Current Reference Optimization for Inverter-Based Resources to Mitigate Grid Voltage Unbalance Factor

Modern grid codes require inverter-based resources (IBRs) to inject reactive current in proportion to voltage drop into the power system to support voltage recovery under voltage faults. Yet the current reference calculated as per the well-established grid code cannot maximize the dynamic voltage support capability of IBRs. In this letter, a novel current reference optimization method that has a better voltage support effect than conventional current reference is proposed. The current constraint of each phase of the IBR is added to the model of optimal attenuation of voltage unbalance factor (OAVUF). By changing the voltage orientation and replacing variables, the OAVUF model is recast as a second-order cone problem. Case studies based on MATLAB/Simulink are carried out to demonstrate the effectiveness of the proposed optimization method.