Our thesis is made in collaboration with Autoliv Sweden and the department Global Development Seatbelt in Vårgårda. Autoliv was founded in 1953 by two brothers from Vårgårda. Since then, they have become world leading in automotive safety and cooperates with several major automotive companies.   The aim of the project was to evaluate a concept that Adrian Bud for Global Development Seatbelt department in Vårgårda had come up with. The concept aims to simplify the design and reduce the number of parts in an adaptive load limiter (LLA). With a reduction in the number of parts, the price for the LLA would decrease and also make assembly easier.   An LLA adjusts the chest compression from the seatbelt in a crash sequence. This helps reducing the injury that might result from such chest compressions in a crash. The load limiter ensures that the slowdown of the body is done in a smooth manner by adjusting the amount of belt released.   Our concept evaluation has included conceptual design, primary design, visualization of design in Catia V5 and FEM analysis. Finally prototypes were built with the help of Autolivs central workshop and tests were performed at Autoliv. The report also includes analyzes of the results, recommendations for the continuation of work and development and a critical review of the evaluation.

Due to the difficulty of reinforcement in power network and the interconnection of more distributed generators, fault current level has become a serious problem in transmission and distribution system operations. The utilization of fault current limiters (FCLs) in power system provides an effective way to suppress the fault currents. In this thesis the sensitivity of impedance matrix due to changes in the branch parameters is derived and used to choose the candidates for FCL installation in a complex power system. The proposed method also considers the effect on power system transient stability due to the installation of FCL. The Extended Equal Area Criterion (EEAC) is used to simplify the multi-machine transient stability problem to a simple equivalent modal and to simplify the transient stability evaluation. A fuzzy logic approach considering impedance of FCL, transient stability and voltage sag effects is used to choose good FCL installation locations in loop transmission systems.

Distributed generation (DG) is increasingly employed in modern utility grids to address the growing complexity and size of consumer energy demands. The obstacles associated with DG integration are related to the additive effect the DG has on the short circuit current characteristics of power systems during short circuit conditions. This thesis proposes a novel mitigation technique for synchronous machine based DG integration effects on existing radial fuse-recloser protection infrastructure. The mitigation method provides a comparative analysis of the utilization of resistive (R), inductive (L) and resonant (LC) type superconducting fault current limiters (FCLs) for prevention of excessive fault current contribution from DG sources. Within the frame of reference of this thesis is an interrogation into the effects of synchronous machine based DG sources, in conjunction with mitigation capabilities of FCL integration in the context of fuse-recloser coordination, recloser sensitivity and recloser directionality behavior during radial distribution short circuit conditions. For validation purposes, the proposed methods are demonstrated on a suburban test benchmark using the PSCAD/EMTDC program.

Shock capturing has been a challenge for computational fluid dynamicists over the years. This article deals with discontinuous Galerkin method to solve the hyperbolic equations in which solutions may develop discontinuities in finite time. The high order discontinuous Galerkin method combining the basis of finite volume and finite element methods has shown a lot of attractive features for a wide range of applications. Various techniques proposed in the literature to deal with discontinuities basically reduce the order of interpolation in the region around these discontinuities. The accuracy of the scheme therefore may be degraded in the vicinity of the shock. The proposed method resolves the discontinuities presented in the solution by applying viscosity into the shock-containing elements. The discontinuity is spread over a distance and is well approximated in the space of interpolation functions. The technique of adding viscosity to the system and the indicator based on the expansion coefficients of the solution are presented. A number of numerical examples in one and two dimensions is carried out to show the capability of the scheme for shock capturing. / Singapore-MIT Alliance (SMA)

This master thesis deals with designing of a recuperative converter system and auxiliary circuits that extend the life of the automotive battery by using supercapacitor as a source of power when starting a car using the start-stop function. The microcontroller is used to measure important circuit values and control the output current of the converter.

The gradual increase in global warming and environmental pollution has made low-carbon technologies an urgent need for the whole world. Superconducting technology, which is known for its extremely high conductivity and high power density, is capable enough to provide novel solutions, contributing to the future smart grid, thus aiding the power industry towards the realisation of a low-carbon and green planet. In recent decades, several industrial applications using superconducting technology have been developed. Of them, particularly in the power industry, a range of superconducting applications including superconducting magnetic energy storage (SMES), superconducting motors/generators, superconducting cables and superconducting fault current limiters (SFCLs) have been developed. Among them, SFCLs are one of the most promising and are successfully being implemented in power distribution networks. SFCLs exhibit low impedance during normal operation and gain considerable impedance under a fault condition, providing a new solution to the increasingly high fault current levels. However, most of the SFCL projects are limited to low-voltage and medium-voltage levels, there are very few successful operational trials of high voltage SFCLs. This thesis, for the first time, studies the comprehensive characteristics of solenoid type SFCLs based on second generation (2G) high temperature superconductors (HTS), which may be successfully implemented in power grids with high voltage levels. The main contributions of this work include three aspects: 1) proposing an innovative method for simulating the AC losses of the solenoid coils and an electro-magneto-thermal model for simulating the SFCL’s current limiting property; 2) comprehensive and in-depth comparison study concerning the application of the two types of non-inductive solenoid coils (braid type and non-intersecting type) in SFCLs both experimentally and numerically; and 3) the first and thorough discussion of the impact of different parameters such as pitch and radius of coils to the overall performance of braid type SFCLs and the validation of the braid type SFCL concept with a 220 V/300 A SFCL prototype. Based on these experimental and simulation works, the thesis provide strong guidance for the development of future non-inductive solenoid type SFCLs based on 2G HTS, which are promising for high voltage level power grid applications.

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