Series-compensated line protection challenges in the CREZ region

Abstract

While series compensation of transmission lines is not new technology, it is becoming more prevalent due to significant changes in the way grids are being operated. Compensating lines makes better use of transmission line investments and available right of way. However, series capacitors create many challenges for protection engineers. These challenges are mitigated using modern protective relays, robust telecommunications channels, and advanced transient simulation tools to validate protection systems. The Lower Colorado River Authority (LCRA) in the United States is protecting a series-compensated line on their transmission grid for the first time as part of the Competitive Renewable Energy Zone (CREZ). This paper discusses experiences in designing, setting, and validating the new protection system.