Control of Shunt Active Filters with Actuation and Current Limits

In this brief, a plug-in unit is presented to manage control voltage saturation and maximum current limit in shunt active filters (SAFs), where unconstrained control algorithms are already defined. The proposed unit extends the operating region of such devices, i.e., under large transients and overload conditions, with performance guarantees. Therefore, improved robustness, availability, and composability of SAFs are obtained. The solution is composed of two parts. An antiwindup (AW) unit is defined to deal with control input saturation by modifying the current references through a suitably designed additional dynamics. In addition, a current saturation strategy is formulated. Again the current reference is modified, accounting for the limitations of the system, augmented with the AW scheme. The approach is valid for any kind of unconstrained controller adopted to steer SAFs. Here, results are presented considering an internal-model-based current controller. Simulation and experimental tests confirm the effectiveness of the method.