TRANSACTIONS ON ELECTRICAL ENGINEERING

ISSN 1805-3386

November 19, 2017








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2017 No.1

Control Systems for Street Lighting

Janiga, P., Lipnický, L., Gašparovský, D.

Public lighting is a specific type of lighting system with various requirements. It is a lighting system which is subject to many influences. Some impacts are changing very rapidly but a lighting system is designed for a specific case. These effects are for example the traffic density or impact of weather. Comprehensive regulation taking into account all the effects does not currently exist but particular systems taking into account the subtasks are occurring. The aim is to show the possibilities and also the technical prerequisites for the realization of such systems.

 

Keywords: public lighting, adaptive control, dimming

 

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Changes of Insulation Properties of Photovoltaic Cables Caused by Ageing Treatment

Packa, J., Kujan, V., Štrkula, D., Šály, V., Perný, M.

An important part of the photovoltaic power plants are cable systems. The dielectric properties of cables, reliability and durability depend on quality of production processes, operating conditions and degradation factors, as well. Expected lifetime of the cable systems is more than 20–30 years in general. Their failure free operation and long-term stability of properties has a direct impact on the economic return of the investments. According to our experiences the tests in compliance with valid standards are not adequate to verify the real life time during operation. The photovoltaic cables intended for use in outdoor applications for the connection between the solar panels and possible connection between panels and inverter were chosen for our experiments. The changes of the insulation resistance and breakdown voltage caused by some degradation factors, mainly water, are presented. This research was inspired by a real failure in operation.

 

Keywords: photovoltaics, cables, insulation resistance, breakdown voltage, water, ageing, degradation factors

 

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Assesment of Damage of Solar Heterojunction a-SiC/c-Si Induced by Neutron Radiation

Perný, M., Šály, V., Mikolášek, M., Janíček, F., Kujan, V., Packa, J., Huran, J.

Amorphous silicon carbide is known as a material resistant except other influences also against radiation. This study investigates the effects of the neutron radiation on electrical characteristics (I-V characteristic, impedance spectra and obtained dynamic parameters of AC equivalent circuit) of solar cell a-SiC/c-Si heterojunction structure. The heterojunction structure was irradiated using neutrons with neutron fluency 1013 cm-2. Existence of neutron induced structural defects, which could be introduced within the semiconductor structure of heterojunction, has been illustrated using DC and AC analyses. The structural defects induced by neutron particle radiation affect mainly the trapping mechanism. The process results in the changes of electronic elements are included into the proposed equivalent circuit.

 

Keywords: amorphous silicon carbide, structural defects, equivalent circuit, dynamic parameters

 

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Analysis of Support Schemes and the Possibilities of Settlement of the Balance of Electricity Generated from Renewable Energy Sources

Holjenčík, J., Janíček, F., Šály, V., Knošková, K., Šišková, D., Perný, M.

Support for electricity produced from renewable energy sources is a key priority for the European Union due to reasons of security and diversification of the energy supply, environmental protection, sustainable development, and because the use of electricity from renewable sources is an important part of the measures necessary to comply with the Kyoto Protocol. The article is also focused on several options of the settlement balance between the producer and supplier of electricity produced from renewable energy sources.

 

Keywords: renewable energy sources, support, price of electricity, the settlement balance

 

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Modelling of Metal Oxide Surge Arresters in Simulation Software DYNAST

Síťař, V., Veleba, J.

This paper describes the possibilities for mathematical modelling of gap-less surge arresters in the simulation software DYNAST. This tool does not belong to standard modelling softwares in the field of electric power engineering. However, it may provide some key advantages when compared to more frequently used software such as EMTP-ATP and MATLAB-Simulink. Description of the metal oxide varistor modelling at temporary and switching overvoltages, fast-front states, and lightning strokes is presented. More information about the defined internal structure of the surge arrester models and ways for implementing respective V-I characteristics are provided. To verify the correct behaviour of the models, both slow and fast overvoltage scenarios are simulated and evaluated.

 

Keywords: metal oxide varistor (MOV), gap-less surge arrester, surge arrester model, V-I characteristic of the surge arrester, temporary and switching overvoltages, lightning stroke, simulation software DYNAST

 

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Data Acquisition System for Cold Crucible

Jiřinec, S., Rot, D.

The purpose of this article is to introduce the data acquisition system for a cold crucible. The first part describes the induction system, cooling system and components used for the measurement and data collection. The next part is devoted to the program created in the LabVIEW software. It describes the parts of the program used for the CompactRIO chassis and program designed for an industrial PC that is used for visualization and data storage. At the end the main features of the user interface are explained.

 

Keywords: data acquisition system, LabVIEW, CompactRIO, induction heating, cooling system

 

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