Identification and Classification of Faults in Utility Grid with Solar Energy Using Discrete Wavelet Transform and Decision Rules

A method supported by the discrete wavelet transform (DWT) and decision rules has been introduced to identify and classify the fault events in the network of utility when solar photovoltaic (PV) generation is available to design a protection scheme. Fault events such as three phases with ground (LLLG), two phases (LL), two phases and ground (LLG) and one phase to ground (LG) on the utility network are examined in the availability of solar PV energy. Signals of current are taken as key quantity for fault identification and processed using DWT with db4 mother wavelet and decomposed up to third level to compute a fault index (FI). Peak magnitudes of this FI are used to design decision rules using rule based decision tree (RBDT) for classifying the fault conditions. It is established that the algorithm using DWT and RBDT effectively identified and classified the faulty conditions incident on the utility network in the presence of solar energy. This approach effectively discriminated the faulty phase from the healthy ones.