Fast MMC-based line energization

A novel strategy for HVDC bipole and asymmetrical monopole line fast re-energizaton using half-bridge MMC internal energy


Besides the recognized advantages over conventional VSCs, one of the remarkable features of the MMC is the ability to store energy in the distributed sub-modules. As a solution to the DC voltage restoration problem, we propose a novel strategy that makes use of the energy storage capability of the MMC to bring the voltage in the HVDC lines back to its rated value. This implies a disconnection of the concerned MMC from its correspondent AC grid, in order to control the lines energization. By employing this method, the total time from the fault occurrence to the power restoring is around 1 sec. The proposed strategy allows to accelerate the time to restore the power while avoiding the use of DC discharging resistors and DC pre-insertion closing resistors. An insulation recovery check can be also performed smoothly.



  • No need for discharge or closing résistors
  • Fast power restoration after a DC fault
  • Capability to check smoothly check voltage recovery


  • Point to point HVDC connection (bipole and asymetrical monopole with an OHL portion)
  • Also applicable to cable-based MTDC grids


Patent appl. FR3065590 PCT/EP2018/059849

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