Generator Parallel Operation Calculator
Calculate load sharing, circulating current, and power distribution for two generators operating in parallel.
Generator 1
Generator 2
System Load
Formulas Used
Proportional kVA Load Sharing:
Share₁ = kVA₁ / (kVA₁ + kVA₂)
kW₁ = P_total × Share₁ | kVAr₁ = Q_total × Share₁
kVA_load₁ = √(kW₁² + kVAr₁²)
Rated Current (3-phase):
I_rated = (kVA × 1000) / (√3 × V)
Circulating Current:
I_c = |E₁ − E₂| / (Z_s1 + Z_s2)
Voltage Regulation:
VR = (E − V) / V × 100%
Short-Circuit Current:
I_sc = E / Z_s
Synchronising Power Coefficient (approx.):
P_sync = (E₁ × E₂) / (Z_s1 + Z_s2)
Copper Loss Estimate:
P_loss = I_load² × R (R ≈ 0.8 × Z_s assumed)
Efficiency Estimate:
η = P_out / (P_out + P_loss) × 100%
Assumptions & References
- Generators are assumed to be synchronous machines with resistive-dominant synchronous impedance.
- Load sharing is proportional to rated kVA — valid when droop settings are equal and governors are matched.
- Circulating current formula assumes both EMFs are in phase (worst-case magnitude); in practice a phase angle exists.
- Copper loss estimate uses R ≈ 0.8 × Z_s (typical X/R ratio ≈ 0.6 for medium generators); no-load / iron losses are excluded.
- Synchronising power coefficient is a per-phase approximation at zero load angle (δ = 0).
- For safe parallel operation: voltages must match within ±2%, frequencies within ±0.5 Hz, and phase sequence must be identical.
- References: Chapman, S.J. — Electric Machinery Fundamentals, 5th ed.; IEEE Std 1110-2002 (Synchronous Generator Modelling).