Modelling of faults on overhead lines in distribution systems using the admittance summation method

Faults analysis in generation/transmission systems is generally done by using the method of symmetrical components. However, this technique is not suitable for faults analysis in distribution networks. This problem is caused by the fact that distribution networks are naturally unbalanced. A very used alternative to overcome this difficulty is the application of the phase coordinates method. This method has basically four versions: Gauss-Zbus method, Kersting method, hybrid compensation method and admittance summation method. In this paper, a model for faults on transmission lines of radial distribution systems is proposed. The proposed model is based upon a combination of the admittance summation method and the Kron reduction method to eliminate the nodes introduced into the electric network due to the connection of fault admittance. The methodology proposed in this paper has been tested in a feeder belonging to a distribution company in Northeast of Brazil.