Stability Assessment of A Radial Grid With Power Converters

Abstract

The increase proportion of power converters causes stability problems in the radial grid. To address these issues, this paper firstly proposes a unified modeling procedure and applies it to two types of converters. Secondly, the impedance models are used to analyze the stability of a radial grid with converters under four cases. The influence of the short circuit ratio (SCR) and line impedance on system stability are investigated. Then, a comprehensive sensitivity analysis is performed in order to investigate the effects of parameters variations on the closed-loop poles of the system under different conditions. Finally, the accuracy of the model and theoretical analysis are verified by simulations and Hardware-in-the-Loop (HiL) tests.

Keywords

• Radial grid
• grid-following converter
• grid-forming converter
• impedance model
• complex frequency domain
• stability