Research on Circuit Matrix Algorithm for Calculation of FRA Results of Lumped Equivalent Circuit of Two-Winding Transformer

To accurately and efficiently calculate the FRA results of the lumped parameter equivalent circuit of a two-winding power transformer with a large number of discs, this paper studies the circuit equation matrix algorithm. First, according to the structure of the two-winding equivalent circuit and the characteristics of the components in each branch, a generalized branch of the equivalent circuit is established, and the branch voltage and branch current matrices are constructed; then, by selecting nodes, independent loops, and independent cut sets, matrix algorithms of the node voltage, loop current, and cut-set voltage equations are derived for frequency response of the circuit based on the KVL and KCL; in particular, the independent cut-set selection method for the equivalent circuit is proposed to avoid the complicated step of selecting the tree branch and the link branch of the circuit diagram when the fundamental cut-set is used; second, the accuracy of the three methods is verified by Multisim; finally, the three methods are compared in terms of the assembly time of the circuit equation matrix, the equation solving time and the total calculation time. The results show that the cut-set voltage equation matrix algorithm has the highest efficiency. However, if the selection time of the independent cut set in the early stage is considered, the node voltage matrix algorithm has more advantages. © 2022 Xi'an Jiaotong University. All rights reserved.