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Tuesday, 4 July 2017

Control of Cascaded H-Bridge Converter based DSTATCOM for High Power Applications

This paper presents the simulation studies on a Cascaded H-Bridge converter based Distribution Static Synchronous Compensator (DSTATCOM) for improving the power quality of a distribution system. Voltage source converter based DSTATCOM has been established as the most preferred solution for management of reactive power in distribution utilities and for improving voltage regulation, power factor and power quality in industries. For high power applications, cascaded H-Bridge converter is the most ideal choice compared to two-level inverter with series connected power devices. In the present work DSTATCOM controller is designed using DQO modelling for reactive power management and thereby improving the power factor in distribution systems. The dc link voltage and the three phase load currents are used as feedback signals for the controller and it is designed in such a way that DSTATCOM is able to supply the reactive current demanded by the load both during steady state and transient conditions using sinusoidal pulse width modulation control.

1.      Cascaded H-Bridge Converter
2.      DSTATCOM
3.      Reactive power compensation
4.       Sinusoidal PWM


Fig. 1. The cascade H-bridge converter based DSTATCOM.


Fig. 2. The phase voltage (top trace ) and line-to-line voltages of H-bridge
cascaded inverter.

Fig. 3. Source phase voltage (top trace) and source phase Current (bottom
trace) with DSTATCOM in closed loop power factor control mode.

Fig. 4. DC link voltage (Vd,) (Top or First Trace), direct and quadrature axis
source currents (Second Trace) ,inverter currents Id and Iq (Third Trace) and
load reactive current (Bottom Trace).

Fig 5. Individual Capacitor voltages of three level Cascaded H-Bridge

The paper presents the principle of operation of cascaded H-bridge converter and simulation studies on cascaded converter based DSTATCOM using Sinusoidal PWM control. It is observed that the DSTATCOM is capable of supplying the reactive power demanded by the load both during steady state and transient operating conditions. The harmonics in cascaded H-bridge three-level inverter current are less compared to two-level inverter operating at same switching frequency.

[1] Jih-Sheng Lal, Fang Zheng Peng," Multilevel Converters - A New Breed of Power Converters", IEEE Transactions on Industry Applications, Vol.32, no.3, pp.509,1996.
[2] Muni B.P., Rao S.E., Vithal J.V.R., Saxena S.N., Lakshminarayana S., Das R.L., Lal G., Arunachalam M., "DSTATCOM for Distribution Utility and Industrial Applications", Conference Proceedings, IEEE, Region Tenth Annual Conference, TENCON-03. Page(s): 278- 282 Vol. 1
[3] Bishnu P. Muni, S.Eswar Rao, JVR Vithal and SN Saxena, "Development of Distribution STATCOM for power Distribution Network" Conference Records, International conference on "Present and Future Trends in Transmission and Convergence", New Delhi, Dec.2002,pp. VII_26-33.
[4] F.Z. Peng, J. S. Lai, J.W. Mckeever, J. Van Coevering, "A Multilevel Voltage - Source inverter with Separate dc sources for Static Var Generation" IEEE Transactions on Industry Applications, Vol. 32, No. 5, Sep 1996, ppl 130-1138.

[5] K.Anuradha, B.P.Muni, A.D.Rajkumar," Simulation of Cascaded HBridge Converter Based DSTATCOM" First IEEE Conference on Industrial Electronics and Applications, May 2006, pp 501-505.