DC grid and a method of limiting the effects of a fault in a DC grid

摘要

A DC grid (100) comprising a plurality of AC/DC converters (105) which are interconnected via DC lines (115) is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones (200) by means of at least one current limiter (205) in a manner so that a current limiter is connected in each of the DC line(s) (115z) by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.

主权项

1. A DC grid comprising:
a plurality of AC/DC converters which are interconnected via DC lines, wherein
the DC grid further comprises at least one current limiter which is capable of breaking the current at at least the rated voltage;the DC grid is divided into at least two zones by the at least one current limiter in a manner so that at least one of the at least one current limiter is connected in each of the DC line(s) by which two zones are interconnected; andthe at least one current limiter dividing the at least two zones is adapted for limiting, but not breaking, a fault current that flows into a fault in a zone from neighbouring zones during a fault-on period; and in connection with a current limiter interconnecting a first and a second zone, a control system for controlling the current-limiting strength of the current limiter, the control system being operable to instruct, if a fault occurs in the first zone, the current limiter to limit the current flowing into the first zone from the second zone through the at least one current limiter, wherein
the control system comprises a current measuring device arranged to measure the current through the current limiter; andthe control system is operable to detect a fault, and if a fault has been detected, to adjust the current-limiting strength of the current limiter in a manner so that:if the current through the breaker exceeds a first current threshold (Imax), the current-limiting strength is increased; andif the current through the breaker falls below a second current threshold (Imin), the current-limiting strength is decreased.