Research On Fault Location For Distribution Network With Distributed Resource

Distributed resource is the supplement and of centralized power grid.With the advantage of cleanness,environmental protection,sustainability and flexibility,the distributed resources obtain the rapid development and application in our country.However,because distributed resources are connected to distribution network in large quantities,the structure of distribution network will be changed;the direction of power flow is no longer single.Therefore,the problem that fault location for distribution network containing distributed resources will be more complicated,this paper mainly aims at above problem to carry on the analytic study.First of all,this paper introduces the current domestic and foreign research situation of fault location for distribution network,as well as the related concepts and the grid-connected standard requirements of distributed resources.Grid-connected control modes of several common distributed resources are described.Then,the distribution network model is built by using PSCAD/EMTDC simulation software to verify the influence of distributed resource on the direction and size of fault current.The impact of distributed resources on the existing fault location algorithm is analyzed in theory.Secondly,this paper presents a novel fault location scheme for distribution network in the presence of any possible distributed resource type.The unbalanced laterals and the capacitive effect of distribution line are considered.Only the fundamental values of voltages and currents measured before and after the fault at the substation and each DG unit bus are required to complete accurate fault location for the proposed method.The proposed scheme identifies the fault location using two steps.In the first step,based on the properties of fault resistance,a general fault location equation is derived,which can identify all possible fault location,this method overcomes the requirement of fault-type identification.In the second step,from the possible fault location,the exact fault location is then identified by matching the measured voltage at the substation bus and each DG unit bus with calculated ones and without using any additional devices.In the end,a modified IEEE 34-bus distribution system with two fixed-speed wind turbines was used to test and evaluate the proposed scheme by using PSCAD/EMTDC software.Test results verified the accuracy and robustness of the proposed scheme to identify the exact location under the effects of fault resistance,fault distance and load uncertainty.Thus,the proposed scheme is promising for practical applications.