Whether PV inverters are allowed to be over-allocated

What is over current protection mechanism in PV inverter?

As previously discussed, the simultaneous injection of peak active power from PVs and reactive power into the grid for voltage support can trigger the over current protection mechanism in PV inverter. The triggering of over current protection will lead to disconnection of inverter from the grid which is unfavourable during LVRT period.

How to ensure maximum exploitation of the inverter capacity?

To provide overcurrent limitation as well as to ensure maximum exploitation of the inverter capacity the performance of the proposed control strategy, is evaluated as per the three generation scenarios given below: In this case, the inverter’s capacity is majorly exploited through the injection of active power under normal operating condition.

How to provide voltage support in PV inverter?

To provide voltage support at the PCC, reactive power is injected into the grid under fault conditions as per the specified grid codes. As previously discussed, the simultaneous injection of peak active power from PVs and reactive power into the grid for voltage support can trigger the over current protection mechanism in PV inverter.

What are the goals of grid-connected PV inverters?

Under grid voltage sags, over current protection and exploiting the maximum capacity of the inverter are the two main goals of grid-connected PV inverters. To facilitate low-voltage ride-through (LVRT), it is imperative to ensure that inverter currents are sinusoidal and remain within permissible limits throughout the inverter operation.

How to avoid over current in PV inverters during fault-ride-through period?

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). $$PIC= \frac {1-VUF} { {u}_ {base}}\times {u}^ {+}\times S$$

Do inverters utilise reactive power for voltage regulation?

Recent standard changes have allowed the inverters that are used to grid connect PV systems, to utilise their reactive power capability for voltage regulation. Although this new capability is desirable, it is important to ensure that it is being applied in the most beneficial way.