Frequency control capability of Vsc-Hvdc for large power systems

The VSC-HVDC transmission system has shown its significant advantage on the independent control capability of active and reactive power in power systems. This flexible controllability can be used for primary frequency control of large interconnected systems and voltage support of local areas. Based on the system models of three large interconnections in North America, the frequency control capability of VSC-HVDC transmission systems used to connect each interconnection is investigated. Simulation results show that VSC-HVDC systems can provide very fast active power support to improve the dynamic frequency performance of interconnections after contingencies of tripping the major generator(s).