Question

3. Figure 2 shows a single line diagram of a 13.8 kV primary feeder supplying power to a load at the end of the feeder. A shunt capacitor bank is located at the load bus. The capacitor bank is Y-connected with a reactance Xc = 400/phase. Assume that the voltage at the sending end of the feeder is 5% above rated and theat the load is Y- connected with Ruoad = 200/phase in parallel with load Xload = 400/phase. Determine: a. The total impedance seen by the source (2 marks) b. the line current (2 marks) c. the voltage drop across the line (2 marks) d. the load voltage (3 marks) e. real and reactive power delivered to the load (2 marks) f. reactive power delivered by the shunt capacitor bank (2 marks) Distribution substation transformer 138/13.8 kV Load voltage Feeder impedance RUNE XLINE 32 1622 VLOAD within Sending end voltage Vs -JXc XLOAD RLOAD Shunt capacitor bank Load

Answer 1

= 400/phase And- Given X Load xe = 40 s/phase Rload = 200/phase Assumption Sending end voltage y feeder is in Question 5% above rated. a) considvring capacitar Bank en Service Total = Rline tsx Line jixo Rload jx Load jxc = 3 + 16 + + 1/4 - 240 Ztoral. = 23+j6 total = 23.77 214.62° / Phase! 1 + } b) dine current VSIN z total 1.05 (13:0/13)_09 I Line 23.77 214.62 0:3520 L-14.62°KAph Voltage drop across the line Vorop = Z line I line = (6-700(03.435*(+352 L-1468) Magnitude IV Drop! 2.361 Luo. Vi ky 2.361 kV

d) LOAD Voltage VLOAD =VSLN-2 Line I Line = 1.05(13.8173) 20° – 2-361 240.81° = 0.366 - (1.555+j 1799) 6.01 - j 1.8770 7.030 L-14.62 KVEN Load) 7.0303 = 12.19 KVLL e) PLOAD 30 2 3 (Moad 2n) Pload 317.0309720 7.430MW Qload 36 3 (Vload La) 7x2000 3(7.0303 40 3.715 Mvas. shunt Real & Reactive power delivered to Load. f) Reactive power deliverid capacitor Bank. Gc 3( Vload LN = 3(7.038) 2/40 3.715 Mars. LN) ²/xe