Measuring AC power based on symmetry principles

The paper applies symmetry principles to measure AC power. After obtaining frequency-dependent rotation phase angle with symmetry groups of voltage, the paper calculates gauge active and reactive power with symmetry groups consisting of instantaneous voltages and currents and obtains real active and reactive power. Similarly, the paper calculates gauge difference active and reactive power with symmetry groups consisting of difference voltages and currents and obtains real active and reactive power. Then, the paper proposes symmetry breaking criterion to distinguish large disturbances. At last, the paper gives a numerical example. All results show that symmetry principles are effective for AC systems.