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Short Circuit Calculation of MV Grid
Knápková, Dagmar ; Topolánek, David (referee) ; Toman, Petr (advisor)
This bachelor’s thesis deals with the faults in the distribution networks, focusing on shortcircuits as the most common and the most signiĄcant types of faults. The thesis is divided into theoretical and practical part. In the theoretical introduction, describes the types of faults in distribution networks with a focus on the short-circiuts, their causes, and the impact on distribution networks. Follows a description of the time course of short-circuit currents, short-circuit calculation simpliĄcation assumptions, the formula for calculating the impedance of the various elements of the short-circuits schema and the calculation methods of short-circuit currents in accordance with ČSN EN 60909-0. In the practical part, there is an example of the calculation of simple network conĄguration. Follows an analysis of the real network, including the analysis of the method of operation and the selection of appropriate method for the calculation of the short-circuit. After that are carried out practical calculations short-circuit conditions in four places on the network, and three diferent types of short circuits. For one-phase short-circuit is subsequently carried out the distribution of currents in a parallel branch of the distribution lines. At the conclusion of the bachelor’s thesis is caried out evaluation the results and analysis of the data obtained by calculation.
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Protection for Generator Unbalance
Kuba, Petr ; Paar, Martin (referee) ; Orságová, Jaroslava (advisor)
The thesis deals with the problem of unbalance in generators and discusses various means of generator protection against the effects caused by this abnormal working condition. The general importance of the problem is described in the introductory part of this work. The theoretical section of the thesis contains an analysis of procedures applied to solve different types of unbalance by the help of the method of symmetrical components. As a central aspect of the topic, the causes of unbalance are examined. This investigation is realized together with a close insight into the diverse possibilities of unbalance reduction and, importantly, in respect the effects of negative sequence current on a generator and its components. The principles of generator protection against unbalance are described at the end of this section. In its practical part, this work deals with the procedure of protection setting and testing. The applied protection is an actual component of the REM 543 machine terminal as made by the ABB company. In order to facilitate the testing of the protection, we used the TZO3 electrical protection testing device provided by the EGÚ Brno, a. s. company. A summary of the most important information and measurement results can be found in the final part of the thesis.
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Calculation of voltages and currents in the point of protection during faults
Tomášek, Lukáš ; Topolánek, David (referee) ; Haluzík, Evžen (advisor)
This work consists of two major parts - theoretical and practical. The theoretical part describes the course of short-circuit current in time, its components, characteristic values, and various types of short-circuits that may occur in electrification network. The theoretical part also describes the method of symmetrical components, its principles, fundamental relations and its use for handling the short-circuit current in electrification network, especially the asymmetrical short-circuits. The last theoretical section following the method of symmetrical components shows a summary of formulas used to calculate substitute short-circuit impedances in various elements of electrification network. The practical part then tries to answer how to handle short-circuit currents in a given network using the method of symmetrical components. Calculation is made for each type of short-circuit that may occur in the network, and voltage and current ratios are given for the point of short-circuit as well as for the point of a distance protection; main evaluated parameter of calculation is a short-circuit impedance measured by the distance protection. The conclusion of the practical part specifies why a compensation of distance protection is needed in ground short-circuits.
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Impact of cross-country double earth faults on voltage condition in LV networks
Fojtášek, Jan ; Vyčítal, Václav (referee) ; Topolánek, David (advisor)
This master's thesis is focused on the influence of double earth fault on voltage ratios in the compensated network. This thesis is focuses on, in particular on the analysis of voltage ratios on the secondary sides of distribution transformers when this non-local fault occurs. The compensation of the non-local double earth fault using the symmetrical components method is performed and the performance of this method is verified. The analysis of the effect of double earth fault on the proposed power system is carried out in PSCAD software and further evaluated. This type of non-local fault is investigated while modifying the various parameters of the designed system. To differentiate the double earth fault from the two phase ground fault, the asymmetry on the LV sides of the distribution transformers is investigated. A locator is provided to locate the location of the double earth fault and the two-phase ground fault, which, combined with the asymmetry values, is able to determine both the location of the fault and the differentiation of the co-located fault from the non-co-located fault.
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Short Circuit Calculation of MV Grid
Knápková, Dagmar ; Topolánek, David (referee) ; Toman, Petr (advisor)
This bachelor’s thesis deals with the faults in the distribution networks, focusing on shortcircuits as the most common and the most signiĄcant types of faults. The thesis is divided into theoretical and practical part. In the theoretical introduction, describes the types of faults in distribution networks with a focus on the short-circiuts, their causes, and the impact on distribution networks. Follows a description of the time course of short-circuit currents, short-circuit calculation simpliĄcation assumptions, the formula for calculating the impedance of the various elements of the short-circuits schema and the calculation methods of short-circuit currents in accordance with ČSN EN 60909-0. In the practical part, there is an example of the calculation of simple network conĄguration. Follows an analysis of the real network, including the analysis of the method of operation and the selection of appropriate method for the calculation of the short-circuit. After that are carried out practical calculations short-circuit conditions in four places on the network, and three diferent types of short circuits. For one-phase short-circuit is subsequently carried out the distribution of currents in a parallel branch of the distribution lines. At the conclusion of the bachelor’s thesis is caried out evaluation the results and analysis of the data obtained by calculation.
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Calculation of voltages and currents in the point of protection during faults
Tomášek, Lukáš ; Topolánek, David (referee) ; Haluzík, Evžen (advisor)
This work consists of two major parts - theoretical and practical. The theoretical part describes the course of short-circuit current in time, its components, characteristic values, and various types of short-circuits that may occur in electrification network. The theoretical part also describes the method of symmetrical components, its principles, fundamental relations and its use for handling the short-circuit current in electrification network, especially the asymmetrical short-circuits. The last theoretical section following the method of symmetrical components shows a summary of formulas used to calculate substitute short-circuit impedances in various elements of electrification network. The practical part then tries to answer how to handle short-circuit currents in a given network using the method of symmetrical components. Calculation is made for each type of short-circuit that may occur in the network, and voltage and current ratios are given for the point of short-circuit as well as for the point of a distance protection; main evaluated parameter of calculation is a short-circuit impedance measured by the distance protection. The conclusion of the practical part specifies why a compensation of distance protection is needed in ground short-circuits.
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Calculation of voltages and currents in the point of protection during faults
Tomášek, Lukáš ; Topolánek, David (referee) ; Haluzík, Evžen (advisor)
This work consists of two major parts - theoretical and practical. The theoretical part describes the course of short-circuit current in time, its components, characteristic values, and various types of short-circuits that may occur in electrification network. The theoretical part also describes the method of symmetrical components, its principles, fundamental relations and its use for handling the short-circuit current in electrification network, especially the asymmetrical short-circuits. The last theoretical section following the method of symmetrical components shows a summary of formulas used to calculate substitute short-circuit impedances in various elements of electrification network. The practical part then tries to answer how to handle short-circuit currents in a given network using the method of symmetrical components. Calculation is made for each type of short-circuit that may occur in the network, and voltage and current ratios are given for the point of short-circuit as well as for the point of a distance protection; main evaluated parameter of calculation is a short-circuit impedance measured by the distance protection. The conclusion of the practical part specifies why a compensation of distance protection is needed in ground short-circuits.
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Protection for Generator Unbalance
Kuba, Petr ; Paar, Martin (referee) ; Orságová, Jaroslava (advisor)
The thesis deals with the problem of unbalance in generators and discusses various means of generator protection against the effects caused by this abnormal working condition. The general importance of the problem is described in the introductory part of this work. The theoretical section of the thesis contains an analysis of procedures applied to solve different types of unbalance by the help of the method of symmetrical components. As a central aspect of the topic, the causes of unbalance are examined. This investigation is realized together with a close insight into the diverse possibilities of unbalance reduction and, importantly, in respect the effects of negative sequence current on a generator and its components. The principles of generator protection against unbalance are described at the end of this section. In its practical part, this work deals with the procedure of protection setting and testing. The applied protection is an actual component of the REM 543 machine terminal as made by the ABB company. In order to facilitate the testing of the protection, we used the TZO3 electrical protection testing device provided by the EGÚ Brno, a. s. company. A summary of the most important information and measurement results can be found in the final part of the thesis.
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