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This paper proposes to combine the voltage monitoring capability of smart meters with impedance-based fault location methods to provide an efficient fault location approach improving service restoration. The first step of the proposed methodology is to apply an impedance-based method to obtain a rough estimation of fault location. Since the result is an estimated distance to the fault, multiple branches can be indicated due to the typical distribution systems topologies. Therefore, the challenge is: how to recognize the actual fault location? To solve this problem, voltage measurements from smart meters are used to build the low voltage zones (LVZs). The main contributions of the proposed fault location technique are to decrease the multiple estimations associated with impedance-based methods, to propose a systematic approach to build the LVZs, and to explore the presence of smart meters for fault location. The proposed method was tested through intensive and extensive simulations in a real distribution system, proving its efficiency.

This paper proposes a fault-location method based on smart feeder meters with voltage sag monitoring capability. The main idea is to explore voltage measurements from monitors placed in different buses of distribution systems to estimate the fault location. The estimation is achieved by relating the voltage deviation measured by each meter to the fault current calculated based on the bus impedance matrix, considering the fault in different points. In order to improve the method accuracy, the loads are represented by constant impedance models and included into the bus impedance matrix. The performance of the proposed method is demonstrated by using a real distribution system. Sensitivity studies results show that the method is robust since it has good performance for different values of fault resistance, quantity, and location of the smart meters.

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Abstract-This paper investigates the voltage sag caused by distributed generation anti-islanding protection. This is a new powerquality concern associated with distributed generation expansion. Anti-islanding protection aims to disconnect distributed generators immediately after the opening of a recloser. As a consequence, after the reclosing operation, voltage sag will occur in some parts of the distribution system, since the loads are energized immediately but the generators are no longer present. In this context, this work presents the findings on our investigations about this problem. The results show that the resulting voltage sag level can violate powerquality limits. Thus, a set of indices has been introduced to characterize the severity of the voltage sag, and a load flow-based method has been proposed to predict the phenomenon. Sensitivity studies are also conducted in order to identify some key factors that influence this type of voltage depression.