Pumped storage motor-generators (synchronous, doubly fed DFIM and full-converter)
Motor-generators for pumped storage plants rated up to 530 MVA and up to 25 kV in synchronous, doubly fed DFIM and full-converter versions. In turbine mode they operate as a generator, in pump mode as the motor of a reversible pump-turbine. They are used at new and refurbished pumped storage plants.
- Output
- up to 530 MVA (Bath County after refurbishment); 433 MVA DFIM (Frades II)
- Rotational speed
- up to 600 rpm (Wehr, Chang Long Shan); variable 350–381 rpm (Frades II), 400–750 rpm (Limberg I)
- Types
- synchronous; doubly fed induction (DFIM); synchronous with full converter
- Voltage
- up to 25 kV
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Motor-generators are intended for pumped storage power plants. In turbine mode the machine operates as a synchronous generator, in pump mode as a motor driving a reversible pump-turbine or a storage pump. The manufacturer has built such machines since the early 20th century and has supplied more than 450 units for pumped storage plants with a total output of more than 60 000 MW.
The programme includes three versions. Fixed-speed synchronous motor-generators remain the classic option for reversible units. Doubly fed induction machines (DFIM) and synchronous machines connected through a full-power frequency converter allow the pump-turbine speed to be varied. Power in pump mode is adjusted to the available energy, the operating range of the turbine is widened, and the machine responds to frequency fluctuations within milliseconds using the kinetic energy of the flywheel masses. Examples include the 433 MVA DFIM for the Frades II pumped storage plant with a range of 350–381 rpm (the largest variable-speed machines in Europe) and 81.5 MVA full-converter machines for Limberg I with a range of 400–750 rpm.
VPI insulation of class 155 per IEC is designed for voltages up to 25 kV. Cooling is by air, with ventilation through the rotor rim or forced, and where required direct water cooling of the stator winding, rotor winding and core. Magnetic thrust bearings reduce the drag torque during start-up in pump mode and the bearing losses. For frequency starting, static frequency converters (SFC) with a redundant digital controller and optical thyristors are used. The manufacturer develops the excitation and SCADA systems itself.
References include 530 MVA machines for Bath County (after refurbishment), 425 MVA for Raccoon Mountain with water-cooled stator and rotor, 380 MVA / 500 rpm for Guangzhou II, 300 MVA / 600 rpm for Wehr, 373.2 MVA for Ingula, 389.9 MVA / 600 rpm for Chang Long Shan and 345 MVA for Rodund II. Applications cover new pumped storage plants and refurbishment of existing ones, systems with ternary units and hydraulic short circuit.
Technical specifications
| Output | up to 530 MVA (Bath County after refurbishment); 433 MVA DFIM (Frades II) |
|---|---|
| Rotational speed | up to 600 rpm (Wehr, Chang Long Shan); variable 350–381 rpm (Frades II), 400–750 rpm (Limberg I) |
| Types | synchronous; doubly fed induction (DFIM); synchronous with full converter |
| Voltage | up to 25 kV |
| Insulation | VPI, class 155 (F) per IEC |
| Cooling | air (rim ventilation or forced), direct water cooling of stator/rotor/core |
| Thrust bearing | magnetic relief thrust bearing to reduce torque during start-up in pump mode |
| Starting | static frequency converter (SFC) |
Request a price and lead time
Pumped storage motor-generators (synchronous, doubly fed DFIM and full-converter). We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What output and voltage do pumped storage motor-generators have?
The largest machine in the programme is 530 MVA (Bath County after refurbishment), and the DFIM for Frades II is 433 MVA. The voltage is up to 25 kV.
How do the variable-speed versions differ?
DFIM and synchronous machines with a full converter allow the speed to be varied, for example 350–381 rpm at Frades II and 400–750 rpm at Limberg I. In pump mode this is used to adjust power to the available energy.
What insulation and cooling are used?
VPI insulation of class 155 (F) per IEC. Cooling is by air with rim ventilation or forced, as well as direct water cooling of the stator, rotor and core.
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