Accuracy improvement of impedance‐based fault locating method in distribution systems with DGs considering loss of laterals and load variations

摘要

Fast and accurate fault location methods will accelerate power system restorationrnprocess and then cause improvement on availability and reliability indices.rnPresenting a modified scheme in order to improve accuracy of impedance‐basedrnfault location method in electric power distribution systems (EPDS) equippedrnwith distributed generation (DG) units is the main goal of this paper. To achievernthis goal, an iterative algorithm is introduced to compensate load variations.rnAlso, a method is presented based on forward/backward sweep load flow tornconsider loss in all laterals of EPDS. Then, fault location will be determinedrnby using a comprehensive method that extracts a fifth‐order algebraic equationrnfor each type of fault. This method will be modified to consider the presence ofrnDGs in EPDS. In this paper, all the specific characteristics of real distributionrnsystems such as unbalanced nature of network and loads, different types ofrnloads, presence of multi‐phase laterals, and capacitive effects of distributionrnlines are taken into account. The proposed scheme uses only 1 measurementrnunit at the main substation and 1 measurement unit at the DG bus. In thisrnpaper, modified IEEE 34 node test system is simulated by using PSCAD/rnEMTDC software, and it is used as a test system to evaluate the performancernof the proposed method. Different scenarios such as the effect of fault distance,rnfault type, different fault resistances, and measurement unit errors are evaluated.rnThe results indicate usefulness and precision of the proposed scheme.