Reactive compensation & filter design — bank sizing, tuned branches, anti-resonance check

Enter the load, the transformer and the harmonic background: you get the reactive compensation in standard kVAR steps, the resulting power factor and loss reduction, the automatically selected filter branches (tuning order, kVAR, C/L/R) and the anti-resonance check. The scope is a 0.4 kV LV bus — the engine's harmonic injection and branch-capacity basis in this tool is calibrated at 0.4 kV.

① Load & system

System voltage (kV)Transformer rating (kVA)Impedance u_k (%)Active load (kW)Load power factor cos φ1Load factor (0–1)Target power factor cos φ2

This tool covers the 0.4 kV LV bus end to end. For 6/10 kV the engine's branch-capacity basis would need re-calibration, so no converted value is shown.

② Harmonic background

Non-linear harmonic source present3rd content (%)5th content (%)7th content (%)9th content (%)11th content (%)

③ Compensation & filter

Existing / planned capacitor bank (kVAR, blank = none)Detuning reactance p (%)Filter branch type

The engine models filter branches on top of an existing capacitor bank. Blank = greenfield (no bank) — a candidate branch may then be rejected by the resonance check, and that verdict is shown as-is.

Basis: Qc = P·(tan φ1 − tan φ2) rounded up to the standard bank list (engine yq-api/calc/pf.js) · harmonic limits per GB/T 14549-1993 / IEEE Std 519-2022 / IEC 61000-2-2 / EREC G5/5 (engine harmonic-limits.js) · filter tuning h_r = n·(1 − 6%) with reactance p = 1/h_r² and R = Xc/(h_r·Q) (engine passive-filter.js, IEEE Std 1531 / PSCAD practice) · anti-resonance from the same Z(h) model (engines/harmonic-scan.js resonanceScan, analytical h = √(Ssc/Qc) and 1/√p plus a 50 Hz coarse grid refined to 5 Hz). The filter design is an engineering approximation and NOT optimal; it excludes manufacturing tolerance, temperature drift and ageing detuning.