As renewable energy penetration accelerates, power grids face growing stability challenges due to the loss of rotating inertia traditionally provided by coal and nuclear plants. To address this, gas turbines can be repurposed to operate as synchronous condensers, decoupling the turbine’s mechanical power from the generator to supply crucial inertia and reactive power support without burning fuel. This approach helps maintain voltage stability and frequency control, especially during periods of low wind or solar generation.
RTS Corporation is an engineering consulting firm specializing in turbo gearbox design and integration. Leveraging decades of expertise, RTS collaborates with leading equipment manufacturers to develop turnkey solutions that transform standard aeroderivative gas turbines into dual-role assets—capable of both power generation and grid-stabilizing condenser operation.
At the heart of every gas-turbine-to-generator drivetrain is the gearbox. RTS selected FLENDER’s turbo gear units for their unmatched precision and reliability:
- Micrometer accuracy in manufacturing, ensuring smooth operation at ultra‑high speeds.
- Speeds up to 40,000 rpm and power ratings up to 100 MW per unit.
- 99 % efficiency, reducing mechanical losses and maintenance needs.
- Individual testing at nominal speeds on dedicated rigs, guaranteeing performance before delivery
These attributes make FLENDER gearboxes an ideal platform for integrating additional coupling and control components required for synchronous condenser functionality.
To enable seamless switching between generation and condenser modes, RTS incorporates synchro‑self‑shifting (SSS) clutches from SSS Clutch Co.:
- Freewheel design adapted for power generation, with models ranging from 100 kW to 400 MW.
- Torque transmission up to 4 MNm at 600 rpm and rotational capabilities to 16,000 rpm, accommodating both aeroderivative and industrial turbines.
- Encased assembly option, providing input/output shafts and support bearings in a modular package requiring only lubrication oil and electrical signals for automated operation
By disengaging the turbine shaft when not producing active power, the generator remains synchronized with the grid, delivering inertia and reactive power support instantly.
The Tennessee Valley Authority (TVA) is phasing out its 1.3 GW Kingston coal plant by 2027 and replacing it with GE Vernova LM6000 PF+ aeroderivative units. Each of these 53.9–57.1 MW turbines now features:
- FLENDER turbo gearbox as the load gear, pre‑aligned and pre‑tested for rapid installation.
- SSS Clutch integrated within the gearbox to switch between power production and synchronous condenser modes.
- Fast response: 30 MW/min ramp rate, 5 min cold start, and 50 % minimum load turn‑down.
This configuration ensures that when solar output dips, the generators instantly provide voltage control and rotational inertia—bolstering grid resilience during peak demand or renewable shortfalls.
The Platte River Power Authority (PRPA) is transitioning its Rawhide facility to a 200 MW aeroderivative gas turbine portfolio—30–50 MW units—to back up wind, solar, battery storage, and a virtual power plant. Scheduled for installation by early 2028 at a cost exceeding $350 million, these turbines will operate only 5–20 % of the time (versus 1–3 % for older units), mitigating “dark doldrums” when renewables falter.
- Specifying FLENDER gearboxes tailored to each turbine’s speed and power output, ensuring compatibility with site-specific foundations and alignment systems.
- Integrating SSS Clutches to enable synchronous condenser mode without on-site turbine modifications, simplifying commissioning and maintenance.
- Providing engineering support for control-system interfacing, enabling remote-mode transitions, and real-time grid feedback loops.
The combined FLENDER‑SSS assembly designed by RTS features:
- Encased SSS Clutch inside the load gear housing, with pre‑mounted support bearings for precise shaft alignment.
- Automatic lubrication circuits integrated into the gearbox skid, minimizing field piping and electrical connections.
- Control logic integration into turbine control systems, allowing automated clutch engagement/disengagement based on grid signals.
- Modular foundation interface matching FLENDER’s pre‑aligned roof skids, reducing installation time by up to 50 %.
This modular approach ensures that gas turbines can switch between producing up to 57 MW of active power and delivering pure reactive support at the generator terminals, without any mechanical reconfiguration on site.
By uniting FLENDER’s precision gear units and SSS Clutch’s proven coupling technology, RTS enables:
- Enhanced grid stability, providing essential inertia and voltage support for high-renewable grids.
- Operational flexibility, with turbines ready to fire for peaking power or operate as condensers at a moment’s notice.
- Reduced water usage, as dry‑low emissions (DLE) combustors eliminate the need for water injection for NOₓ control.
- Hydrogen readiness, with dual‑fuel capability ensuring future compliance with decarbonization pathways.
As solar and wind capacity continues to climb, such hybrid solutions will be critical. RTS’s collaboration with FLENDER and SSS Clutch demonstrates the power of interdisciplinary engineering to deliver resilient, carbon-friendly grid infrastructure.
If you are an OEM packager, contact RTS Corporation to support with your turbo-gearbox (integrated clutch) for synchronous condenser application. Let’s discuss your specific requirements. For more information on the FLENDER gearbox or to consult with RTS Corporation, give us a call today at (203) 459-9835.
