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Steady state and short-circuit conditions in 110kV E.ON network fed from Sokolnice transformer station
Vyčítal, Václav ; Rampl, Martin (referee) ; Blažek, Vladimír (advisor)
This thesis can be divided into five main parts. The first part deals with theoretical analysis of power flow calculation in power network during steady state condition. Load flow calculation is presented here as a linear and nonlinear problem. Newton iteration method is proposed for solving power flow as nonlinear problem. The second part of this thesis deals with the analysis of short-circuit calculation in accordance with valid International Standard IEC 60909. The equivalent voltage source method is adopted in case of the short-circuit calculation. For the calculation of unbalanced short-circuit currents, the symmetrical components method is also presented. The last three parts of this paper are focused on calculations of power flow and short-circuit conditions in power grid Sokolnice. So in the third part is the description of nodal area Sokolnice with its substations and the calculation of load flow and short-circuit conditions for two different power supply options. For each supply option is also considered an abnormal (fault) grid condition. (overall there are solved four different options) The fourth part of this thesis deals with the result analysis and also the results of different power supply options are compared. In the last part there are presented necessary technical improvements for fault-free operation of power grid Sokolnice based on the result of power flow and short-circuit conditions in that grid.
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Calculation of the network steady state on the voltage level 110 kV
Macháč, Petr ; Vaculík, Petr (referee) ; Mastný, Petr (advisor)
This thesis deals with load flow calculation of electrical network 110 kV before and after the connection to the 70MW gas supply and the 58MW steam and gas supply. This grid can be powered from two 400/110kV substations, namely Sokolnice and Otrokovice. The load flow calculation is realized for the power supply either from Otrokovice or Sokolnice. Furthermore, the calculation of the uni-phase and three phase short circuits in the substations of 110kV network is realized in this thesis. The result of the thesis is the assessment of the voltage ratio in the network, current load of the power line and short circuit resistance of the substations.
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Generating of the fault record for protection and fault indicator testing
Bažata, Petr ; Jinderle, Pavel (referee) ; Topolánek, David (advisor)
The thesis is focused on a presentation of a model creating which is followed by the simulation of running real network with using the compensatory elements to minimize the incurred failures. This thesis is divided into two thematic parts – the first theoretical one deals with the basis structuring of short-circuit faults and more detailed study of ineffective ground connection. Particularly this part attends to the problematic of a network description with extinguishing suppression. Using the compensation minimizes the impact of the failure state. A short-term fixing of a resistor improves the function of the ground-fault protection and helps to detect the outgoing section damaged by the defect. Furthermore the thesis indicates simulation programs, compares them and chooses the most suitable one for the next practical part. This is focused on a simulation of a real network run, together with elements for an effective defect-reduction or easier detection of ground connection. As a simulation of a ground short-circuit is the model in the end of the thesis modified on a network with an effective grounded bundle. Testing of the model correctness and creating a record of a model using the real ground protection settings is also one part of this thesis.
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Stabilized operation and short - circuit conditions within E.ON 110 kV power network supplied from Čebín 110kV switching station, during the period of 2011
Chrástek, Radim ; Janda, Petr (referee) ; Blažek, Vladimír (advisor)
The aim of this thesis is to project an operation of bridge connection in distribution network in Čebín’s nodal area. The main task is to check a fulfilment of voltage tolerance in distribution substations 110 kV, load transformer control (400/110 kV, 110/VN kV), distribution power line 110 kV control and short - circuit conditions control. Relevant calculations are performed by dispatching control system, which works with the actual parameters of all distribution network‘s 110 kV facilities. The theoretical part of this thesis is devoted to the way of the calculation of stabilized operation and the short-circuit conditions. In practical part, first we perform an analyse of stabilized operation and the short-circuit conditions of distribution network 110 kV in actual operation. Next step deals with bridge connection design and analysing its operation. The operation of bridge connection is verificated even in specific conditions (disturbance state, increased load). The next section evaluates the results of the calculations. First we deal with actual operations evaluation and proposed the bridge connection. In the next section we evaluate the operation of the bridge connection in the specific operating conditions. Finally, we evaluate the losses in the distribution network 110 kV. If the calculations of the stabilized operation or the short-circuit conditions of distribution network discovers that some of its elements are overloaded, we propose changes to ensure safe and reliable operation of the distribution network.
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High-voltage/low-voltage prefabricated substantions
Loveček, Michal ; Šafránek, Ivan (referee) ; Haluzík, Evžen (advisor)
The diploma thesis is dedicated to modern kiosk-type transformer substations PET, that are used when modernizing distribution network. Since such substations are placed on publicly accessible places it is really important that they are safe for service staff as well as for the public. Apart from the highest characteristic values stress is put upon the safety. Right construction, functionality and safety is verified using the type-tests as stated in ČSN EN 62271-202. In the last part of the thesis there are the methods and procedures of type-testing described.
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Simulation of phenomena in switchgears
Daševič, Ladislav ; Vávra, Zdeněk (referee) ; Valenta, Jiří (advisor)
Aim of the thesis is to explain the issue of forces acting in circuit breaker caused by magnetic fields induced by short-circuit current. This thesis is focused on force affecting in concrete system of a circuit breaker. The given circuit breaker is made by OEZ Letohrad, the type Modeion BD250. In the thesis the way of creating 3-D model is shown for the purpose of creating numeric simulation by ANSYS 11. The next approach of the thesis is the description of applicating the results for DC and AC current calculations. The noted calculation is made in the programme MATLAB 6.5. The solutions are mentioned at calculations both in the graphic form and numeric specifications. Visualisation was made by using GIF graphic system animation. The individual pictures processing was done in the programme UNLEAD GIF ANIMATOR 5.
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MV Overhead Line Protections and their Coordination with Autoreclosers
Šoustal, Petr ; Skala, Petr (referee) ; Orságová, Jaroslava (advisor)
The aim of this Master’s Thesis is to describe protections for overhead lines in distribution networks. Here are described requirements for the protection and the basic protections. Protections are divided according to their protective function. For each protection is given its use and its power plans. It is stated in the work setting of protection in the real network. On this network is simulated place with short-circuit and described the action of protection. The work also deals with the coordination of protection with automatic circuit breakers. This chapter shows that, given the selectivity is not possible to deploy two or more reclosers (remotely-operated switches) to the core network management. The next chapter describes two representatives reclosers available on the Czech market OSM 27 and GVR 27. Chapter describes and compares their performance characteristics. Conclusion the work includes a proposal protected the lead in incorporating automatic circuit breakers (remotely operated circuit breakers and reclosers). The proposal is based on two different levels of annual number of interruptions and duration of annual general interruption of electricity supply. For these levels the company EGÚ Brno, a.s. proposed several variants of the use of remote-controlled in terms of reducing the cost of the penalty. Our task was to choose a variant that would be applicable in the real network. Reducing costs is feasible only in the limits Ln = 6 failures / year and Lt = 720 min / year, where the selected option No. 4. The limits Ln = 8 failures / year and Lt = 1,080 min / year, not in the real network may no option in terms of selectivity.
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Project of Outgoing Transformer Unit for the Photovoltaic Power Station
Hanák, Miroslav ; Procházka, Aleš (referee) ; Orságová, Jaroslava (advisor)
This master’s thesis engages in project of outgoing transformer unit for the photovoltaic power station. It describes project and its design documentation what conducts to practising of construction. It has compared investing to more expansive transformer what has lower loss. It describes charges of operation’s transformer in twenty years. It leads project of cable low voltage. It compares whether is better to use aluminium or cupric cables. Project is led with respect for investment costs and minimum of operation loss.
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