Study On Regulation Of Frequency And Voltage Based On VSC-HVDC At The Early Stage Of Network Restoration

At the early stages of electric network restoration, the capacity of power system is relatively small, and adding large power load to such a power system will result in severe fluctuation of system frequency and voltage. Thus the stable operation and the restoration speed of power system will be affected seriously. VSC-HVDC (Voltage Source Converter based HVDC) can control active and reactive power injected into network independently and rapidly. Based on the characteristics of VSC-HVDC, a coordinated control method between VSC-HVDC and conventional speed governing system or automatic voltage regulator (AVR) is proposed to maintain the stability of frequency or bus voltage at the early stage of network restoration. The whole system model is established in RTDS environment. Simulation results show that the fluctuations of frequency and voltage are diminished remarkably, and the stability is improved by adopting the method proposed. It's conducive to expediting the restoration process of power system.