Multi-terminal DC power transmission system, common control device thereof, and fault recovery method for multi-terminal DC power transmission system

A common control device of a multi-terminal DC power transmission system,

• the multi-terminal DC power transmission system comprising:
• a multi-terminal DC power grid including a plurality of protection zones, each protection zone being divided from an adjacent protection zone by a DC circuit breaker;
• and
• a plurality of individual protective devices provided corresponding to the protection zones,
• wherein each of the individual protective devices is configured, when detecting change in voltage or current in a corresponding protection zone due to fault occurrence in any of the protection zones, to output a fault signal pertaining to the fault occurrence and open a DC circuit breaker that divides the corresponding protection zone such that the corresponding protection zone is disconnected from the multi-terminal DC power grid and deenergized,
• the common control device comprising:
• a communication unit connected to the individual protective devices via a first communication network, the communication unit being configured to receive the fault signal from each of the individual protective devices detecting change in voltage or current due to the fault occurrence;
• and
• a computation processing unit configured to estimate a fault occurrence zone where a fault occurs among the protection zones, based on a plurality of fault signals, each being the received fault signal,
• wherein the communication unit is configured to output an instruction to reclose a DC circuit breaker to an individual protective device of the plurality of individual protective devices, corresponding to a deenergized protection zone of the plurality of protections zones excluding the fault occurrence zone such that the deenergized protection zone is restored.

A fault recovery method for a multi-terminal DC power transmission system,

• the multi-terminal DC power transmission system comprising:
• a multi-terminal DC power grid including a plurality of protection zones, each protection zone being divided from an adjacent protection zone by a DC circuit breaker;
• a plurality of individual protective devices provided corresponding to the protection zones;
• and
• a common control device connected to the individual protective devices via a first communication network,
• the fault recovery method comprising:
• when detecting, by any one of the individual protective devices, change in voltage or current in a corresponding protection zone due to fault occurrence in any of the protection zones, outputting, by the individual protective device, a fault signal pertaining to the fault occurrence to the common control device via the first communication network, and opening, by the individual protective device, a DC circuit breaker that divides the corresponding protection zone such that the corresponding protection zone is disconnected from the multi-terminal DC power grid and deenergized;
• estimating, by the common control device, a fault occurrence zone where a fault occurs among the protection zones, based on a plurality of received fault signals, each being the output fault signal;
• and
• requesting, by the common control device, an individual protective device of the plurality of individual protective devices, corresponding to a deenergized protection zone of the plurality of protection zones to reclose the DC circuit breaker that divides the deenergized protection zone such that the deenergized protection zone is restored.