Method for coordinating switches in multiple reclosers in a distribution feeder line in response to detection of a fault

A method for controlling multiple switching devices positioned at certain intervals along a feeder line in an electrical power distribution network in response to detecting a fault, where each switching device has a first time current characteristic (TCC) curve during normal operation where no fault is present in the feeder line, the method comprising:

• measuring a current flow through the switching devices;
• determining that a fault current is present indicating a fault in the feeder line;
• opening a switch in each of the switching devices in response to detecting the fault current so as to prevent current flow through the switching devices;
• initiating a current pulse of a first pulse duration in a farthest upstream switching device relative to the current flow;
• closing the switch in the farthest upstream switching device if no fault current is detected during the first pulse duration time;
• temporarily changing the TCC curve of the farthest upstream switching device to a second TCC curve that is an instantaneous or near instantaneous TCC curve;
• and
• initiating a current pulse for a second pulse duration time in a next farthest upstream switching device that is downstream of the farthest upstream switching device a predetermined time after the switch in the farthest upstream switching device is closed.

A system for controlling multiple switching devices positioned at certain intervals along an electrical line in an electrical power distribution network in response to detecting a fault, where the switching devices are operable to allow or prevent current flow, and where each switching device has a first time current characteristic (TCC) curve during normal operation when no fault is present in the line, said TCC curve identifying how fast the switching device will be closed in response to certain current levels, the system comprising:

• means for measuring a current flow through the switching devices;
• means for determining that a fault current is present indicating a fault in the electrical line;
• means for opening a switch in each of the switching devices in response to detecting the fault current so as to prevent current flow through the switching device;
• means for initiating a current pulse in a farthest upstream switching device relative to the current flow in a pulsed manner for a first pulse duration time;
• means for analyzing the current flow through the farthest upstream switching device that occurred during the first pulse duration time after the first pulse duration time has ended;
• means for closing the switch in the farthest upstream switching device if no fault current is detected during the first pulse duration time;
• means for temporarily changing the TCC curve of the farthest upstream switching device to a second TCC curve that is an instantaneous or near instantaneous TCC curve;
• means for initiating a current pulse for a second pulse duration time in a next farthest upstream switching device that is downstream of the farthest upstream switching device a predetermined time after the switch in the farthest upstream switching device is closed;
• means for temporarily changing the TCC curve of the farthest upstream switching device from the second TCC curve to a third TCC curve at or near the same time that the next farthest upstream switching device initiates the current pulse for the second pulse duration time;
• means for analyzing the current flow through the next farthest upstream switching device that occurred during the second pulse duration time after the second pulse duration time has ended;
• means for closing the switch in the next farthest upstream switching device if no fault current is detected during the second pulse duration time;
• means for temporarily changing the TCC curve of the next farthest upstream switching device to the second instantaneous or near instantaneous TCC curve;
• means for detecting that the fault current has returned in the next farthest upstream switching device;
• and
• means for opening the switch in the next farthest upstream switching device.