EE & CPEN 7 - Avista Project

Student Team: Brett Bazaldua, Rodney Mori, Daniel Austin, Michael DeHaan, Catherine Kerns, Michael Matre
Advisor: Dr. Peter McKenny
Sponsoring Organization:  Avista
Liaisons: Randy Spacek, Kevin Damron

 Optimization of Polarizing and Directional Elements in an SEL-421

            Relay for the Avista 230 kV Transmission System


The Avista 230 kV transmission system carries the bulk power from the Clark Fork river hydroelectric system to Spokane. The system has become complex as many of the lines run in parallel with Bonneville Power Authority (BPA) transmission lines. Autotransformers, connecting 230 and 115 kV transmission systems are interspersed at many locations. Abnormal conditions such as faults are detected by relays that operate circuit breakers, thus disconnecting a line and interrupting the flow. At certain times of the year, the loss of a line can trigger generation dropping at the Clark Fork hydroelectric plants. Due to the criticality of the system, false operations by relays for problems on parallel lines may cause greater loss of generation or disruption of flow. Avista has had false operations in the past and optimizing the relay polarizing and directional element settings will ensure proper operation for abnormal system conditions.