http://www.jsetms.com/
https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal of Science Engineering Technology and Management Science
Volume 02, Issue 05, May 2025 ISSN: 3049-0952
www.jsetms.com DOI:10.63590/jsetms.2025.v02.i05.pp32-38
Published by: Surya Publishers www.jsetms.com
32 | Page
Converters for Power Electronics in Variable Speed Pump Storage
Pravallika
Department of Electrical and Electronics Engineering, PES University, Bangalore
Corresponding Author: pravallikaeee@gmail.com
To Cite this Article
Pravallika, “Converters for Power Electronics in Variable Speed Pump Storage”, Journal of Science Engineering
Technology
and
Management
Science,
Vol.
02,
Issue
05,
May
2025,
pp:32-38,
DOI: http://doi.org/10.63590/jsetms.2025.v02.i05.pp32-38
Submitted: 15-02-2025 Accepted: 28-04-2025 Published: 05-05-2025
_____________________________________________________________________________________________
Abstract: The power electronics method serves to regulate variable speed operation within variable speed pump
storage systems according to this research. Research focused on reviewing different variable-speed pump storage
systems by analyzing both power electronics converters and doubly fed asynchronous machines. The model uses
Cyclo-converter and two-level along with three-level voltage source-converter and H-bridge cascaded eleven-level
converters as power electronics converters. This analysis evaluates the speed variation together with total harmonic
distortion appearing in rotor current of double-fed asynchronous machines for various converter types. The study
confirms that the H bridge eleven level converter provides the best available solution. Every simulation model needed
the PSIM software for execution.
Keywords: Double-fed asynchronous machine, cyclo-converter, Pump storage, variable speed, pulse width
modulation and multilevel converter
This is an open access article under the creative commons license https://creativecommons.org/licenses/by-nc-nd/4.0/
_____________________________________________________________________________________
I. Introduction
The variable-speed pump storage system stands as the most efficient method to store extensive amounts of
electrical energy at present. The implementation of variable-speed pump storage improves all aspects of power
network control including balance and stability while enhancing energy efficiency. The two varieties of variable-speed
pump storage systems include the single reversible pump turbine machine (the Francis machine) that performs as both
pump and turbine simultaneously as well as the separate pump and turbine combination with the generator or motor
connection (currently unused) [1]. The achievement of variable speed operations relies on a doubly fed adjustable
speed pumped storage unit (DFASPSU) system according to [2] through [5].
The double fed induction machine operates as a variable speed adjustable speed doubly fed system that today
serves wind generators. A depiction of the doubly fed adjustable speed pumped storage unit layout appears in Figure
1. A block transformer enables the power network to connect to the stator section of the doubly fed machine. A power
electronics converter delivers electricity to the rotor and has its power source in a turbine containing moving blades.
Research shows that a multilayer inverter serves as the power electronics converter for variable-speed pump storage
applications in the present.
The three types of multilevel inverters include Diode clamped inverters along with H-bridge cascade inverters
and flying capacitor inverters. The output voltage capabilities of multilayer inverters surpass those of traditional two-
level inverters and cycle-converters while using the same switching frequency by providing exceptionally low
distortion together with diminished dv/dt and smaller CM voltage. All previous variable speed operations for variable
speed pump storage systems have used diode clamped in addition to H-bridge cascaded inverters.
A power system benefits considerably from variable speed operation of pumped storage because it enables
power regulation during the pumping phase. The electrical machine's inertia in addition to the pump-turbine function
leads to the core requirement of power electronics for controlling power at a quick responsiveness.
Converters for Power Electronics in Variable Speed Pump Storage
33 | Page
Fig 1: DFASPSU
II. Power Electronics Solutions
Power electronics converters that include cycle-conversion or back-to-back converters supplied power to the
rotor of the induction machine at this time. The two kinds of back-to-back converters include three-level diode
clamped converters and two-level converters. Variable-speed pump storage presently investigates the multilevel
cascaded H-bridge converter as a potential new technological solution [6]. Cycloconverters function as AC to AC
converters by transforming grid frequency between 50 or 60 Hz to low frequencies when controlling high-power
synchronous applications that drive induction machines. During the late 1980s the company introduced and deployed
cycloconverters to control speeds in hydroelectric plant variable-speed drives throughout Japanese facilities. The
variable-speed pump storage system employs thyristor type GTO as its main component.
Fig 2: 3 phase-3 phase bridge cycloconverter
Converters for Power Electronics in Variable Speed Pump Storage
34 | Page
Fig 3: Rotor current from cycloconverter with THD 18.99%
Fig 4: Back to back two levels AC/DC/AC circuit
Fig 5: Rotors currents of two level VSI with THD 4.42%
Converters for Power Electronics in Variable Speed Pump Storage
35 | Page
III. Three Level Diode Clamped Voltage Source Inverter
The three-level voltage source inverter (AC-DC-AC) used for variable-speed pump storage operates under
the circuit schematic shown in Figure 6. The selection of switching devices relies on IGBT, GCT, GTO, thyristor
technology and GCT offered in practical applications. A variable speed operation results from connecting the rotor of
the DFAM to the output of the inverter system. The switch control mechanisms for three-level voltage source inverters
consist of SVM and carrier-based PWM. The simulation model implemented in PSIM relies on carrier-based PWM
because the additional approach proves to be complex.
The Figure 7 illustrates the three-phase rotor currents which originate from the AC side. The THD
performance of the three-level inverter surpasses both two-level voltage source inverters and cycloconverters. The
main disadvantages of this technology stem from the requirement of high-speed clamping diodes which need to
withstand the whole load current stream while also being subjected to intense reverse recovery pressures and
presenting challenges when developing systems beyond three-level systems (five and seven).
Fig 6: Back to back three levels AC/DC/AC circuit
Fig 7: Rotors currents of three level VSI with THD 4.19%
Converters for Power Electronics in Variable Speed Pump Storage
36 | Page
As seen in Figure 8. A power cell contains a single-phase H-Bridge inverter and three-phase diode rectifier
together with a dc capacity. Each phase consisting of five rated 690V cells generates phase voltage at 3450 V and line
voltage at 6000 V respectively as shown in Figure 9.
Fig 8: 11 levels H-bridge cascaded multilevel converter
Fig 9: Phase and line voltages of power cell
High costs related to phase changing transformers together with the requirement for many cables stand as
major limitations of multi-layer CHB drives. The Xiang Hong station of China utilizes an H-bridge cascaded
multilevel converter for starting synchronous motors within its pumped storage power facilities. The figure below
shows the rotor currents which power variable speed pump storage in figure 10.
Converters for Power Electronics in Variable Speed Pump Storage
37 | Page
Fig 10: Rotors currents of H-bridge cascaded multilevel converter with THD 1.065%
The speed control of the wound rotor is illustrated through Figure 11 for a succession of three-level voltage
source inverter and two-level voltage source inverter alongside the eleven-level H bridge cascaded inverter.
Fig 11: PSIM simulation of variable speed of three types of inverters used in variable speed pump storage
IV. Conclusion
An evaluation of power electronic converter technologies appropriate for variable-speed pump turbine
operation has completed in this research. The analysis includes four power electronics converter types which include
cyclo-converters, two-level, three-level back-to-back voltage source inverters and H-bridge cascaded multilevel
inverters. The H-bridge cascaded multilevel converter proves superior to all other converter types in current
evaluations. The converter reacts rapidly and produces lower dv ⁄ dt together with reduced current THD. The PSIM
tool served for complete analysis of all model types.
References
[1] J. K. L. Lung, Y. Hung, W. L. and W. S. Kao, “Modeling and dynamic simulations of doubly fed adjustable-speed pumped storage units”,
Energy Conversion, IEEE Transactions on, vol. 22, pp. 250-258, 2007.
[2] T. S. Kuwabara, A. Furuta, H. Kita, E. Mitsuhashi, K., “Design and dynamic response characteristics of 400 MW adjustable speed pumped
storage unit for Ohkawachi power station”, Energy Conversion, IEEE Transactions on, vol. 11, pp. 376-384, 1996.
Converters for Power Electronics in Variable Speed Pump Storage
38 | Page
[3] J. A. U. Suul, K. Undeland, T., “Variable speed pumped storage hydropower for integration of wind energy in isolated grids–case description
and control strategies”, Proc. NORPIE, p. 1, 2008.
[4] A. S. Hodder, J. J. Schwery, A., “Double-fed asynchronous motor-generator equipped with a 3-level VSI cascade”, in Industry Applications
Conference. 39th IAS Annual Meeting. Conference Record of the 2004 IEEE, 2004, pp.2762-2769 vol. 4.
[5] J. Janning and A. Schwery, “Next generation variable speed pump-storage power stations”, in Power Electronics and Applications. EPE '09.
13th European Conference on, 2009, pp. 1-10.
[6] O. H. Abdalla and M. X. Han, “Variable speed pumped storage based on the use of H-bridge cascaded multilevel converter”, in 2012 IEEE
7th International Power Electronics and Motion Control Conference - ECCE Asia, China, 2012, pp. 402-405.
[7] A. Bocquel and J. Janning, “Analysis of a 300 MW variable speed drive for pump-storage plant applications”, presented at the Power
Electronics and Applications, European Conference on, Dresden, Germany, 2005.
[8] R. K. Saiju, J. Krueger, K., “Dynamic analysis of start-up strategies of AC excited Double Fed Induction Machine for pumped storage power
plant”, 2009, pp. 1-8.
[9] C. P. Nicolet, Y. Kawkabani, B. Schwery, A. Avellan, F. Simond, JJ, “Benefits of variable speed pumped storage units in mixed islanded
power network during transient operation”, 2009.
[10] J. B. KOUTNIK, M. Meier, L. Nicolet, C., "Pump storage-grid requirments for behavior of large motor-generators and confirmation of
compliance through simulation”, Proceedings of HydroVision International, pp. 19-22, 2011.
[11] B. Wu, “High-power converters and AC drives”, ed: Wiley-IEEE Press, 2006.
[12] Y. K. Pannatier, B. Nicolet, C. Simond, J.J. Schwery, A. Allenbach, P., “Investigation of control strategies for variable-speed pump-turbine
units by using a simplified model of the converters”, Industrial Electronics, IEEE Transactions on, vol. 57, pp. 3039-3049, 2010.