Smart Switch Non-Three-Phase Fault Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric power fault detection and isolation systems often drop distributed generators during non-three-phase fault responses, leading to extended outages and increased customer impact, due to their inability to effectively manage distributed generation resources and communication system vulnerabilities.
Innovation Solution
The implementation of smart switches that quickly detect non-three-phase faults, identify responsive sectionalizer switches, and direct back-feed tie switch operations to maintain synchronous connection with the grid, preventing distributed generators from disconnecting during fault clearing and isolation procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sectionalizing techniques are used to isolate faults, then fault isolation is achieved, but distributed generators are dropped during non-three-phase fault responses leading to extended outages
Solution Approach 1:
The system performs preliminary actions by pre-configuring responsive sectionalizer switches and back-feed tie switches before faults occur. When a non-three-phase fault is detected, the predetermined back-feed tie switch immediately closes to provide an alternate power path, preventing distributed generators from dropping. This preliminary configuration enables instant response without waiting for fault analysis or manual intervention.
Solution Approach 2:
The patent introduces back-feed tie switches as intermediary devices that create alternate power paths between different feeders. When a fault occurs on one feeder, the back-feed tie switch acts as a mediator to redirect power flow from a healthy feeder through the distributed generators, maintaining their connection to the grid and preventing outages while the faulted section is isolated.
2Extent of automation
If conventional reclosers are used to automatically reclose after tripping, then reclosing attempts are made, but manual intervention is required for reset after fault persistence
Solution Approach 1:
The system implements self-service by enabling automatic reclosing of back-feed tie switches after fault isolation. Following the initial trip and fault isolation sequence, the back-feed tie switch automatically recloses after a predetermined time delay, restoring power to the distributed generators without requiring manual intervention. This self-service capability eliminates technician travel time and manual reset operations.
3Ease of operation
If communication systems are installed at transmission tap points for remote monitoring, then remote control capability is achieved, but system cost and complexity increase significantly
Solution Approach 1:
The patent applies universality by designing smart switches that perform multiple functions: fault detection, selective tripping of non-three-phase faults, coordination of back-feed operations, and communication. Rather than adding separate communication systems to existing tap points, the communication capability is integrated into the smart switch itself, which already performs switching and protection functions, thereby avoiding significant complexity increases.
4Reliability
If distributed generators are disconnected during fault clearing procedures, then fault isolation is completed, but mechanical wear on switches increases and grid stability is compromised
Solution Approach 1:
The system maintains continuity of useful action by keeping distributed generators connected to the grid throughout the fault clearing process. The back-feed tie switch provides a continuous power path that allows generators to remain synchronized and operational. This eliminates the stop-start connection/disconnection cycles that cause mechanical wear and grid instability, while still achieving effective fault isolation through selective tripping of only the faulted phases.
Data Source
AI summary
A smart switch allows distributed generators to “ride through” non-three-phase faults by very quickly detecting a non-three-phase phase fault, locating the fault, identifying the “responsive sectionalizer switches” that will be involved in clearing or isolating the fault, and selecting one of the responsive sectionalizer switches to direct back-feed tie switch operations. The responsive sectionalizer switches trip only the faulted phase(s), and the selected sectionalizer switch instructs a back-feed tie switch to close to back-feed the distributed generators prior to conducting the typical fault response operation. This typically occurs within about three cycles, and is completed before the normal fault clearing and isolation procedures, which momentarily disconnect all three phases to the distributed generators from the normally connected feeder breaker. The looped connection to an alternate feeder breaker during these operations allows the distributed generators to “ride through” the normal fault clearing and isolation procedures.