Static Voltage Stability Analysis of Renewable Energy Multi-Infeed Systems Based on Margin Index

Substituting a high proportion of renewable energy sources for traditional synchronous generators can lead to a deterioration in the system's static voltage stability. This paper proposes extending margin-based voltage stability indices based on the load side Thevenin equivalent, to the renewable energy source side for assessing the static voltage stability of renewable energy multi-infeed systems. Firstly, a comprehensive analysis of both the load and renewable energy sources is conducted, and normalized expressions for three margin indices are derived based on a single-machine black-box system. Secondly, the characteristics of the margin indices are analyzed, validating their applicability in a single-infeed system. Thirdly, a method is introduced for conducting static stability analysis on the renewable energy source side of multi-infeed systems using Thevenin equivalent. Finally, the effectiveness of the indices under different growth scenarios is verified in a modified IEEE 39-node system, expanding the application scenarios of these indices.