The Research on the Emergency DC Power Support Strategies of Deyang-Baoji HVDC Project

The mechanism of Emergency DC Power Support (EDCPS) is analyzed based on a model in which two AC systems are connected by a HVDC Link. This model can be considered as an equivalent two-machine power system, and it is demonstrated that stepping up (or stepping down) DC power during the angle-swing-up (or angle-swing-back) course of the equivalent system can help absorb (or compensate) active power which will advance the transient stability of AC/DC system through extended equal area criterion (EEAC). In accordance with the conclusion, the case of summer peak load in 2010 about Sichuan Power Grid connected with Southwest Power Grid by Deyang-Baoji HVDC project is studied including short-circuit fault of AC lines, fault-free generation shedding and fault-free load shedding in Sichuan Power Grid. The results prove that the High Level Modulation is efficacious against the first fault while the DC Emergency power rise/drop combined with High Level Modulation works with the latter two faults.