Fast recovery strategy for MMC-HVDC based on coordination of fault current suppression and adaptive restart

Abstract

The rapid suppression of fault current flowing through overhead transmission lines and safe restart of the system are critical problems to be solved urgently to improve the stability of the DC grid. A novel adaptive restart strategy combined with fault current suppression is proposed, which suitable for full-bridge modular multilevel converter high voltage direct current system. The resistance-capacitance energy transfer branch is used to achieve a large reduction and rapid attenuation of the fault current amplitude at restart time. The transient fault and permanent fault can be discriminated in a short interval after restarting based on the frequency domain amplitude characteristics. The proposed scheme has both restart-current protection and fault property identification functions, overcoming the high cost and low component reusability of traditional single-function fault current limiting schemes. The simulation results show that the scheme has a significant fault current suppression effect and accurately discriminates the fault property to realize rapid recovery.

Novel adaptive reclosing scheme of MMC‐HVDC transmission lines based on phase synchronization compensation control

“…The transient electrical information in the time-domain and the mode-domain can be used as characteristic fault signals. It is transmitted as activation to coordinate accurately between multiple devices [17][18][19]. However, stochastic noise and transition resistance adversely affect the accuracy of the data transmission.…”