Generatori za pretvaranje energije vetra u električnu energiju

This paper presents the characteristes of an electrical generators which are being used for conversion of wind energy to electrical energy. There has been performed analysis of the work of induction generators whith the squirrel-cage rotor, as well as analysis of synchronous generator and double-fed induction generator in the systems where electric energy is generated from wind energy, upon which is concluded what kind of generators is optimal for specific cases.U radu su date karakteristike električnih generatora koji se koriste u vetroelektranama, za pretvaranje energije vetra u električnu energiju. Izvršena je analiza rada asinhronih generatora sa kaveznim rotorom, sinhronih generatora i asinhronih generatora sa dvostranim napajanjem u uslovima koji se imaju prilikom rada u vetrogeneratorskim postrojenjima i izvedeni zaključci u pogledu izbora optimalne vrste generatora za konkretne uslove

Energetski potencijal sunca u srbiji i primena energije sunca u poljoprivredi

On the basis of meteorological data, as well as on the performed additional measurements, in the paper is estimated the solar energy potential of Serbia. This paper represents a part of author’s activities in the course of work on the scientific research project: Atlas of the energy potential of Sun and wind in Serbia. Serbia has economic and ecological problems which are caused by the import of energy (oil, gas) which becomes more and more expensive and also pollutes air, water and soil. Serbia is well irradiated by Sun and because of that Serbia is bound to meet their energy needs in future by using solar energy more. In this paper is also analyzed the application of Sun energy in various fields of agriculture.Na osnovu meteoroloških podataka, kao i izvršenih dopunskih mnogobrojnih merenja, u radu je procenjen energetski potencijal Sunca u Srbiji. Rad je deo aktivnosti autora tokom izrade naučno-istraživačkog projekta Atlas energetskog potencijala Sunca i vetra u Srbiji. Već duži niz godina Srbija ima ekonomske i ekološke probleme zbog uvoza energije (nafta, gas), koja je sve skuplja i ugrožava vazduh, vodu i zemljište. Rezerve uglja u Srbiji, koji je prilično lošeg kvaliteta, procenjene su na još 50-ak godina. U radu je pokazano da je Srbija dobro osunčana zemlja i moraće svoje energetske potrebe u budućnosti sve više da zadovoljava Sunčevom energijom. Takođe, u radu je analizirana i primena energije Sunca u različitim oblastima poljoprivrede

Aktivna i reaktivna snaga asinhronog generatora sa dvostranim napajanjem

This paper presents the characteristics of active and reactive power of a double-fed asynchronous generator. Mathematical model are defined applying a theory of space vectors. Expressions for active and reactive power on stator and rotor are derived and obtained main characteristics are processed. A power flow analysis for speed less and great then synchronous is performed. According to the obtained characteristics it is pointed out that a double-fed asynchronous generator may be used in wind power plants, where electric power is generated from wind energy.U radu su date karakteristike aktivne i reaktivne snage asinhronog generatora sa dvostranim napajanjem. Definisan je matematički model primenom teorije prostornih vektora. Izvedeni su izrazi za aktivnu i reaktivnu snagu statora i rotora. Na osnovu njih nacrtane su karakteristike u funkciji klizanja za konstantne vrednosti ugla opterećenja, kao i u funkciji ugla opterećenja, za konstantno klizanje. Izvršena je analiza tokova snaga za brzine manje i veće od sinhrone. Na osnovu toga, ukazano je na mogućnost korišćenja asinhronog generatora sa dvostranim napajanjem u vetroelektranama

Stanje i perspektive obnovljivih izvora energije u Srbiji

This paper presents a review of the current technologies of renewable sources of the energy and the prospects for their future development. In this paper are analyzed the development of the renewable sources of energy in and their influence on the development of the improved concept of the electric power system with distributed sources of electrical energy. The state and prospects of the future development of renewable energy in Serbia are presented in detail. While doing this study, the fascinating development of these sources of energy in Europe and worldwide was taken into account.U radu je prikazan pregled aktuelnih tehnologija obnovljivih izvora energije i perspektiva za njihov dalji razvoj. Analiziran je razvoj obnovljivih izvora energije u elektroenergetici i njihov uticaj na razvoj unapređenog koncepta elektroenergetskog sistema sa distribuiranim izvorima električne energije. U radu je detaljno prikazano stanje i perspektive razvoja obnovljivih izvora energije u Srbiji imajući u vidu fascinantan razvoj ovih izvora energije u Evropi i svetu

Карактеристика момента асинхроног gенератора са двостраним напајањем pимењеног у ветроелектранама

Doubly-fed asynchronous generator expresses an especial regime of work asynchronous generator with winding rotor. This generator can works in oversynchronous and subsynchronous situation. Stator and rotor windings are connected to the same electrical grid. However, the rotor winding is fed through a semiconductor converter which can vary the electrical frequency and voltage. Doubly-fed asynchronous generator is a most useful in wind power plants. In this work we are analysed electromechanical torque of doubly-fed asynchronous generator, related with the maximum efficiency.Асинхрони генератор са двостраним напајањем представља специјални режим рада асинхроне машине са намотаним ротором. Може да ради са брзинама мањим или већим од синхроне брзине (брзине обртног магнетног поља). Намотаји статора и ротора се везују на исту мрежу, статор директно, а ротор преко полупроводничких претварача напона и учестаности. Због особине да може радити са различитим брзинама обртања, представља веома повољно решење за примену у ветроелектранама, за конверзију енергије ветра у електричну енергију. У раду је анализиран електромагнетни момент асинхроног генератора са двостраним напајањем, јер се утицајем на ову значајну величину може остварити режим рада са максималним искоришћењем ветротурбине

Laboratorijsko postrojenje za prečišćavanje i magnetnu obradu otpadnih voda

In this paper we present the description of laboratory installation for filtration and magnetic treatment of oiled waste water, whose integral parts are the magnets for magnetic treatment of water, and attached is equipment for electrical power supply, magnetic measurement, control and protection of overheating Addition to basic application of this installation is that it can be used for testing and monitoring of the effects of magnetic treated water which is used in different fields of industry, agriculture, medicine, etc.U radu je dat prikaz laboratorijskog postrojenja za prečišćavanje i magnetnu obradu zauljenih otpadnih voda. Sastavni deo postrojenja su i magneti za magnetnu obradu vode sa pratećom opremom za električno napajanje, magnetna merenja, regulaciju i zaštitu od preteranog zagrevanja. Pored osnovne namene postrojenje može da se koristi i za ispitivanje efekata magnetne obrade vode za primenu u različitim oblastima industrije, poljoprivrede, medicine i dr

Hidraulički sistemi prenosa snage u poljoprivrednoj tehnici

Current development of agriculture is being determined with research and implementation of new technologies and modern technical appliances which will be able to provide quality and economically approved application for all technological operations all mentioned, with the least possible consumption of energy and human resource and engagement, as well as to achieve environment preservation, and provide healthy working conditions. One of the most important matters, from the aspect of usage and market value of agricultural machinery and the others working machines, is the choice of propulsion. Mechanical power transmission does not satisfy newly established conditions for changes in output parameters, or these solutions are becoming too complex and expansive. Therefore, power transmission in agricultural technics is often based on hydraulic transmission systems. In this work will be presented new solutions for hydrostatical and hydrodynamical power transmission, and applycability analysses of connection between electric motor and internal combustion engine with turbojoints and turbotransmiters.Današnji razvoj poljoprivrede karakteriše osvajanje i primena novih tehnologija i savremenih tehničkih sredstava koja će obezbediti kvalitetno i ekonomski opravdano obavljanje predviđenih tehnoloških operacija, uz što manji utrošak energije, ljudskog rada i vremena, očuvanje okoline i obezbeđenje humanih uslova za rukovaoce. Izbor vrste pogona poljoprivrednih mašina predstavlja značajno pitanje koje utiče na upotrebnu i tržišnu vrednost mašina. Mehanički prenosnici snage ne zadovoljavaju sve strožije zahteve za promenom izlaznih parametara ili ova rešenja postaju komplikovana i skupa. Zbog toga se savremeni razvoj prenosa snage u poljoprivrednoj tehnici sve više bazira na hidrauličkom prenosu snage. U radu će biti prikazane varijante hidrostatičkog i hidrodinamičkog prenosa snage i analiza pogodnosti povezivanja elektromotora i motora SUS sa turbospojnicama i turbomenjačima

Vetroenergetski potencijal u našoj zemlji i primena vetroenergije u poljoprivredi

Today, wind energetics is a modern, technically and technologically highly developed industry, with the biggest trend of development in the last decade (about 32%). In the entire today’s production of electric energy in the world, wind energy accounts for about 0.6%. However, judging by world trends, this percentage should reach a fantastic 20% in the next several decades. In this paper we analyze the availability of wind energy in Serbia and Montenegro. It is shown in this paper that the potential of wind energy in our country is about 20 TWh/year (~10 GW) whose activation would greatly enlarge already installed capacities, increase the diversity of types of energy sources and reduce the dependance on the importation of raw energy sources. In this way, wind generators could be used very successfully in agriculture.Vetroenergetika danas predstavlja modernu, tehnički i tehnološki visokorazvijenu industriju sa najvećim trendom razvoja u poslednjoj deceniji (oko 32%). U ukupnoj proizvodnji električne energije u svetu energija vetra danas učestvuje sa oko 0,6%. Međutim, sudeći po svetskim trendovima ovaj procenat bi u narednih nekoliko decenija trebao da dostigne i fantastičnih 20%. U radu je analizirana raspoloživa energija vetra u Srbiji i Crnoj Gori i pokazano je da je vetar energetski resurs naše zemlje čiji potencijal iznosi oko 20 TWh/godini (~10 GW) i čijim aktiviranjem bi se značajno povećali instalisani kapaciteti i raznovrsnost energetskih resursa, smanjila zavisnost od uvoza sve skupljih energetskih sirovina (nafta, gas) i omogućila intenzivnija primena vetroenergije u poljoprivredi

Merenje vlažnosti zemljišta

Because the humidity of soil is one of the essential factors that determine the optimal plant growth and crop production, this paper discusses in detail various techniques, methods and modes of the measurement of soil humidity. Devices, sensors and additional equipment for the measurement of humidity are analyzed depending on the different types of the agricultural crops and characteristics of the soil. In this paper is given a review and a comparative analysis of sensors as the parts of the various products which measure a soil humidity (analog and digital). The selection of the most suitable location for sensors, their installation, placement and necessary depth is also presented. In this paper are analyzed the characteristics of sensors (performances, cost-effectiveness in the agricultural production), their maintenance and the timely detection of failures while in operation.Sadržaj vlage u zemljištu je jedan od značajnih faktora koji utiče na optimalan rast biljaka i proizvodnju useva. U radu su prikazane različite tehnike i načini merenja vlažnosti zemljišta. Analizirani su uređaji, senzori i dodatna oprema za merenje vlažnosti zemljišta u zavisnosti od vrsta poljoprivrednih kultura i karakteristika pojedinih zemljišta. Dat je pregled i uporedna analiza senzora različitih proizvođača za merenje vlažnosti zemljišta (analogni i digitalni), analiziran je izbor najpogodnijeg mesta za postavljanje senzora, instalacija i potrebna dubina senzora u zemljištu. Takođe, razmatrane su karakteristike senzora (performanse, način rada, isplativost u poljoprivrednoj proizvodnji), njihovo održavanje i detekcija kvarova tokom rada

Praktičan primer povećanja energetske efikasnosti malih pumpnih stanica reprojektovanjem

The suction station "Gnjilan", belonging to the "Water-supply" Pirot municipal enterprise, has been used as an example of small pump stations energy efficiency increasing by replacement of existing old pumps with new ones. It has been shown that it was possible to identify the pipeline characteristic and an optimum system operating point, even in the absence of appropriate flow measuring devices. This has been done using an indirect method of flow estimation by measurement of driving induction motor elecrtical parameters. In accordance with the obtained results, the new pump has been chosen. Huge savings in the electrical energy consumption referred to actual situation will be achieved through the application of the new pump.Na primeru Crpne stanice "Gnjilan" u okviru JP "Vodovod" Pirot, prikazan je način za povećanje energetske efikasnosti malih pumpnih stanica zamenom postojećih pumpnih agregata novim. Pokazano je da je, čak i u situaciji kada ne postoje odgovarajući uređaji za merenje protoka, moguće identifikovati karakteristiku cevovoda i optimalnu radnu tačku sistema primenom indirektne metode merenja električnih veličina pogonskog motora. U skladu sa identifikovanim parametrima, izvršen je izbor novog pumpnog agregata čijom primenom se mogu ostvariti znatne uštede u odnosu na postojeće stanje sistema