Passivity-based control of grid-forming inverters in presence of constant-power loads

In recent years, microgrids are becoming more widespread as a paradigm of energy generation and utilization. In this scenario, power electronic converters play a very important role as interface between the various sources and the various loads. This massive presence of such devices is arising issues related to their interaction, since they operate simultaneously. For this reason, research activity on how to drive them stably in such conditions is gaining more and more importance in order to guarantee reliable power exchange, continuous operation of microgrids and hence limitation of black-out occurrence. Nevertheless, the stable operation of grid-forming inverters is the most challenging task to be accomplished when it comes to feed some types of load whose presence is considered the main triggering factor for the electrical quantities to deviate from the set-point values thus leading the system to instability. To this end, this paper aims to present a control technique that is based on the theory of passivity and that can guarantee stable operation in one of the most critical operating conditions that occurs when a grid-forming inverter supplies constant power loads such as speed-controlled electric drives. These kinds of loads are very common on microgrids for industrial environments that can hence remarkably benefit from the proposed control technique. The results of the simulation tests prove the effectiveness of the proposed control technique in stably operating the considered system also in presence of parameters variation.