For high voltage grids containing distributed new energy sources, there are a range of adaptability problems with traditional line protection due to the variety of new energy sources and complex fault characteristics. The time domain differential equation algorithm can solve for fault distances, which has good applicability in systems containing new energy sources, but there is a "transient override" phenomenon and "voltage dead zone" problem. For this reason, a new line protection scheme is proposed. When a fault occurs on the line and it is not near the outlet of the line protection, the fault point voltage is reconstructed and isotransformed, and then substituted into the time domain differential equation algorithm, which is the isotransformed fast distance protection algorithm; when a fault occurs near the outlet of the line protection, the correlation coefficient between the measured voltage drop and the calculated voltage drop are calculated and the consistency of the two trends is used to determine the direction of the outlet fault. The line protection scheme can accurately determine line faults, regardless of the type of new energy source, capacity and fault characteristics. Simulation analysis shows the applicability of the scheme.