Energy Transmission Lines
Power transmission lines are infrastructure designed to transmit electrical energy from generation centers (hydroelectric, thermal, wind, solar, nuclear, etc.) to demand centers at high voltage levels with low loss, safely and without interruption.
Basic Concepts and High Voltage (HV)
Transmission – Distribution Separation
Transmission carries energy over long distances at high voltage levels (generally ≥ 35 kV); distribution delivers it to the end consumer at lower voltages.
Voltage Classes (general framework):
- HV (High Voltage): ~35–220 kV range
- EHV (Extra High Voltage): ~220–800 kV
- UHV (Ultra High Voltage): ≳ 800 kV
Note: Ranges may vary depending on the country and standard.
HVAC vs HVDC
HVAC (Alternating Current): Easy integration into the existing grid, practical level change with transformers. HVDC (Direct Current): Lower losses over long distances and in submarine cables, precise control of the direction and magnitude of power flow, stability advantage in interconnections.
Main Components of the Transmission System
- Overhead Transmission Lines (OHTL): Steel lattice/pipe poles, conductor bundles, insulator strings, ground wire (often OPGW—optical fiber integrated).
- Underground/Submarine Cables: XLPE or oil-impregnated paper insulated cables; tunnel/duct applications; joint and terminal systems.
- Substations: Voltage transformation, circuit breakers, disconnectors, instrument transformers, reactor/capacitor banks, protection and control (SCADA/EMS).
- Telecom & Synchronization: OPGW, microwave/radio link; PMU (synchrophasor) measurements.
Transmission Line Components
Pole, insulator, and conductor selection and installation details ensure safe, efficient energy transmission in compliance with standards.
Type Test Certification
Type test certification independently verifies the product's electrical and mechanical performance in accordance with applicable standards.