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

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

Electrical Part of Power Stations

Import 03/08/2012Tato bakalářská práce popisuje problematiku elektráren, zejména jejich elektrické části. Jsou zde popsány základní principy funkce různých druhů elektráren, možnosti provozu, jednotlivá technologická zařízení a jejich vliv na chod a celkovou účinnost elektrárny. Podrobně jsou popsány jednotlivé prvky elektrické části elektráren, možné způsoby jejich provozu a zapojení. Jsou zde také popsány možnosti realizace a zapojení ochran jednotlivých prvků elektrické části a také možné způsoby pokrytí vlastní spotřeby elektrárny. Poslední část práce popisuje některé ze současných trendů.This thesis describes the problem of power stations, especially their electrical parts. It describes the basic operational principles of different types of power stations, the possibility of operation, individual technological devices and their effect on the operation and overall efficiency of power stations. There are described in detail the individual elements of the electric part, possible ways of their operation and connection. There are also discussed the possibilities of protection individual elements of electrical parts and possible ways of covering power station own consumption. The last part describes some of the current trends.410 - Katedra elektroenergetikyvelmi dobř

Photovoltaic Panels Power Supply for the Crossing Safety Devices

Import 05/08/2014Tato práce se zabývá problematikou napájení přejezdových zabezpečovacích zařízení fotovoltaickými panely. Za tímto účelem byla vypočtena spotřeba nejběžnějších přejezdových zabezpečovacích zařízení na našem území a vyhodnoceny možnosti jejich napájení. Rovněž byla zpracována data z dlouhodobého měření na zkušebním přejezdu, napájeném fotovoltaickými panely. Na základě tohoto měření byl navržen zdroj pro přejezdové zabezpečovací zařízení typu JLC z produkce firmy AŽD Praha.This thesis deals with the problems of power supplies for the crossing safety devices, provided by photovoltaic panels. For this purpose, the consumption of the most common crossing safety devices in the Czech Republic was calculated. The data from long-term measurement of the test crossing, fed by photovoltaic panels, was also processed. Based on this measurement, a power source for crossing safety device type JLC (production of AŽD Praha company) was designed.410 - Katedra elektroenergetikyvýborn

Fast algorithm for contactless partial discharge detection on remote gateway device

Detection of the high impedance fault caused by vegetation is one of the biggest challenges brought by the usage of covered conductors in medium voltage overhead power lines. One of the accompanying events of long-term contact of vegetation with the XLPE insulation is partial discharge which damages the insulation. Current systems for the detection of partial discharge have two major problems: the price and difficult installation. In this paper, an approach for the detection of the partial discharge from the data collected by the antenna is described. This approach is focused on the small computational demand and low false positive rate. Thanks to the small computational requirements, it can be run on the remote gateway devices which are collecting the data from the antenna. It is composed of four steps: outlier detection, outlier clustering, feature extraction, and classification. It is shown that this approach greatly improves the detection rate and lowers false positives compared to the previous algorithm used for partial discharge detection based on the data from an antenna, making it fit to use in the production environment.Web of Science3732130212

A simple method for tree fall detection on medium voltage overhead lines with covered conductors

Covered conductors are an alternative to aluminum core steel reinforced medium voltage overhead lines in forested terrains. The covered conductors are highly reliable due to the XLPE insulation system, which prevents the short-circuit current in case of contact of phases with the surrounding vegetation. However, the disadvantage of the covered conductor operation is the problematic detection of high impedance faults. Such type of faults is usually caused by the surrounding vegetation. The covered conductor may get ruptured or damaged due to the destructive degradation of the insulation system during the high impedance fault. This article contains a description and results of a new fault detection system for medium voltage overhead lines with covered conductors. The method of insulation fault identification is based on partial discharge activity detection. Our aim is to develop cheap and reliable online detector, which could be installed in large quantities for optimal high impedance fault detection and localization. Common partial discharges detectors are too expansive for this purpose.Web of Science3631417141

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

Antenna contactless partial discharges detection in covered conductors using ensemble stacking neural networks

High impedance faults caused by vegetation are difficult to detect when covered conductors in medium voltage overhead power lines are used. Long-term contact of XLPE insulation with vegetation causes partial discharges (PDs) which damage the insulation. Although a cheap and easy to install, contactless detection method was developed using an antenna, there is a lack of classification algorithms for this method. Only two custom machine learning algorithms have been tested so far, and both rendered unsatisfactory results for the real application. This work investigates the use of neural network algorithms for this problem and the application of heterogeneous stacking ensembles using neural networks. We used real data collected from a number of detection stations in the Czech Republic. Also, we limited ourselves to supporting edge computing using devices such as Edge TPU. We propose the application of a heterogeneous stacking ensemble neural network to classify PDs obtained by the contactless method. The algorithm we propose is based on a stacking ensemble with a novel combination of base learners, and the Wide and Deep neural network is used as a meta-learner. We compared the results of our algorithm with other algorithms designated for time series classification. Also, an ablation study of the ensemble was conducted, and satisfactory results were obtained using the proposed algorithm. The ensemble outperformed all algorithms tested and is usable on the edge using AI HW accelerator as the ensemble is only feedforward and contains only well-used and known layers. This research improves our understanding of the classification of PDs using the contactless PD detection method and also introduces a stacking ensemble of convolutional neural network and autoencoders for a time series classification for the first time.Web of Science213art. no. 11891

Identification of partial discharges in medium voltage insulation systems

Izolované závěsné vodiče představují alternativu k AlFe vodičům při realizaci nadzemních vedení VN, a to zejména v zalesněném terénu. Jejich hlavní výhodou je vyšší spolehlivost. Ta je zajištěna izolací vodiče, takže v případě kontaktu fázových vodičů s okolní vegetací nedojde ke zkratu či zemnímu spojení, popřípadě mezifázovému zkratu. Nevýhodou jejich použití je však problematická detekce izolačních poruch, které jsou způsobeny poškozením izolace výbojovou činností či pádem vodiče na zem. Jelikož je poruchový proud díky izolaci v takových případech velmi malý, nelze tyto stavy detekovat běžnými číslicovými ochranami. Tato práce obsahuje popis nového systému detekce izolačních poruch závěsných vodičů a výsledky z jeho testování. Izolační porucha je detekována na základě činnosti částečných výbojů, které jsou průvodním jevem těchto poruch, s využitím bezkontaktního snímání výbojové činnosti.Covered conductors are alternative to aluminum core steel reinforced medium voltage overhead lines in a forested terrain. The main reason for the use is their high reliability. It is given by the XLPE insulation system, when in case of contact of phases with surrounding vegetation, there is no short-circuit current. However, the disadvantage of the covered conductors operation is the problematic detection of faults, when the covered conductor is ruptured due to atmospheric overvoltage or is damaged due to destructive degradation of the insulation system. The fault detection is problematic because of the very small value of the fault current. The starting element of the standard digital relay protection cannot detect this type of faults. This thesis contains description and results of a new fault detection system for overhead lines with covered conductors. The method of insulation fault determination is based on partial discharges activity detection.410 - Katedra elektroenergetikyvyhově

A complex classification approach of partial discharges from covered conductors in real environment

Partial discharges are known as indicators of degradation of insulation systems. In case of medium voltage overhead lines with covered conductors, the internal partial discharges indicate the degradation of insulation system, rupture or downfall of the line. The reliability and selectivity of methods to detect internal partial discharges in the covered conductors are mainly given by the level of background noise. The background noise distorts the pattern of partial discharges (PD-pattern) and decreases the capability of detection methods to recognize the features of PD-pattern corresponding to the degradation of an insulation system. This paper presents the results from the testing of a developed and optimized model for detection of covered conductor faults. The ability to identify covered conductor faults was verified in the real environment.Web of Science2421104109