A recursive wavelet transform analysis of earth fault currents in Petersen-coil-protected power distribution networks

Earth-phase faults are the most frequent faults likely to occur in a power distribution network. In the case of Petersen-coil-protected power networks, meaningful information is contained in the transient fault signals and should be used in the protections to increase their speed and accuracy. An earth-phase fault is simulated with EMTP (ElectroMagnetic Transient Program). Then, a recursive wavelet transform is applied on two kinds of fault currents that are the zero-sequence currents in the faulty feeder and in the healthy one. The instantaneous time-frequency information obtained may be useful for the design of a fast relay algorithm