Trans connection phase determining device, method, and program

PROBLEM TO BE SOLVED: To determine the connection phase of a transformer even when only information about power consumption by some of users connected to the transformer is usable.SOLUTION: A filter application unit 30 applies a filter for attenuating a low-frequency component to a phase current arising from the power consumed by at least one user connected to the transformer connected to either of phases corresponding to two combinations of a plurality of power-distribution lines. Similarly, the filter application unit 30 applies the filter to each of line currents flowing in each of the plurality of power-distribution lines. A correlation coefficient calculation unit 16 calculates each of correlation values indicating correlation between the phase current to which the filter is applied and each of the line currents. A connection phase determination unit 18 determines the phase to which the transformer is connected on the basis of each of the correlation values.