Pilot protection for transmission line of large-scale renewable energy system based on morphological similarity distance

With the access of large-scale renewable energy (wind energy, solar energy, etc.), renewable energy systems have fault characteristics such as amplitude limitation, frequency offset, and phase angle distortion compared to traditional power grids, which may lead to reduced sensitivity of conventional pilot protection or even failure/maloperation. To ensure the reliable identification of transmission line fault in large-scale renewable energy systems, a novel pilot protection based on morphological similarity distance is proposed and the corresponding protection threshold determination method is elaborated. The proposed pilot protection utilizes the similarity of the current waveforms at both ends of the transmission line to construct the protection criterion, and can still operate reliably even under the fault resistance of 300 Ω. To verify the effectiveness of the proposed protection, extensive hardware-in-loop experiments based on real time digital simulator are conducted refer to the dynamic simulation test benchmark.