(1) The UHV DC transmission system does not drop in the middle and can send power point to point, high power and long distance directly to the load centre. In the case of clear delivery-receiver relationship, the use of UHV DC transmission realizes parallel AC-DC transmission or non-synchronous networking, and the grid structure is relatively loose and clear.
(2) UHV DC transmission can reduce or avoid a large number of over-grid currents and change the currents in accordance with the changes in the operating mode of both the sending and receiving ends. Both the direction and size of tidal currents in the UHV DC transmission system can be easily controlled.
(3) The high voltage, large transmission capacity and narrow line corridors of UHV DC transmission make it suitable for high-power and long-distance transmission.
(4) In the case of parallel AC-DC transmission, the use of DC active power modulation can effectively suppress the power oscillations of the AC lines in parallel with it, including regional low-frequency oscillations, and significantly improve the transient and dynamic stability performance of AC.
(5) High power DC transmission, when the DC system lockout occurs, the AC system at both ends will be subject to large power shocks.
