| 摘要 |
PROBLEM TO BE SOLVED: To provide a direction discriminating method which accurately performs direction discrimination in a short time. SOLUTION: A voltage waveform is presumed sinusoidal with the same frequency as the power source. According to the measured sampled voltage and sampled periods, a voltage waveform composed of an amplitude and a phase, by which the error between the presumed voltage waveform and a sampled voltage becomes minimum is presumed by the method of least squares, and a current waveform is similarly presumed. The direction of a short circuit and the direction of power are discriminated by the phase difference between the presumed current waveform and voltage waveform. Accordingly, voltage waveform and current waveform can be presumed from the measured values obtained without using any filter. Delays produced by a transient characteristic by a filter are prevented, and direction can be discriminated accurately in a short time. |
