Pilot Protection Based on Amplitude Comparison for Renewable Power Teed Lines

Fault behaviors of inverter-interfaced renewable energy generators (IIREGs) are quite diverse from those of synchronous generators (SGs). They show the variable system impedance, the limited current and low inertia, so the proportional brake differential protection installed on the transmission line has a high risk of failure for phase-phase failures. To cope with this adaptive problem, a new pilot protection is proposed considering the huge differences in both current amplitudes. Also, an improved criterion is presented for a scenario with a teed line. The existing protection principles focus excessively on the fault current characteristics of IIREGs, so they cannot operate correctly once IIREGs do not output their fault current. This happens when IIREGs produce no power or the circuit breakers exactly reclose on permanent failures. However, the proposed method has good performance for the above cases. The proposed method only requires current amplitude information, and in this case the strict synchronizing measurement is not necessary. Case studies are performed under different fault conditions, and they confirm the proposed method has good performance under different fault conditions. Furthermore, it is also verified using field-testing data.