3. Doktoritööd
Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7081
Sirvi
Sirvi 3. Doktoritööd Autor "Allik, Alo" järgi
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Kirje Design of Distributed Energetics Solution Based on the Increasing of Direct Consumption of Electricity Generated from Wind and Solar Energy(Eesti Maaülikool, 2016) Allik, Alo; Annuk, Andres; Karapidakis, Emmanuel S. (opponent)This doctoral thesis presents six original papers, which are used to demonstrate the design possibilities for increasing the local renewable energy consumption of buildings equipped with renewable energy production devices. The findings and visualisations can be used for educational purposes as well as for the practical engineering of building based energy systems. The findings from papers can be used to decrease the necessary grid connection capacity of buildings. It was found in the thesis that nominal or high power consumption and production occurs only for a very small fraction of the time. This is evident from the output power data of large wind parks as well as small wind turbines. On the basis of that it was proposed in the thesis that the inverter size of small wind turbines can be reduced significantly, when the pre-inverter energy is utilized for heating purposes. High resolution and quality data is necessary for some the optimization processes. It was found that the data from wind turbine nacelle anemometers is biased by the rotor and therefore empirical correction factors were found during the studies. High resolution measurements enable to apply demand side management in the near future. The demand side management can decrease the standard deviation of the consumption curve which increases the locally consumed renewable energy and decreases the energy exchange with the electrical grid. The application of energy storage and the combination of different energy sources like wind- and solar energy has similar effects. In cases when the self-sufficiency is low, like in buildings with high energy demand (for example in industries), and the supply and demand coincide then there is no need for demand side management. The increase of fR can vary to a big extent dependant on the applied method and the case. The best case showed an increase of up to 36% in the renewable fraction.Kirje Novel application principles for energy storage technologies in nearly zero energy buildings(Eesti Maaülikool, 2021) Lill, Heiki; Allik, Alo; Annuk, Andres; Colak, Ilhami (opponent); Hamburg, Arvi (opponent)In this thesis the renewable energy storage options in residential buildings are under investigation. This is to store cheap electricity due to the temporary overproduction of large wind farms and also on-site solar and wind farms. In an electric system, there should be a balance at all times between energy production and consumption: as much as is produced should also be consumed. Deviating significantly from this balance can damage electrical equipment or cause serious network failures and even blackouts. Unfortunately, both solar and wind energy generation possibilities are associated with (rapid) changes in production. The simplest examples are wind gusts for wind turbines and intermittent cloud cover for solar panels where the electric output power changes in seconds. In order to smooth out the rapid changes in electricity production, the work proposes the possibility to add ultracapacitors to the battery bank for temporary energy storage, which would act as a buffer and are able to temporarily store the produced electricity. So far, the sale of green energy to the electricity grid has been supported at the state level. However, this paper examines the next step in how to support the storage capacity of the produced energy in order to increase self-consumption. To this, a state subsidy measure for battery banks is proposed. Due to short-term overproduction of electricity, there are more and more situations where electricity is sold at zero or even negative prices on the power exchange. The reason is simple - it is more practical for producers to temporarily pay to consumers for electricity consumption than to stop production for a while. This work also proposes a method for storing energy in heat carriers under favorable conditions for the consumer in order to ensure a balance between the production and consumption of the electricity network.