Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Main Advantage of DC transmission over AC
Maintenance of substations is easy
Switches & breakers have no limits
No commutation problems
Reduced corona loss & interference
No commutation problems
DC transmission systems do not involve the rotation of vectors or the periodic reversal of current, which eliminates the need for complex commutation processes found in AC converters and rotating machinery. Consequently, DC links are free from the synchronizing, stability, and commutation-related synchronization issues that plague high-voltage AC systems.
DC transmission systems do not involve the rotation of vectors or the periodic reversal of current, which eliminates the need for complex commutation processes found in AC converters and rotating machinery. Consequently, DC links are free from the synchronizing, stability, and commutation-related synchronization issues that plague high-voltage AC systems.
P=VI тАФ Power transmitted in DC system
XLтАЛ=2╧АfL тАФ Inductive reactance which is zero for DC (f=0)
In AC systems, the periodic zero-crossing of voltage requires phase-locked loops and precise synchronization for power converters. DC transmission operates at a constant potential, meaning the power flow is controlled purely by the magnitude of voltage and resistance, bypassing the need for frequency synchronization or commutation cycles.
DC transmission is ideal for long-distance, high-power bulk transmission.
Elimination of frequency-dependent effects like skin effect and proximity effect improves efficiency.
HVDC links provide asynchronous interconnection between different grids.
No reactive power compensation needed for line charging current.
Higher power transfer capacity for the same conductor size.
Lower dielectric stress on cables compared to AC.
High cost of converter stations.
Difficulty in interrupting DC fault currents due to lack of natural current zero.
Generation of harmonics requiring expensive filtering.
Long-distance overhead bulk power transmission.
Submarine cable links.
Interconnection of asynchronous AC grids.
| Feature | AC System | DC System |
|---|---|---|
Commutation Requirement | Required in Converters | Not Required |
Option A is incorrect because DC converter stations are complex and require sophisticated maintenance.
Option B is incorrect because DC breakers are actually more difficult to build than AC breakers due to the lack of natural zero-crossing.
Option D is partially true, but 'No commutation problems' is a fundamental operating characteristic advantage of DC transmission.
C is correct тАФ DC transmission systems inherently eliminate the complex commutation and synchronization problems required to match AC frequency and phase.
Always remember that while DC avoids commutation issues in the line, the converter stations themselves (if line-commutated) still rely on the AC grid for commutation.