A Method for Voltage Sag Source Location Based on Vague-Value Similarity

Voltage sag causes abnormal operation of the sensitive load. Locating sag source is the basis of troubleshooting and improving power quality. The methods employed to locate the source of voltage sags rely on a physical quantity that is sensitive to the number of measurements and dependent upon the voltage sag source. A vague-set-based sag source location method is proposed. Firstly, the positive sequence set of the node voltage is calculated in different faulty lines and points, and the positive sequence components are combined with the Gauss membership function of the monitoring quantity to calculate the support degree. Secondly, the hesitancy degree and opposing degree are computed and the vague values of the faulty line can be obtained according to the support degree, hesitancy degree and opposing degree. In addition, the similarity between the vague value of each line and the reference value [1, 1] is calculated. Besides, the sag source positioning index of each line is calculated by the largest similarity value among various line faults. Finally, taking the IEEE 14 and IEEE 118 bus systems as examples, eight types of similarity definitions are used to verify the accuracy of the method. The result illustrates that the proposed method has a good performance in locating the source of voltage sag with fewer measurements and hypo-sensitivity of the voltage sag source.