Protection issues during system restoration

Power system blackouts are a very rare phenomenon in a well-planned interconnected power system. Nevertheless it is very important to have plans and systems in place to handle any eventuality even if it is remote. This report brings out various issues related to protection during a system restoration process. Power system protection is critical to a safe, efficient, and reliable power system. Protection engineers take every possible care to ensure that protection systems are designed considering all predictable eventualities and these constraints have grown over time. However, during system restoration, after a major blackout, it is possible for the protection elements to be presented with situations, which they can mistake for an unhealthy power system and the protection elements may operate. The prime concern during a power system blackout is to bring the system back to normalcy as fast as possible. At times, if proper care is not taken, the protection system can hinder and delay the restoration of the power system. This report discusses various such conditions that can occur during the blackstart of a power system and also suggests solutions to manage them without compromising the objectives of protection system i.e., to ensure a safe, efficient, and reliable power system.