Grid-connected converter active and reactive power production maximization with respect to current limitations during grid faults

Abstract During the grid disturbances, particularly voltage sags, if the grid-connected converter’s (GCC’s) power references are kept at the pre-fault level, the excessive currents would flow. This could force the inverter disconnection, which is in conflict with the grid codes and the tendency to keep the GCC system connected to the grid as long as possible. Keeping the system connected for a prolonged periods of time offers a possibility of a more effective grid support, better exploitation of available energy resources and generally more reliable power supply. The aim of this paper is to address the utilization of active and reactive power production capacities during unbalanced voltage sags with respect to the current limits. First proposed algorithm gives the grid operator the opportunity to choose whether active or reactive power production is prioritized during voltage disturbance, with the curtailment done only to the extent that the current limits are not surpassed. Second approach allows for the power factor to stay the same before and during the sag. Selected hardware-in-the-loop experiments are presented to validate the developed theoretical background and implemented algorithm.