph in which nodes represent the visit-points and edges are considered as the roads between these visit-points. We focus on keeping the structure of the model close to reality following hierarchical traffic systems. The model is implemented in a simulator to be validated. The results show that our model does not capture all the characteristics as expected. To be precise, the model does not create truncated power-law flight lengths or truncated power-law radius of gyration. Our experiments, verifying our assumptions, show that the algorithms used for defining the area that the user can move within, and also choosing the next destinations, result in a sharing-area among users: the sharing-area is the common set of visit-points that all users usually choose to visit. The existence of this sharing-area is the reason that the results are not as expected. We suggest that for future work, it is interesting to improve the model by changing the way of the user-area selection and the next destination selection with consideration of distance together with visit-point weight.

In the chain of electrical energy, the proper operation of transmission networks is essential forguaranteeing the reliability of energy supply to consumers. However, for economical andphysical reasons, transmissions network cannot have an infinite capacity. Therefore operatingconstraints such as voltage stability and line overloads can lead to congestions by preventingthe transmission system operator from transferring electricity according to the market desire.To avoid outages due to congestions, congestion management methods have been developedby transmission system operators. In France, congestions are managed by the transmissionsystem operator (RTE: Réseau de Transport d'Electricité) through a balancing mechanism. Itaims at adjusting the production of some specific power plants. This regulation has a cost.This cost paid by RTE is important since it has an impact on the rate charged for using thepublic transmission and distribution network. However the congestion cost is hardlypredictable since it depends on the availability of load, generation and transmission devices.In this master thesis, historical data will be analyzed to study the geographical structure andthe causes of congestion in French transmission network. Moreover, a method to forecast thecongestion costs will be described. First dynamic simulations are run to find the constraintsissued by voltage stability. Then scenarios are created by a Monte-Carlo simulator to knowthe probability of occurrences of situations with constraints. Finally, the amount of regulatedproduction activated to solve congestion issues must be valued to derive a cost. The pricingissues are tackled by focusing on the marginal balancing price and the prices of the offerssubmitted to the balancing mechanism. The method is used to forecast the congestion costs atseveral horizons of time. The results are analyzed and some other utilization of this methodare discussed.

Thanks to growing environmental concerns, renewable energies take a higher andhigher share of electricity generating portfolios. In Germany particularly, the installedcapacity of wind and solar plants has increased continuously for the past ten years. Given theprinciple of the merit-order dispatch, a greater use of wind and solar power allows theelectricity spot prices to drop significantly. However, wind and sun are both intermittentresources, and this leaves great room for uncertainties on prices. As a consequence, pricesbecome much more dependent on the weather conditions and show greater volatilities,making hedging much more difficult. At the same time, the mechanism of market coupling inthe Central West Europe (France, Germany, Benelux) goes toward a harmonization of prices.As such, the cross-border interconnections play a decisive role in the electricity pricing.This paper deals with the actual influence of the interconnections between France andGermany on electricity spot prices when renewable energies are added to the energy mix. Amodel of a French-German market is made in order to see the impact of an increasingpenetration of renewable energies on spot prices. The wind and solar generations aremodelled using artificial neural networks, ANN. Multiple linear regression is employed tomodel the French and German loads. The cross-border interconnections are modelled basedon the capacity allocations published by RTE (the national French grid operator) and finallythe French and German prices are modelled with a GARCH process to study the volatilities.The study is made for three different scenarios: the reference scenario, with a penetration ofrenewable energies as seen in 2012, a 2020 scenario, with a penetration of renewable energiesas predicted in 2012, and a 2020 scenario with increased interconnection capacities betweenFrance and Germany.Running the models shows that a higher penetration of renewable energies lowers spotprices in average, but introduces price spikes that did not exist beforehand. On short periodsof observation, the volatility seems to decrease, but on longer periods, the spikes increase thevolatility. Also, increasing the interconnection capacities does make the prices converge, butto a certain extent only.Finding fitting hedging strategies becomes more delicate when prices vary with suchuncertainty. The study could be more developed (by extending it to the whole Europeancontinent) in order to get a more accurate vision of how energy markets will look like in a fewyears. However, it must be understood that the future scenarios depend on many variablefactors, and no mathematical model is able to capture all those factors accurately.

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