Power quality analysis and techno-economic modeling for microgrids

The work done in this thesis considers microgrids from two different aspects. Power quality and techno-economics of microgrids. Detailed power quality measurements have been made at a single house hydrogen-solar microgrid that consists of state-of-the-art energy efficiency technology, energy production and energy storage. The microgrid can both connect to the grid and operate in islanded operation. The power quality is quantified from these measurements where several power quality parameters during islanded operation go beyond the limits set by standards such as EN 50160 and IEEE 519-2014. The effect on connected equipment from both frequency variations and voltage quality is also discussed. Four new performance indexes are presented in the thesis that are based on apparent impedances. The first with the name PHIPI quantifies how much the harmonic voltage magnitude changes with an increase in harmonic current magnitude on the same phase. The second with the name SHIPI quantifies how much the harmonic voltage magnitude changes with an increase in harmonic current magnitude on another phase. The third with the name AHSI uses the harmonic voltage and current magnitudes of all phases to create a single performance parameter expressed as an apparent impedance for the system. The fourth with the name ARMSSI quantifies the phase RMS voltage drop for a certain phase RMS current rise in terms of an apparent impedance. The thesis also shows techno-economic modeling with times series energy flow to study the investment risks related to consumption changes in a standalone microgrid. The results show that consumption changes are an important parameter when designing a standalone microgrid and that the risk can be mitigated with changes to the system design, but at a larger system cost. The projected cost reduction until the year 2050 for standalone hydrogen based microgrids and some risk aspects with hydrogen based microgrids are also discussed in the thesis.