According to Mr. Pham Nguyen Hung - Chairman and General Director of the Power Engineering Consulting Joint Stock Company No. 1 (PECC1): HVDC power transmission system is a form of bulk and long – distance transmission of electric power. This type of project is mainly built in countries having large areas or stretching terrain.
Benefits of HVDC over alternating current systems are the transmission of bulk electric power over a long distance with lower electrical losses, controlling power flow very quickly, thus improving the stability not only for HVDC links but also for surrounding AC systems. The connection of grid systems by direct current power transmission lines will limit short-circuit power in the interconnected power system.
A HVDC system can transmit a larger quantity of electric power with the same conductor size compared to an AC system; allowing power transmission between AC grid systems running at different frequencies (inter-connection between two AC systems with different frequencies).
However, the cost of HVDC system is still high, which requires the installation of additional compensation capacitors at converter stations and is more complicated to control.
According to PECC1, in the current Vietnam's power system, power sources are allocated unevenly among regions throughout the country, posing the need for large power transmission in the North - Central - South direction, whereas the capacity of inter-regional power transmission is still limited, which causes a low reserve and safety in power transmission, and the transmission capacity on the North - Central - South transmission line is always high.
With the development of power sources in the coming years, the improvement of inter-regional power transmission to share power from the North, the Central to the South until 2025 and from the Central to the North and the South until 2030 is essential to ensure the safety of electricity supply, enhance the stability and contribute to the economical operation of power system.
With the North - South transmission distance of more than 1,700 km, the transmission capacity of 3,500 MW, HDVC is considered suitable so as to transmit electric power over a large distance with lower electrical losses than alternating current transmission lines.
At this meeting, EVN’s Vice President Nguyen Tai Anh viewed that the consortium had formulated a relatively complete report with due caution in the study. PECC1 and PECC2 should absorb comments from domestic and foreign experts to finalize the report in May 2020. EVN will continue to work with the Institute of Energy and the Electricity and Renewable Energy Agency (Ministry of Industry and Trade). If the construction plan meets the requirements, EVN will propose inclusion of this project into the Master Plan VIII.