Recloser Coordination via Pulse Testing and TCC Curve Management
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Solution Overview
Problem
Conventional reclosers in electrical power distribution networks face challenges in accurately identifying intermittent faults without subjecting the feeder line to full fault current, which can cause equipment stress and lead to inaccurate fault predictions.
Innovation Solution
A method for coordinating switches in multiple reclosers along a distributed feeder line involves detecting fault currents, initiating pulses of varying durations to assess fault presence, and temporarily changing the time current characteristic (TCC) curves to differentiate between fault states, allowing for precise fault detection without full current application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reclosers apply full fault current to detect intermittent faults, then fault detection capability is improved, but equipment stress and damage risk increase
Solution Approach 1:
The patent applies partial action by using pulse closing instead of full fault current application. The recloser closes for a brief pulse duration (e.g., 10-50 milliseconds) to test for faults, rather than applying sustained full fault current. This partial application of closing action allows fault detection while limiting equipment stress and mechanical wear.
Solution Approach 2:
The patent implements periodic action through multiple pulse closing cycles. The recloser performs a sequence of pulse closings with intervals between them, allowing the system to test for intermittent faults repeatedly over time. This periodic testing approach improves detection accuracy for intermittent faults while maintaining equipment protection through the pulsed nature of each test.
2Speed
If conventional reclosers use minimal wait time after opening, then response speed is improved, but fault detection accuracy deteriorates
Solution Approach 1:
The patent uses periodic pulse closing actions with optimized intervals. After opening the recloser, it waits a brief interval then performs a pulse closing test. This periodic sequence of open-test-close operations allows the system to maintain fast response while accurately detecting intermittent faults that may not be present during every test cycle.
Solution Approach 2:
The patent applies preliminary action by performing pulse closing tests before committing to a locked-out state. The recloser executes preliminary pulse tests to determine whether faults are intermittent or permanent, only locking out after multiple failed tests. This preliminary testing approach maintains fast response while improving fault detection accuracy.
3Device complexity
If multiple reclosers operate independently with same TCC curves, then device simplicity is improved, but coordination accuracy deteriorates
Solution Approach 1:
The patent applies local quality by assigning different TCC curves to different reclosers based on their location along the feeder line. Upstream reclosers have different time-current characteristics than downstream reclosers, allowing the system to maintain simplicity in individual recloser design while achieving accurate coordination and fault location identification through the network as a whole.
Solution Approach 2:
The patent implements parameter changes by modifying TCC curve parameters (time delays, current thresholds) for different reclosers in the network. These parameter adjustments enable coordinated operation where each recloser operates with optimized settings for its specific position, improving fault location accuracy without significantly increasing device complexity.
Data Source
AI summary
A method for controlling multiple switching devices in an electrical power distribution network in response to detecting a fault. The method determines that a fault current is present, and opens a switch in each of the switching devices in response thereto. The method then initiates a current pulse in the switch in a farthest upstream switching device for a first pulse duration time, closes the switch in the farthest upstream recloser if no fault current is detected during the first pulse duration temporarily changes the TCC curve of the farthest upstream recloser to a second TCC curve that is an instantaneous or near instantaneous TCC curve, and initiates a current pulse in the switch in a next farthest upstream switching device that is downstream of the farthest upstream switching device after the switch in a farthest upstream switching device is closed.