Non-communication protection for radial connected distribution systems

This paper presents a new noncommunication protection scheme for distribution systems by combining the new techniques developed with the conventional directional overcurrent protection. In the scheme, the relay equipped with a number of new protection techniques to detect the system operating condition and adaptively select the protection function to be used, depending on the direction of the source to the relay location, therefore, accelerating the operation that isolates the fault from the both ends of the line section. Consequently, the system can be reconfigured automatically to allow the power supply to healthy line sections to be restored quickly. Extensive EMTP simulation studies with respect to a typical open ring main system under various fault conditions have been conducted. The results show that the proposed techniques are able to accelerate the automatic fault clearance function from both ends of the protection line section.