Voltage sag judgment method considering influence of phase angle on amplitude characteristics during sag

Abstract

The key to realize voltage sag compensation is to judge the occurrence of sag events quickly and accurately. The problems of existing small angle delay detection method are analyzed, and an improved voltage sag judgment method is proposed. Based on the construction of αβ coordinate system with small angle delay, the voltage characteristics of dq coordinate system at the time of sag are analyzed, and the expression of d axis component with amplitude information is derived. By predicting the change trend and magnitude of d axis component at the time of sag, the voltage sag can be quickly determined. The proposed method can overcome the influence of amplitude fluctuation in small angle delay detection method, improve the detec-tion speed, and is conducive to the follow-up compensation effect. Simulative results verify that the proposed method can effectively improve the real-time performance and accuracy of detection.