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Here, the impacts of biogas power plants and photovoltaic (PV) power plants on the power quality in the distribution network are presented and analysed. The biogas power plant's influence on the current harmonics is explored, as a synchronous generator powers the biogas power plant, and the PV plants are connected to the distribution network via the inverter. All the analyses are based on actual measurements that are performed in the last 10 years. Results of the analysis of these numerous measurements were a challenge for investigation how large share of PV systems in distribution network with non-linear loads influence on THD from one side and how biogas power plant with a synchronous generator can improve THD from the other side. In order to investigate interaction of the biomass power plant and PV power plants on the power quality in distribution network, computer model was developed in DIgSILENT Power Factory where PV power plant and household were modelled as a source of current harmonic injections and biomass power plant was modelled as synchronous machine, as a source of voltage harmonics. Analysis of harmonic behaviour in different scenarios is examined through the performed simulations.

This paper presents measurement uncertainty propagation through four basic photovoltaic cell models: One-diode model without resistances, with one resistance and with two resistances and two-diode model with two resistances. The expressions for the output current of all photovoltaic cell models is presented as a function of global irradiance G and temperature T. Next, the expressions for all fill factor parameters: short-circuit current, open-circuit voltage, current and voltage at the maximum power point, depending on the global irradiance G and temperature T are derived as well. For each parameter, Monte Carlo simulations to calculate the measurement uncertainty of the parameter are performed and the results were used as input values for the calculation of measurement uncertainty of fill factor. Practical calculations are performed in laboratory for renewable energy sources located on 45°32′ N and 18°44′ E. Final fill factor calculations are compared for three different module technologies.

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Abstract:Modern society has a growing need for the electricity. To protect the environment, future energy demand must be met with more environmentally friendly technologies, such as renewable energy sources. Because of its vast availability, solar radiation has been used for decades to generate electricity through photovoltaic systems (PV) for residential, educational, and commercial buildings. However, the growth of distributed generation (and renewable energy sources) across power systems in industrialized countries has created new challenges. Random renewable generation causes an imbalance between electricity production and consumption, so smart grids and microgrids may be solutions. In this article, we investigate improving the energy efficiency in the Faculty of Electrical Engineering building in Osijek by using a microgrid. To do so, we compared the total electricity consumption of the building and the production of a 10 kWp photovoltaic power plant on that building. The improvement in energy efficiency of the building produced a maximum savings of up to 10% of the building's total electricity consumption.Keywords: distributed generation; renewable energy sources; energy efficiency; microgrid; PV power plant POBOLJŠANJE ENERGETSKE UČINKOVITOSTI U ZGRADARSTVU POMOĆU MIKROMREŽA Sažetak: Moderno društvo ima sve veću potrebu za električnom energijom. Kako bi se zaštitio okoliš, buduća potražnja će morati biti pokrivena s više ekološki prihvatljivih tehnologija, poput obnovljivih izvora energije. Zbog svoje visoke dostupnosti, Sunčevo zračenje se već desetljećima koristi za proizvodnju električne energije putem fotonaponskih sustava (PV) na stambenim, obrazovnim ili poslovnim zgradama. Prodor distribuirane proizvodnje (i obnovljivih izvora energije) u elektroenergetske sustave industrijaliziranih zemalja stvara nove izazove. Nestalna proizvodnja obnovljivih izvora električne energije stvara neravnotežu između proizvodnje i potrošnje, a kao moguće rješenje općenito je prihvaćen koncept napredne mreže i mikromreže. Ovaj članak istražuje mogućnosti povećanja energetske učinkovitosti pomoću mikromreže u zgradi Elektrotehničkog fakulteta Osijek. Uspoređuje se ukupna potrošnja električne energije u zgradi Fakulteta s proizvodnjom od 10 kWp fotonaponske elektrane ETFOS 1, koja se nalazi na krovu iste zgrade. Usporedba navedenih rezultata pokazala je poboljšanje energetske učinkovitosti zgrade u obliku maksimalne uštede, koja doseže i do 10 % ukupne potrošnje.