Islanding detection using sparse S-transform in distributed generation systems

Abstract

Anti-islanding protection is a mandatory requirement for grid-connected distributed generation system so as to avoid the adverse effect of islanding. In order to achieve the objective of negligible non-detection zone along with fast detection and to reduce the computational burden, sparse S-transform (SST) is proposed here. The SST matrix is computed by considering the selected frequency components containing substantial information about signal irregularities caused by islanding and ignores the irrelevant data. The modal voltage signal of the voltage at point of common coupling is processed through the SST. The energy, standard deviation and entropy values are obtained from the transformed signal for islanding detection. The proposed scheme is validated for islanding cases under closely matched power scenarios and simultaneous occurrence of islanding event with power quality disturbances. Similarly, scheme is tested for normally occurring non-islanding disturbances. The performance of the scheme is validated in IEEE-13 bus distribution system. From the simulation results, it is found that the proposed scheme performs satisfactorily under almost all practical network disturbances. The SST technique reduces the computational burden and memory requirement significantly; hence, it is more suitable for real-time implementation.