Upstream and Downstream Localization of Voltage Sag Source Based on Downstream Equivalent Fault Distance

Voltage sags cause significant economic losses in people's daily lives, making it particularly important to pinpoint the location of the disturbance source to clarify the responsibilities of both upstream and downstream parties. Most current methods do not account for the presence of distributed generation (DG) on the user side, leading to less-than-ideal accuracy. This paper proposes a method for voltage sag source location based on downstream equivalent fault distance, which can achieve upstream and downstream localization of voltage sag source in distribution networks with DG. The method first involves identifying the equivalent parameters of the system's three-sequence network, then calculating the equivalent fault distance based on the identified fault type, and finally determining the relative position of the disturbance source based on the equivalent fault distance. Testing and analysis using the improved IEEE 33 system demonstrated high localization accuracy, validating the effectiveness of the method.