High Voltage DC (HVDC) Transmission
HVDC
High Voltage Direct Current transmission involves transmitting Voltage at a very high value of DC, 500 kV instead of adopting AC, thus reducing skin losses, which constitutes a major part of the losses in a transmission line. HVDC, due to its many advantages is emerging as a choice to the Conventional AC transmission. HVDC was first implemented in 1953 in the erstwhile Soviet Union for the power transmission between Moscow and Kashira. The main purpose of transmitting power in DC is for the bulk transfer of power between two regions, as also interconnecting power grids that operate at different frequencies.
HVDC to reduce Power Outages
As HVDC allows power transmission between unsynchronized AC distribution systems, it can help increase system stability, by preventing cascading failures from propagating from one part to another of a wider power transmission grid, whilst still allowing power to be imported or exported in the event of smaller failures. Moreover, HVDC systems make it possible to interconnect unsynchronized AC networks, and also add the possibility of controlling AC voltage and reactive power flow.This has caused many power system operators to contemplate wider use of HVDC technology for its stability benefits alone.
Existing & Prospective HVDC systems in India & abroad
Some of the HVDC links existing in India have been shown in the background. The HVDC project at Vizag enables increased power interchange between the Eastern and Southern region. The 500 MW Vindhyachal back-to-back HVDC station interconnects the Northern and Western Regions. In addition, the system provides voltage and frequency support for both grids during power disturbances. HVDC limks can interconnect the electrical grids that operate on 50Hz and 60Hz.For example, Japan has 50 Hz and 60 Hz networks.Brazil and Paraguay, which share the massive Itaipu hydroelectric plant, operate on 60Hz and 50Hz respectively.
SUMMARY:
- transmission of power in DC at voltages of 500kV or above
- employed for bulk transfer of power
- reduces transmission losses
- increases system stability and reduces power breakdowns
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