Enhanced Operational Flexibility and Efficiency
- CFSMs enable variable-speed operation of pumped storage units, allowing the turbine and pump to operate efficiently over a range of speeds rather than at fixed synchronous speed. This leads to improved efficiency in both pumping and generating modes compared to fixed-speed machines.
- Variable speed operation also allows for rapid changes in load and quick responses to grid demands, helping maintain grid stability with high penetration of intermittent renewable energy sources.
Reduced Start-up Time and Improved Reliability
- With CFSMs, pumping mode start-up can occur without the need for dewatering the turbine, reducing the time and complexity required to begin pumping. This minimizes downtime and improves plant responsiveness.
- The ability to control torque at all rotor speeds through power electronic converters means pump units can start and accelerate smoothly, avoiding the lengthy start acceleration typical for traditional synchronous machines.
Cost-Effective Upgrades and Space Efficiency
- Existing pumped storage plants that already use synchronous machines can upgrade cost-effectively to CFSM technology by retrofitting converters, leveraging current assets while improving performance.
- Multi-winding transformers paired with CFSMs can reduce converter harmonics and allow smaller converter sizes, optimizing space usage—critical for underground powerhouses.
Enhanced Grid Support and Ancillary Services
- CFSMs can operate in synchronous condenser and static synchronous compensator (STATCOM) modes, providing reactive power support, voltage regulation, and frequency control services crucial for modern grids with significant renewable integration.
- They contribute to grid inertia and stability, addressing challenges of grid instability caused by increasing intermittent renewable sources.
Long-Term Economic and Environmental Benefits
- The improved efficiency and flexibility of CFSM-based variable-speed pumped hydro storage systems translate into better utilization of stored energy and greater economic returns over plant lifetime.
- Pumped hydro storage with CFSM is renewable, sustainable, and has a long operational lifespan (electromechanical equipment over 40 years, dams over 100 years), offering a reliable large-scale energy storage solution with minimal environmental impact.
Summary Table of Main Advantages of Converter-Fed Synchronous Machines in Pumped Hydro Storage
| Advantage | Description |
|---|---|
| Variable-speed operation | Efficient operation over wider speed range, improving pumping and generating efficiency |
| Fast and smooth start-up | Minimizes pumping start time without dewatering, increasing responsiveness |
| Cost-effective plant upgrades | Retrofit capability leveraging existing synchronous machines |
| Reduced converter size and harmonics | Use of multi-winding transformers reduces harmonics and converter footprint |
| Enhanced grid services | Provides reactive power, voltage, and frequency support through synchronous condenser/STATCOM modes |
| Improved grid stability | Supports grid inertia and balances variability from renewable energy |
| Long lifespan and sustainability | Durable, renewable technology with minimal environmental impact |
These benefits make converter-fed synchronous machines a key technology for modern, flexible, and efficient pumped hydroelectric energy storage systems, playing a vital role in integrating renewable energy while maintaining grid reliability and economic performance.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-main-advantages-of-using-converter-fed-synchronous-machines-in-pumped-hydroelectric-energy-storage/
