Increasing Ride-Through Capability of Control Panels Using Square-Wave Series Voltage Compensator

Voltage sag is the most important power quality problem. The classical solution to protect industrial processes against voltage sags is based on the use of a large series voltage compensator (SVC), such as the dynamic voltage restorer. Although the SVCs are a general solution, in most cases alternative measures should be checked before purchasing such an expensive piece of hardware. For instance, some adjustable speed drives (ASDs) have embedded protection functions to mitigate voltage sags. In addition, contactors and power line carriers could be protected by low-power single-phase square-wave SVCs, which have been shown to be cost effective. This paper shows that, using the “ride-through” function of ASDs combined with cost-effective square-wave SVCs, a significant improvement in the ride-through capability of the protected process is achieved. Extensive testing of a low-power ASD panel supports the proposed voltage sag mitigation alternative.