Digital calculation of sequence networks including mutual impedances

A method of including mutual impedances in the bus-impedance matrix by addition and matrix reduction is derived. It is shown how this procedure can be extended, to take into account the modification of an established matrix when the impedance of network elements is changed, and to the calculation of the matrix of a subnetwork which is part of a larger network system. A sample calculation of a four-bus network with three mutually coupled line elements, showing the derivation and modification of its bus-impedance matrix and the derivation of the matrixes when it is divided into two networks, is included in the Appendix.