Patent ID: 7504818
Filing Date: 2009-03-17
Classification: G01R,Y02E,Y04S

Abstract:
1. A rotation phase angle measuring device comprising: voltage measuring means for measuring a voltage instantaneous value v of an electric power system in a period of 1/(4N) of one period of a reference wave, where N is a positive integer, when the voltage instantaneous value v of said electric power system is expressed by a voltage rotation vector rotated in the counterclockwise direction with an origin 0 on a complex plane as a center; voltage amplitude calculating means for calculating a voltage amplitude value by an integral arithmetic calculation of a squared value of said measured voltage instantaneous value v in arbitrary timing for measuring said voltage instantaneous value v; chord length calculating means for calculating the length of a chord connecting tips of the voltage rotation vectors in said two timings by the integral arithmetic calculation with respect to a difference between two measured adjacent voltage instantaneous values v in one pitch period including said timing; and rotation phase angle calculating means for calculating a phase angle of said voltage rotation vector in one pitch period including said timing on the basis of the voltage amplitude value calculated by said voltage amplitude calculating means and the chord length value calculated by said chord length calculating means.