The operation of inverter-based resources (IBRs) in regions with low system strength and high grid impedance has been identified as a primary cause of various power system instabilities. These instabilities often manifest as oscillations and dynamic interactions that, if not properly mitigated, can jeopardize the reliable operation of the grid. Weak grid conditions amplify such issues, particularly when multiple IBRs operate in close proximity and are interconnected within low-strength power networks.

Traditionally, synchronous generation-based resources inherently provided grid strength through their physical electromechanical characteristics, without the need for specialized control schemes. In contrast, IBRs lack this natural contribution to system strength, making the role of control strategies and system support technologies much more critical. Grid strength profoundly influences the overall stability of islanded or inland power systems with high IBR penetration, particularly affecting voltage regulation, fault response, and transient stability.

Technology selection therefore plays a pivotal role in achieving the desired level of grid strength in a secure and reliable manner. This paper presents research conducted at the National Laboratory of the Rockies (formerly NREL) on stability-oriented modeling and testing of hybrid systems designed to enhance the dynamic performance of islanded grids. The work includes case studies evaluating the optimal balance between grid-following and grid-forming inverters, as well as the application of stability-enhancing technologies such as hybrid plants, synchronous condensers, and battery energy storage systems.