Protective Relay Studies for the Nigerian National Electric 330 KV Transmission System
An indepth study and analysis has been performed on the 330KV transmission protective relay schemes of the National Electric Power Authority. Some of the basic considerations taken into account in the study to optimize the settings on the existing protective relay schemes are presented. Typical calculations are performed to illustrate the guidelines enumerated in the setting philosophy. These settings as calculated are presented and major defects existing in the protective schemes pointed out. The fundamental reasons for requiring these specific protective relaying features are also reviewed. Other protective relaying schemes that can accomplish the same basic protection objectives are presented. Based on the Nigerian special system characteristics, schemes to correct existing protection inadequacies are recommended.