| 摘要 |
PROBLEM TO BE SOLVED: To prevent the erroneous discrimination of the peak and bottom of electric power by discriminating whether or not the power reaches the peak in accordance with the sign of the changing rate of the current, when the sign of the changing rate of the power changes from positive to negative in a state where the bottom information of the power is stored. SOLUTION: A current changing rate detecting section 11 detects the current changing rate ΔI/ΔT corresponding to a time interval ΔT in a power changing rate ΔP/ΔT by using digital data Dn2 based on current signals. A current changing rate sign discriminating means 12 outputs '1' when the ΔI/ΔT is negative and '0' at other times. An AND gate section 13 computes the AND of the outputs of the discriminating section 12 and an AND gate section 55P and, when both the outputs are '1', namely, when both the ΔP/ΔT and ΔI/ΔT are negative after a power fluctuation curve rises, outputs '1'. A peak detecting section 56PA discriminates that the peak of power fluctuation is over, sets the outputs of a peak storing section 54N and a bottom storing section 54P at '1' and '0', respectively, and supplies a stepping-out phenomenon discriminating and processing section 57 with peak detecting information. |
