FLISR Switches Using Definite Time Coordination
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Solution Overview
Problem
Existing fault location, isolation, and service restoration (FLISR) techniques in electrical distribution grids rely on real-time communications between switches, which are vulnerable to disruptions and can lead to prolonged outages when communication channels are interrupted.
Innovation Solution
A control system that uses definite time coordination and local measurements between feeder switches to isolate faults and restore service without requiring real-time communications, by sharing time-current characteristics and feeder topology prior to a fault event, allowing switches to determine when to open or close based on pre-defined protection curves and timer values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time communications are used between switches for FLISR, then fault location and isolation can be achieved, but the system becomes vulnerable to communication disruptions and outages
Solution Approach 1:
The patent extracts the communication dependency from the FLISR system by implementing local decision-making logic at each switch. Each switch independently determines fault location and isolation actions based on pre-programmed time-current characteristics and local measurements, eliminating the need for real-time communication infrastructure and thereby removing the vulnerability to communication disruptions.
Solution Approach 2:
Each switch is equipped with self-service capabilities to autonomously perform fault detection, location, and isolation functions. The switches use locally stored time-current characteristics and their own measurement data to make independent decisions about opening or closing, without requiring external communication or control signals, thus achieving FLISR reliability independent of communication systems.
2Productivity
If real-time communications are required for FLISR, then centralized control can be maintained, but service restoration is delayed when communication channels are interrupted
Solution Approach 1:
The patent implements preliminary action by pre-programming time-current characteristics and feeder topology information into each switch before faults occur. When a fault happens, switches immediately use this pre-loaded information combined with local measurements to rapidly determine isolation and restoration actions, eliminating the time delay associated with real-time communication and centralized processing.
Solution Approach 2:
The centralized FLISR control function is segmented and distributed to individual switches. Each switch independently executes fault detection, location, isolation, and restoration functions using its own processing capabilities and pre-stored information. This segmentation eliminates the single point of failure and communication dependency in centralized systems, enabling immediate service restoration even when communication channels are interrupted.
3Reliability
If communication channels are used for FLISR, then coordination between switches can be achieved, but the system fails completely when communication is interrupted
Solution Approach 1:
The patent applies local quality by equipping each switch with locally stored time-current characteristics and feeder topology specific to its position in the network. Each switch uses this localized information combined with its own measurements to make independent FLISR decisions, eliminating the need for communication-based coordination and ensuring continuous operation under any communication conditions.
Data Source
AI summary
A control system and method for a feeder, or portion of the distribution grid, which enables fault location, isolation and service restoration without communications between the feeder switches. The method uses definite time coordination between feeder switches and local measurements to determine which switches should open or close in order to isolate the fault and restore service downstream of a faulted section. Time-current characteristics and feeder topology are shared with all switches in the feeder prior to a fault event. When a disturbance occurs, a timer is started at each switch. When a switch measures voltage loss in all three phases, it stops its timer. Each switch evaluates the timer values and, when a particular switch determines based on the time-current characteristics that the immediate upstream switch opened to isolate the fault, that particular switch also opens. Power upstream of the particular switch is then provided by an alternative source.