The invention provides an electric energy quality regulation method, voltage temporary change detection method and dynamic voltage restorer. The voltage temporary change detection method comprises thefollowing steps: acquiring an electric grid voltage signal, selecting a decomposition scale, performing initial wavelet transformation, and acquiring wavelet coefficients of a first set frequency band and a second frequency band; performing single reconstruction for the wavelet coefficient of the first frequency band, and acquiring a fundamental wave signal of the electric grid voltage; performing secondary wavelet transformation, acquiring a first frequency band component and a second frequency band component; performing single reconstruction for the second frequency band component, and determining start and stop time of occurrence of voltage temporary change; and performing single reconstruction for the first frequency band component, and determining fundamental wave electric grid voltage temporary amplitude information. Double wavelet transformations are used for detection of the voltage signal containing temporary change and harmonic waves, based on wavelet transformation multiresolution analysis characteristics and singularity detection property, decoupling of harmonic waves and temporary change electric energy quality problems is solved, noise influence is restrained, accurate positioning of a temporary change signal is completed, time delay can be reduced effectively, and influence on electric grid real-time compensation is reduced.