Integrating Flywheel Energy Storage System to Wind Farms-Fed HVDC System via a Solid State Transformer


As the power of wind farms (WFs) considerably proliferates in many areas worldwide, energy storage systems will be required to dynamically compensate the wind energy intermittency and increase power system stability. In this paper, a backup power conditioning strategy for wind energy-fed voltage source converter HVDC transmission systems is presented. An induction machine based flywheel energy storage systems (FESS) is integrated to the HVDC system via a solid state transformer (SST). The FESS is connected in parallel with the dc-link of the grid side converter; therefore, the excess wind energy can be stored in the flywheel and then restored during the energy shortage periods. The proposed system aims to compensate the power fluctuations caused by the intermittent nature of wind energy, levels the power-fed to the grid, and improves the quality of delivered power. The proposed system including FESS with an interfacing SST is modeled, simulated, and analyzed in MATLAB/SIMULINK environment. The results verify the effectiveness of the proposed system.



  1. HVDC
  2. Wind generation
  3. Storage system
  4. Smart grid
  5. Flywheel





Figure 1. The proposed system



Figure 2. Simulation results of power smoothing operation in pu (a) grid power, wind power, and flywheel power, (b) flywheel speed, (c) phase shift between two H-bridges of DAB, (d) HV dc link, (e) LV dc link.

Figure 3. Simulation results of HFT waveforms, in pu, employing soft switching using phase shift technique (a) positive power flow (from H2 to H1), (a)negative power flow (from H1 to H2).

Figure 4. Simulation results of power leveling operation in pu.



In this paper, a new strategy of improving the integration of large scale wind farms into HVDC transmission system using SST based FESS has been proposed to compensate for the wind power oscillations and to enhance the power profile at grid side. In the proposed technique a low speed induction machine based flywheel energy storage system is connected in parallel with the DC link of the grid side converter. Therefore, the excess wind power is stored in FESS and restored in case of wind power shortage and/or power demand increase preserving the grid power profile at its required value. The simulation results have demonstrated that the FESS compensates for power fluctuations caused by wind nature during different load conditions and exhibits good system performance with a relatively fast response and high dynamics.



  • Schettler, and H. Huang, N. Christl, “HVDC transmission systems using voltage sourced converters design and applications,” Power Engineering Society Summer Meeting, 2000. IEEE, vol.2, pp.715-720 vol. 2, 2000.
  • Long and S. Nilsson, “HVDC transmission: yesterday and today,” Power and Energy Magazine, IEEE, vol.5, no.2, pp.22-31, March-April 2007.
  • P. Bahrman and B.K. Johnson, “The ABCs of HVDC transmission technologies,” Power and Energy Magazine, IEEE, vol.5, no.2, pp.32- 44, March-April 2007.
  • M. Kirby, Lie Xu; M. Luckett, and W. Siepmann, “HVDC transmission for large offshore wind farms,” Power Engineering Journal, vol.16, no.3, pp.135-141, June 2002.
  • Jiancheng Zhang, “Research on Flywheel Energy Storage System Using in Power Network,” International Conference on PowerElectronics and Drives Systems, 2005. PEDS 2005, vol.2, no., pp. 1344- 1347, 28-01 Nov.2005.

A Two-Level 24-Pulse Voltage Source Converter with Fundamental Frequency Switching for HVDC System


This paper manages the execution investigation of a two-level, 24-beat Voltage Source Converters (VSCs) for High Voltage DC (HVDC) framework for power quality enhancement. A two dimension VSC is utilized to understand a 24-beat converter with least exchanging misfortune by working it at fundamental recurrence exchanging (FFS). The execution of this converter is contemplated on different issues, for example, consistent state activity, dynamic conduct, responsive power pay, control factor amendment, and sounds mutilation. Reproduction results are exhibited for a two dimension 24-beat converter to show its ability.



 Fig. 1 A 24-Pulse voltage source converter based HVDC system Configuration



Fig. 2 Synthesis of Stepped AC voltage waveform of 24-pulse VSC.



Fig. 3 Steady state performance of proposed 24-pulse voltage source Converter


Fig. 4 Dynamic performance of proposed 24-pulse voltage source converter



Fig. 5 Waveforms and harmonic spectra of 24-pulse covnerter i) supply voltage ii) supply current (iii) converter voltage


A two dimension, 24-beat voltage source converter has been structured and its execution has been approved for HVDC framework to enhance the power quality with major recurrence exchanging. Four indistinguishable transformers have been utilized for stage move and to understand a 24-beat converter alongside control conspire utilizing a two dimension voltage source converter topology. The enduring state and dynamic execution of the planned converter setup has been exhibited the very attractive task and found appropriate for HVDC framework. The trademark sounds of the converter framework has likewise enhanced by the proposed converter design with least exchanging misfortunes without utilizing additional sifting necessities contrasted with the ordinary 12-beat thyristor converter.



Analysis and Design of Three-Level, 24-Pulse Double Bridge Voltage Source Converter Based HVDC System for Active and Reactive Power Control


This paper manages the investigation, plan and control of a three-level 24-beat Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) framework. A three dimension VSC working at essential recurrence exchanging (FFS) is proposed with 24-heartbeat VSC structure to enhance the power quality and decrease the converter exchanging misfortunes for high influence applications. The structure of three-level VSC converter and framework parameters, for example, air conditioning inductor and dc capacitor is displayed for the proposed VSC based HVDC framework. It comprises of two converter stations encouraged from two diverse air conditioning frameworks. The dynamic power is exchanged between the stations in any case. The receptive power is autonomously controlled in every converter station. The three-level VSC is worked at advanced dead edge (β). A planned control calculation for both the rectifier and an inverter stations for bidirectional dynamic power stream is created dependent on FFS and neighborhood responsive power age. This outcomes in a significant decrease in exchanging misfortunes and maintaining a strategic distance from the responsive influence plant. Recreation is conveyed to confirm the execution of the proposed control calculation of the VSC based HVDC framework for bidirectional dynamic power stream and their autonomous receptive power control.



Fig. 1 Three-level 24-pulse double bridge VSC based HVDC system




Fig. 2a Performance of rectifier station during reactive power control of three level 24-pulse VSC HVDC system


Fig. 2b Performance of Inverter station during reactive power control at rectifier station of three-level 24 pulse VSC HVDC system


Fig. 2c Variation of (δ) and (α) values for rectifier and inverter Stations for reactive power variation of a three-level 24-pulse VSC HVDC system


Fig. 3a Rectifier station during active power reversal of three-level 24-pulse VSC HVDC system


Fig. 3b Inverter station during active power reversal of three-level 24-pulse VSC HVDC system


Fig. 3c Variation of (δ) and (α) values during active power reversal of three level 24-pulse VSC HVDC system.


Another three-level, 24-beat voltage source converter based HVDC framework working at essential recurrence exchanging has been planned and its model has been produced and it is effectively tried for the autonomous control of dynamic and receptive forces and satisfactory dimension consonant prerequisites. The responsive power has been controlled free of the dynamic power at the two conditions. The converter has been effectively worked in each of the four quadrants of dynamic and responsive forces with the proposed control. The inversion of the dynamic power stream has been actualized by switching the course of dc current without changing the extremity of dc voltage which is exceptionally troublesome in traditional HVDC frameworks. The power nature of the HVDC framework has additionally enhanced with three-level 24-beat converter task. The symphonious execution of this three-level, 24-beat VSC has been seen to an identical to two-level 48-beat voltage source converter.