Frequency Quality Assessment of GFM and GFL Converters and Synchronous Condensers

TL;DR

This paper evaluates how different inverter-based resources and synchronous condensers affect grid frequency quality, highlighting that GFM IBRs improve frequency stability, but combinations of GFL IBRs and condensers can also meet standards.

Contribution

It provides a comprehensive comparison of GFM and GFL IBRs, synchronous condensers, and their impact on frequency quality through extensive simulations.

Findings

GFM IBRs significantly improve frequency quality.

Combining GFL IBRs with condensers can meet frequency standards.

The role of automatic generation control is less clear in GFM-dominated grids.

Abstract

This paper compares the impact of different conventional and emerging technologies and control strategies on frequency quality. We study, in particular, the long-term dynamic performance of grid-forming (GFM) and grid-following (GFL) inverter-based resources (IBRs) as well as conventional synchronous machines. Extensive simulations and several realistic scenarios consider both short-term and long-term aspects of frequency quality. It is shown that, while overall GFM IBRs significantly improve frequency quality, a combination of GFL IBRs providing frequency support such as wind and batteries, and synchronous condensers, might be enough to meet similar frequency quality standards. Another result of the paper is that the need for automatic generation control (AGC) becomes less clear in GFM IBR-dominated grids from a frequency quality perspective.