Pilot protection based on current sequence component differences for offshore wind power low-frequency transmission line

Abstract The various control strategies used by the inverters in the offshore wind power low-frequency transmission system will result in variations in the current composition at the two ends. These variations will raise the phase angle difference of the same-phase fault currents, decreasing the protection system’s sensitivity and possibly causing it to fail. To solve this problem, the study proposes to construct a new protection criterion using zero-sequence currents and negative-sequence currents, which can more accurately identify and differentiate between normal operation states and fault states by analyzing these sequence currents, thus the performance of differential protection for low-frequency transmission lines is greatly enhanced and the classic current differential protection is optimized.