(Solved): The single-line diagram of a three-phase system is shown below. 1. Generator G1 at 20kV. 2. Step ...

The single-line diagram of a three-phase system is shown below. 1. Generator ${\mathrm{G}}_1$ at $20\mathrm{kV}$. 2. Step-up transformer ${\mathrm{T}}_{1}20/110\mathrm{kV}$ 3. Sending-end, high voltage Bus 1 at $110\mathrm{kV}$ to: a) A long transmission Line 1 at $110\mathrm{kV}$, receiving-end Bus 2 at $110\mathrm{kV}$. b) Another long transmission Line 2 at $110\mathrm{kV}$, receiving-end Bus 3 at $110\mathrm{kV}$. 4. After Bus 3, a step-down transformer $T_3,110/11\mathrm{kV}$, supplying $11\mathrm{kV}$ to Bus 4 to Load. 5. Generator ${\mathrm{G}}_2$ at $13.8\mathrm{kV}$. 6. Step-up transformer ${\mathrm{T}}_{2}13.8/110\mathrm{kV}$ 7. Sending-end, high voltage Bus 2 at $110\mathrm{kV}$ to: a) A long transmission Line 1 at $110\mathrm{kV}$, receiving-end Bus 1 at $110\mathrm{kV}$. b) Another long transmission Line 3 at $110\mathrm{kV}$, receiving-end Bus 3 at $110\mathrm{kV}$. 8. After Bus 3, a step-down transformer ${\mathrm{T}}_3,110/11\mathrm{kV}$, supplying $11\mathrm{kV}$ to Bus 4 to Load. 9. All devices are protected by oil circuit breakers (OCBs) Using the common base $S_{\mathrm{b}}=50\mathrm{MVA}$. The three-phase load at bus 4 absorbs $60\mathrm{MVA}$ at 0.75 power factor (lagging), and lines 1,2 , and 3 have the reactance of $40\Omega ,32\Omega$, and $30\Omega$, respectively.