محولات خفض الجهد للمحطات الفرعية (110 kV إلى 330 kV): التصميم والتنظيم بمغير النقرات OLTC

بنية محولات القدرة للنقل الفرعي عالي الجهد، وقلب بثلاثة أعمدة، وتنظيم آلي للجهد بمغير OLTC، ومشعات تبريد متعددة المراحل ONAN/ONAF/OFAF.

1. High-Voltage Substation Step-Down Architecture

Primary transmission substation step-down transformers (25 MVA to 250 MVA, 110 kV to 330 kV) reduce grid transmission voltages to intermediate distribution networks.

2. Technical Rating & Insulation Levels (IEC 60076-3)

Nominal Voltage (Un)Highest System Voltage (Um)Lightning Impulse (BIL)Power Frequency Withstand (Ud)
110 kV / 115 kV123 kV550 kV peak230 kV RMS
132 kV / 154 kV145 kV / 170 kV650 kV / 750 kV peak275 kV / 325 kV RMS
220 kV / 230 kV245 kV1050 kV peak460 kV RMS
330 kV362 kV1175 kV peak510 kV RMS

3. Multi-Stage Cooling Control Regimes

Radiator banks with automated dual-stage forced fans:

  • ONAN Stage: Natural circulation up to 60% - 70% rated power.
  • ONAF Stage 1: First fan bank activated at top-oil >65°C (85% power).
  • ONAF Stage 2: Full cooling capacity for continuous 100% rated MVA.

4. Winding Construction & Short-Circuit Withstand

HV windings utilize interleaved continuous disc windings with CTC conductors to withstand electrodynamic forces during external busbar short circuits per IEC 60076-5.

*Reference: IEC 60076-1:2011; IEC 60076-3:2018; IEC 60076-5:2006.*