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Real-time detection of stator resistance unbalances in three phase drives / Realtids detektering av obalanser i statorsmotstånd i trefasiga enheterSingh, Bhanu Pratap January 2020 (has links)
An estimated 30% of the faults in Induction Machine (IM) are related to its stator. These faults are mostly in the form of an Inter-Turn Short Circuit (ITSC) fault i.e., when two winding inside the stator of IM are shorted due to insulation failure. However, ITSC fault can be avoided by detecting them in advance and then scheduling the maintenance of the IM. This thesis studies two methods for detecting this incipient ITSC fault in a three-phase IM and then estimating the stator resistance unbalance due to the ITSC fault. The first method is based on the asymmetry caused in the IM by the ITSC fault. As a result of this asymmetry, the negative sequence components of the stator voltages and the stator currents are generated inside the IM. A healthy IM also have these negative sequence components due to the manufacturing process and the supply voltage unbalances. The characteristics and the compensation methods of these negative sequence components in a healthy IM are discussed. The results show that after compensating the negative sequence components in a healthy machine, they can be used for detecting an ITSC fault and then to calculate the fault quantities as well as the stator resistance unbalances. The second method for detecting an ITSC fault is based on analysing the stator resistance unbalances. A three-phase drive is used to inject DC voltage in the stationary reference frame. The DC current generated by this DC voltage is measured and then by applying Ohm’s law stator phase resistances are calculated. In a healthy IM, the phase resistances are balanced. However, in case of ITSC fault in any of the phases, the phase resistance of that phase deviates from those of the other two phases which can be utilized for detecting ITSC fault. / Uppskattningsvis 30% av alla fel i induktionsmaskiner (IM) är kopplad till dess stator. Dessa fel är i huvudsak Inter-Turn Short Circuit (ITSC)-fel, dvs. två lindningar inom IM:ens stator blir kortsluta pga. ett isoleringsfel. Emellertid kan man undvika ITSC-fel genom att detektera dem i förhand och planera underhåll. Det här examensarbetet undersöker två metoder för att detektera ett förestående ITSC-fel i en tre-fas IM. Den första metoden är baserad på asymmetrin i IM:er pga. ITSC-felet. Resultatet av den här asymmetrin är att en negativ sekvens genereras i IM:ens statorspänning och statorström. En oskadad IM kan också visa dessa negativa sekvenser pga. tillverksprocessen och statorspänningsobalanser. Egenskaperna och kompensationsmetoderna för dessa negativa sekvenser i en oskadad IM kommer att diskuteras. Resultaten visar att efter kompenseringen av de negativa sekvenserna i en oskadad IM, kan de användas för att detektera ITSC-fel och efteråt för att beräkna felstorheter och även statormotståndobalanser. Den andra metoden för att detektera ITSC-fel är baserad på en undersökning av statormotståndobalanser. Ett tre-fas-drivsystem används för att injektera likspänning i den stationära referensramen. Likströmmen som följer av denna likspänning mäts och statorfasmotstånden beräkna efteråt med Ohms lag. I en oskadad IM är fasmotstånden balanserade. Däremot, när ett ITSC-fel uppstår i en fas, avviker fasmotståndet i den felaktiga fasen från de andra två fasernas, vilket kan användas för att detektera ITSC-fel.
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Evaluation of Symmetrical Components Theory in Power Systems with Renewable SourcesDanylov, Daniil January 2021 (has links)
Rapidly growing Inverter- Based Resources (IBR) have different fault properties compared to Synchronous Generators (SG). Therefore, it is necessary to study the fault behavior of systems that contain different types of IBR and compare it to the conventional system responses in order to understand what steps should be taken to adapt conventional protection settings for new types of sources. For a two bus model, it is found out that sequence profiles in a system with one IBR are different from those observed in conventional system. Thermal and electrical limitations of the power electronics reduce the fault current from the IBR significantly, driving negative sequence current to small values compared to conventional sources. This is true for all studied types of IBR. Moreover, if IBR is connected to the grid through one line only, during Three Phase Fault (3hp) it is possible to lose synchronism with grid due to erroneous estimation of the grid angle through the Phase-Locked Loop (PLL). Verification of the obtained results is made through comparison to the Fault Recordings taken from the protection relays placed at substations. It is shown that for some faults simulation results can predict the behavior of symmetrical components in the network whereas for others they do not. To explain the latter behavior modifications to the sequence networks are proposed. / Snabbt växande inverterbaserade resurser (IBR) har olika felinmatningsegenskaper jämfört med synkrongeneratorer (SG). Därför är det nödvändigt att studera felbeteende hos system som innehåller olika typer av IBR och jämför det med konventionella källor för att kunna förstå vilka steg som ska göras för att anpassa konventionella skyddsinställningar för nya typer av källor. Under litteraturöversikten introduktion till det fast jordade systemet och dess speciella fall med isolerad transformatorjordning är klar. Kort introduktion till den studerade IBR och typer av simulerade fel görs också. För en tvåbussmodell har det visat sig att sekvensprofiler i ett system med en IBR skiljer sig från de som observerats i konventionella system. Termisk och elektrisk begränsningar i kraftelektroniska komponenter minskar felströmmen från IBR avsevärt och driver negativ sekvensström till små värden jämfört med konventionella källor. Detta gäller för alla studerade typer av IBR. Dessutom, om IBR är ansluten till nätet endast genom en linje, är det möjligt under trefasfel (3hp) att tappa synkronisering med nätet på grund av felaktig uppskattning av fasvinkeln genom styrsystemets faslåst slinga (PLL). Verifiering av de erhållna resultaten görs genom jämförelse med Fel Inspelningar från reläet placerade på transformatorstationer. Det visas att för vissa fel simuleringsresultat kan förutsäga symmetriska komponenters beteende i nätverket medan andra inte gör det. För att förklara de senare beteendena föreslås modifieringar i sekvensnätverket.
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A strategic sequential, integrated, sustainable organisation-stakeholder relationship (SISOSR) model for building stakeholder partnerships : a corporate communication perspectiveSlabbert, Yolandi 11 1900 (has links)
A dominant focus on organisational stakeholders is currently evident in both the literature and in practice since it is argued that the success of organisations is predominantly dependent on stakeholders’ perception of the organisation. This stakeholder emphasis is evident in the inclusion of a chapter on governing stakeholder relations in the King III report and the development of various stakeholder standards in South Africa, including corporate social investment, corporate governance, corporate citizenship, corporate sustainability and the triple bottom line. Despite the recognition of the importance and necessity of building and maintaining stakeholder relations in the literature, there is a dearth of research on how to actually build these relationships. The aim of this study was to address this shortcoming by proposing a generic, integrated approach to sustainable organisation-stakeholder relationship (OSR) building with strategic stakeholders whereby strategic stakeholder identification, OSR development and OSR maintenance, which are often studied independently, would be integrated in order to constitute a new unified model. This model will promote a sustainable OSR-building process for organisation-stakeholder partnership (OSP) development.The following three building blocks for such a model were proposed: a strategic communication foundation that promotes the integration of specific corporate communication functions that is practised from a two-way symmetrical communication perspective as the basis for effective OSR building; a theoretical foundation, which is an integration of Freeman’s stakeholder concept (1984) from a normative, relational viewpoint, Ferguson’s relational paradigm for public relations (1984) and Ledingham’s (2003) theory of relationship management, encapsulated by Grunig’s (1984) excellence theory, of which the proposed OSR-building model would be a pragmatic representation; and a conceptualisation of the OSR-building model where the actual phases of the OSR-building process would be proposed to provide step-by-step guidance for OSR building. This model promotes a partnership approach with strategic stakeholders, which is based on the proposition of an OSR development continuum, which implies that an OSR could grow in intensity over time, from a foundational OSR, mutually-beneficial OSR, sustainable OSR, to ultimate organisational-stakeholder partnerships (OSPs).
This model was built from a corporate communication perspective, and subsequently highlighted the contribution of corporate communication in the organisation as an OSR-building function to ensure organisational effectiveness. This study provided an exploratory literature review to constitute a conceptual framework for OSR-building of which the principles of the framework would be further explored and measured in leading listed South African organisations, by means of a quantitative web-based survey and qualitative one-on-one interviews to compose an OSR-building model that provides guidance on the process of OSR building on the basis of insights from theory and practice. / Ingevolge die argument dat die sukses van organisasies hoofsaaklik afhanklik is van die persepsies wat belangegroepe oor organisasies het, word ‘n dominante fokus tans op organisatoriese belangegroepe in die literatuur en praktyk geplaas. Die fokus op belangegroepe is sigbaar in die insluiting van ‘n hoofstuk oor die bou van belangegroepverhoudings in die King III verslag asook die ontwikkeling van verskeie belangegroepstandaarde in Suid Afrika, wat korporatiewe sosiale verantwoordelikheid, korporatiewe burgerskap, korporatiewe volhoubaarheid en drievoudige eindresultaat insluit. Ten spyte daarvan dat die belangrikheid en noodsaaklikheid van die bou en behoud van belangegroepverhoudings erken word in die literatuur, is daar ‘n tekort aan navorsing oor hoe om die verhoudings te bou. Die studie poog om dié tekortkoming aan te spreek deur middel van ‘n generiese, geϊntegreerde benadering vir volhoubare organisatoriese-belangegroepvershoudings (OBV) met strategiese belangegroepe voor te stel, waar strategiese belangegroep identifikasie, OBV ontwikkeling en OBV instandhouding, aspekte wat dikwels afsonderlik bestudeer word, geintegreer word in ‘n nuwe, verenigde model. Hierdie model sal ’n volhoubare OBV verbouiingsproses voorstel vir die ontwikkeling van organisatoriese-belangegroepvennootskappe.
Drie boustene word vir die model voorgestel naamlik; ‘n strategiese kommunkasie fondasie wat die integrasie van spesifieke korporatiewe kommunikasie funksies vanuit ‘n twee-rigting simmetriese kommunikasie perspektief as basis vir die effektiewe bou van OBV insluit; ‘n teoretiese fondasie wat ‘n integrasie van Freeman (1984) se belangegroepkonsep van ‘n normatiewe, verhoudingsstandpunt, Ferguson (1984) se verhoudingsparadigma vir openbare skakelwerk en Ledingham (2003) se verhoudingsbestuursteorie insluit, omhul deur Grunig (1984) se uitnemendheidsteorie, waarvan die voorgestelde OBV model ‘n praktiese voorstelling sal wees; en ‘n konseptualisering van OBV-verbouing wat die fases van die OBV proses sal stipuleer om stap-vir-stap riglyne vir die bou van OBV voor te stel. ‘n Vennootskapsbenadering met strategiese belangegroepe word voorgestel deur die model, wat gebaseer is op die proposisie van ‘n OBV ontwikkelingskontinuum, wat impliseer dat ‘n OBV oor tyd in intensiteit kan groei van ‘n basiese OBV, wedersydse voordelige OBV, volhoubare OBV tot ‘n uiteindelike organisatoriese-belangegroepvennootskap.
Die model is gebou uit ‘n korporatiewe kommunikasiestandpunt, wat gevolglik die bydrae van korporatiewe kommunikasie in die organisasie as ’n OBV-verbouingsfunksie om organisatoriese effektiwiteit te verseker, beklemtoon. Die studie bied ‘n verkennende literatuurstudie om ’n konseptuele raamwerk vir OBV-verbouing daar te stel, waarvan die beginsels van die raamwerk verder verken en gemeet is in gelysde Suid-Afrikaanse organisasies deur middel van ‘n kwantitatiewe web-gebaseerde opname en een-tot-een onderhoude om ’n OBV-verbouingsmodel te ontwikkel wat riglyne vir die proses van OBV-verbouing bied, gebaseer op beide teoretiese en praktiese insigte. / Communication Science / D. Litt. et Phil. (Communication)
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Vnímání krásy - biologické vs. kulturní determinanty / Perception of beauty - biological vs. cultural determinantsObdržálková, Zita January 2013 (has links)
This thesis deals with problems of biological and cultural determinants influencing perception of beauty. It attempts to find out if there is a common biological basis of perception of beauty or if beauty represents merely a sociocultural construct - product of a specific culture. With respect to biological determinants it concerns biological processes significantly influencing perception of beauty. In this context, these processes include probably innate evolutionary adaptations, effects of brain cognitive systems and neural correlates processing perceptions of beautiful objects. In connection with cultural determinants it presents studies emphasizing cross-cultural differences in perception of beauty. Further subject of the thesis is an aesthetic conception of subjective and objective beauty and related concept of beauty based on mathematical relations. In this connection, the creation of universally beautiful objects based on fixed mathematical rules as well as the possibility of exact measurement of beauty are discussed.
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A strategic sequential, integrated, sustainable organisation-stakeholder relationship (SISOSR) model for building stakeholder partnerships : a corporate communication perspectiveSlabbert, Yolandi 11 1900 (has links)
A dominant focus on organisational stakeholders is currently evident in both the literature and in practice since it is argued that the success of organisations is predominantly dependent on stakeholders’ perception of the organisation. This stakeholder emphasis is evident in the inclusion of a chapter on governing stakeholder relations in the King III report and the development of various stakeholder standards in South Africa, including corporate social investment, corporate governance, corporate citizenship, corporate sustainability and the triple bottom line. Despite the recognition of the importance and necessity of building and maintaining stakeholder relations in the literature, there is a dearth of research on how to actually build these relationships. The aim of this study was to address this shortcoming by proposing a generic, integrated approach to sustainable organisation-stakeholder relationship (OSR) building with strategic stakeholders whereby strategic stakeholder identification, OSR development and OSR maintenance, which are often studied independently, would be integrated in order to constitute a new unified model. This model will promote a sustainable OSR-building process for organisation-stakeholder partnership (OSP) development.The following three building blocks for such a model were proposed: a strategic communication foundation that promotes the integration of specific corporate communication functions that is practised from a two-way symmetrical communication perspective as the basis for effective OSR building; a theoretical foundation, which is an integration of Freeman’s stakeholder concept (1984) from a normative, relational viewpoint, Ferguson’s relational paradigm for public relations (1984) and Ledingham’s (2003) theory of relationship management, encapsulated by Grunig’s (1984) excellence theory, of which the proposed OSR-building model would be a pragmatic representation; and a conceptualisation of the OSR-building model where the actual phases of the OSR-building process would be proposed to provide step-by-step guidance for OSR building. This model promotes a partnership approach with strategic stakeholders, which is based on the proposition of an OSR development continuum, which implies that an OSR could grow in intensity over time, from a foundational OSR, mutually-beneficial OSR, sustainable OSR, to ultimate organisational-stakeholder partnerships (OSPs).
This model was built from a corporate communication perspective, and subsequently highlighted the contribution of corporate communication in the organisation as an OSR-building function to ensure organisational effectiveness. This study provided an exploratory literature review to constitute a conceptual framework for OSR-building of which the principles of the framework would be further explored and measured in leading listed South African organisations, by means of a quantitative web-based survey and qualitative one-on-one interviews to compose an OSR-building model that provides guidance on the process of OSR building on the basis of insights from theory and practice. / Ingevolge die argument dat die sukses van organisasies hoofsaaklik afhanklik is van die persepsies wat belangegroepe oor organisasies het, word ‘n dominante fokus tans op organisatoriese belangegroepe in die literatuur en praktyk geplaas. Die fokus op belangegroepe is sigbaar in die insluiting van ‘n hoofstuk oor die bou van belangegroepverhoudings in die King III verslag asook die ontwikkeling van verskeie belangegroepstandaarde in Suid Afrika, wat korporatiewe sosiale verantwoordelikheid, korporatiewe burgerskap, korporatiewe volhoubaarheid en drievoudige eindresultaat insluit. Ten spyte daarvan dat die belangrikheid en noodsaaklikheid van die bou en behoud van belangegroepverhoudings erken word in die literatuur, is daar ‘n tekort aan navorsing oor hoe om die verhoudings te bou. Die studie poog om dié tekortkoming aan te spreek deur middel van ‘n generiese, geϊntegreerde benadering vir volhoubare organisatoriese-belangegroepvershoudings (OBV) met strategiese belangegroepe voor te stel, waar strategiese belangegroep identifikasie, OBV ontwikkeling en OBV instandhouding, aspekte wat dikwels afsonderlik bestudeer word, geintegreer word in ‘n nuwe, verenigde model. Hierdie model sal ’n volhoubare OBV verbouiingsproses voorstel vir die ontwikkeling van organisatoriese-belangegroepvennootskappe.
Drie boustene word vir die model voorgestel naamlik; ‘n strategiese kommunkasie fondasie wat die integrasie van spesifieke korporatiewe kommunikasie funksies vanuit ‘n twee-rigting simmetriese kommunikasie perspektief as basis vir die effektiewe bou van OBV insluit; ‘n teoretiese fondasie wat ‘n integrasie van Freeman (1984) se belangegroepkonsep van ‘n normatiewe, verhoudingsstandpunt, Ferguson (1984) se verhoudingsparadigma vir openbare skakelwerk en Ledingham (2003) se verhoudingsbestuursteorie insluit, omhul deur Grunig (1984) se uitnemendheidsteorie, waarvan die voorgestelde OBV model ‘n praktiese voorstelling sal wees; en ‘n konseptualisering van OBV-verbouing wat die fases van die OBV proses sal stipuleer om stap-vir-stap riglyne vir die bou van OBV voor te stel. ‘n Vennootskapsbenadering met strategiese belangegroepe word voorgestel deur die model, wat gebaseer is op die proposisie van ‘n OBV ontwikkelingskontinuum, wat impliseer dat ‘n OBV oor tyd in intensiteit kan groei van ‘n basiese OBV, wedersydse voordelige OBV, volhoubare OBV tot ‘n uiteindelike organisatoriese-belangegroepvennootskap.
Die model is gebou uit ‘n korporatiewe kommunikasiestandpunt, wat gevolglik die bydrae van korporatiewe kommunikasie in die organisasie as ’n OBV-verbouingsfunksie om organisatoriese effektiwiteit te verseker, beklemtoon. Die studie bied ‘n verkennende literatuurstudie om ’n konseptuele raamwerk vir OBV-verbouing daar te stel, waarvan die beginsels van die raamwerk verder verken en gemeet is in gelysde Suid-Afrikaanse organisasies deur middel van ‘n kwantitatiewe web-gebaseerde opname en een-tot-een onderhoude om ’n OBV-verbouingsmodel te ontwikkel wat riglyne vir die proses van OBV-verbouing bied, gebaseer op beide teoretiese en praktiese insigte. / Communication Science / D. Litt. et Phil. (Communication)
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Vliv cestovního ruchu na místní rozvoj v regionu Bystřice nad Pernštejnem / Impact of tourism on local development in the region Bystřice nad PernštejnemCISÁROVÁ, Jitka January 2012 (has links)
The main objective of this thesis is the definition of tourism supply and demand of tourism to the region Bystřice Pernštejnem. The demand for the region is established on the basis of the survey. The first sub-goal is to evaluate the impact of tourism on the budget of municipalities. In this first part is carried out field research among the mayors of municipalities in the region on their perceptions of tourism. Evaluation of the impact of tourism is carried out on the town budget Bystřice Pernštejnem.First discussed are the revenues, expenditures, and finally the overall impact. Part of this section are evaluated impacts on employment and value of tourist activities found in the region. The second sub-goal is to assess the impact of subsidies on production in the region. This section compares the projects in the field of tourism and other projects on the basis of the calculated gross value added of these observed effects support. The last sub-goal is to determine the multiplier of tourism. Part of this section is a national regionalization symmetric input-output tables for the region SO ORP Bystřice Pernštejnem. Based on the tables are compiled using the technical coefficients matrix, Leontief inverse matrix and matrix Leontieofovi input multipliers calculated for each economic activity. Consequently, expenditure of tourists found the overall multiplier of tourism for the region Bystřice Pernštejnem spending tourists and the impact on production in the region.
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