Detection of embedded generator islanding condition using elliptical trajectory technique

The number of renewable energy-based generators has continued to grow in recent years. Such generators are usually integrated or embedded into utilities´ network at distribution voltage levels and therefore commonly known as embedded generators. This type of operation in essence transforms a distribution network from being a passive to an active network. This in turn has created safety as well as technical problems. In addition to that a generator of this type is usually not under utilities´ direct control. Consequently it is very important to ensure that an embedded generator does not effect the quality of the supply to the customers during both normal and abnormal operating conditions. A major concern by industry is the islanding operation condition whereby a generator is disconnected from the associated utility´s network, for example due to a fault condition, but left to supply power to a part of the public network. The consequence of this happening could be very serious as far as the safety of personnel is concerned as well as the quality of power supply to the customers in the islanded network. This paper presents the results obtained from an investigation related to the application of elliptical trajectory technique for detecting the islanding condition described above. The proposed technique was tested on a simulated distribution system with an embedded generator and a criteria for detecting islanding condition has been identified