The transition to inverter-based power plants (IBPs)—such as solar PV, wind, and battery storage—is reshaping power grids globally. However, this shift introduces new stability challenges, particularly sub-synchronous oscillations (SSO), necessitating dedicated studies to ensure grid reliability.
Understanding SSO
SSO refers to destabilizing oscillations below the grid’s fundamental frequency (50/60 Hz). Historically, SSO risks emerged with series-compensated lines interacting with synchronous generators, exemplified by the 1977 Mohave incident, where turbine-generator shafts sustained damage. Traditional grids relied on synchronous machinery’s inherent inertia and damping to suppress such oscillations.
IBPs: A New Dynamic Challenge
Unlike synchronous generators, IBPs employ power electronics with fast digital controls (e.g., phase-locked loops, current regulators). These controls, while enabling precise grid integration, can introduce unintended resonances. When IBPs interface with grid components like capacitors or weak networks, impedance mismatches may trigger SSO. For instance, multiple IBPs interacting can create complex, overlapping resonance modes, especially in low-inertia grids.
Why SSO Studies Matter
Consequences and Mitigation
Unchecked SSO can damage equipment, trigger protection misoperation, or cause blackouts. Recent grid incidents, such as oscillations in Texas’ wind-rich grid, underscore these risks.
As renewables dominate, proactive SSO studies are vital. They inform robust inverter designs, grid codes, and operational practices, ensuring IBPs enhance—not jeopardize—grid stability. Without them, the energy transition risks trading fossil-fuel dependence for unpredictable instability. For more details please get in touch with us.
We at JEF have the ability to study any possible steady state, dynamic, EMT & Hormonic issues, in a new or existing plant. Get in Touch with us to know more.
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