ROTATING MACHINE BASED DG ISLANDING DETECTION ANALYSIS USING WAVELET TRANSFORM

Abstract

The increased use of distributed generation in the power system due to increased load demand has brought about  many  benefits  to  the  power  grids.  This  is  due  to  the  concerns  about  whether  the  technology  in  use currently  in  power  generation  and  distribution,  is  sufficient  to  cover  the  future  increasing  demand  with  the limited supply. In response to this problem of increased load demand, efforts have been made to decentralize this  infrastructure  through  the  use  of  distributed  generators.  The  benefits  of  using  distributed  generation include;  improved  reliability  and  increased  efficiency  in  power  supply,  avoidance  of  transmission  and distribution capacity upgrades, improved power quality and reduced line losses, minimize peak  load demand,
reduce voltage flicker and eliminate the need of having high spinning reserve. Despite these advantages, un intentional islanding remains a big challenge and has to be addressed in integration of Distributed Generation
to the power system. Unlike inverter based distributed generators, rotating machine based generators with fast response governors and AVRs are highly capable of sustaining an island. Therefore, anti -islanding protection for these  generators  is  a  more  challenging  problem  in  comparison  with  the  inverter-based  DG.  This  paper  has analysed  the  various  methods  currently  used  in  islanding  detection  especially  for  rotating  machine  based distributed  generators  especially  by  use  of  DWT.  It  can  be  seen  that  there  is  a  quick  response  to  islanding detection due to the changing of the point of measuring of the current signals from the usual PCC to just after the utility circuit breaker. Hence islanding detection time is not affected here by the circuit breaker operation
time.  Though the kind of detection can be determined by human experts from the diagram, it is desirable and recommended to process the obtained wavelet transform results further with artificial intelligence techniques Such as fuzzy logic control.

Key words: Distributed generation, islanding detection, rotating machines