Power factor correction calculations for power system – MS Excel Spreadsheet

Power Factor correction using a static capacitor

Calculation formulas as follows:

• Q₁ =  I _losses + Cu _losses
• Q₂ = P_kW · (Tanφ₁ – Tanφ₂)
• I _losses = 2% ·  S_tr
• Cu _losses = U_SC% · S_tr
• Q = Q₁ + Q₂

Where:

• Q₁ = Reactive power to be compensated at the terminals of a transformer due to no load and load losses.
• Q₂ = Reactive power to be compensated due to total reactive components of lighting, power and mechanical loads.
• Q = Overall reactive power to be compensated to achieve target power factor.
• I _losses = Transformer no load losses = Iron core losses.
• Cu _losses = Transformer load losses = Copper losses.
• S_tr = Transformer rating (KVA).
• P = Maximum demand load on the Main distribution board (kW).
• φ₁ = Inverse cosine of power factor before compensation.
• φ₂ = Inverse cosine of target power factor.
• U_sc% = Short circuit percentage impedance voltage of the transformer.

Power Factor Values assumptions before compensation:

• For lighting outlets = 0.96
• For power outlets and receptacles = 0.8
• For motors = 0.8