Using Nominal_T method, determine: i. Send-end voltage ii. Voltage regulation

3. (b) Derive an expression for zero sequence current ($I_0$) in terms of unbalanced currents in the Red ($I_R$), Yellow ($I_Y$), Blue ($I_B$) phases.

Given the phase currents in terms of symmetrical components: $I_R = I_{R1} + I_{R2} + I_{R0} \quad (1)$ $I_Y = a^2 I_{R1} + a I_{R2} + I_{R0} \quad (2)$ $I_B = a I_{R1} + a^2 I_{R2} + I_{R0} \quad (3)$ where $a = 1 \angle 120