Transmission line fault location, isolation and system restoration (FLISR) system

A power restoration system for an electrical power transmission network, the power restoration system comprising:

• a transmission power line;
• a first substation providing high voltage power to one end of the power line;
• a second substation providing high voltage power to an opposite end of the transmission power line;
• a first fault interrupting device electrically coupled to the one end of the transmission power line, the first fault interrupting device being operable to detect fault current and perform reclosing operations;
• a second fault interrupting device electrically coupled to the opposite end of the power line, the second fault interrupting device being operable to detect fault current and perform reclosing operations;
• a plurality of switching devices electrically coupled along the transmission power line between the first and second fault interrupting devices, the plurality of switching devices each having current and voltage sensing capability, have the capability to provide pulse testing for detecting fault presence and have the same or similar opening response time, wherein in response to a fault on the power line, the first and second fault interrupting devices perform reclosing operations, and wherein when the plurality of switching devices detect fault current a predetermined number of times in coordination with reclosing operations performed by the fault interrupting devices and detect loss of voltage when the fault interrupting devices open following a reclose operation will open;
• and,
• the fault interrupting devices close when the plurality of switching devices open, and wherein the plurality of the switching devices sequentially pulse test and close from a furthest upstream switching device when detecting return of voltage and no fault presence is detected until a switching device closest to the fault pulse tests and detects fault presence and locks open.

A method for restoring power in an electrical power network comprising:

• detecting fault current on a power line flowing from at least one power source to a fault by at least one fault interrupting device and a plurality of switching devices distributed along the power line, the switching devices each having current and voltage sensing capability, are capable of providing pulse tests for detecting fault presence and have the same or similar opening response time subject to the influences of load;
• performing reclosing by the at least one fault interrupting device to determine if the fault is still present;
• accumulating a number of times that the plurality of switching devices detect fault current in response to the reclosing operations performed by the at least one fault interrupting device;
• opening all of the plurality of switching devices when the accumulated number of times reaches a predetermined number and detecting loss of voltage when the at least one fault interrupting device opens following a reclosing operation;
• closing the at least one fault interrupting device when the plurality of switching devices open;
• and
• sequentially pulse testing and closing the switching devices from a furthest upstream switching device when detecting return of voltage and no fault presence until a switching device closest to the fault pulse tests and detects fault presence and locks open.