Measuring AC frequency and amplitude with gauge voltage group

This paper proposes a new method to measure AC frequency and amplitude by combining group theory and spiral vector theory. At first, the real frequency of power system is defined associated with a rotation phase angle in the complex plane. Then with the rotation phase angle and three voltage vectors, a gauge voltage group is constructed. Therefore the group´s two invariants - frequency coefficient and gauge voltage are discovered, and naturally AC frequency and amplitude are obtained with these invariants. Furthermore, for reducing the influence of noise, gauge sampling frequency is separated from data collecting rate, symmetry breaking criterion is proposed, and simple moving average is made. At last, three numerical examples and one field measurement example are provided. All results show that the proposed method is effective.