A low cost approach to provide ride-through for critical loads

In this paper a low cost approach to provide ride-through for critical loads connected in buildings and/or an industrial system is explored. In this approach a three-phase IGBT inverter with a built in DC-link voltage regulator, is suitably controlled along with static by-pass switches to provide continuous power to critical loads. During a disturbance, the input utility source is disconnected and the power from the inverter is connected to the load. After detecting normal utility conditions, power from the utility is restored to the critical load. The proposed approach does not require an external energy source (flywheel, fuel cell or battery) to protect against disturbances such as: voltage sags, voltage swells, flicker, etc. An external energy source can be incorporated in the DC link, to provide ride-through during short-term power interruptions. Since the inverter provides power only during a disturbance, the size and weight is small. Analysis, simulation and experimental results are presented on a 230 V, three-phase, three-wire, 3 kVA laboratory prototype.

[1]  Deepak Divan,et al.  Dynamic sag correctors: cost effective industrial power line conditioning , 1999, Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370).

[2]  E. H. Camm,et al.  Power quality evaluation at medical center , 1999, 1999 IEEE Transmission and Distribution Conference (Cat. No. 99CH36333).

[3]  Mark Johnson,et al.  Power interruption costs to industrial and commercial consumers of electricity , 1996 .

[4]  C. J. Melhorn,et al.  An evaluation of energy storage techniques for improving ride-through capability for sensitive customers on underground networks , 1996, Proceedings of 1996 IAS Industrial and Commercial Power Systems Technical Conference.

[5]  J. Douglas.  Power quality solutions , 1994, IEEE Power Engineering Review.

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

[7]  Masatoshi Takeda,et al.  Improved power quality solutions using advanced solid-state switching and static compensation technologies , 1999, IEEE Power Engineering Society. 1999 Winter Meeting (Cat. No.99CH36233).

[8]  R. S. Weissbach,et al.  Dynamic voltage compensation on distribution feeders using flywheel energy storage , 1999 .

[9]  V. Karasik,et al.  SMES for power utility applications: a review of technical and cost considerations , 1999, IEEE Transactions on Applied Superconductivity.

[10]  P.N. Enjeti,et al.  Effect of voltage sags on adjustable speed drives-a critical evaluation and an approach to improve its performance , 1999, APEC '99. Fourteenth Annual Applied Power Electronics Conference and Exposition. 1999 Conference Proceedings (Cat. No.99CH36285).