Imperial’s Inverter Screening Tool Prevents Grid Instability with Admittance Analysis

As power grids integrate more inverter-based resources (IBRs), small-signal instability—especially sub-synchronous oscillations (SSOs)—has become a growing concern. The impact of a new inverter connection depends heavily on location, operating mode, control settings, and system conditions, making planning complex. Researchers from Imperial College London have developed the Inverter Connection Screening Tool (ICST), an admittance-based approach that efficiently predicts how prospective inverter configurations affect small-signal system strength. The tool evaluates candidate inverters using their admittance at critical modal frequencies combined with the system’s admittance spectrum, eliminating the need for full analytical models.

The ICST was validated on a modified IEEE 57-bus system, where it accurately predicted modal impacts and identified the most suitable inverter configurations for a given connection point. The tool can both avoid degradation of small-signal stability and even enhance it, supporting higher IBR penetration. This planning procedure aids system operators, asset owners, and developers across multiple stages of grid planning. Comparisons with model-based studies confirm the ICST’s accuracy and effectiveness, offering a practical screening method to prevent SSOs as renewable energy integration accelerates.