Field Experience Commissioning Reactor Projects

This paper discusses the field experience gained from commissioning multiple San Diego Gas & Electric (SDG&E) reactor projects, as well as upgrading the protection of tertiary, line, and bus reactors in the SDG&E system. SDG&E was interested in providing more comprehensive protection packages for substation reactors. In 2019, SDG&E started upgrading reactor protection using modern relays and protection practices per recommendations that were ultimately published in IEEE C37.109-2023.

SDG&E presented the tech paper “SDG&E Relay Standards—Updating Tertiary Bus and Reactor Protection” in 2019, discussing the approach for 500/230/12 kV transformer tertiary bus and reactor protection. SDG&E subsequently has upgraded and commissioned shunt reactors with updated protection and turn-to-turn protection schemes, as discussed in the latest revision of the IEEE standards.

SDG&E line reactors are located near series-compensated lines, and various literature exists discussing subsynchronous resonance for these conditions and the challenges for sensitive protection elements. This paper also discusses delayed-current zero crossing due to high X/R and conventional protection schemes, such as differential, directional overcurrent, neutral overvoltage, and normalized negative-sequence voltage and current. The paper also highlights the latest protection techniques for turn-to-turn faults and the optimization of set points for each installation to get the most benefit out of sensitive protection elements. Highlights of field commissioning, with references to actual field events, include:

• Sensitivity of protection schemes during system transients and changes used to optimize performance. • Undesired trip outputs during system testing and mitigation used to remove undesired tripping. • Dependence of phasor quantities on voltage reference settings and reference changes made to provide security. • Value of continuous monitoring data using synchrophasors, allowing operational review during system events.