Voltage Sag Mitigation Technology

The platform-mounted Dynamic Voltage Restorer (DVR PM) system is the company's latest advancement in its DVR power quality technology. The system protects smaller electrical loads from voltage disturbances the same way larger, trailer-mounted series compensation systems protect larger loads. Designed for critical-load commercial and small industrial customers, the system compactly packages power electronics on an overhead platform for installation on the utility or customer's electrical distribution system.

The technology compensates for voltage sags and swells by sensing the incoming voltage supply and instantly reacting to provide what is "missing" when a distortion is detected. It compensates each phase as needed for voltage variation and phase shift during a deviant voltage event through three independent single-phase series injection transformers. In the short span of 2 milliseconds, the control system determines the appropriate voltage components to inject to restore the affected waveform. The load-side line energy supply rectifier can supply up to 50% voltage injection, enabling the system to correct the most common voltage sags and swells for at least one second. It has a hybrid solid-state and mechanical bypass system for overcurrent protection. This first series is rated to serve loads up to 600 kVA on 3- or 4-wire, 3-phase, 15 or 25 kV-class distribution systems, at either 50 or 60 Hz. Other sizes and voltage ratings are also available.

Siemens Power Transmission & Distribution, Inc. (SPT&D), PO Box 29503, Raleigh, NC 27626. Tel: 888-416-0655