Zenodo (CERN European Organization for Nuclear Research), Oct 26, 2014
This paper explains the role of diagnostic centre in remote monitoring of the productional and op... more This paper explains the role of diagnostic centre in remote monitoring of the productional and operational parameters of the electric power industry in order to apply maintenance management system (MMS), outage management system (OMS) and asset management system (AMS). The establish of this center with using the modern management theory and complex system of remote monitoring should bring multiple benefits to the power sector at all. In addition to conventional methods of monitoring, maintenance, testing and measurements that are carried out over the equipment installed in the production, transmission and distribution systems, it is necessary to apply the new methods of management, supervision and control that usually involve the simultaneous remote monitoring of few relevant parameters. The linked remote monitoring, SCADA and telecommunication systems are useful for monitoring, processing and analysing the various parameters. The diagnostic centre plays vital role in remote monitoring conditions and fault detections in almost all emergency situations in power system. The economic analysis should be carried out and implemented on the basis of correct information about the equipment status, technological processes and resources (hydropower potential, coal mines, coal transportation, wind and sunny days for renewable energy...). These are important starting points for a predictions, estimates, analysis and planning aspects that directly affect on the economic parameters of the electricity market.
Facta universitatis - series: Electronics and Energetics, 2020
Power transformers are constantly exposed to mechanical, thermal and electrical stresses during o... more Power transformers are constantly exposed to mechanical, thermal and electrical stresses during operation. In this paper, the authors propose an improved aging model of power transformers by adding the impact of mechanical deteriorations. In the current practice, the mechanical deformation and dislocation of the windings and core are not sufficiently distinguished as components that influence the aging of the transformer. Hence, the current aging model was expanded with a functional block that contains several typical failures in order to emphasize their impact on the lifetime of transformers and their aging as well. The authors used the Frequency Response Analysis (FRA) method for the fault detection and location of the mechanical deformations of its active parts. The correlation function is used to determine the level of the detected failure. All presented test results are obtained in real exploitation conditions.
Zenodo (CERN European Organization for Nuclear Research), Oct 28, 2014
Apstract: U radu je detaljno objašnjena primena metoda analize frekventnog odziva namotaja (Sweep... more Apstract: U radu je detaljno objašnjena primena metoda analize frekventnog odziva namotaja (Sweep Frequency Response Analysis-SFRA) energetskih transformatora sa ciljem analize i provere stanja geometrije aktivnog dela. Prikazani su osnovni principi metode, a zatim je ukazano na njene prednosti u odnosu na klasičan pristup. Metoda je od koristi pri proceni stanja velikih energetskih transformatora i pri proceni preostalog životnog veka. Predložena metoda može u većini slučajeva da zameni potrebu za vizuelnim pregledom transformatora, što u mnogome pojednostavljuje i pojeftinjuje procenu stanja transformatora u celini. Njena jednostavna primena je svrstava u red metoda pogodnih u redovnim profilaktičkim ispitivanjima. S obzirom na mogućnost kratkotrajnih isključivanja transformatora, metoda može da se koristi u preventivne svrhe, ali i da bude jedna od osnovnih metoda koja se uklapa u princip "održavanja po stanju".
Zbornik radova, Elektrotehnicki institut Nikola Tesla, 2014
Kratak sadržaj: Namotaji energetskih transformatora su u pogonu neprekidno izloženi elektromehani... more Kratak sadržaj: Namotaji energetskih transformatora su u pogonu neprekidno izloženi elektromehaničkim naprezanjima i vibracijama. Usled velikih prenapona, tokom atmosferskih pražnjenja ili kratkih spojeva, može doći do slabljenja mehaničke strukture za utezanje jezgra i namotaja. Bilo kakvo narušavanje projektovane geometrije namotaja umanjiće njegovu sposobnost da podnese naredno prenaprezanje, što može dovesti do velike deformacije namotaja. U radu je prikazana analiza frekvencijskog odziva (Sweep Frequency Response Analysis-SFRA) dva tipa transformatora: energetskog transformatora i transforamtora koji se koristi u napajanjima električnih uređaja mrežnog napona od 220V. Prikazani su laboratorijski rezultati primene SFRA metode za narušenu geometriju transformatora Kljućne reči: analiza frekventnog odziva, transformator, SFRA metoda, deformacije jezgra i namotaja.
U radu je prikazana analiza frekvencijskog odziva transformatora (Sweep Frequency Response Analys... more U radu je prikazana analiza frekvencijskog odziva transformatora (Sweep Frequency Response Analysis-SFRA) kao metode za snimanje frekvencijskog odziva namotaja transformatora u cilju prepoznavanja potencijalnih defekata u geometriji jezgra i namotaja, poput pomeraja jezgra, kratko spojenog ili otvorenog navojka, neželjenih kontakata jezgra sa masom i sl. Izvršena je uporedna analiza pomenute metode sa klasičnim metodama. Prednosti SFRA metode su velika pouzdanost i ponovljivost merenja, i pripadnost kategoriji neinvazivnih metoda. Zbog velike pouzdanosti i ponovljivosti merenja, metoda se pokazala izuzetno pogodnom za utvrđivanje promene u geometriji namotaja i jezgra pri profilaktičkim ispitivanjima na terenu, u pogonu ili nakon transporta transformatora.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2021
High-voltage motors are one of the most important components in thermal power plants and industri... more High-voltage motors are one of the most important components in thermal power plants and industrial facilities. However, they are often neglected in terms of preventive maintenance. Maintenance in power plants in Serbia still takes place according to the outdated model of maintenance based on fixed time intervals operations - time based maintenance. This is why emphasis has to be put on electrical testing of high-voltage motors in order to have a better insight into their condition, to prevent unwanted failures and to improve their service. This paper provides an overview of the currently available prophylactic tests of high-voltage motors. Also, the most common testing methods are described, which provide information on the current motor condition, so it is possible to make further repairs or corrective actions timely. Case examples and experiences from practice in power plants in Serbia are further presented and discussed in the paper.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2021
During operation, the electrical insulation system (EIS) of high-voltage motors is exposed to var... more During operation, the electrical insulation system (EIS) of high-voltage motors is exposed to various factors that can accelerate its aging. Timely knowledge of the actual state of the EIS is of great help in allocating funds for service activities. The condition of the EIS of the HV motor can be assessed to some extent by performing available electrical tests. A major shortcoming is the lack of accuracy and the lack of well-defined criteria in the current standards. In that way, a potential error can bias the evaluation of recorded results. The paper proposes the use of a fuzzy logic expert system for assessing the condition of EIS stators of HV motors based on the results of electrical measurements. Also, the proposed fuzzy approach is fully discussed. The created expert system fully relies on the criteria defined in the IS32-Internal Standard of PE EPS.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2020
The unconventional UHF (Ultra High Frequency) method of measuring partial discharges (PD) is base... more The unconventional UHF (Ultra High Frequency) method of measuring partial discharges (PD) is based on measuring electromagnetic waves (EM) in the UHF frequency band (300-3000) MHz, using appropriate antennas. This method is unconventional, but is widely accepted due to the possibility of application in plants in the online mode and quick review (screening) of the plant. Also, this method is characterized by a high degree of measurement sensitivity and relatively good resistance to interference. As the PD pulses are of very short duration, of the order of nanoseconds, they generate an electromagnetic pulse whose spectrum reaches GHz. In the conductive structures of an object, these pulses induce electromagnetic wave transients. A certain type of antenna has the ability to receive these transient waves. The paper gives an example of field and laboratory tests that show the correlation between the detection of PD using UHF devices and devices based on the principle of acoustic detectio...
Zbornik radova, Elektrotehnicki institut Nikola Tesla, 2016
Izolacioni sistemi snažnijih obrtnih mašina se već dugi niz godina podrobnije ispituju metodama k... more Izolacioni sistemi snažnijih obrtnih mašina se već dugi niz godina podrobnije ispituju metodama koje su konstantno unapređivane i potvrđene. Mašine manjih snaga i, uslovno rečeno, manjeg značaja, kao što su visokonaponski motori, su često održavani minimalnim sredstvima i neretko ne podležu ozbiljnijim električnim ispitivanjima. Uvođenjem EDA (Electronic Dielectric Analyzer) metodologije u praksu stvaraju se uslovi za pouzdanu i potpuniju dijagnostiku stanja statorskih namotaja velikih mašina, kao i brz, jednostavan i jeftin "screening" velikog broja mašina manjih snaga kao što su visokonaponski motori. U radu će biti prikazana EDA metodologija i mogućnosti koje pruža, kao i mogućnosti softverskog i hardverskog rešenja.
Aproveito este espaço para deixar registrado meu agradecimento a pessoas que, de diferentes forma... more Aproveito este espaço para deixar registrado meu agradecimento a pessoas que, de diferentes formas, fizeram parte deste processo e foram essenciais para conclusão desta importante etapa da minha vida. Começo agradecendo àqueles que sempre estiveram ao meu lado, minha família. Foram nos exemplos diários de meus pais, de perseverança, valorização ao estudo, que este projeto se sustentou. À Prof.ª Dra. Maria Aparecida Gouvêa, minha gratidão, pela condução em sua orientação, fundamental para o desenvolvimento da pesquisa, e por acreditar neste projeto. Têla ao meu lado foi uma oportunidade única de aprendizado. Aos colegas de trabalho, pelo apoio recebido, principalmente, à equipe do INPES, pela solidariedade e motivação durante este período. Ofereço especial agradecimento ao amigo e professor Dr. Leandro Prearo o qual me incentivou a iniciar o mestrado, por suas inestimáveis considerações e ensinamentos. Por fim, agradeço a todas instituições que tornaram esta dissertação possível: à Faculdade de Economia, Administração e Contabilidade da Universidade de São Paulo -FEA-USP, que por meio de seus professores, promove um excepcional espaço de conhecimento científico, de crescimento acadêmico e profissional, em particular, à figura do Prof. Dr. Gilberto Martins pelas valiosas sugestões na banca de qualificação. À Universidade Municipal de São Caetano do Sul -USCS, pela oportunidade, confiança estabelecida e por sempre apoiar o aperfeiçoamento profissional de seus funcionários. A todos esses, meu muito obrigado! "É no problema da educação que assenta o grande segredo do aperfeiçoamento da humanidade" (Kant, 1803, p. 460) RESUMO SOUSA, Daniel Giatti de. (2018). Determinantes da qualidade do ensino: um estudo na rede pública do estado de
Zenodo (CERN European Organization for Nuclear Research), Oct 26, 2014
This paper explains the role of diagnostic centre in remote monitoring of the productional and op... more This paper explains the role of diagnostic centre in remote monitoring of the productional and operational parameters of the electric power industry in order to apply maintenance management system (MMS), outage management system (OMS) and asset management system (AMS). The establish of this center with using the modern management theory and complex system of remote monitoring should bring multiple benefits to the power sector at all. In addition to conventional methods of monitoring, maintenance, testing and measurements that are carried out over the equipment installed in the production, transmission and distribution systems, it is necessary to apply the new methods of management, supervision and control that usually involve the simultaneous remote monitoring of few relevant parameters. The linked remote monitoring, SCADA and telecommunication systems are useful for monitoring, processing and analysing the various parameters. The diagnostic centre plays vital role in remote monitoring conditions and fault detections in almost all emergency situations in power system. The economic analysis should be carried out and implemented on the basis of correct information about the equipment status, technological processes and resources (hydropower potential, coal mines, coal transportation, wind and sunny days for renewable energy...). These are important starting points for a predictions, estimates, analysis and planning aspects that directly affect on the economic parameters of the electricity market.
Facta universitatis - series: Electronics and Energetics, 2020
Power transformers are constantly exposed to mechanical, thermal and electrical stresses during o... more Power transformers are constantly exposed to mechanical, thermal and electrical stresses during operation. In this paper, the authors propose an improved aging model of power transformers by adding the impact of mechanical deteriorations. In the current practice, the mechanical deformation and dislocation of the windings and core are not sufficiently distinguished as components that influence the aging of the transformer. Hence, the current aging model was expanded with a functional block that contains several typical failures in order to emphasize their impact on the lifetime of transformers and their aging as well. The authors used the Frequency Response Analysis (FRA) method for the fault detection and location of the mechanical deformations of its active parts. The correlation function is used to determine the level of the detected failure. All presented test results are obtained in real exploitation conditions.
Zenodo (CERN European Organization for Nuclear Research), Oct 28, 2014
Apstract: U radu je detaljno objašnjena primena metoda analize frekventnog odziva namotaja (Sweep... more Apstract: U radu je detaljno objašnjena primena metoda analize frekventnog odziva namotaja (Sweep Frequency Response Analysis-SFRA) energetskih transformatora sa ciljem analize i provere stanja geometrije aktivnog dela. Prikazani su osnovni principi metode, a zatim je ukazano na njene prednosti u odnosu na klasičan pristup. Metoda je od koristi pri proceni stanja velikih energetskih transformatora i pri proceni preostalog životnog veka. Predložena metoda može u većini slučajeva da zameni potrebu za vizuelnim pregledom transformatora, što u mnogome pojednostavljuje i pojeftinjuje procenu stanja transformatora u celini. Njena jednostavna primena je svrstava u red metoda pogodnih u redovnim profilaktičkim ispitivanjima. S obzirom na mogućnost kratkotrajnih isključivanja transformatora, metoda može da se koristi u preventivne svrhe, ali i da bude jedna od osnovnih metoda koja se uklapa u princip "održavanja po stanju".
Zbornik radova, Elektrotehnicki institut Nikola Tesla, 2014
Kratak sadržaj: Namotaji energetskih transformatora su u pogonu neprekidno izloženi elektromehani... more Kratak sadržaj: Namotaji energetskih transformatora su u pogonu neprekidno izloženi elektromehaničkim naprezanjima i vibracijama. Usled velikih prenapona, tokom atmosferskih pražnjenja ili kratkih spojeva, može doći do slabljenja mehaničke strukture za utezanje jezgra i namotaja. Bilo kakvo narušavanje projektovane geometrije namotaja umanjiće njegovu sposobnost da podnese naredno prenaprezanje, što može dovesti do velike deformacije namotaja. U radu je prikazana analiza frekvencijskog odziva (Sweep Frequency Response Analysis-SFRA) dva tipa transformatora: energetskog transformatora i transforamtora koji se koristi u napajanjima električnih uređaja mrežnog napona od 220V. Prikazani su laboratorijski rezultati primene SFRA metode za narušenu geometriju transformatora Kljućne reči: analiza frekventnog odziva, transformator, SFRA metoda, deformacije jezgra i namotaja.
U radu je prikazana analiza frekvencijskog odziva transformatora (Sweep Frequency Response Analys... more U radu je prikazana analiza frekvencijskog odziva transformatora (Sweep Frequency Response Analysis-SFRA) kao metode za snimanje frekvencijskog odziva namotaja transformatora u cilju prepoznavanja potencijalnih defekata u geometriji jezgra i namotaja, poput pomeraja jezgra, kratko spojenog ili otvorenog navojka, neželjenih kontakata jezgra sa masom i sl. Izvršena je uporedna analiza pomenute metode sa klasičnim metodama. Prednosti SFRA metode su velika pouzdanost i ponovljivost merenja, i pripadnost kategoriji neinvazivnih metoda. Zbog velike pouzdanosti i ponovljivosti merenja, metoda se pokazala izuzetno pogodnom za utvrđivanje promene u geometriji namotaja i jezgra pri profilaktičkim ispitivanjima na terenu, u pogonu ili nakon transporta transformatora.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2021
High-voltage motors are one of the most important components in thermal power plants and industri... more High-voltage motors are one of the most important components in thermal power plants and industrial facilities. However, they are often neglected in terms of preventive maintenance. Maintenance in power plants in Serbia still takes place according to the outdated model of maintenance based on fixed time intervals operations - time based maintenance. This is why emphasis has to be put on electrical testing of high-voltage motors in order to have a better insight into their condition, to prevent unwanted failures and to improve their service. This paper provides an overview of the currently available prophylactic tests of high-voltage motors. Also, the most common testing methods are described, which provide information on the current motor condition, so it is possible to make further repairs or corrective actions timely. Case examples and experiences from practice in power plants in Serbia are further presented and discussed in the paper.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2021
During operation, the electrical insulation system (EIS) of high-voltage motors is exposed to var... more During operation, the electrical insulation system (EIS) of high-voltage motors is exposed to various factors that can accelerate its aging. Timely knowledge of the actual state of the EIS is of great help in allocating funds for service activities. The condition of the EIS of the HV motor can be assessed to some extent by performing available electrical tests. A major shortcoming is the lack of accuracy and the lack of well-defined criteria in the current standards. In that way, a potential error can bias the evaluation of recorded results. The paper proposes the use of a fuzzy logic expert system for assessing the condition of EIS stators of HV motors based on the results of electrical measurements. Also, the proposed fuzzy approach is fully discussed. The created expert system fully relies on the criteria defined in the IS32-Internal Standard of PE EPS.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2020
The unconventional UHF (Ultra High Frequency) method of measuring partial discharges (PD) is base... more The unconventional UHF (Ultra High Frequency) method of measuring partial discharges (PD) is based on measuring electromagnetic waves (EM) in the UHF frequency band (300-3000) MHz, using appropriate antennas. This method is unconventional, but is widely accepted due to the possibility of application in plants in the online mode and quick review (screening) of the plant. Also, this method is characterized by a high degree of measurement sensitivity and relatively good resistance to interference. As the PD pulses are of very short duration, of the order of nanoseconds, they generate an electromagnetic pulse whose spectrum reaches GHz. In the conductive structures of an object, these pulses induce electromagnetic wave transients. A certain type of antenna has the ability to receive these transient waves. The paper gives an example of field and laboratory tests that show the correlation between the detection of PD using UHF devices and devices based on the principle of acoustic detectio...
Zbornik radova, Elektrotehnicki institut Nikola Tesla, 2016
Izolacioni sistemi snažnijih obrtnih mašina se već dugi niz godina podrobnije ispituju metodama k... more Izolacioni sistemi snažnijih obrtnih mašina se već dugi niz godina podrobnije ispituju metodama koje su konstantno unapređivane i potvrđene. Mašine manjih snaga i, uslovno rečeno, manjeg značaja, kao što su visokonaponski motori, su često održavani minimalnim sredstvima i neretko ne podležu ozbiljnijim električnim ispitivanjima. Uvođenjem EDA (Electronic Dielectric Analyzer) metodologije u praksu stvaraju se uslovi za pouzdanu i potpuniju dijagnostiku stanja statorskih namotaja velikih mašina, kao i brz, jednostavan i jeftin "screening" velikog broja mašina manjih snaga kao što su visokonaponski motori. U radu će biti prikazana EDA metodologija i mogućnosti koje pruža, kao i mogućnosti softverskog i hardverskog rešenja.
Aproveito este espaço para deixar registrado meu agradecimento a pessoas que, de diferentes forma... more Aproveito este espaço para deixar registrado meu agradecimento a pessoas que, de diferentes formas, fizeram parte deste processo e foram essenciais para conclusão desta importante etapa da minha vida. Começo agradecendo àqueles que sempre estiveram ao meu lado, minha família. Foram nos exemplos diários de meus pais, de perseverança, valorização ao estudo, que este projeto se sustentou. À Prof.ª Dra. Maria Aparecida Gouvêa, minha gratidão, pela condução em sua orientação, fundamental para o desenvolvimento da pesquisa, e por acreditar neste projeto. Têla ao meu lado foi uma oportunidade única de aprendizado. Aos colegas de trabalho, pelo apoio recebido, principalmente, à equipe do INPES, pela solidariedade e motivação durante este período. Ofereço especial agradecimento ao amigo e professor Dr. Leandro Prearo o qual me incentivou a iniciar o mestrado, por suas inestimáveis considerações e ensinamentos. Por fim, agradeço a todas instituições que tornaram esta dissertação possível: à Faculdade de Economia, Administração e Contabilidade da Universidade de São Paulo -FEA-USP, que por meio de seus professores, promove um excepcional espaço de conhecimento científico, de crescimento acadêmico e profissional, em particular, à figura do Prof. Dr. Gilberto Martins pelas valiosas sugestões na banca de qualificação. À Universidade Municipal de São Caetano do Sul -USCS, pela oportunidade, confiança estabelecida e por sempre apoiar o aperfeiçoamento profissional de seus funcionários. A todos esses, meu muito obrigado! "É no problema da educação que assenta o grande segredo do aperfeiçoamento da humanidade" (Kant, 1803, p. 460) RESUMO SOUSA, Daniel Giatti de. (2018). Determinantes da qualidade do ensino: um estudo na rede pública do estado de
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