Q4Power System - I
Question
Q.4. What are the advantages of adopting EHV/UHV for transmission of AC electric power?
Answer
EHV/UHV transmission reduces line current for a given power (since P=√3VIcosφ), thereby reducing I²R losses, voltage drop, and conductor size requirements, while increasing the power transfer capacity of a given right-of-way corridor.
Adopting Extra High Voltage (EHV, 220-765 kV) or Ultra High Voltage (UHV, above 800 kV) for AC transmission offers several advantages: for the same power to be transmitted, a higher voltage proportionally reduces the required line current, which directly reduces I²R transmission losses and voltage drop for a given conductor size, or alternatively allows a smaller, more economical conductor to be used for the same loss/drop performance; it substantially increases the power transfer capacity achievable per transmission corridor (right-of-way), which is increasingly valuable as land acquisition for new transmission corridors becomes more difficult and expensive; and it reduces the number of parallel circuits/towers needed to transmit a given total bulk power over long distances, lowering the overall capital cost per MW-km transmitted despite the higher per-tower insulation and clearance requirements of EHV/UHV lines.