Multi objective optimization in charge management of micro grid based multistory carpark

Distributed power supply with the use of renewable energy sources and intelligent energy flow management has undoubtedly become one of the pressing trends in modern power engineering, which also inspired researchers from other fields to contribute to the topic. There are several kinds of micro grid platforms, each facing its own challenges and thus making the problem purely multi objective. In this paper, an evolutionary driven algorithm is applied and evaluated on a real platform represented by a private multistory carpark equipped with photovoltaic solar panels and several battery packs. The algorithm works as a core of an adaptive charge management system based on predicted conditions represented by estimated electric load and production in the future hours. The outcome of the paper is a comparison of the optimized and unoptimized charge management on three different battery setups proving that optimization may often outperform a battery setup with larger capacity in several criteria.Web of Science117art. no. 179

Low-cost extra-low voltage LED dimmer for tuneable white lighting

The colour appearance of light sources has a major impact on how people perceive space. With LED illumination lighting, the colour output can be tuned to virtually any perceivable colour, including any hue of white light. It has been established that the right shade of white light during the 24-hour day cycle has a positive effect on the human body's biological system. For this reason, it is very important to focus on the development and application of new lighting systems that have dynamically variable light outputs in order to imitate the sunlight. Circadian regulation is most responsive to short-wavelength light (460 nm = blue colour). This paper describes the development of a low-cost extra-low voltage LED dimmer for tunable white lighting systems aiming to achieve maximum electrical performance and light-output. This dimming module has two independent LED control channels and allows for a variable colour temperature control from warm white to cold white light. Experimental results of the dimming module efficiency measurements, correlated colour temperature (CCT), colour rendering index (CRI), illuminance and power consumption of the luminaire depending on the duty cycle for different control frequencies (200 Hz, 1.5 kHz, 5 kHz, 10 kHz and 20 kHz) are presented. The paper further describes the principle of creating control curves for an independent regulation of correlated colour temperature and illuminance. In the form of a table, the control curve outputs may be uploaded into a microcontroller. The paper details the construction, function and the advantages of this LED dimmer prototype.Web of Science253494

Modular Intelligent Image Storage

Import 26/06/2013Zjednodušenie a zjednotenie prístupu k určitému problému v informatike je cieľom akéhokoľvek rámcového riešenia, inak povedané frameworku. V rámci diplomovej práce som sa snažil využitím dostupných metód a spôsobov nasadenia, pokryť požiadavky zadania za účelom zisku čo najjednoduchšie rozšíriteľného riešenia. Uvedomenie si pojmu digitálneho spracovania obrazu a postavenie zadania na tomto požiadavku, tvorilo profilovanie konkrétneho využitia celého projektu. Diplomová práca postupne prechádza jednotlivými etapami vývoja od objasnenia problematiky oblasti, cez výber technológií vhodných pre riešenie, ďalej popisuje jednotlivé naimplementované celky a ich dôležité detaily. Súčasťou je takisto návod na nasadenie a jednoduché testovanie s popísanými výsledkami.Simplifying and unifying approach to some problems in computer science is the goal of any solution framework. In the thesis I tried using available methods and ways of usage to cover the requirements of the assignment to profit for as easy as possible extensible solutions. Realising of the concept of digital image processing and state of assignment on this requirement formed a specific usage of the entire project. Diploma thesis is gradually going through various stages of development from clarification of the issues through selection of appropriate technologies to the solution, further describes the implemented units and the important details. It also includes instructions for simple deployment and testing of with described results.460 - Katedra informatikyvelmi dobř

Towards the text compression based feature extraction in high impedance fault detection

High impedance faults of medium voltage overhead lines with covered conductors can be identified by the presence of partial discharges. Despite it is a subject of research for more than 60 years, online partial discharges detection is always a challenge, especially in environment with heavy background noise. In this paper, a new approach for partial discharge pattern recognition is presented. All results were obtained on data, acquired from real 22 kV medium voltage overhead power line with covered conductors. The proposed method is based on a text compression algorithm and it serves as a signal similarity estimation, applied for the first time on partial discharge pattern. Its relevancy is examined by three different variations of classification model. The improvement gained on an already deployed model proves its quality.Web of Science1211art. no. 214

An examination of thermal features' relevance in the task of battery-fault detection

Uninterruptible power supplies (UPS), represented by lead-acid batteries, play an important role in various kinds of industries. They protect industrial technologies from being damaged by dangerous interruptions of an electric power supply. Advanced UPS monitoring performed by a complex battery management system (BMS) prevents the UPS from sustaining more serious damage due to its timely and accurate battery-fault detection based on voltage metering. This technique is very advanced and precise but also very expensive on a long-term basis. This article describes an experiment applying infrared thermographic measurements during a long term monitoring and fault detection in UPS. The assumption that the battery overheat implies its damaged state is the leading factor of our experiments. They are based on real measured data on various UPS battery sets and several statistical examinations confirming the high relevancy of the thermal features with mostly over 90% detection accuracy. Such a model can be used as a supplement for lead-acid battery based UPS monitoring to ensure their higher reliability under significantly lower maintenance costs.Web of Science82art. no. 18

Usage of antenna for detection of tree falls on overhead lines with covered conductors

The direct contact of a tree or a branch of tree with Covered Conductors (CC) overhead lines causes Partial Discharges (PD) inside the insulation. The presence of PD degrades the insulation systems and eventually destroys insulation, which may lead to power delivery interruption. The detection and diagnosis of PD is an important tool to address the problem of tree caused faults in forested terrains. The PD occurs in the impulse component of the signal, which is usually measured by Rogowski coil (current signal) or single layer inductors (voltage signal). In this paper, we introduce a possibility to detect the tree caused faults with the usage of whip antenna. The advantage of the antenna is a very low price and the possibility to install antenna under voltage. The disadvantages are sensitivity to ferromagnetic materials and impossibility to distinguish affected phase. The measurements were carried out in the real environment in forested terrain in Jeseniky Mountains. The real environment is different from a laboratory conditions due to heavy noise (e.g. corona, radio emissions). This paper provides an examination of the background noise from the antenna signal. The experimental results indicate that the antenna may be successfully used instead of the current approach

Fault Detection for Covered Conductors With High-Frequency Voltage Signals: From Local Patterns to Global Features

The detection and characterization of partial discharge (PD) are crucial for the insulation diagnosis of overhead lines with covered conductors. With the release of a large dataset containing thousands of naturally obtained high-frequency voltage signals, data-driven analysis of fault-related PD patterns on an unprecedented scale becomes viable. The high diversity of PD patterns and background noise interferences motivates us to design an innovative pulse shape characterization method based on clustering techniques, which can dynamically identify a set of representative PD-related pulses. Capitalizing on those pulses as referential patterns, we construct insightful features and develop a novel machine learning model with a superior detection performance for early-stage covered conductor faults. The presented model outperforms the winning model in a Kaggle competition and provides the state-of-the-art solution to detect real-time disturbances in the field.Comment: To be published in IEEE Transactions on Smart Gri

Innovative bidirectional isolated high-power density on-board charge for vehicle-to-grid

This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm(3), and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching, the switching frequency was set to 150 kHz. A laboratory prototype was built to verify the properties and operating principles of the described charger topology. The on-board charger has been tested in a microgrid test platform. Due to the parasitic properties of the transformer and other electronic components, overvoltage with subsequent oscillations occurred on the primary side of the transformer and damped resonance on its secondary side. These parasitic properties caused interference and especially voltage stress on the semiconductor elements. These undesirable phenomena have been eliminated by adding an active element to the charger topology and a new transistor control strategy. This new switching control strategy of transistors has been patented.Web of Science2221art. no. 847

Individual Professional Practice in the Company

Import 04/07/2011Táto bakalárska práca pojednáva o priebehu absolvovania individuálnej odbornej praxe vo firme Tieto Czech s.r.o. Prax znamenala zúčastnenie sa na dvoch rozpracovaných projektoch v dvoch rôznych open-source frameworkoch, takže čítanie množstva kódu, učenie sa nových technológií, využívanie profesionálnych nástrojov bolo náplňou každého môjho dňa na praxi. V prvom projekte išlo zväčša o prácu na doplnkoch funkcionality a testovanie, v druhom bolo jeden z hlavných bodov implementovanie hierarchie medzi užívateľmi z dôvodu bezpečnosti a poriadku.This bachelor thesis discuss about the duration of passing the individual professional practice in the company Tieto Czech s.r.o. The praxis means an attendance at two semi-finished projects in two difference open-source frameworks, so the reading of a lot of code, learning a new technics, using of the professional devices was the filling of my each day on praxis. In the first project I had a work on addons and testing, in the second project there was one of the most important points to implement a hierarchy between users in case of security and order.460 - Katedra informatikyvýborn

Analýza časových řad

Nowadays emergence of the innovative approaches in data science and machine learning, enforces their use in modeling of the real world physical problems, even when they have been already explored and modeled with solid results. The evaluation of a partial discharge activity, as a phenomenon implying malfunction on an observed system, is one of such problems. The motivation of its reexamination and use of new data science approaches is motivated to increase the relevance of extracted knowledge which will be beneficial for the overall detection performance. The original data obtained by a patented metering device, deployed in the real environment, only underlines this need. This thesis deals with an analysis and feature extraction from the time series data in order to design a robust fault detection mechanism. The robustness means the ability to correctly process an input data with various defects and interferences while focusing only on what is relevant and to gather as much valuable information about it as possible. The entire work is a set of experimental models and analyses interconnecting a fundamental knowledge of the observed data with modern bio-inspired and soft-computing based machine learning algorithms and optimization approaches. The referential solution inspired by a state-of the art knowledge is designed with adjustable feature extraction process which parameters are further optimized making use of an swarm based optimization. Another models using evolutionary based feature synthesis, wavelet based signal decomposition or denoising driven by weighted singular values serve as the competitors in order to reveal other possibilities in studied problem. The estimation of entropy, complexity and chaos in the data was supposed to increase the set of applicable features for the detection. The separability of several complexity indicators, like sample entropy, approximate entropy, 0-1 test for chaos and correlation dimension, was examined on data containing all kinds of measured malfunctions. Gathered results were accompanied with a discovery of a significant instability of one testing indicator, which has been found and reported for the first time. The another author's proposals to represent the partial discharge pattern as a complex network are also novelties and they brought superior results in comparison with the state-of the art based classification models. They solid reasoning and simplicity offered multiple optimizations and evaluations which are documented in this work.Dnešní vývoj inovativních přístupů v oblasti vědy o datech a strojovém učení vynucuje jejich využití při modelování fyzických problémů v reálném světě, a to i tehdy, když již byly prozkoumány a modelovány se solidními výsledky. Vyhodnocení aktivity částečných výbojů, jako fenomén, který znamená poruchu pozorovaného systému, je jedním z těchto problémů. Motivace jeho přezkoumání a využívání nových přístupů v oblasti analýzy dat je motivována k tomu, aby se zvýšila důležitost získaných poznatků, což bude přínosem pro celkovou výkonnost detekce. Původní data získaná patentovaným měřicím zařízením, nasazeným v reálném prostředí, podtrhují tuto potřebu. Tato práce se zabývá analýzou a dolovánim vlastností z dat časových řad s cílem navrhnout robustní mechanismus detekce chyb. Robustnost znamená schopnost správně zpracovat vstupní data s různými vadami a rušeními, přičemž se soustřeďuje pouze na to, co je relevantní, a shromažďuje co nejvíce cenných informací o tom. Celá práce je sada experimentálních modelů a analýz propojujících základní znalosti pozorovaných dat s moderními bio-inspirovanými a soft-computing algoritmy pro strojové učení a optimalizačními přístupy. Referenční řešení inspirované nejmodernějšími poznatky je navrženo s nastavitelným procesem extrakce vlastností, které jsou dále optimalizovány pomocí optimalizace založené na hejnové inteligenci. Další modely používající evoluční syntézu vlastností, vlnový rozklad signálu nebo potlačení šumu řízené váženými singulárními hodnotami slouží jako konkurenty k odhalení dalších možností studovaného problému. Odhad entropie, složitosti a chaosu v datech měl zvýšit soubor použitelných vlastností pro detekci. Statistická oddělitelnost několika indikátorů složitosti, jako je entropie vzorku, přibližná entropie, test 0-1 pro chaos a korelační dimenze, byla zkoumána na datech obsahujících všechny druhy měřených poruch. Shromážděné výsledky byly doprovázeny objevem významné nestability jednoho testovacího indikátoru, který byl nalezen a poprvé publikován. Jiné autorské návrhy na reprezentaci částečných výbojů jako komplexní sítě jsou také novinkami a přinesly vynikající výsledky ve srovnání s nejmodernějšími klasifikačními modely. Jejich jasné odůvodnění a jednoduchost nabízejí řadu optimalizací a hodnocení, které jsou v této práci zdokumentovány.460 - Katedra informatikyvyhově