Abstract：In the scenario of large-scale grid connection of grid-forming type renewable power, the fault response characteristics of outgoing lines are complex. Traditional longitudinal differential protection is prone to reduced sensitivity or even refusal to operate. This paper conducts research on the protection of AC outgoing lines for grid-forming type renewable power. Firstly, taking the grid-forming photovoltaic station controlled by the virtual synchronous machine as the research object, the equivalent circuits of each sequence during the power grid fault period are established to analyze its fault current characteristics and verify the applicability of traditional longitudinal differential protection in this scenario. Secondly, considering the filter’s cut-off frequency, harmonic interference avoidance, and power quality constraints, the 8th harmonic is selected as the characteristic signal, and the proportional- resonant (PR) controller is adopted to realize independent control and flexible injection of the characteristic signal and the power frequency signal. Finally, based on the distribution differences of characteristic signals under faults within and outside the zone, a protection criterion is constructed using the amplitude ratio of the harmonic component of the differential current to the characteristic signal injected on the station side. Simulation results on the Matlab/Simulink platform show that the proposed method can accurately distinguish various faults both within and outside the zone. It can operate reliably under different fault types and locations, and has a strong ability to resist transition resistance.
李亚未, 解超, 陈俊儒, 刘牧阳, 尹纯亚. 基于特征信号幅值比的构网型新能源送出线路保护新策略[J]. 电气技术, 2026, 27(8): 1-12.
LI Yawei, XIE Chao, CHEN Junru, LIU Muyang, YIN Chunya. A new protection strategy for grid-forming type renewable power outgoing lines using characteristic signal amplitude ratio. Electrical Engineering, 2026, 27(8): 1-12.
2026, Vol. 27 
