Provider: - Institution: - Data provided by Europeana Collections- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain ...Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering, Computer Science and Information Technology Osijek. Department of Communications. Chair of ...Radiocommunications and Telecommunications. - Data provided by Europeana Collections- Bežiˇcne senzorske mreže, BSM (engl. Wireless Sensor Networks; WSN) predstavljaju strukturu
sadržanu od senzorskih cˇvorova raspored¯enih u promatranom prostoru. Ova disertacija stavlja u
prvi plan posebnu vrstu bežiˇcnih senzorskih mreža koja uz osjetni (senzorski) element ukljuˇcuje i
aktorski (djelatni) element. Ove vrste BSM-a nazivaju se još i bežiˇcne senzorske i aktorske mreže,
BSAM (engl. Wireless Sensor and Actor Networks, WSAN). Razvojem BSAM pojavljuju se nove
primjene i aplikacije gdje postoje´ci modeli koordinacije nisu odgovaraju´ci. Primjer primjene je
okruženje gdje aktorski cˇvor u mreži šalje upit odred¯enog sadržaja prema centru obrade izvan
same BSAM i oˇcekuje odgovor na postavljeni upit. Zbog mogu´cih industrijskih primjena ovog
modela zahtjevi koji se postavljaju na mrežu ukljuˇcuju visoku pouzdanost, malo kašnjenje i veliku
zalihost mreže, što nije mogu´ce ostvariti koriste´ci postoje´ce modele koordinacije u BSAM.
Ovi zahtjevi se mogu svesti pod pojmom podrške kvaliteti usluge (engl. Quality of Service, QoS)
u BSAM. U okviru ove disertacije predložen je novi hibridni model koordinacije u BSAM koji
omogu´cuje visoku pouzdanost komunikacije i zalihost mreže te toleranciju na kvarove. Kako bi
se smanjio problem dijeljenog medija i stvaranja zagušenja na strani krajnjeg odredišta u mreži,
u ovoj disertaciji predložen je protokol komunikacije med¯uslojnim pristupom, tj. poprecˇnim dizajnom
slojeva (engl. cross-layer approach), koji koristi višekanalnu arhitekturu i višeodredišnu
topologiju, s ciljem poboljšanja kvalitete usluge u BSAM: H-CLMC. Implementacijom predloženog
protokola smanjuje se utjecaj dijeljenog medija korištenjem višekanalne arhitekture. Konaˇcni
rezultat je smanjenju vremena odziva te pove´canjem vjerojatnosti uspješnog upita u BSAM, što rezultira
poboljšanjem kvalitete usluge. Predloženi H-CLMC protokol vrednovan je metodom simulacije
i eksperimentom u laboratorijskim uvjetima, te je prikazana prednost predloženog protokola
u usporedbi s postoje´cim rješenjima iz literature (ACS i CONTROL). Naposljetku, za predloženi
protokol komunikacije predložena je metoda procjene kvalitete usluge u velikim BSAM, postupkom
skaliranja mreže iz laboratorijskih uvjeta. Predložena je metoda procjene kvalitete usluge
temeljena na empirijskom modelu kumulativnog broja upita u mreži, u jedinici vremena (CQPS) i
vjerojatnosti uspješnog upita. Predložen je model vjerojatnosti uspješnog upita za razliˇcite brojeve
krajnjih odredišta u mreži, te model vremena odziva. Naposljetku, opisane su prednosti i nedostatci
predložene metode te su predložene smjernice za budu´ce istraživanje.- Wireless Sensor Networks (WSNs) are networks formed by sensor nodes deployed within the
area of interest. With the development of microelectronics and embedded systems, WSNs are becoming
more advanced and their sensor nodes are becoming smaller and more efficient. There is
a special type of WSNs that integrates sensing and acting components. These networks are called
Wireless Sensor Networks and Actor Networks (WSANs). They have the ability to respond to a
specific action obtained by a sensor. An application example is a communication model focused
on a request initiated by an actor node where the actor node sends a query to the data processing
center outside WSAN and awaits the response. Due to a possible industrial application of this model,
the demands that are placed on the network are high reliability and redundancy of the network,
which cannot be achieved by using the existing coordination models. This problem can be defined
as Quality of Service (QoS) provisioning in WSANs. This thesis proposes a new hybrid coordination
model for WSANs. The model allows high data reliability, network redundancy and fault
tolerance. To avoid shared media issues and congestion at the network sink, the thesis proposes
a cross layer algorithm and communication protocol named Hybrid - Cross Layer Multi Channel
protocol (H-CLMC). The protocol uses a multisink topology and multichannel architecture with
the goal of Quality of Service (QoS) enhancement in WSANs. By using multichannel architecture
and multisink topology, the proposed algorithm reduces the impact of shared media using redundant
multi-channel architecture. H-CLMC reduces round-trip-time and increases the probability
of a successful query in WSANs. The protocol is evaluated by simulation and experimental validation,
and the advantages of the protocol are shown in comparison to the existing solutions from the
literature (CONTROL and ACS). Finally, a method for estimating QoS in large WSANs and the
suggested H-CLMC is proposed by scaling networks from laboratory conditions to large networks.
The proposed method is based on an empirical model of Cumulative Queries per Second (CQPS)
metric and the probability of a successful query. An empirical model for the probability of successful
queries estimation and round trip time estimation is proposed. Finally, the advantages and
disadvantages of the proposed method are presented and the guidelines for future work are given- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering, Computer Science and Information Technology Osijek. Department of Power Engineering. Chair of ...Power Systems and Substations. - Data provided by Europeana Collections- U ovoj disertaciji predstavljen je novi, poboljšani model za planiranje niskonaponskih
distribucijskih mreža. Model koristi hijerarhijske i stohastičke metode optimizacije, kao i
suvremene programe za crtanje i proračune tokova snaga. Iz skupine hijerarhijskih metoda u
modelu su korištene metoda neizrazitog grupiranja i analitički hijerarhijski postupak. Uporaba
ovih metoda daje najbolje prostorno rješenje niskonaponske distribucijske mreže. Iz skupine
stohastičkih metoda u modelu je korištena metoda simuliranog kaljenja. Uporaba ove metode
daje optimalno uklopno stanje najboljeg prostornog rješenja. Za crtanje prostornih rješenja
distribucijske mreže u modelu je korišten AutoCAD, dok je za proračune tokova snaga korišten
Matlab–Matpower. U prvom dijelu disertacije dane su kratke teorijske postavke o
distribucijskim mrežama, te matematička interpretacija procesa optimizacije i korištenih
optimizacijskih metoda. U drugom dijelu je prezentiran novi, poboljšani model planiranja,
rezultati primjene modela za određeno zemljopisno područje, odnosno skupinu potrošača, kao
i usporedba rezultata sa postojećom distribucijskom mrežom. Iz rezultati dobivenih primjenom
predloženog modela može se uočiti da se dobiva niz prostornih rješenja, pri čemu projektant
odabire najprihvatljivije. Također, model daje mogućnost dobivanja optimalnog uklopnog
stanja odabranog prostornog rješenja. Usporedni rezultati dobiveni primjenom modela i
postojeće distribucijske mreže pokazuju znatna poboljšanja parametara mreže. To je praktična
potvrda opravdanosti primjene predloženog modela planiranja. Njegova primjena naročito
dolazi do izražaja u neplanski građenim distribucijskim sustavima gdje se zbog velikog broja
sličnih mreža, sa izraženim problemima u eksploataciji, njihovim rješavanjem mogu postići
značajne financijske uštede. Mogućnost uporabe modela za detektiranje problema u postojećim
mrežama i provjeru predloženih rješenja predstavlja dodatnu prednost. Jedna od prednosti
modela je i mogućnost uporabe i drugih optimizacijskih metoda koje su prihvatljivije za druge
projektante, ovisno o njihovim programerskim sposobnostima, ali uz primjenu istih koraka u
implementiranoj proceduri. U disertaciji je obrađen primjer niskonaponske distribucijske
mreže, ali model se uspješno može koristiti i za projektiranje distribucijskih mreža srednjeg
napona, što dodatno proširuje opseg njegove primjenjivosti. Obzirom na jednostavnost
procedure koju je potrebno provesti iskusnim inženjerima i planerima distribucijskih mreža
model može poslužiti kao vrlo koristan alat i ima svoje mjesto u praktičnoj primjeni.- A new, improved model for planning of low–voltage distribution networks is presented in this
dissertation. The model uses hierarchical and stochastic optimization methods, as well as
modern programs for drawing and load flow calculations. From the group of hierarchical
methods, fuzzy clustering method and analytic hierarchy process are used in the model. Usage
of these methods gives the best spatial solution of low–voltage distribution network. From the
group of stochastic methods, simulated annealing method is used in the model. Usage of this
method gives the optimal switching condition of the best spatial solution. For drawing the
spatial solutions of distribution network AutoCAD is used in the model, while for load flow
calculations Matlab–Matpower is used. In the first part of the dissertation a short theoretical
assumptions about distribution networks are given, as well as mathematical interpretation of
optimization process and used optimization methods. In the second part, a new, improved
planning model, the results of model application to the specific geographical area or group of
customers, as well as the comparison of results with the existing distribution network are
presented. From the results obtained by the usage of proposed model it can be seen that a series
of spatial solutions is obtained, and the designer can select the most appropriate. Also, the model
provides the possibility of obtaining the optimal switching condition of selected spatial solution.
Comparable results obtained by model implementation and existing distribution network show
significant improvement of network parameters. That is a practical confirmation of a
justification for the proposed planning model application. Its application is particularly evident
in unplanned built distribution systems, where there is a large number of similar networks, with
distinct problems in exploitation, so their resolution can give a significant financial savings.
The ability of the model to detect problems in the existing networks and verification of proposed
solutions is an additional advantage. One of the advantages of the model is the ability for usage
the other optimization methods as well, that are more acceptable for other designers, depending
on their programming skills, but the same steps in the implemented procedure have to be used.
In the dissertation is presented an example of low–voltage distribution network, but the model
can be successfully used for designing the medium–voltage distribution networks, which
further expands its scope of applicability. Considering the simplicity of the procedure that is
necessary to be conducted for experienced engineers and planners of distribution networks the
model can serve as a very useful tool and has its place in the practical application.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Doprsni kip elektrotehniškega strokovnjaka, profesorja, šahista in filozofa Milana Vidmarja st.. Postavili so ga 1977, kip je ...izdelala Teodora Novšak.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering, Computer Science and Information Technology Osijek. Department of Power Engineering. Chair of ...Power Systems and Substations. - Data provided by Europeana Collections- Postupnim otvaranjem tržišta električne energije, te nastajanjem sve većeg broja
distribuiranih izvora električne energije rastu zahtjevi prema uslugama očitanja parametara
električne energije bitnih za brzo, sigurno i efikasno funkcioniranje tržišta električnom
energijom, pa u prvi plan dolaze sustavi koji mogu ispuniti postavljene zahtjeve. Sustavi AMR
se pokazuju kao jedini koji efikasno mogu prikupiti mjerne podatke potrebne tržištu tipa krivulje
tereta djelatne energije. Primjenom ovakvih sustava povećana je pouzdanost obračunskih
podataka, jer je izbjegnut ljudski faktor pri očitanju i obradi obračunskih podataka sa mjernih
uređaja i znatno umanjena mogućnost pogrešnog obračuna i prigovora kupca na račun za
električnu energiju. Povećane mogućnosti brojila, kao što je: daljinsko isključenje i uključenje
kupca i proizvođača, provjera ispravnosti rada mjernog uređaja, provjera neovlaštenog korištenja
električne energije, nadzor parametara kvalitete električne energije, sustavi daljinskog očitanja i
upravljanja brojilima (AMR/AMM) se sve više primjenjuju, te osim toga u sinergiji sa modernim
softverskim rješenjima (EasyPower), moguće je sudjelovati i u modeliranju distribucijskih
mreža, koristeći veličine izmjerene i spremljene u memoriju pametnih brojila.- The gradual opening up of the electricity market, and the formation of a growing number of
distributed sources of electricity growing demands on services readings electricity parameters
essential for fast, safe and efficient functioning of the electricity market, however, come to the
fore systems that can meet the requirements. AMR systems appear to be the only one that can
efficiently collect the metrics needed market-type curve load active energy. The application of
such systems has increased the reliability of accounting data, because it avoided the human
factor in the reading and processing of accounting data from the measuring device and
significantly reduced the possibility of an incorrect calculation and objections on the electricity
bill. Increased opportunities counters, such as: remote shutdown and engaging the customer and
91
the manufacturer, check the correctness of the measuring device, check unauthorized use of
electricity, monitoring power quality, systems for remote reading and management of meters
(AMR / AMM) is increasingly applied, and moreover, in synergy with the modern software
solutions (Easypower), it is possible to participate in the modeling of distribution networks,
using the size of the measured and stored in the memory of smart meters.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering. Department of Electromechanical Engineering. Chair of Electric Machines and Power ...Electronics. - Data provided by Europeana Collections- U doktorskoj disertaciji izvršena je sinteza nelinearnog IDA stabilizatora elektromehaničkih njihanja koji ujedinjuje automatski regulator napona i stabilizator elektromehaničkih njihanja. Polazište za izgradnju nelinearnog IDA stabilizatora elektromehaničkih njihanja je nelinearni model sinkronog generatora s istaknutim polovima trećeg reda čiji je izvod detaljno analiziran. Za sintezu IDA stabilizatora povoljno je matematički model sinkronog generatora zapisati PCH obliku. Osim poznatog postupka sinteze IDA regulatora, koji daje algoritam stabilizatora elektromehaničkih njihanja, implementirana je povratna veza po armaturnom naponu generatora, čime je ostvarena funkcionalnost automatskog regulatora napona. Nakon sinteze IDA stabilizatora dokazana je asiptotska stabilnost sustava koji se sastoji od sinkronog generatora s istaknutim polovima spojenog na električnu mreţu. Simulacije rada sustava s implementiranim IDA stabilizatorom elektromehaničkih njihanja načinjene su u programskom paketu Matlab. Za ispitivanje je korišten model sinkronog generatora s istaknutim polovima sedmog reda, a moguće je ispitati odziv sustava u slučaju promjene referentne veličine napona generatora, zatim u slučaju promjene mehaničke snage na osovini generatora te kratki spoj na generatorskoj sabirnici. Simulacijskim ispitivanjima je dokazano da je uspješno realizirano slijeĎenje referentne vrijednosti napona generatora. Ispitivanjem kvalitete regulacije sustava u slučaju velikog poremećaja u smislu kratkog spoja na sabirnici generatora te u slučaju promjene radne točke generatora dokazana je robusnost dobivenog upravljačkog algoritma. Usporedbom kvalitete regulacije IDA stabilizatora i klasičnih linearnih regulatora utvrĎeno je da klasični linearni regulatori pokazuju bolju kvalitetu regulacije u slučaju malih poremećaja. U slučaju pojave velikih poremećaja IDA stabilizator daje bolju kvalitetu regulacije u odnosu na klasične linearne regulatore. TakoĎer je dokazana stabilnost sustava s implementiranim upravljačkim algoritmom u kapacitivnom reţimu rada.- In this doctoral thesis synthesis of nonlinear IDA power system stabilizer is made. IDA stabilizer also includes functionality of automatic voltage regulator. The basis for nonlinear IDA power system stabilizer constructing is salient pole synchronous generator nonlinear model of third order, synthesis of which is analyzed in detail. For IDA stabilizer synthesis it is convenient to represent synchronous generator mathematical model as PCH system. Apart from known procedure of IDA regulator synthesis that gives power system stabilizer algorithm, generator voltage feedback is also implemented and functionality of automatic voltage regulator is achieved. After IDA stabilizer synthesis, asymptotical stability of system which consists of salient pole synchronous generator connected to electrical power system is proven. Simulations of system with implemented IDA power system stabilizer are made in Matlab software. In simulations salient pole synchronous generator seventh order model is used for IDA stabilizer testing. Simulation model gives possibility of testing generator voltage reference value change, generator mechanical power change and occurrence of short circuit on generator bus voltage. Simulation results prove that generator voltage reference value tracking is successfully realized. Control algorithm robustness is proven by regulation quality testing in case of large disturbance, such as short circuit on generator bus and generator operating point change. Regulation quality comparison for IDA stabilizer and classical linear regulators show that linear regulators have better regulation quality in case of small disturbances. In case of large disturbances IDA stabilizer gives better regulation quality comparing to classical linear regulators. Stability of system with implemented IDA stabilizer in generator capacitive operating mode is also proven.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering. Department of Computer Engineering and Automation. Chair of Computer Engineering. - Data ...provided by Europeana Collections- Upravljanje sigurnošću informacijskih sustava je vrlo važan segment upravljanja tvrtkama u cijelosti. Količina podataka koja se svakodnevno obrađuje, a i pohranjuje se povećava i često istovremeno postaje i prednost i nedostatak. Takvi podaci često služe samo za forenzičke analize. Cilj ovoga rada je iskoristiti podatke koji se pohranjuju u informacijskim sustavima izgradnjom modela za izračun vjerojatnosti budućeg događaja. Događaj je prema tezi rada često određen parametrima iz okruženja koji svojim intenzitetom mogu utjecati na ishod događaja i razinu njegovog utjecaja na informacijski sustav. Korišten je Bayesov teorem pomoću kojega je moguće izračunati vjerojatnost ostvarenja događaja na temelju vjerojatnosti praćenih parametara.
U radu su prikazani rezultati eksperimenata u kojima su ispitivani načini rada modela unutar različitih okruženja. Cilj je pronaći optimalan način rada modela i definirati uvjete koji trebaju biti ispunjeni za postizanje željenih rezultata. Rezultati su predstavljeni kroz ispravne prijedloge odluka na temelju kojih je moguće poduzimati korektivne i preventivne aktivnosti.
Evaluacija rezultata eksperimenata je također provođena na različite načine. Rezultati simulacija čije je rezultate moguće usporediti s pripadajućim sustavom ili alatom su evaluirani usporedbom s referentnim rezultatima. Evaluacije su provođene i usporedbom s mišljenjem eksperata iz područja upravljanja informacijskim sustavima. Svi rezultati su na jednak način ocijenjeni pomoću pokazatelja točnosti.
Model predstavljen u radu je moguće koristiti u opisanim okruženjima, ali i kao modul u većim ekspertnim sustavima gdje je potrebno nadzirati određene sustave kroz praćenje parametara iz okruženja. Agentski način rada je prednost jer omogućava upravljanje sustavima u stvarnom vremenu.
Najveća prednost modela je mogućnost primjene u različitim okruženjima što ne znači nužno unutar upravljanja informacijskim sustavima nego i poslovnim i socijalnim osobinama sustava koji su pogonjeni informacijskom i komunikacijskom tehnologijom.- Security management of information systems is a very important part of the company management in entirety. The amount of data to be processed and stored every day is increasing and often at the same time becomes an advantage and a disadvantage. Data are used either only for forensic analysis or not used at all. The aim of this paper is to use data stored in information systems to propose a model for calculating the probability of future events. The event regarding the thesis of the paper is often determined by the parameters of the environment whose intensity can affect the outcome of the event and its impact on information systems. The Bayes' Theorem is used by which it is possible to calculate the probability of realization of events based on probability of monitored parameters.
The paper presents the results of experiments in which they studied modes of models within different environments. The goal is to find the optimal way of working and define conditions that must be met to achieve the desired results. Results are presented through proper draft decisions on the basis of which it is possible to take corrective and preventive actions.
Evaluation of results is also performed in different ways. The results of simulations whose results can be compared with the corresponding system or tools are evaluated by comparison with reference results. Evaluations are conducted also through comparison with the opinion of experts in the field of management information systems. All results are equally evaluated using accuracy indicators.
The model presented in this paper can be used in the described environments, as well as a separate module in larger systems where it is necessary to monitor certain systems through monitoring the parameters of the environment. Agent mode is advantageous because it allows managing systems in real time.
The biggest advantage of the model is the possibility of application in different environments but not necessarily within the management of information systems but also business and social characteristics of systems that are driven by information and communication technology.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Extended description:
Naš kraj: Čeče, panorama kraja; krajevna tabla in prometni znak v klavrnem stanju, cerkev, zajetje vode, ...izjava Jera PERGER, predsednica KS Čeče, gasilski dom, cesta v gradnji, sanacija plazovitega zemljišča ob cesti, Sveta Katarina (ime kraja po cerkvi do leta 1945), stara gostilna Matko, krušna peč, miza, star radijski sprejemnik, gasilci pri delu, izjava Rudi SENČAR, poveljnik PGD, kulturni dom z odrom in dvorano (prazno).- Original language summary:
Naš kraj: predstavitev kraja Čeče.- Our place: introducing Čeče.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering. Department of Power Engineering. Chair of Power Systems and Substations. - Data provided by ...Europeana Collections- U doktorskoj disertaciji razvijen je neizraziti ekspertni sustav (off-line) za dijagnozu kvara u
distributivnoj mreţi na bazi strukturalnog i funkcionalnog djelovanja releja i prekidača.
Prikazan je novi način modeliranja funkcionalnog djelovanja releja i prekidača koji je opisan
pomoću neizrazite logike. Neizrazita logika (više-vrijednosna logika) je metoda koja se bavi
modeliranjem nepreciznosti, nesigurnosti kod donošenja odluka. Poboljšava i povećava
potencijal kod modeliranja ljudskog razmišljanja koje koristi lingvističke varijable. Neizrazita
logika (teorija) je u suprotnosti s klasičnom teorijom vjerojatnosti, jer je prva deterministička,
a druga stohastička u naravi. Teorija vjerojatnosti se koristi bi-vrijednosnom logikom (0 ili 1),
dok neizrazita teorija moţe poprimiti bilo koju vrijednost izmeĎu 0 i 1. Neizrazita logika nudi
jednostavan pristup modeliranju nejasnih, neprecizni, izobličeni i nepostojećih ulaznih
informacija. Neizraziti dijagnostički sustav kao ulazne podatke koristi statuse releja i
prekidača te njihove vremenske oznake. Dijagnostički sustav iz ogromnog broja alarma
postavlja, logički organizira i kvantificira dijagnoze. Razvijeni dijagnostički sustav za
dijagnozu kvara uspješno dijagnosticira djelovanje, krivo djelovanje i otkazivanje djelovanja
releja i prekidača. TakoĎer ima mogućnost lociranja (identificiranja) kvara te njegovog
kvantificiranja na bazi hibridnog operatora unije koji je iskazan kao aritmetička sredina
Hamackerovog i Schweizerovog operatora unije. Pored navedenog uspješno se nosi i s
kvarovima telemetrije koristeći novi način modeliranja nepostojećih informacija pomoću
linearne funkcije pripadnost u odnosu na vrijeme.- In this doctoral dissertation was developed off-line fuzzy expert system for fault diagnosis in
distribution network based on the structural and functional operation of relays and circuit
breakers. Functional operation of relays and circuit breakers is described by fuzzy logic as a
new way of modeling. Fuzzy logic (multiple-value logic) is a method that deals with the
modeling of imprecision, uncertainty in decision-making process. It improves and increases
the potential in the modeling of human thinking which uses linguistic variables. Fuzzy logic
(theory) is in contrast with the classical theory of probability, since the first is deterministic
and the other is stochastic in nature. Probability theory uses bi-value logic (0 or 1), while
fuzzy theory can take any value between 0 and 1. Fuzzy logic offers a simple approach for
modeling vague, inaccurate, distorted and missing informations. Imput information of fuzzy
diagnostic system are the status of relays and circuit breakers and their time stamps.
Diagnostic system logically organize and quantifie diagnosis from the huge alarm
streams.Operation, false operation and failure of operation for circuit brakers and realays can
be diagnosed with the developed diagnostic system. Fault location (identification) is
quantified with hybrid union operator which is discribed as the arithmetic mean of Hamackers
and Schweizers operator. New method of modeling the missng information as linear
membership functions with respect to time is used for dealing with failures of telemetry.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. Faculty of Electrical Engineering. Department of Power Engineering. Chair of Power Systems and Substations. - Data provided by ...Europeana Collections- Ferorezonancija se pojavljuje u elektroenergetskim sustavima se kao neželjeno stanje sustava koje može dovesti do oštećenja pojedinih dijelova sustava. Osnovna komponenta ferorezonantnog dijela elektroenergetske mreže je nelinearna zavojnica sa željeznom jezgrom koju u stvarnosti predstavljaju energetski i mjerni transformatori i kompenzacijske prigušnice. Opisano je nekoliko karakterističnih primjera ferorezonantnih dijelova elektroenergetske mreže koji se mogu modelirati jednostavnim RLC krugom kojega nazivamo ferorezonantnim krugom.
U ferorezonantnom krugu mogu se pojaviti različite vrste ustaljenih stanja ovisno vrijednosti bifurkacijskog parametra. Kroz slijed bifurkacija udvostručavanja periode pojavljuje se i kaotično ustaljeno stanje. Identifikacija ustaljenih stanja provedena je s pomoću frekvencijske analize varijabli stanja, Poincaréovih slika i bifurkacijskih dijagrama.
Opisana je grafo-analitička metoda analize stabilnosti pretkaotičnih ustaljenih stanja ferorezonantnog kruga temeljena na metodi inkrementalne opisne funkcije. Pomoću ove metode objašnjena je pojava ferorezonantnog skoka kao nestabilnost sustava na frekvenciji poticaja. Slijed pretkaotičnih bifurkacija objašnjen je kao slijed nestabilnih stanja i oscilacija na točno određenim harmonicima osnovne frekvencije poticaja.
Model zavojnice sa željeznom jezgrom ima ključan utjecaj na ponašanje ferorezonantnog kruga. Definirani su bitni parametri modela nelinearne zavojnice (ekvivalentna impedancija, početna ili linearna admitancija, ovojnica prijenosne funkcije) na osnovu kojih se izrađuje portret nelinearne komponente. Portret nelinearne komponente služi kao podloga za analizu stabilnosti ferorezonantnog kruga i predviđanje ferorezonancije. Analiza mogućnosti nastanka ferorezonancije provedena je na dva praktična primjera elektroenergetskih postrojenja.
Modeliranje zavojnice sa željeznom jezgrom svodi se na dvije bitne komponente: modeliranje nelinearne karakteristike induktiviteta i modeliranje otpora koji predstavlja gubitke u jezgri. Parametari modela zavojnice sa željeznom jezgrom određuju se na osnovu mjerenja U-I-P karakteristike. Predložena je mjerna metoda za izravno mjerenje ekvivalentne impedancije te način modeliranja zavojnice sa željeznom jezgrom na osnovu ekvivalentnog induktiviteta i ekvivalentne vodljivosti.- An initiation of ferroresonance in the electrical power networks is an undesirable phenomenon with possible harmful consequences. The main component of a ferroresonant part of the electrical power network is a nonlinear iron-cored coil, which represents a power transformer, a wound potential transformer or a shunt reactor. A few typical examples of ferroresonant parts of the electrical power networks are described which can be modeled with a ferroresonant circuit as a simple RLC circuit.
Varying one of the parameters of the ferroresonant circuit, called bifurcation parameter, several steady-states types can be obtained. Furthermore, a chaotic steady-state can be obtained following a sequence of period doubling bifurcations, known as period doubling route to chaos. Ways of identification and presentation of steady-states are described: harmonic content of a state variable, Poincáre maps and bifurcation diagrams.
A grapho-analytical analysis method of stability of pre-chaotic steady states is described. The method is based on the incremental describing function method. A phenomenon of ferroresonant jump is explained by instability of the system on the fundamental frequency of excitation. The pre-chaotic bifurcation sequence is explained by sequence of unstable states and oscillations on certain frequencies.
The model of iron-cored coil has substantial impact on the behavior of the ferroresonant circuit. A graphical portrait of a nonlinear component is created which is based on substantial parameters of nonlinear coil (equivalent impedance, linear admittance, transmission function envelope). The graphical portrait of nonlinear component is used to analyze ferroresonant circuit and predict an initiation of the ferroresonance. The ferroresonance possibility analysis on two practical examples of real electrical power systems is carried out.
There are two component of iron-cored coil model: nonlinear inductor representing saturation effect and nonlinear resistor representing coil loss. The commonly used method to obtain the model parameters is based on standard U-I-P measurements. The method of measuring of equivalent impedance is proposed. According to such measurements the model of iron-cored coil can be obtained involving equivalent inductance and equivalent conductivity.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
