Calculateur de puissance pour grues portuaires et métallurgie
Dimensionnez l'alimentation pour grues de quai, équipements portuaires et fours à arc — compensation réactive de charge d'impact (SVC/SVG), filtrage harmonique et vérification de la chute de tension au démarrage des moteurs, avec nomenclature et schéma unifilaire.
Les grues et les fours à arc sont des charges d'impact extrêmes : les variations rapides provoquent un scintillement de tension, et les variateurs de fréquence/redresseurs injectent d'importants harmoniques. Ce calculateur dimensionne le transformateur pour la demande moyenne, vérifie la chute au démarrage du plus grand variateur, et dimensionne la compensation réactive dynamique ainsi que le filtrage harmonique désaccordé.
regenerative VFD (energy feedback on lowering) · per crane
4
Shore power supply (岸电)
300 kVA
50/60 Hz frequency converter + shore connection panel · IEC/ISO 80005-1 · quoted per project
1
📐 Single-line diagram
⚙️ Electrical schematic (protection & metering)
⛳ Grounding grid layout
🔌 Cable schedule & routing
🗄 Switchgear arrangement
🛡 Protection configuration
📋 Protection settings
Circuit
Protection
Setting
Time
Standard
HV incoming 35 kV
50 instantaneous
211 A
inst
IEC 60255-151 / IEEE 242
HV incoming 35 kV
51 overcurrent
32 A
0.5 s
IEC 60255-151 / IEEE 242
HV incoming 35 kV
51N earth-fault
5 A
0.5 s
IEC 60364-4-41
Transformer 1600 kVA
49 thermal overload
79% of rated
alarm 90%
IEC 60076-7 / IEEE C57.91
LV incoming 0.4 kV
50 instantaneous
18475 A
inst
IEC 60947-2
LV incoming 0.4 kV
51 overcurrent
2771 A
0.3 s
IEC 60947-2 / IEC 60255
LV incoming 0.4 kV
51N earth-fault
462 A
0.3 s
IEC 60364-4-41
Quay crane 1
50/51/51N (MCCB)
Ir 1134 A - Im 8248 A - Ig 206 A
0.1 s (grading)
IEC 60947-2 / IEC 60255
Quay crane 2
50/51/51N (MCCB)
Ir 1134 A - Im 8248 A - Ig 206 A
0.1 s (grading)
IEC 60947-2 / IEC 60255
Quay crane 3
50/51/51N (MCCB)
Ir 1134 A - Im 8248 A - Ig 206 A
0.1 s (grading)
IEC 60947-2 / IEC 60255
Quay crane 4
50/51/51N (MCCB)
Ir 1134 A - Im 8248 A - Ig 206 A
0.1 s (grading)
IEC 60947-2 / IEC 60255
Settings are illustrative starting points — confirm with a protection coordination study per IEC 60255 / IEEE 242.
📚 Calculation book
CALCULATION BOOK
1600 kVA - 35kV/0.4kV - single - illustrative
1. Load calculation
Standard: IEC 60076 - IEC 60364-5-52
Parameter
Formula
Value
Connected load
P = sum(kW)
2,000 kW
Demand factor
Kd
0.6
Demand power
Pd = P x Kd
1,200 kW
Power factor
cos(phi) before -> after
0.70 -> 0.95
Design apparent power
Sd = Pd / cos(phi)
1,263 kVA
Transformer loading
Sd / Srated
79%
2. Short-circuit calculation
Standard: IEC 60909
Parameter
Formula
Value
System impedance (pu)
Zs = S / Ssc
0.32% (on 1600 kVA base)
Transformer impedance
Zt = Z%
4%
Total impedance
Z = Zt + Zs
4.32%
LV prospective Isc
Isc = In / Z
53.5 kA
HV prospective Isc
Isc = Ssc / (sqrt(3) x V)
8.2 kA
Breaking check
Icu >= Isc
LV 65 kA (1.2x margin) PASS
3. Voltage drop
Standard: IEC 60364-5-52 Annex G
Parameter
Formula
Value
Main feeder
dU = sqrt(3) x I x L x R / V
300 mm2 - dU 1.50% @ 100 m
Limit
max 3%
within limit
Transformer volt. reg.
dU ~ loading x Z% x sin(phi)
1.0% at full load
4. Reactive power / harmonics
Standard: IEC 61921 (PFC) - IEEE 519 (harmonics)
Parameter
Formula
Value
Required compensation
Qc = Pd x (tan1 - tan2)
0 kvar
PFC bank
standard step
0 kvar
Detuned reactor
p = 6%
n/a
5. Grounding
Standard: IEC 60364-5-54 earthing arrangements and protective conductors LV earthing target 10 ohm (TN systems); 4 ohm used as a conservative design target - target 4 ohm
Parameter
Formula
Value
Single rod resistance
R1 = rho/(2 x pi x L) x ln(4L/d)
39.6 ohm
Rods required
n = R1 / (target x 0.8)
13 rod(s) <= 4 ohm
Rod spec
dia x length
20 mm x 2.5 m
This calculation book is illustrative it consolidates the computed values with the referenced standards. A licensed engineer must verify and seal final design documents for construction.
Cable & grounding pricing:Cable conductors and grounding are priced from the confirmed cables-trays-grounding price reference (per-metre copper YJV; aluminium remains POA). The main copper busbar is POA — its length is project-specific.
Busway (high-current feeders):For LV feeders above ~2500 A, a busway (母线槽) trunking system is recommended instead of parallel cables.
Impact load:Impact factor 1.3× — rapid load swings from cranes/arc furnaces cause voltage flicker; dynamic SVC/SVG compensation is required.
Starting:Largest 500 kW drive started via VFD draws a 2.2% bus dip (within the 10% limit).
Harmonics:30% THDi from VFD/rectifier loads — a 7% detuned filter keeps the branch inductive below the 5th harmonic.
SVC/SVG pricing:Dynamic reactive compensation is priced at $183,000/unit (±5 Mvar, FOB reference).
Crane regenerative drive:Quay cranes use four-quadrant (regenerative) VFDs that feed lowering energy back to the bus — this reduces energy consumption and DC-bus overvoltage, quoted per project.
Shore power (岸电):A shore power supply converts the port grid to the vessel’s voltage/frequency (IEC/ISO 80005-1) so berthed ships shut down their auxiliary engines — quoted per project.
Comment cela a été calculé
Comment fonctionne le dimensionnement
Pic d'impact = charge connectée × facteur d'impact. La compensation réactive Qc = P × (tanφ₁ − tanφ₂) corrige le mauvais facteur de puissance naturel, avec un SVC/SVG rapide pour le scintillement et une batterie désaccordée pour les harmoniques. La puissance de démarrage en kVA du plus grand variateur est vérifiée par rapport à une limite de chute de tension (généralement 10 % pour les jeux de barres sensibles au scintillement).
Normes applicables
Le dimensionnement fait référence à GB/T 12326 (fluctuation de tension et scintillement), GB/T 14549 et IEC 61000-3-2 (harmoniques), IEC 61642 (filtres désaccordés), IEC 60034 (machines tournantes) et GB 50052 (conception de l'alimentation électrique).
Questions fréquentes
How do impact loads affect power quality at a port?
Quay cranes and winches impose rapid, large load swings (impact loads) that cause voltage flicker. The impact factor is the ratio of peak to average load, often 1.3-1.5. When flicker violates GB/T 12326 limits, a dynamic reactive compensator (SVC or SVG) with 5-20 ms response is added. The calculator sizes compensation from the impact factor.
Why do arc furnaces need SVC or SVG compensation?
Electric arc furnaces draw erratic current with severe flicker and Harmonics, pulling Power Factor down to 0.6-0.7 during meltdown. An SVC or SVG rated 30-50% of furnace capacity restores power factor and damps flicker to meet GB/T 12326 and IEEE 519. A 50 MW furnace typically needs 15-25 Mvar of dynamic compensation.
What voltage level feeds a port crane system?
Large quay cranes (500 kW-1.5 MW per crane) are fed at 10 kV or 35 kV, stepped down near the berth to 0.4/0.69 kV for drives. A 10 kV ring feed with RMU or Switchgear along the quay is standard. The calculator's 35 kV default models a multi-berth crane cluster; smaller ports use 10 kV.
How are crane harmonics controlled?
Crane drives are VFD-based, injecting 5th, 7th, 11th harmonics; THDi commonly reaches 30% without treatment. Active front-end (AFE) drives or a passive detuned filter plus an APF keep THD under the IEEE 519 limit of 5-8% at the point of common coupling. The calculator sizes harmonic filtering when THDi exceeds the threshold.
What is the typical crane duty cycle for sizing supply?
Quay cranes run intermittent duty (hoist/lower/travel), so average demand is 40-60% of installed power even during busy periods. Supply transformers are sized to the peak simultaneous demand plus starting inrush of the largest hoist, not the sum of nameplates. The calculator applies an impact factor and diversity to avoid oversizing.
What short-circuit duty must port switchgear withstand?
Port 35 kV switchgear is usually rated 25-31.5 kA; 10 kV panels 25-31.5 kA; LV boards 50-65 kA. The rating must exceed the computed Fault Current at each busbar (IEC 60909). Crane drives contribute fault current, so a 35 kV bus fed by a 50 MVA source needs at least 25 kA. The calculator checks panel ratings against the fault level.
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Copiez le code iframe ci-dessous pour intégrer ce calculateur sur n'importe quel site. La page intégrée est en noindex et s'adapte à toute largeur.
Les résultats sont des estimations d'ingénierie à titre indicatif. La conception finale doit être confirmée par un ingénieur local agréé en fonction des conditions du site et des codes applicables. Les prix sont FOB Qingdao (EXW) et n'incluent pas le fret, les droits de douane ou l'installation.
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