- 2072 Magh · 6 marks
Two generators 200∠30° and 210∠50° V
Short answer
Using per-phase values, I from G1 to G2 is 8.716 angle -133.84 A. Three-phase totals: G1 consumes 5.02 kW and generates 1.46 kvar; G2 generates 5.48 kW and 0.37 kvar; the line absorbs 0.46 kW and 1.82 kvar. Real power flows from G2 to G1.
Two 3-phase synchronous generators connected in star with neutral grounded are connected to each other through a line with series impedance per phase of 2 + j8 Ω. The terminal voltages of generators 1 and 2 are 200∠30° V and 210∠50° V respectively. Determine the active and reactive power generated/consumed by each generator.
The given terminal voltages are taken as per-phase (line-to-neutral) values, since the generators are star connected with neutral grounded and the impedance is per phase. Three-phase power is 3 times the per-phase power.
Let I flow from G1 to G2 through . Then is the power delivered by G1 and is the power received by G2.
Current
Powers per phase
Interpretation
| Quantity | Per phase | Three-phase |
|---|---|---|
| G1 real power | consumes 1674.31 W (motoring) | consumes 5022.92 W |
| G1 reactive power | generates 485.19 var | generates 1455.57 var |
| G2 real power | generates 1826.24 W | generates 5478.73 W |
| G2 reactive power | generates 122.55 var | generates 367.66 var |
| Line loss | 151.94 W, 607.74 var | 455.81 W, 1823.23 var |
Check: W and var.
Real power flows from G2 to G1 because leads by 20°. G1 behaves as a synchronous motor. Both machines supply reactive power, which is consumed by the line reactance.
Answer: G2 generates 5.48 kW and 0.37 kvar. G1 absorbs 5.02 kW (motor) and generates 1.46 kvar. The line absorbs 0.46 kW and 1.82 kvar (three-phase totals).
✓ Answer checked by Claude Opus 5.5 (high effort)
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