A Two-Level, 48-Pulse Voltage Source Converter for HVDC Systems


This paper deals with an analysis, modeling and control of a two level 48-pulse voltage source converter for High Voltage DC (HVDC) system. A set of two-level 6-pulse voltage source converters (VSCs) is used to form a 48-pulse converter operated at fundamental frequency switching (FFS). The performance of the VSC system is improved in terms of reduced harmonics level at FFS and THD (Total Harmonic Distribution) of voltage and current is achieved within the IEEE 519 standard. The performance of the VSC is studied in terms of required reactive power compensation, improved power factor and reduced harmonics distortion. Simulation results are presented for the designed two level multipulse converter to demonstrate its capability. The control algorithm is disused in detail for operating the converter at fundamental frequency switching.


Two-Level Voltage Source Converter

HVDC Systems


Fundamental Frequency Switching





Fig. 1 A 48-Pulse voltage source converter based HVDC system configuration



Fig. 2 Steady state performance of proposed 48-pulse voltage source converter

3 4

Fig. 3 Dynamic performance of proposed 48-pulse voltage source converter

 5 6

 Fig. 4 Waveforms and harmonic spectra of 48-pulse converter (a) supply voltage (b) supply current (c) converter voltage


A 48-pulse two-level voltage source converter has been designed, modeled and controlled for back-to-back HVDC system. The transformer connections with appropriate phase shift have been used to realize a 48-pulse converter along with a control scheme using a set of two level six pulse converters. The operation of the designed converter configuration has been simulated and tested in steady sate and transient conditions which have demonstrated the quite satisfactory converter operation. The characteristic harmonics of the system has also improved by the proposed converter configuration.


[1] J. Arrillaga, Y. H. Liu and N. R. Waston, “Flexible Power Transmission, The HVDC Options,” John Wiley & Sons, Ltd, Chichester, UK, 2007.

[2] Gunnar Asplund Kjell Eriksson and kjell Svensson, “DC Transmission based on Voltage Source Converter,” in Proc. of CIGRE SC14 Colloquium in South Africa 1997, pp.1-8.

[3] Y. H. Liu R. H. Zhang, J. Arrillaga and N. R. Watson, “An Overview of Self-Commutating Converters and their Application in Transmission and Distribution,” in Conf. IEEE/PES Trans. and Distr.Conf. & Exhibition, Asia and Pacific Dalian, China 2005.

[4] B. R. Anderson, L. Xu, P. Horton and P. Cartwright, “Topology for VSC Transmission,” IEE Power Engineering Journal, vol.16, no.3, pp142- 150, June 2002.

[5] G. D. Breuer and R. L. Hauth, “HVDC’s Increasing Poppularity”, IEEE Potentials, pp.18-21, May 1988.

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.