Photovoltaic inverter overcurrent protection

Do photovoltaic power systems need overcurrent protection?

Photovoltaic power systems, like other electrical power systems, require overcurrent protection for conductors, bus bars, and some equipment. However, some of the electrical sources in PV systems are unique when compared with the typical utility source provided by the utility grid.

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.

Do PV circuits need overcurrent protection?

Some PV circuits differ from that general rule. Since several pieces of PV equipment such as PV modules, dc-to-dc converters, charge controllers and interactive inverters have current-limited outputs, circuits connected to those devices as sources require special consideration with respect to overcurrent protection.

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

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.