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Influences of electromagnetic fields on the natural environment

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This paper deals with electromagnetic field generated by human-made sources and its impact on natural environment. The biological effects of low and high frequency electromagnetic fields are presented. Results of investigation with animals are shown. The norms and regulations concerning the levels of electromagnetic field intensity are reviewed. Finally some recommendations respecting protection[...]

Use of fuzzy based valve operation for transient stability improvement

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This paper proposes a fuzzy based valve to divert the steam to a storage tank during the occurrence of a fault in a power system in order to improve stability of the system. The advantages of this technique over fast valving are discussed. The rate of opening and closing of valve are decided by the fuzzy controller. The valve operation is coordinated with fuzzy based braker. The technique is demonstrated for a single machine infinite bus system. Streszczenie. W artykule zaproponowano zastosowanie sterowania zaworów opartego na technice rozmytej, odwracającego przepływ pary w zbiorniku podczas wystąpienia awarii w systemie elektroenergetycznym, w celu poprawy stabilności systemu. Przedyskutowano zalety tego rozwiązania przy zastosowaniu szybkiej regulacji turbin. O szybkości otwarcia i zamknięcia zaworu decyduje układ regulacji rozmytej. Działanie zaworów jest skoordynowane z hamulcami regulowanymi w technice rozmytej. Technika ta jest przedstawiana w odniesieniu do układu jednomaszynowego. (Wykorzystanie logiki rozmytej w sterowaniu zaworami) Keywords: fuzzy controllers, fast valving, transient stability Słowa kluczowe: sterowanie rozmyte, szybka regulacja turbin, stabilność przejściowa. Introduction Since 1920, when the grids were formed, the engineers experienced the problem of transient instability. The first measure taken against this phenomenon was to make use of fast circuit breakers which reduced the fault clearing time. Meanwhile the power system network grew rapidly and utilities started sharing their generation by borrowing power from each other. The interconnectivity of the network made this problem even more complex as fault in one area may result in a generat[...]

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