Z bus computation for networks having mutually coupled elements using uncoupled equivalents of coupled groups

This paper presents a new algorithm for the formation and modification of bus impedance matrix of networks having mutually coupled elements. The key idea in the proposed algorithm is obtaining the uncoupled equivalent circuit of a coupled group. Using such equivalents, the bus impedance matrix is formed using the well-known and extremely simple Z_BUS building algorithm applicable for uncoupled networks. A new algorithm to obtain the elements of such uncoupled equivalent circuits is proposed. This idea is extended for modifying the bus impedance matrix to account for changes in the network due to addition/deletion/modification of a mutually coupled element. The proposed methods are illustrated using examples.