Effective System Grounding. Analysis of the effect of High penetration of IBRs

The transmission system has been grounded since its interconnection began in the 1900s. For over a century, generation was overwhelmingly provided by rotating machinery, and industry standards were implemented to keep the grounding effective. With the growing interconnection of large quantities of electronic power sources (inverter-based resources, for example) on the transmission system, some underlying assumptions related to the sources being rotating machinery are no longer valid. Consequently, traditional system grounding practices must be reexamined to ensure proper grounding as the transmission system evolves. This paper reviews why transmission systems are designed to be grounded, then discusses ways to keep the system grounded when most of its generation sources are inverters.