Evaluation Of Voltage Sags Instigated By DG With Anti-Islanding Protection(AIP)

The voltage drops due to temporary faults or starting heavy loads,named voltage dip or voltage sag.The most severe effect of voltage sags is the sudden and unexpected interruption of manufacturing processes,which can cause significant economic damage to the customers fed by the distribution network.The surveys showed that average value of cost per dip event is between ∈2000 and ∈4000.The voltage sag is a key issue and this arise problem is being discussed.Distributed generation(DG)is an approach that employs small-scale technologies to produce electricity close to the end users of electric power.DG units may also cause a voltage dip in the system that may be experienced by other customers as DG can take power from system for its operation.Such voltage sags occur after fault events,which are different from those caused by faults,or motor or transformer energizing.Not much work has been done on voltage sag caused by DG with configuration of anti-islanding protection.To address this key issue,this work analyses the voltage sag occur due to DG anti-islanding protection(AIP).In order to analyze this problem and its solutions to mitigate voltage sag(V.S),this work presents load flow analysis of an electrical distribution network with condition of anti-islanding protection(AFP)that aims to disconnect DGs right after the opening of a re-closer.As a result of this,voltage sag will occur in some parts of the distribution system after the re-closing operation.The results illustrate that the resulting voltage sag level can deviate power quality limits.Thus,a set of indices has been introduced to describe the intensity of the voltage sag,and a load flow-based(LF)technique has been suggested to conclude the phenomenon as the voltage sag caused by DG anti-islanding protection can be characterized by using three indices.This work investigates three potential solutions(ENTM,ICVRM and PVDGM)can be adopted by the utility and/or by the DG owners.In ENTM,activate step voltage regulator(SVR)to non-sequential mode(or voltage averaging)tap changing function.In ICVRM,control voltage regulator devices to operate within defined regions and auto-cap banks can be operated to work in reactive power bands.Finally,in PVDGM,configure all DGs to PV control mode and set their voltage reference in such a way that PCC voltage must equal to that calculated without generators.