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.