Power limitation occurs during inverter operation

Although it adjusts the active power reference during faults to extend the critical clearing time, the current increase caused by the reactive power control loop keeps the inverter in current limitation. This limitation persists even after fault clearance, causing the inverter operate abnormally with larger output voltage and output current values.

Without proper safeguards, excessive currents during disturbances can damage the inverter's power stage, leading to system failures and jeopardizing grid stability. Addressing this challenge is where current limiters come into play. Current limiters are the first line of defense during grid disturbances.

This is only possible when you define a low voltage for your array, i.e. few PV modules in series. Therefore in many cases when the operating (or nominal) current of the array is above the acceptable current for the inverter input, you will not see any Current loss during operation, but only Power overload.

However there are limits in power, voltage and current. When attaining one of these limits, the inverter will clip the operating point on the intersection of the I/V curve and this limit. The power difference between the MPP of the arrays' I/V curve and the effective power of this operating point on the limit curves is accounted as inverter loss:

Hence, to avoid over current in PV inverters during fault-ride-through period, active power curtailment is necessary. The authors have formulated an expression to evaluate pseudo inverter capacity (PIC) for over current limitation as in (25).

In this case, the inverter capacity is exploited by partially injecting both active and reactive power under fault conditions. Since the generated active power is not high, the remaining inverter capacity is utilized by injecting reactive power as in (30).