Addressing key design challenges through digital modelling of dissociated phases phase-shifting transformers

Transformer (PST) built as a dissociated phases six-pole system to minimize transportation constraints and installation footprint, where the main requirements that influenced the electrical and mechanical designs are highlighted.

In addition to the typical considerations involved in power transformer design, the specific characteristics of PSTs give rise to further significant technical challenges, comprising the assessment of internal power-frequency overvoltages (causing core overexcitation under specific operating conditions that also include the short-circuit events), and the multi-terminal lightning impulse test (LIMT), which requires validation through a high-frequency digital model of increased complexity.

These digital models enabled accurate simulation of critical phenomena and an adequate design, compatible with increasingly shorter deadlines for the delivery of time-consuming engineering studies.

Power frequency analytical models were also developed and compared with the correspondent digital model, showing consistent results, and thus reinforcing confidence in the simulations.

Subsequently, the simulation results were validated through Factory Acceptance Tests (FAT) and special laboratory tests for model calibration, ensuring reliability and robustness.