Short-circuit current calculation model for symmetrical two-core phase-shifting transformer

The symmetrical two-core phase-shifting transformer (ST-PST) has a flexible control role for line power flow, and its operating characteristics are closely related to the operating state of the grid. Since the connection method of ST-PST is quite different from that of conventional transformers, the analysis method of conventional transformers is not fully applicable. To address the problem that the existing mathematical model of ST-PST is derived under symmetric operating conditions and does not reflect the ST-PST operating conditions under asymmetric conditions, this paper derives the node admittance matrix of the ST-PST based on the application of the phase component method and establishes a mathematical model to accommodate both symmetric and asymmetric fault operating conditions. The feasibility and accuracy of the phase-component method are verified by comparing the calculation with the EMTDC/PSCAD simulation results through the Matlab program example.