Ehv Reactor Protection: A Utility’s Perspective

Shunt reactors on extra-high-voltage (EHV) lines and buses are becoming more common. The grid is changing with investment in long lines to bring remote, renewable resources to load centers. Utility-scale generating facilities made up of inverter-based resources are displacing conventional generation and often have little ability to absorb reactive power.

Coincident with the need to install more shunt reactors on the system, reactor protection practices have evolved with new technology and new ideas. IEEE C37.109-2024, IEEE Guide for the Protection of Shunt Reactors represents a significant update over the previous version published in 2006. As is characteristic of an IEEE guide, it presents many generally accepted practices, and it is up to the user to select those that best fit within their practical requirements and general philosophies.

Ameren has updated their protection standards to take advantage of the best ideas from the new guide. This paper describes Ameren’s new reactor protection standard and the perspectives that defined the design. Readers can use this paper as a practical reference for navigating this new 93-page guide.