Photovoltaic inverter wave-by-wave current limiting fault

How does a PV inverter limiting strategy work?

After detecting the occurrence of a fault, the current limiting strategy acts in order to avoid damages to the PV inverter components. Therefore, shortly after the peak current, the inverter returns to the constant current from the second half cycle.

How does a fault condition affect the output current of an inverter?

Under the fault condition, the grid voltages are still harmonically-polluted, however, the imbalance ratio increases considerably to 40%. As shown in Fig. 7 (e), the proposed current limiting strategy properly limits the output currents of the inverter under short circuit conditions.

How do PV inverters respond to a fault?

For different fault types, after a brief spike (transient response), the currents of the three PV inverters returned near to the nominal value (steady-state response). Also, the inverters injected steady-state fault current (≈ 1 p.u.) for two cycles until their disconnection.

Can a fault current limit a PV inverter?

The technique is developed by combining distance protection and overcurrent protection, and simulation results under different fault conditions show the feasibility of the proposed scheme. According to the authors, the fault current of PV inverters is limited within 1.5 times the rated current in order to avoid damage to the equipment.

Is a PV inverter a constant power source?

The PV inverter is modelled as a constant power source, however, for fault analysis, the authors assumed the limiting current to be twice the rated current, for the worst-case scenario. The inverter current and voltage are considered in phase for unit power factor operation.

Is fault contribution associated with nominal power of commercial PV inverters?

Based on the results obtained from commercial PV inverters, it can be concluded that the fault contribution is not associated with their nominal power. However, articles (Varma et al. 2016) and (Kasar & Tapre, 2018) combine these two characteristics, confusing readers.