The catalogued data of transformer are following: nominal power Snom=10 MVA; resistance Rt=7.95 Ω; reactance Xt=139 Ω. The nominal voltage of primary winding Vpr nom=115 kV. The nominal voltage of secondary winding

Vs nom=11 kV. The adjustment range of voltage ±9x1.78%. The level of voltage at the power source buses V0=107 kV. The power flow S1=6+j3 MVA.

The task is to maintain voltage level to Vadjusted=10.5 kV.