| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the system protective function having serious influence on social life from being performed unnecessarily and easily, by enhancing the reliability on detection of power oscillation. SOLUTION: A p-side oscillation condition discriminating 4 operates the amplitude value of the p-side oscillation of power wave and the attenuation factor, and discriminates the p-side oscillation condition, based on this operation result. Moreover, an n-side oscillation condition discriminating unit 5 operates, for power, the n-side amplitude of the system and the attenuation factor, and judges the n-side oscillation condition, based on this operation result. An AND circuit 6 outputs a power oscillation detection signal, when both the p-side oscillation condition and the n-side oscillation conditions are materialized.
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