Three-phase voltage source inverters are increasingly employed in power systems and industrial applications. Various pulse width modulation strategies have been applied to control the voltage source inverters. This dissertation presents a hybrid 2D-3D space vector modulation algorithm for three-phase voltage source inverters with both three-wire and four-wire topologies. The voltage magnitude and phase angle of the inverters fundamental output phase voltage are precisely controlled under either balanced or unbalanced load conditions, and hence, the space vector algorithm offers synchronization controllability over generation control in distributed generation systems. The numerical efficiency and simplicity of the proposed algorithm are validated through conducting MATLAB/Simulink simulations and hardware experiments. Mathematical description and harmonic analyses of output phase voltages of three-phase voltage source inverter which employs a hybrid 2D-3D SVM are presented in this dissertation. Explicit time domain representation of the harmonic components in addition to the total harmonic distortion of the output phase voltages are given in terms of system and switching parameters. The dissertation also investigates the harmonic characteristics and low total harmonic distortion performance against the linearity of modulation region which helps in the harmonic performance and design studies of such inverters employing the hybrid 2D-3D SVM. Experimental results are used to validate these analyses. In addition, the performance and the harmonic contents of the inverter output phase voltage when applying the proposed hybrid 2D-3D SVM are compared to that obtained from conventional 2D SVM and 3D SVM. As a result, the proposed new algorithm shows advantages in terms of low total harmonic distortion and reduced harmonic contents in both three-wire and four-wire systems.

This project is aimed at developing a model for an off-grid microgrid by studying the wind and solar resource at Östergarnsholm, an island to the east of Gotland, Sweden. For the required consumption, a study and analysis of Herrvik’s local demand has been made which is a village close to the island and the possibility for implementing the microgrid to supply electricity to the inhabitants of Herrvik has been examined. Renewable resource is paired with batteries for mitigating intermittency and using a generator running on biofuel is proposed during hours with no wind and sun.The data for wind and solar resource is obtained from Department of Earth Sciences, Uppsala University and household load is estimated for a typical detached Swedish house from a study funded by International Energy Agency. Microgrid is modelled and simulated in MATLAB and the simulation results show that the proposed microgrid can provide 100% availability for local load. Results also show that not only the inhabitants of the village can have their independent electricity supply for the whole year, but the excess electricity can also be used to desalinate the seawater at Herrvik’s desalination plant for around 90% of the time during the year.