Synchrophasor Initiative in India - erldc

SYNCHROPHASORS - INITIATIVE IN INDIA JUNE 20125 CHAPTER 5: UTILIZATION OF SYNCHROPHASOR IN OFF LINEThe synchrophasors data from the PMUs archived in the historian has been utilized extensivelyin analysis of grid events and validation of protection system. These applications have beenillustrated with the help of case studies in the sections ahead.5.1 Identifications of the type, nature and duration of faultA fault in A.C system gets reflected in the entire synchronized grid. Hence it is possible toanalyze the fault at a particular location by analyzing PMU data of any other substationconnected in the grid. Using voltage and current 40 ms data plots, it is possible to find out thetype of fault, fault duration, successful/ un-successful auto-reclosure and operation/ misoperationof protection system.Faults in transmission line could be balanced (Three phase line to line or line to ground) orunbalanced (Line to line or line to ground). During the fault, the voltage in the faulted phase dipssharply while the current rises sharply. The voltage/current normalize after the fault is cleared byoperation of the protective switchgear. Thus, the examination of the 3-phase voltage/currenttrends available from synchrophasors would reveal the time of the fault, the type/nature of faultthat has occurred and the duration in which it was cleared.5.1.1 Case Study-6: Three phase fault at 400kV Dadri on 13-Mar-2012The figure below shows the 400kV Agra bus voltage profile (Phase to Earth) during the threephase fault at 400 kV Dadri at 17:37:920 hrs on 13 th March 2012. It can be observed that thereis a sharp dip in voltage in all the three phases.POSOCO Page 61 of 143