Shaping Frequency Dynamics in Modern Power Systems with Grid-forming Converters

TL;DR

This paper analyzes how grid-forming converters influence frequency stability in modern power systems, highlighting their potential to enhance controllability and system resilience amid increasing converter-based generation.

Contribution

It provides a fundamental and small-signal analysis of frequency dynamics with high converter penetration, demonstrating the benefits of grid-forming converters for system control.

Findings

Grid-forming converters improve initial frequency response.

System inertia reduction enhances frequency controllability.

Validated results in IEEE 118-bus system simulation.

Abstract

In this paper, frequency dynamics in modern power systems with a high penetration of converter-based generation is analysed. A fundamental analysis of the frequency dynamics is performed to identify the limitations and challenges when the converter penetration is increased. The voltage-source behaviour is found as an essential characteristic of converters to improve the initial frequency derivative of Synchronous Generators (SGs). A detailed small-signal analysis, based on the system's eigenvalues, participation factors and mode shapes, is then performed in a reduced system for different converter penetrations, showing that the flexibility of grid-forming (GFOR) converters as well as the system's inertia reduction may lead to have a more controllable system frequency. First-order frequency responses can be programmed for high converter penetrations, when GFOR operation can impose their dominance over SGs. These results have been validated in the IEEE 118-bus system simulated in PSCAD.