Mapping of Dynamics between Mechanical and Electrical Ports in SG-IBR Composite Grids

TL;DR

This paper introduces a port-mapping method that unifies mechanical and electrical dynamic analyses in power grids with inverter-based resources, enhancing understanding of subsystem interactions and aiding parameter tuning.

Contribution

A novel bidirectional port-mapping approach that bridges mechanical and electrical views in SG-IBR composite grids, providing a comprehensive analysis framework.

Findings

Effective in single-SG-infinite-bus system

Applicable to weak-grid IBR systems

Demonstrated on IEEE 14-bus system

Abstract

Power grids are traditionally dominated by synchronous generators (SGs) but are currently undergoing a major transformation through the increasing integration of inverter-based resources (IBRs). The SG-dominated grid is traditionally analyzed in a mechanical-centric view which ignores fast electrical dynamics and focuses on the torque-speed dynamics. By contrast, analysis of the emergent IBR-dominated grid usually takes the electrical-centric view which focuses on the voltage-current interaction. In this article, a port-mapping method is proposed to fill the gap between these approaches and combine them in a unified model. Specifically, the mechanical dynamics are mapped to the electrical impedance seen at the electrical port; and the electrical dynamics are also mapped to the torque coefficient seen at the mechanical port. The bidirectional mapping gives additional flexibility and insights to analyze the sub-system interactions in whole-system dynamics and guide the tuning of parameter. Application of the proposed method is illustrated in three cases with increasing scales, namely a single-SG-infinite-bus system, a single-IBR-weak-grid system, and a modified IEEE 14-bus SG-IBR composite system.