Missing-operation Risk of Directional Comparison Teleprotection with Photovoltaic Power Integration

Although the ac fault current provided by photovoltaic (PV) power plant is limited as a weak-infeed power or a electric load, the voltage and current directions are different from conventional synchronous source, since the current is highly controlled by the PV inverter. This paper investigates the measured impedance and the distance directional element of PV side line protections. The impedance trajectory are drawn and compared with conventional power source. Simulation result shows that the directional comparison teleprotections may miss operate under a line internal fault, since the measured impedance drops into the negative direction area, even though the weak-infeed tripping function is activated.