Advantages of Direct current transmission compare to AC transmission
Why we use HVDC transmission instead ac transmission?
1) HVDC Transmission can operate with one conductor and ground as return path.on other hand AC transmission required 2 or more conductor, Hence conductor material saved.
Each conductor operate independently.
2)DC power transmission is use for long distance
3) two different DC grid ( same voltage) can be connected together because frequency of dc voltage is zero. We can not connected two grid with different frequencies in ac transmission without using dc link.
4) skin effect is absent in DC transmission.
5) In DC bulk power can be transfer
6) No charging current needed in DC transmission for underground cable
7) Power factor is unity hence reactive power compensation not required
8) Power transfer per conductor is more
9) simple construction
10) Less corona loss
11) Synchronous operation not required. Hence distance of transmission is not limited by power stability
12) Single conductor with ground return can be compared with AC 3 phase single circuit line