Island effect detecting method based on wavelet analysis

The invention relates to an island effect detecting method based on wavelet analysis, and belongs to the field of detection of electrical power systems. Problems that in the prior art, harmonics are inevitably injected in a power grid, and the quality of the power grid is damaged when an active detecting method is adopted, a wider undetected range appears, and detecting time is uncertain when a general passive detection method is adopted are solved. An island effect detector is used for detecting an island effect of a power supply system in the method, and a power grid in the power supply system and a distributed grid-connected generation system jointly supply power to an electricity load. The method comprises that a detector samples voltage signals of a common connection point of the power grid, the distributed grid-connected generation system and the electricity load; the voltage signals are decomposed in a four-order wavelet manner; and whether conditions that Ed4 is larger than or equal to A and Ed4 (i) is larger than or equal to B are simultaneously met or not is judged so as to determine generation of the island effect.