Pages: 11-20

Abstract

Along with the development of power systems, the need to provide reliable power is also increased. So that electricity consumers expect to see the least amount of interruptions in received electrical energy. One of the things that makes it difficult is detection of the errors of short circuit caused in the network in terms of current transformers saturation. With the saturation of current transformers, protective relays encounter numerous problems in dealing with current transformers. In this research, it was tried to provide useful and practical solutions to this. It has been suggested that current transformer saturation in terms of network error is detected using wavelet transform and then the protective relay zone is changed to deal with this. Differential and distance relays are selected for this and for each of them, an algorithm has been suggested to detect saturation current, and then to deal with it. In order to detect current transformers saturation, wavelet transform, which is a new method in digital signals processing, was used. Wavelet transform has high-speed performance and Due to its simple structure, it can also be implemented in protective relays. Simulation on a modeled power system was performed based on the actual network in EMTDC/PSCAD software and its outputs were analyzed by using