Dynamic Control of Reactive Power. Industrial Static Equipments

This article deals mainly with reactive energy compensators for industrial networks and not for public transmission or distribution networks. Although both applications use the same technologies, the sizing and control aspects are different.

Today's reactive power compensation devices for industry are classically based on thyristors on the one hand, and on blockable components such as IGCTs (Integrated-Gate-Commutated-Thyristor) or IGBTs (Insulated-Gate-Bipolar-Transistor) on the other. These devices provide a satisfactory solution to the problems of compensating for load imbalances, regulating network voltage in the face of reactive power fluctuations, and adjusting power factor. Reactive power compensators range from a few megavars to several hundred megavars. There are two families of static reactive power compensators (RECs) for industry: TCR (Thyristor Controlled Reactor)-based RECs for high power ratings, and voltage intermediate circuit converter (VICC) CERs based on blockable components such as IGCTs and IGBTs for small, medium and high power ratings. Their efficiency depends on two main factors:

• sizing or the ratio between the power of the disturbing equipment and the power of the equipment (reactive power of the capacitor bank and thyristor absorber, power of the IGBT converter);

• the control device for the adjusting element, whose speed is a key factor.

This speed aspect is fundamentally different between the technologies. While TCRs are limited by the thyristors used, the dynamic performance of converters using blockable components such as GTOs (Gate-Turn-Off), IGCTs (Integrated Gate-Commutated Thyristor) or high-power IGBTs (Insulated Gate Bipolar Transistor) is greatly enhanced, especially as these new modern actuators also have an active filter function...

The topic of industrial static reactive power compensators is the subject of three articles:

• Voltage fluctuations and flicker. Assessment and mitigation (part 1) [D 4 315] ;

• Voltage fluctuations and flicker. Assessment and mitigation (part 2) [D 4 316]...