Issued topics of Doctoral Study Program:|
- Advanced Diagnosis of Middle and High Voltage Power Cables
Diagnostic of middle and high voltage power cables is currently based on measuring of the partial discharges and electronic bridge measurements. The methodology of measurement in these areas is constantly improved and adapted to the modern trends and requirements of the customer. The goal of this thesis is the unification of the measurement methods according to current standards, optimization of the measuring procedures and the development of new measuring principles based on the knowledge gained in this problematic.
- Centralized protection system for distribution network
Centralized protection system is based on the monitoring of currents and voltages in distribution network through modern transducers with digitized outputs in accordance with the Sampled Values (SV) protocol according to IEC 61850-9-2. The work is focused on research of new protective features built on the possibility of these converters (high linearity and accuracy measurement, dynamic correction of measured values) as well as the concentration measured variables in one place (Process Bus). Its aim is to program functional application for monitoring and protecting specific part of distribution network that will use advanced protection algorithms and completely new functionalities for centralized systems of protection, control and optimization of power systems.
The theme of this work cover besides power systems also information technology. Knowledge of computer networks, development of realtime applications and design of user interfaces for data presentation will be applied. Therefore, this work is recommended to candidates who have completed the information technology studies.
- Conditions for the implementation and operation of stochastic power sources up to 10 kW in the Czech Republic - arrangements for the limit the effects of power quality
Current connection conditions for micro-sources with power up to 10 kW allow this kind of resources to connect only to announcement (the classic procedure for connecting to the grid is not needed). The increase in these installations brings some operational problems, such as affecting of power quality at the point of connection or energy overflow to the grid. The aim of the research is to define the conditions for the correct connection and operation of these resources with a focus on preserving the quality of electric power. In the context of the definition mentioned rules is also required to revise the current legislative rules and make an adjustment of the rules in relation to new findings. Part of the thesis will be (out of basic math modeling) verification of theoretical findings to real applications and verification results an experimental hybrid system which is operated in laboratories at Department of Electrical Power Engineering.
- Conducted disturbances in power systems in audio-frequency range
Increasing deployment of power converters in distribution systems leads to rise in high-frequency conducted disturbance level related to the converters switching frequencies. The switching disturbances occur dominantly in frequency range from 2 kHz to 150 kHz. Current experience shows that such disturbance may lead to serious malfunction of grid-connected sensing, measuring and/or controlling systems of analog or digital nature. At the same time there is significant gap in EMC coordination and standardization since the frequency range was for a long time out of interest. It is just between low-frequency disturbances connected to power quality and radio-frequency disturbance. The project is focused firstly on development of suitable measuring apparatus and procedure to monitor the disturbances in distribution systems in the audio-frequency range. Then origin and propagation of the disturbance should be studied and finally EMC concept is expected to be proposed.
The theme takes a part of research project in cooperation with Czech utilities and with foreign universities (Germany, Italy). Ask for more details at firstname.lastname@example.org.
- Control and Protection on AC/DC Hybrid Microgrids
Future trends in the electrical power engineering predict the development of dispersed generation, accumulation and microgrids. With respect to the output voltage of the photovoltaic panels and the batteries there are integral parts of the development of microgrids also DC installations and hybrid AC / DC grids.
The aim of PhD study is to analyse the key challenges of hybrid AC / DC networks operation and to propose a methodology for cost effective voltage and current measurements for systems of adaptive control and protection respecting eg. different levels of short circuit power in all operating conditions, specific characteristics of DC current at fault clearance.
- DC Power Systems Voltage Quality
With increasing number of DC power network related applications, necessity of the power/voltage quality assessment in those DC Power Systems can be expected. The aim of the work is to develop DC voltage quality indices starting from DC traction systems and AC public distribution systems voltage quality assessment practice. The theme takes a part of a research project in cooperation with K M B systems company. More information: email@example.com.
- Electric power and energy components definition and measurement in future distribution systems
The topic is aimed to critical revision of power components theories taking into account physical merits of measured phenomena related to nonlinear, dynamic and active distribution systems. It is expected to develop a metrics for revenue meters which will cope correctly with nowadays phenomena in order to measure really passing active energy. The theme takes a part of research project in cooperation with Czech utilities and with foreign universities. Ask for more details at firstname.lastname@example.org.
- Charging stations for electric vehicles as an element of electricity system
The urgent need for the development of charging stations for hybrid cars and electric vehicles (EV) still shows as important in the context of the current gradual development of this type of transport. The theme is focused on energy analysis of the concept of charging stations with integrated accumulation and renewable energy sources. Based on the concept will be developed the mathematical models. It will be performed energy-economic analysis in order to verify the possibility of using the concept in this way to reduce the load of the network at the connection point. Direct possibility of cooperation on concrete solution with an energy company is expected.
- Chromatic flicker perception modeling in flickermeters
Visible light variation may leads to disturbance of human’s visual perception. The origin of such negative effect is in the eye anatomy and physiology. The major influence on the flickering light perception can be found in eye viewing field, photoreceptors (cones of three types and rods) and their distribution at retina as a part of eye anatomy and in eye adaptation mechanisms like pupil, photo-chemical and neural adaptation (response) to luminous variations (including the photoreceptors spectral luminous efficiency) as a part of eye physiology. The human eye can be seen as specialized luminance multi-detector where the stimulation contrast is as important as radiant density. There are differentiated three types of flicker: temporal, spatial and chromatic. All of these flickers are joyless and may involve many psychological interactions. In artificially illuminated areas, lamps light variations due to variations in supply voltage may also lead to flicker perception. Such lamp possibly will produce light with time-varying radiant flux and its spectral distribution. The lamps flickering is produced by a voltage Phase Modulation (PM), mainly by Phase Jumps (PJ) and by Interharmonic Voltages (IH) superimposed on a voltage waveform.
Thesis is focused on the voltage fluctuation to lamps time-varying radiant flux and its spectral distribution fluctuation transfer analysis and on the utilization of the analysis results for development and realization of an objective flickermeter having response to both the temporal luminance and chromatic flicker. The thesis aim is the realization of the new flickermeter types implemented in LabVIEW, with the experimental verification. The thesis covers theoretical-analytical, developmental and also practical-experimental part of study.
More information: email@example.com.
- Islanding operation of distribution systems with distributed generation
The aim is to develop technically correct, reliable and verified concept for islanding operation (IO) of dedicated part of distribution system with distributed generation dealing mainly with definitions of conditions necessary to successful transition to IO, correct and reliable detection of conditions for transition to IP and back to parallel operation, development of power sources (loads) control strategy, etc. For more information email to: firstname.lastname@example.org.
- Modeling of current interruption in electric fuses
Electric fuses are protection elements widely used in low- and medium voltage power distribution networks. Fuses are typically designed to have fuse elements as segmented thin metal conductors that are embedded in silica sand. Due to over currents and short circuit currents the fuse elements are heated up and melted, an electric arc is ignited. Thus the mode of operation can be separated into a pre-arcing and a arcing phase. In the arcing phase the generated plasma is interacting with the filler medium (sand) and the fault energy is stored in the sand, leading to melting of the sand. The morphometric properties of the filler have an influence on the arc plasma, e.g. the plasma composition, thermodynamic and transport properties. The approach for this thesis is to first identify existing modeling approaches and evaluate from a numerical and result quality point of view. Starting point are existing arc models that are developed mainly for atmospheric gas discharge, but have limited validity in this application. As a second step a suitable model should be adopted or implemented and the identified model shortcomings should be addressed. The necessary transport, thermodynamic and absorption coefficients for the metal vapor and silica sand mixture need to be gathered. As a third step the model is applied to predict the interruption process for a specified fuse. By means of comparison of test results and simulation results the model accuracy and sensitivity is evaluated.
- Modeling of switching arcs in mineral oil
Mineral oil is used as an insulation medium in medium voltage power distribution equipment, like transformers or pad mount switchgear. In different applications switching is performed by means of electromechanical contacts that are submerged in mineral oil. During contact opening, an electric arc is formed and energy is transferred into the mineral oil, mainly by heat conduction and radiation. As a result, mineral oil is vaporized and gas bubbles are formed that are interacting with the oil. Close to current zero, the gas bubble starts collapsing since the energy input is decreasing. This will change the plasma conditions like pressure and temperature, which influences the plasma decay and therefore the dielectric recovery. The main goal of the thesis is to develop and implement a stable and performant multiphase flow solver in order to be able to simulate the complex interactions that occur during arc switching/arc interruption in mineral oil. This includes the modeling of phase change (oil oil vapor) and determining the necessary thermodynamic, transport and radiation properties. Starting point are existing arc models that are developed mainly for atmospheric gas discharged, but have limited validity in this application. In a second step the processes during recovery should be investigated, since a prediction of successful interruption is determined by the rise of transient recovery voltage vs. dielectric recovery. In a third step the model accuracy and sensitivity is evaluated by comparison with actual test results.
- Power system with electric energy accumulation
Stability of electric power supply is - as a term - closely related with electrical energy production gained from renewable power sources (mainly from wind and photovoltaic power plants). The research will be focused on possibilities of accumulation of electric energy produced from renewable power sources with the help of modern technologies while focusing on hydrogen (VRB systems) utilization, accumulators based on Lithium and pumped storage hydro plants for its accumulation. The result of the work will be the draft measures in the energy system, which can solve time disproportion between electrical energy supply and take-off from the renewable power sources. The solution is connected with computer simulation (Matlab) and experimental measuring on a real model.
- System for monitoring of power quality and energy power flows in buildings with renewable energy sources.
Evaluate current options (worldwide) management and monitoring of building energy systems with renewable energy sources. Design and create a unified system of regulation and control for the system, which will include heat pumps, solar thermal collectors and hybrid energy system with accumulation (photovoltaics, wind turbines) in order to achieve the maximum possible interactions between different sources and devices with respect to environmental influences. Underlying assumption of the proposed system is based on the concept of using PLC.
- Test system for evaluation of electronic current and voltage transducers
The aim is to create a testing system that enables detailed analysis of current and voltage transducers with digitized output SampleValue (electronic sensor) according to IEC 61850-9-2. The test system has to be designed to evaluate the real time delay of the primary signal, error of amplitude and phase displacement of entire system and also its individual parts (the current / voltage transducer, digitizing units (A/D converter) and merging unit). The proposed system will be utilized not only for standard tests, but also for extended testing of frequency characteristic, the temperature dependence etc. The results of the tests will be used for determination of correction factors or curve to improve accuracy of such electronic sensors. The test system will be based primarily on the LabView platform.
- The island DC network for objects with renewable energy sources
Conceptual solution of an island DC networks where resource base consists of hybrid energy system (photovoltaic, wind turbine, accumulation). The goal is to propose a technical solution of energy system enabling in case of lack/excess energy cooperation with AC network and simultaneously ensure the safe power to the object. The solutions will be also the design and testing of control and monitoring algorithm.
- Using of the partial discharge for identification of fault in distribution networks
The power system reliability is high priority of present society. The main aim of the thesis is the analysis of present methods of condition evaluation of distribution network equipments and using the got information for fault detection in distribution networks. The example could be worse insulation state of transformers, bushings, single phase fault in line with covered conductors etc.
- Utilization of advanced revenue meters for distribution systems control and automation
The aim is to define expected functionalities of the revenue meters and their integration to individual security-technical layers of a distribution system management, furthermore to optimize metering features and data concentration for individual tasks.