Study of novel sine fitting differential protection algorithm in distribution system with high penetration of DGs

The utility of distributed generation brings about different types of impact to the relay protection of distribution system, which the conventional methods of distribution system protection could hardly be adapted to. The mainly performance of that is the malfunction of protective relaying with high penetration of DGs. Moreover, during fault, series of harmonics and aperiodic components exist in the current signal; quickness and preciseness in recovering the fundamental or specific harmonic signal would play significant roles in the performance of protective relaying. Traditional methods of recovering the needed parameters are mainly full-cycle Fourier algorithm and half-cycle Fourier algorithm, yet neither of them works both quickly and precisely. This paper studies a novel algorithm based on both sine fitting and differential protection, the parameters identification could be done within one cycle, and the preciseness is also satisfactory.