Impact of windings configuration of three-phases power distribution transformer on ferroresonance

This paper dealt with the impact of ferroresonance on four common windings configurations of three-phases power distribution transformer, that were wye-wye (Y-Y), wye-delta (Y-Δ), delta-delta (Δ-Δ), and delta-wye (Δ-Y). The ferroresonance was initiated by the occurrence of open-phase faults of transformer primary windings, such as opened single-phase and opened two-phases (unbalanced system) as well as opened three-phases. The investigation of ferroresonance was based on simulation using ATPDraw. The results showed that the transformer windings configuration affected the ferroresonance responses. Subharmonic and quasi-periodic mode appeared on all configurations, whereas fundamental mode was only seen on Y-Δ configuration. The worst overvoltage on primary windings during opened single-phase and opened two-phases was observed on Y-Y configuration, that was about 554 % and 223 % at the R phase, respectively, while the worst overvoltage on primary windings during three-phases opened was obtained on Y-Δ configuration, that was about 150 % at the T phase. However, the primary three-phases voltage on Y-Δ configuration during opened single-phase and two-phases was generally the lowest compared to the other configurations. These results also revealed that Y-Y configuration was the most susceptible to overvoltage due to ferroresonance. On the other hand, Y-Δ configuration was the most robust to overvoltage due to ferroresonance.