UHV; UHV; The voltage symbol is U (some places are useful for V); The unit of voltage is the volt, and the unit symbol is also V; Larger than the volt has kV (thousand volts), smaller than the volt mV (millivolts), uV (microvolts), and between them is the kilocare. In China, UHV refers to the voltage level of ±800 kV and above direct current and 1000 kV and above alternating current.
(1) UHV DC transmission system in the middle of the non-landing point, can be point-to-point, high-power, long-distance direct power to the load. In the case of clear transmit-receive relationship, UHV DC transmission is used to achieve AC-DC parallel transmission or asynchronous networking, and the grid structure is relatively loose and clear.
(2) UHVDC transmission can reduce or avoid a large number of power flow over the network, and change the power flow according to the change of the operation mode at both ends of the transmission and reception. The power flow direction and size of UHVDC transmission system can be easily controlled.
(3) UHVDC transmission has high voltage, large transmission capacity and narrow line corridors, which is suitable for high-power and long-distance transmission.
(4) In the case of AC and DC parallel transmission, the use of DC active power modulation can effectively suppress the power oscillation of its parallel AC lines, including regional low-frequency oscillation, and significantly improve the transient and dynamic stability of AC.
(5) High-power DC transmission, when the DC system is blocked, the AC system at both ends will bear a large power impact.