3. Doktoritööd
Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7081
Sirvi
Sirvi 3. Doktoritööd Autor "Annuk, Andres" järgi
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Kirje Compatibility of Energy Consumption with the Capacity of Wind Generators(Eesti Maaülikool, 2011) Põder, Vahur; Annuk, AndresTaastuvenergia osatahtsus Eestis peab erinevate arengukavade alusel kasvama. Erinevatest taastuvenergia liikidest on koige kiiremini kasvanud tuule osatahtsus ja toodetud energia hulk. Tuulegeneraatorite valjundvoimsus voib tuule stohhastilise iseloomu tottu kiirelt muutuda, aga energiasusteemis peab tootmine ja tarbimine tasakaalus olema. Uheks voimaluseks tagada elektrisusteemi stabiilsus on tuulegeneraatorite toodangu piiramine, mida saab teha energiasusteemi dispetšer. See juhtimismeetod vahendab tuulepargi toodangut ja seega maksimaalvoimsuse kasutustegurit. Uks voimalus on kasutada liigset elektrit soojuse tootmiseks. Autonoomsed tuuleenergiasusteemid voivad leida kasutust ilma elektrivorgu uhenduseta asukohtades. Selline susteem koosneb tuulegeneraatorist ja salvestusseadmest. Samuti voib olla lisatud mingisugune taiendav energiaallikas (PV paneel, diiselgeneraator). Tuuleandmete analuus on vajalik generaatori toodangu hindamiseks. Mingi ajaperioodi hetke- ja keskmisi tuulekiiruseid saab kasutada potentsiaalse tuuleenergia hulga hindamiseks. Selle too eesmargiks oli efektiivse tuuleenergiasusteemi kirjeldamine. See tahendab tuuleenergiasusteemi maksimaalselt korge voimsuse kasutusteguriga ja kindla energiaga varustatusega. Elektrivorguga uhendatud susteemi korral tuleb arvestada elektrisusteemi tootmis- ja tarbimisvoimsuste tasakaaluga. Autonoomse energiasusteemi korral tuleb arvestada pusiva energiavarustuse tagamiseks vajaliku salvestusseadme mojuga. Too eesmargi saavutamiseks olid ette nahtud jargmised tegevused: 1. Uurida energiasusteemi tootmis- ja tarbimisgraafi kuid (II); 2. Analuusida erinevat tuupi tuulegeneraatorite tunnusjooni (III) ja arvutada tuule mooteandmete alusel uhikgeneraatori aastane energiatoodang (I); 3. Analuusida tuule mooteandmeid, leidmaks energiatoodanguta perioode (”energiaauke”) ja otsida meetod nende kirjeldamiseks (I, IV); 4. Analuusida tuulegeneraatori, salvestusseadme ja tarbija vahelisi seoseid energiavarustuse tookindluse leidmiseks ja voimalusi neid suhteliste uhikutega kirjeldada (I, III, IV). Too kaigus koguti vaikese voimsusega tuulegeneraatorite andmeid ja analuusiti nende tunnusjooni. Koostati teise astme polunoom generaatori tunnusjoone kirjeldamiseks. Hangiti ning moodeti 6 Eesti asukoha tuulekiiruse mooteandmed ja arvutati aastane keskmine toodang, kasutades eespool koostatud vaikese voimsusega tuulegeneraatori tunnusjoont. Tuuleandmete ja eeldatava generaatori voimsuse alusel on voimalik arvutada aastane energiatoodang, aga see ei kirjelda energiavarustuse tagatust. Voivad esineda suhteliselt pikad tuuleta ajaperioodid. Voeti kasutusele energiaaukude moiste, et kirjeldada tuuleenergia toodanguta ajaperioode. Salvestusseade peab olema voimeline tagama tarbija toite maksimaalse energiaaugu pikkuse ajal. Selleks leiti energiaaukude pikkused tuule mooteandmete alusel. Eri asukohtades paiknevate autonoomsete tuuleenergia susteemide energiatoodangut ja tarbimist modelleeriti erinevate tarbimistegurite β korral. Tulemused ja jareldused: 1. Maksimaalne tuuleenergia toodang on piiratud elektrisusteemi voimega genereeritud tuuleelektrit kasutada. Osa toodetud elektrienergiast voiks kasutada soojuse tootmiseks. 2. Vaikese voimsusega tuulegeneraatorite (voimsus < 100 kW ja kaivitumine tuulekiirusel < 2.5 m/s) tunnusjooned on vastavalt kovera kujule peale maksimumvoimsuse saavutamist voimalik jagada 2 gruppi. Kuna tuulekiirused ule 13 m/s on Eesti sisemaal haruldased, on voimalik tunnusjoone tousuosa modelleerida 2-astme polunoomiga. 3. Energiaaugud on ajaperioodid ilma tuuleenergia toodanguta. Energiaaukude ajaline kestvus on suurem sisemaal ning luhemate aukude esinemissagedus on suurem. Energiaaukude esinemise toenaosust on voimalik kirjeldada Weibulli jaotusega. 4. Autonoomse tuuleenergiasusteemi salvestusseadme vajalik mahtuvus soltub pigem tarbimistegurist kui keskmisest tuulekiirusest.Kirje Computer-aided Optimization of Pig Farming Technologies and Machinery Use(Eesti Maaülikool, 2007) Vettik, Raivo; Möller, Heino; Annuk, AndresVäitekirja kirjanduse analüüsi osas on kirjeldatud seakasvatustehnoloogiaid, seakasvatusega kaasnevaid keskonnakaitse nõudeid, “parimat võimalikku tehnikat” (PVT) seakasvatuses ning on esitatud ülevaade seakasvatuses kasutavatest arvutiprogrammidest maailmas ja Eestis. Samuti on kirjeldatud sea- ja teraviljakasvatuse modelleerimise võimalusi. Töö eesmärgiks oli välja töötada meetodid erinevaid seakasvatustehnoloogiaid iseloomustavatele parameetritele optimaalsete väärtuste leidmiseks sea- ja teraviljakasvatusega tegelevas ettevõttes. Eesmärgist lähtuvalt koostati metoodikad ja vastavad arvutiprogrammi rakendused: 1) tööajakulude määramiseks erinevate seakasvatustehnoloogiate korral; 2) nii söödakultuuride kasvatamiseks kui ka toodetava sõnniku realiseerimiseks vajaliku haritava maa pindala määramiseks; 3) seakohtade arvu leidmiseks sõltuvalt tööpäeva kestusest tööde kõrgperioodil, arvestades sõnniku kasutamise piirangut. Uurimistöö uudsus seisnes metoodika ja vastava arvutiprogrammi rakenduse loomises, mille abil on võimalik leida ja sea- ja teraviljakasvatusega tegeleva ettevõtte optimaalne suurus teravilja erinevate saagikustasemete ja sigade pidamistehnoloogiate korral, sõltuvalt tööpäeva kestusest tööde tippkoormuse perioodil, arvestades ühtlasi sõnniku kasutamise piirangut Eestis kehtivatest keskkonnakaitse nõuetest lähtudes. Koostatud söödaratsioonide koostise ja söödavajaduse määramise metoodika on kasutusel Eestimaa Talupidajate Keskliidu nõuande- ja infosüsteemi “TALUTARK” komplekses seakasvatusprogrammis. See võimaldab leida sigade söödavajadusi võimalikult täpselt rahuldavad ja samas odavaimad söödaratsioonid, samuti söödavajaduse päevas, erinevatel nuumanädalatel ja aastas. Söödavajaduse prognoosimise metoodika võimaldab leida madalamate saagikuste korral seakasvatuses puudujääva ja kõrgemate saagikuste korral seakasvatusest ülejääva söödakoguse. Söödaratsioonide koostise määramise arvutiprogrammi rakenduse testimisel selgus, et söödaratsioonide koostis oli sarnane söödalisandeid pakkuvate firmade (Anu Ait, Feedline, Vitamex jne) söötmissoovitustes esitatud koostisele. Seda muidugi juhul kui söödaratsioonides kasutatakse vastavate firmade söödalisandeid. Sigade talitustööde ajakulu prognoosimisel regressioonivõrrandiga leitud tööajakulud on sarnaste tehnoloogiavariantide korral võrreldavad Eestis kogutud talitustööde ajakulu andmetega (Reppo ja Sada, 2000; Sada, 2003). Koostatud inimtöö vajaduse prognoosimismetoodika on rakendatud Eestimaa Talupidajate Keskliidu nõuande- ja infosüsteemi “TALUTARK” komplekses seakasvatusprogrammis. Autori poolt on koostatud metoodika ja vastav arvutiprogrammi rakendus MS Exceli keskkonnas, mille abil on võimalik leida teravilja- ja seakasvatusega tegeleva ettevõtte optimaalne suurus sõltuvalt tööpäeva kestusest tööde kõrgperioodil, arvestades ühtlasi sõnniku kasutamise piirangut. Arvutusi on võimalik teostada sigade erinevate pidamistehnoloogiate ja teravilja erinevate saagikustasemete korral. Arvutustulemustest selgus, et ühe töötajaga sea- ja teraviljakasvatusega tegelev ettevõte, kus toodetakse ka sigade põhisöödad, ei suuda masinaparki, mis baseerub 60 kW-sele traktorile, piisavalt koormata. Masinapargi paremaks koormamiseks peaks olema mitu töötajat. Mitme töötajaga ettevõtte töötajate tööaja taime- ja seakasvatuse vahel jaotumise võimalusi on palju. Mitme töötaja korral on võimalik ettevõtte masinapark piisavalt koormata, nt vahetustega töö kasutamisega jms. Arvutustulemustest selgus, et sigade söödakultuuride kasvupinna 50%-lise osakaalu korral külvikorras, piiras seakohtade arvu ettevõttes iga vaadeldud tootmisvariandi korral söödanappus. Suurendades söödakultuuride kasvupinna osakaalu kolmveerandini haritava maa pindalast, piiras saagi kuste 2000…3000 kg/ha korral seakohtade arvu samuti söödanappus. Saagikuse 3500…4500 kg/ha korral muutus seakohtade arvu piiravaks teguriks ettevõttes toodetav sõnniku kogus. Sea- ja teraviljakasvatusega tegeleva ettevõtte tootmisnäitajate prognoosimise metoodika võimaldab arvestada teraviljade külviperioodi kestuse, st ka masinapargi töökoormuse, mõju tootmistulemustele. Kasutades majandusnäitajate prognoosimiseks loodud metoodikat selgus, et sõltuvalt teravilja (teravilja hind 1,7 kr/kg) ja sealiha realiseerimishinna vahekorrast võib teravilja- ja seakasvatusega tegeleva ettevõtte kasum olla suurem (sealiha realiseerimishind 26 kr/kg, ostupõrsa hind 600 kr) või ka väiksem (sealiha realiseerimishind 21 kr/kg, ostupõrsa hind 400 kr) ainult teravilja kasvatamisega tegeleva ettevõtte kasumist. Mudeli testimisel OÜ Linnamäe Peekon tootmisandmetega selgus, et enamike vaadeldud tootmisnäitajate korral jäi erinevus mudeliga prognoositud ja tegelike tootmisnäitajate vahel 10% piiresse.�.�.�.�.�.�.�.�.�.�.�.�.� Suur erinevus (94%) oli mudeliga prognoositud vajaliku teravilja kasvupinna ja ettevõtte tegeliku haritava maa pindala vahel. See on seletatav sellega, et oma põldudel kasvatatav teravili moodustab ainult 23% sigadele söödaks vajalikust teraviljast ja ülejäänud 77% ostetakse juurde.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 Multiple stage storage strategy for the increasing of renewable fraction of the consumer(Estonian University of Life Sciences, 2024) Hovi, Mart; Annuk, Andres; Karapidakis, Emmanuel; Institute of Forestry and Engineering; Galinš, Ainars (opponent); Hamburg, Arvi (opponent); Gevorkov, Levon (opponent)ABSTRACT. In this work, various solutions for storing renewable assets were studied. By renewable resources, the author understands sources that are based on natural resources that are constantly renewable and can be used in unlimited quantities without harming the environment or depleting resources. In a narrower sense, they are treated as sources of energy. The work focused on multistage storing in cases where receipts and consumption are of the same order of magnitude. The aim was to raise the share of the property used on the spot in relation to what was given away and received from other sources. To summarize: • The combination of different renewable storage devices increases the likelihood that the share of on-site consumption of the collected energy or other assets can be significantly increased. • When storing renewables, it is important that the system preserver is always ready to receive the flow of tops of the production schedule. For example, its increase in the considered model up to 6 kW·h leads to an increase in the self-consumption factor by 5%. • Priority is given to the supply of non-displaced customers, which will be covered by the battery in the event of an energy deficit. The lack of a battery leads to a self-consumption factor below the value of 32%. • When storing stored property, it is necessary to maintain it. For example, in the case of rainwater, its regular relocation between storage tanks should be carried out, during which additional filtration will also take place. An analogy of energy storage devices to this would be conversion, but also inevitable self-discharge. The transport, storage and use of non-renewables of an incidental nature is more complex and costly than the use of non-renewable energy sources and other assets. However, this is compensated by local use, taking into account the values of the environment and the community. The use of a pre-storage device in series with a liquid storage allows different values of the session peak cutting factor to significantly increase the self-consumption of renewable energy.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.Kirje Possibilities for balancing wind generators´output power(Eesti Maaülikool, 2012) Toom, Kaupo; Annuk, AndresThe importance of renewable energy is growing. More and more wind parks, CHP-s and biogas stations are being erected and connected to the electrical grid. Of the range of different renewable resources, the proportion and growth of wind generated electricity is the highest. Due to the stochastic nature of wind, the output of wind generators changes quickly, but the production and consumption in the energy system must be in balance. The actual production from wind generators and the forecasted energy are usually different and this energy must be obtained somewhere else, which means extra expense. Wind generator output power is harder to forecast than for example heat power plant output. Errors in forecasting should be minimized. The aim of the research was to fi nd ways to balance wind generators’ output power. Wind generators with greater power must forecast their production and send information to TSO. To reduce errors on forecasting, wind generators production chart peaks could be cut. To balance small wind generators, PV panels and batteries could be added to systems. List of the tasks to be solved to achieve the aim were: 1. Overview of wind data analysis methods (I, II). 2. Analysis of different wind parks’ data, to fi nd ways to correct forecast errors (I, II). 3. Analysis of ways to balance power curves, using wind-solar hybrid systems (III, IV). Data from Pakri and Aulepa wind park was collected and analysed from different angles. At the beginning of the research the data series were shorter. Then methodology and hypotheses were developed, which were also confi rmed on long data series. Forecast errors were calculated and the results compared with wind parks in Estonia, Germany and Denmark. Single wind park results are comparable with Estonian wind parks total. Wind data was also collected form Tiirikoja (EMHI), solar irradiation data was collected from Tõravere (EMHI) and annual electricity consumption data from an Estonian typical countryside dwelling (E. Jõgi). Data have been used in a system, where a wind generator, PV panel and battery are 54 added. Different parts of the system and their sizes, also their production, are explored and analysed, so that the system would be optimal to the unit consumer. Results and conclusions: 1. The forecast error is estimated by three methods: Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE) and Mean Percentage Error (MPE). 2. The biggest forecast errors could be observed when the wind park output power was in the range of 0.5–0.8. The higher the wind park output power, the lower is MAPE, and vice versa. The forecast error increases as the wind park output power increases. the forecast error decreases as the production chart peaks are cut off. MAPE and MPE do not change signifi cantly. 3. Nowadays PV-wind hybrid systems are used in two ways: autonomous and grid connected. It is important for a gridconnected system to minimize energy from the grid and to have the highest share of renewable fraction possible, while having an optimal confi guration and not using other fuels. It is important, since by doing so energy dependence is decreased and therefore energy security is increased. When batteries are added to the grid-connected wind-PV system, the renewable fraction is the highest at the standard deviation is δ = 0.25 ± 0.05 kW of the consumption curve. If the value is higher or lower, the renewable fraction decreases. Therefore the consumption curve should not be too fl at.Kirje Solar and wind energy seasonal heat storage systems for residential buildings in Nordic climate(Eesti Maaülikool, 2020) Kalder, Janar; Annuk, Andres; Kokin, Eugen; Galinš, Ainars (opponent)In this doctoral thesis are handled possibilities, how to increase renewable energy on-site usage, which is produced from wind and sun. In the Nordic climate, the main share of energy consumption in buildings is the need for heating, being ~ 80% in Estonia. To increase the share of renewable energy for heating buildings, the energy storage systems are needed, because this renewable energy is fluctuating. The doctoral thesis is based on a four scientific publications, the first of which examines the behaviour of a system without storing devices, changing the ratio of wind and solar energy production, if the heat pump is used for heating. In this case, if ratio of wind and solar energy is 70% and 30%, the annual coverage of electricity supply can be up to 37.5%. The second publication presents the results of using the hot water boilers as energy storage in different wind conditions. In a good wind conditions, the share of renewable energy can be 68%. In the third and fourth publications, the results of using the vacuum insulated tank in the house heating system are presented. In this tank, the heat energy can be stored for a long time. Producing the heat energy with the solar collectors in summertime and storing it in the vacuum insulated tank, allows cover 41% of the heat energy demand from the renewable sources. Integrating the vacuum insulated tank in to the renewable energy system, where the electricity is produced from sun and wind, the annual share of renewable energy is 79%. In this case, the additional heating devices are not needed, because amount of the electricity from the grid is comparable small.