doc. Ing. Stanislav Mišák, Ph.D.
Vysoká škola báňská - Technická univerzita Ostrava,
Fakulta elektrotechniky a informatiky,
Katedra elektroenergetiky
17. listopadu 15
708 33, Ostrava-Poruba
místnost CPIT E208
telefon: +420 59 732 9308
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The majority of medium-voltage overhead lines are currently operated with AlFe conductors which have a simple construction and which rank among the cheapest versions of overhead lines from the point of view of initial investments. These overhead lines can be susceptible, however, to faults primarily in mountain and wooded areas, with an ensuing decrease in safety and operations reliability, as well as with limitations to the electric power supply. This draws attention to outdoor overhead lines with covered conductors, which are relied upon for use for connecting "defined" systems (SMART GRIDS) with an external electric power system. These conductors, with mostly XLPE and PE basic insulation, are able to resist both mechanical and electric strain caused by falling trees or branches and consequently their total number of faults is significantly lower. Massive usage of overhead lines with covered conductors is currently contradicted by prevailing difficulties in detecting faults. This article describes the possibility of detecting covered conductor faults and verifying the methodology under both laboratory and real conditions.
Číst dál...Nowadays, runs an intensive research in development area of energy system with specific requirements, so-called SMART-Grid and Off-Grid. Researchers deal with this phenomenon at several levels across the spectrum, e.g. in scientific research teams, commercial teams and private sector - represented by multinational companies and investments groups. Specific requirements include energy independence of external power supply, operation with equally generation-consumption balance, maximal utilization of renewable energy sources and utilization of the energy storage covering the energy deficit and vice versa. In most cases is generally discussing only the benefits and proactive development direction of these concepts, but as usually with every product, there is no longer mentions the issues of the operations in long time term. The goal of this paper is to point out the operation issues of SMART-Grid and Off-Grid systems with specific requirements, especially with regard to the protection methods and abnormal operating conditions as well as the possibility of using a Multiagent system for the management and the control of a small Off-Grid system.
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