Title :
An adaptive differential relay for ct saturation based on wavelet Transform
Author_Institution :
Electr. & Comput. Eng. Dept., Ilam Univ., Ilam, Iran
Abstract :
Differential protection relays may false tripping for external faults due to current transformer saturation (CT). This paper presents an adaptive technique for transformer differential protection against saturation of current transformers, based on differential currents. A Wavelet Index (WI) by wavelet Transform has been devised using extracted feature from differential currents due to saturation currents. In this technique, with beginning of saturation of current transformers, the restrain currents in area zone of the differential relay will increase. The proposed algorithm is evaluated by using various simulated internal fault on a power transformer, saturation current cases and different magnetizing inrush currents that has been modeled using Electromagnetic Transients Program software. Results of evaluation study show that, proposed wavelet based differential protection scheme can stable in CT saturation events. The obtained results demonstrate precise operation of the proposed algorithm in different conditions.
Keywords :
EMTP; current transformers; power system faults; power system protection; power transformers; relay protection; relays; wavelet transforms; CT saturation; current transformer saturation; different magnetizing inrush current; differential current; differential protection relays; electromagnetic transients program software; power transformer fault; saturation current; wavelet index; wavelet transform; Circuit faults; Current transformers; Fault currents; Power transformers; Relays; Surges; Wavelet transforms;
Conference_Titel :
Advances in Energy Engineering (ICAEE), 2010 International Conference on
Conference_Location :
Beijing
Print_ISBN :
978-1-4244-7831-6
DOI :
10.1109/ICAEE.2010.5557608