System and method for determining active and reactive currents during asymmetrical low-voltage ride through (LVRT) conditions

A system for determining active and reactive currents during asymmetrical low-voltage ride through (LVRT) conditions at an inverter, the system comprising a processing unit in communication with a non-transitory computer-readable medium comprising instructions to cause the processing unit to execute:

• receiving of an indication of an LVRT condition;
• where there is an active current such that the largest phase current magnitude does not exceed a phase current limit, determining a maximum active current for associated positive-sequence and negative-sequence reactive currents by determining a largest active current magnitude;
• where there is an active current such that the largest phase current magnitude does not exceed the phase current limit, outputting the largest active current and associated positive-sequence and negative-sequence reactive currents to the inverter;
• where there is no active current such that the largest phase current magnitude does not exceed the phase current limit, scaling down each of the positive-sequence and negative-sequence reactive currents, or superimposed positive-sequence and negative-sequence reactive currents, to determine revised positive-sequence and negative-sequence reactive currents;
• where there is no active current such that the largest phase current magnitude does not exceed the phase current limit and a β condition for each phase after the scaling down is within a predetermined range, determining a non-zero positive-sequence revised active current where the magnitudes of all of the phase currents are below the phase current limit, the β condition based on a negative voltage angle (θV−) and a positive voltage angle (θV+);
• and
• output the revised active currents and the revised positive-sequence and negative-sequence reactive currents to the inverter.