A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide voltage harmonic compensation capabilities with minimal effect on the sag compensation performance of the basic DVR. The proposed controller has been experimentally verified on a medium-voltage (10 kV) three-phase DVR prototype under a range of conditions, including distorted supply voltages, nonlinear loads, and operation during distorted voltage sags.

[1]  D. G. Holmes,et al.  Frequency domain analysis of three phase linear current regulators , 1999, Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370).

[2]  John Godsk Nielsen,et al.  Design and Control of a Dynamic Voltage Restorer , 2002 .

[3]  F. Blaabjerg,et al.  A detailed comparison of system topologies for dynamic voltage restorers , 2005, IEEE Transactions on Industry Applications.

[4]  Donald Grahame Holmes,et al.  A universal custom power conditioner (UCPC) with selective harmonic voltage compensation , 2002, IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02.

[5]  Paolo Mattavelli.  A closed-loop selective harmonic compensation for active filters , 2001 .

[6]  F. Blaabjerg,et al.  Comparison of system topologies for dynamic voltage restorers , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[7]  M. D. Stump,et al.  The role of custom power products in enhancing power quality at industrial facilities , 1998, Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137).

[8]  L. Morgan,et al.  Experience with an inverter-based dynamic voltage restorer , 1999 .

[9]  A. Sannino,et al.  Static series compensator for voltage sag mitigation supplying nonlinear loads , 2002, 2002 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.02CH37309).