Numerical simulations play a vital role in both static and dynamic stability assessment of electric power systems and the foreseeing of voltage collapse. Simulations performed by Svenska Kraftnät(SvK) are mainly done in the specialized voltage collapse predicting software tool, SPICA and the more all?purpose software tool, ARISTO.The grid operators at SvK use SPICA to predict the maximum transfer limit at specified sections (in this report the section in concerns is the southern part of Sweden i.e. interface1 4). SPICA is mainly used as an online application by using actual states from the grid, these states update every quarter of an hour.This thesis is a continuation of the master thesis SPICA ? ARISTO JÄMFÖRELSE by Jakob Katzman and Johan Fält.

When drivers overnight in the truck lots of electric energy is consumed by heaters, fans, lights and other extra equipment. If the engine is not running, this energy is taken from the lead/acid batteries of the truck which then needs to be recharged during operating hours. The fact that the charge acceptance of the lead/acid batteries is dependent on the temperature makes it hard to fully recharge the batteries at lower temperatures. A negative charge balance can lead to starting problems within a few days use in cold climate.In this thesis work, the effects of different battery charging concept are evaluated on the most common Scania battery (175Ah). A battery model is implemented in Matlab and some simulations of charging are made.

A power system will inevitably be subjected to transient overvoltages, most often produced by switching operations and lightning strikes. These transient overvoltages may harm sensitive equipment without sufficient protection, but it is not an easy task to predict what transients may occur or how they affect the system. A fault occurred in a low voltage system at Forsmark 2012 and overvoltages from lightning were concluded as the probable cause. The three aims with this thesis are to develop and test a model of the power system at Forsmark 3, analyse the transient behaviour of the system when subjected to lightning surges and identify critical parameters, and lastly to provide a tool for investigating the protection of the system. The modelling and simulations were performed in the freely available simulation program LT Spice.

The purpose of this project is to analyze earthing systems for houses. By practical measurements and theoretical analyzes consequences of possible faults, that can occur within the facility and in the low-voltage distribution network, is illustrated.  The reason for this project is that nowadays one has to arrange with a main equipotential bonding system for buildings. Apart from that, if necessary, bathrooms must be provided with a supplementary equipotential bonding system.The practical measurements verify that potential differences in facilities may be due to voltage drops in the PEN conductor between the origin of the electrical installation and the power transformer.Based on the theoretical analyzes of possible faults, it is considered that the requirement for  supplementary equipotential bonding systems for bathrooms in most cases can be questioned, when basic insulation, fault protection, residual current devise and main equipotential bonding system already provides an adequate level of protection.A PEN conductor loss may result in a situation where metallic parts attached to the equipotential bonding system starts working as earth electrodes. Equipotential bonding system may also increase the incidence of stray currents. If TN-C-S systems is provided with a local connection to earth a redundant system against PEN conductor loss is obtained.

The technological legacy from the early electrification of the Swedish railroads has resulted in a power grid with a lower grid frequency than the national power grid from which it is fed. Energy transfer between these power grids with different frequencies requires substations, adapting the grid frequency for the rail road power grid. For this purpose, a feeding power grid has been built, stretching across the country from Boden in the north to Tälle/Häggvik in the south.Power transfer in the Swedish power grid results in voltage angle differences which increase with increasing loads and transfer distance. These voltage angle differences are transferred from the power feeding substations to the rail road power grid, will in some extent cause loss of energy due to unwanted power flows from north to south.To minimize the losses due to this phenomenon, a power management system called EFS 132 kV has been developed and implemented. The system minimizes the unwanted power flows and controls the desired power flow for a good distribution of loads between the power feeding substations.This thesis investigates the extent of the transmission losses avoided due to the EFS 132 kV that coordinates the idling angles to a common reference point.The results indicate that EFS 132 kV affects the power flow, especially between the northern substations through an improved load distribution.

One of ABB Power Systems´s business areas is HVDC (High Voltage Direct Current) technology. HVDC is used for transmissions for both short and long distances. One of Power Systems?s products is called HVDC Light. HVDC Light is a relatively new technology for power transmission, but have before only been used for motor drives applications.

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

The aims of the following project has beento make a proposition how to create aspecific kind of transformer. Thefollowing report evaluates the differentimportant variables and contains asuggestion for a possible design. Intheory it's an ordinary transformer that'ssuppose to transform electrical effect toa high voltage line. The design of thetransformer is using an already existingcurrent transformer design and is adjustedto work for it's specific purpose. Theproject also contains the developing of atransformer simulation model that will beused to evaluate and optimize thedimensions of the resulting transformer..

The aims of the following project has beento make a proposition how to create aspecific kind of transformer. Thefollowing report evaluates the differentimportant variables and contains asuggestion for a possible design. Intheory it's an ordinary transformer that'ssuppose to transform electrical effect toa high voltage line. The design of thetransformer is using an already existingcurrent transformer design and is adjustedto work for it's specific purpose. Theproject also contains the developing of atransformer simulation model that will beused to evaluate and optimize thedimensions of the resulting transformer..

A current conveyor is an active building block that can be used to implement most active and passive components. It differs from the operation amplifier in that it uses current instead of voltage. The current conveyor also has significantly higher voltage gain over a broader frequency range. To simplify the construction of analogue circuits and increase the construction efficiency it is desirable to use a top-down methodology. This means that the whole system is partitioned into a hierarchy of subsystems.

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

The escalating usage of pyrethroids has resulted in an increased awareness about resistance towards pyrethroids in insects. Pyrethroids inhibit voltage-sensitive sodium channels (VSSC) in nerve cell membranes and are composed of synthetic molecules based on pyrethrins present in pyrethrum extracts from Chrysanthemum species. VSSC are transmembrane proteins that are important for electric signalling over the membrane in insects. Mutations in the gene encoding the sodium channel have proved to be a common reason for resistance against pyrethroids. Pyrethroid resistance among pollen beetles is spread all over Sweden and also abroad and is increasing.

Detta arbete behandlar mätmetoder för detektering av partiella urladdningar (kallad PD från engelska benämningen Partial Disharge) i HVAC- och HVDC- högspänningskablar. HVAC står för ?High Voltage Alternative Current? och HVDC står för ?High Voltage Direct Current?. När en viss hög spänningsnivå överskrids i kabeln uppstår olika typer av partiella urladdningar och dessa skadar kabelns isoleringsmaterial. PD- intensiteten ökar med tiden och om de tillåts fortlöpa under en längre tid kan de med tiden helt bryta ned isoleringsmaterialet vilket leder till ett fel.

In this thesis a number of energy saving methods for a multiplier on algorithmic level are investigated. For the investigation a multiplier is constructed in VHDL, after which the circuit's performance is investigated. A number of techniques for reduced power consumption are introduced in the circuit and are then evaluated. The conclusions are that all investigated methods, pipelining, interleaving and voltage scaling, should be maximally made use of in order to minimize the power consumption..

Transmission of reactive power is well known to cause active power losses. Thus, newcomponents who can help minimizing these expensive reactive power flows are ofgreat interest to the power distribution companies. ABB Corporate Research hasdeveloped the first electronic power breaker. One possible application for thisbreaker is transient-free switching of capacitor banks. This could prove a usefuldistribution voltage complement to the switch-sync technique, mainly applied to transmissionvoltage level.