- TRANSIENT PROTECTION FOR MULTI-TERMINAL HVDC GRID

摘要

The present invention discloses a method and device for providing protection of a multi-terminal HVDC grid from failures. The method includes measuring a DC displacement voltage Ud having a polarity and a value, determining whether a short circuit fault exists by comparing the DC displacement voltage Ud with a critical displacement voltage Ut and the polarity of the DC displacement voltage. And identifying the failure type based on the value. The disclosed device includes a converter having a positive and negative pole, a DC-switch substation, a DC line connecting the converter and the DC-switch substation, and a transient fault detector. The transient fault detector is a positive voltage sensor for detecting positive transient voltage (Up) of the positive pole and a negative voltage sensor for detecting a negative transient voltage (Un) of the negative pole and a positive transient voltage (Up) and negative transient voltage And a control unit configured to derive the DC displacement voltage Ud from Un.