FAULT LOCATION IN DC NETWORKS

摘要

This application relates to methods and apparatus for fault protection in a DC power transmission network or grid (200) that aid in determining the location of a fault in the network. The method involves, in the event of a fault, controlling at least one current limiting element (201; 202) of the network so as limit a fault current flowing to below a first current level which is within the expected current operating range of the network in normal operation, i.e. a safe level. The current limiting element (201) may be part of a suitable voltage source converter (101) or a DC breaker (202) capable of current limiting. The fault current is then controlled to maintain a non-zero level of fault current flow. The characteristics of the fault current flow at different parts of the network are then determined by fault current detection modules (203a-d). The location of the fault is then determined, by the fault current modules (203a-d) or a control system (205), based on the determined characteristics of the fault current flow at different parts of the network. The characteristic may include the direction or polarity of current flow. In some embodiments the current limiting elements may impose an AC modulation on the fault current which differs across the network and the characteristics of fault current may include the presence or absence of such modulation.