Aiming at the problem of poor real-time performance at the beginning and end of the positioning voltage sag that traditional method has

a detection algorithm for single-phase voltage sag disturbance localization based on the combination of αβ-dq transformation and Sobel operator at a small phase shifting angle is proposed.Firstly

voltage sag signal is preprocessed by morphological filter

and then the DC component is extracted by αβ-dq transformation with a small phase shift angle.Then

morphological Top-hat transformation and Sobel edge detection algorithm are introduced to carry out the square and amplification transformation of the amplitude of the fundamental wave voltage to further suppress the influence of the background gradient

so as to achieve the final positioning result.By comparing the simulation results with different methods

it can be seen that the proposed method has the advantages of small computation quantity and strong real-time performance

and greatly enhances the positioning precision of the voltage sag disturbance point.