Rework Example 3.12 for a \(+10 \%\) tap, providing a \(10 \%\) increase for the high-voltage winding.

Example 3.12

A three-phase generator step-up transformer is rated \(1000 \mathrm{MVA}, 13.8 \mathrm{kV} \Delta / 345 \mathrm{kV}\) \(\mathrm{Y}\) with \(Z_{\mathrm{eq}}=j 0.10\) per unit. The transformer high-voltage winding has \(\pm 10 \%\) taps. The system base quantities are
\[
\begin{aligned}
\mathrm{S}_{\text {base3 } \phi} & =500 \mathrm{MVA} \\
\mathrm{V}_{\text {baseXLL }} & =13.8 \mathrm{kV} \\
\mathrm{V}_{\text {baseHLL }} & =345 \mathrm{kV}
\end{aligned}
\]
Determine the per-unit equivalent circuit for the following tap settings:

a. Rated tap

b. \(-10 \%\) tap (providing a \(10 \%\) voltage decrease for the high-voltage winding)

Assume balanced positive-sequence operation. Neglect transformer winding resistance, exciting current, and phase shift.