Relay Logic for Downed Conductor Fault Detection

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Solution Overview

Problem

Energized downed conductors pose a significant public safety hazard, and existing methods have failed to effectively detect and isolate them, leading to unreliable alarm generation and automatic isolation in electrical transmission systems.

Innovation Solution

A method and system that utilize protective relay logic to generate a per-phase alarm and automatically trip and isolate high-impedance faults by detecting faults in multiple phases, employing a variable pickup timer to filter out false alarms and initiate a protective trip and reclose, with the option to transmit alarms to a distribution management system for operator response or automatic isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing detection methods are used, then alarm generation is simple, but reliability of detection is poor leading to false alarms or missed detections

Engineering Contradiction:

Improvedetection reliabilityVSAvoidrelay logic complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The relay logic is segmented into distinct functional blocks: HIF detection circuit, variable pickup timer, alarm generation circuit, and automatic isolation circuit. Each block performs a specific function in the detection and response sequence, allowing for modular implementation and improved reliability through functional separation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The variable pickup timer is triggered in advance upon detecting a first HIF condition, creating a time window before alarm generation. This preliminary action allows the system to verify whether a second HIF occurs within the expected time frame, reducing false alarms while maintaining rapid response capability.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If automatic isolation is implemented, then public safety is improved, but system complexity and potential for false tripping increase

Engineering Contradiction:

Improvepublic safety hazardVSAvoidfalse tripping risk

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system performs preliminary verification by triggering a variable pickup timer upon detecting a first HIF condition. The automatic isolation is only activated if a second HIF is detected within the timer window, ensuring that transient or false HIF conditions do not trigger unnecessary isolation events.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates feedback through the variable pickup timer mechanism, which monitors whether a second HIF condition occurs within the expected time frame. This feedback loop validates the authenticity of the HIF condition before committing to automatic isolation, significantly reducing false tripping while maintaining public safety.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If per-phase alarm generation is implemented, then fault location precision is improved, but alarm reliability may decrease due to phase-specific false alarms

Engineering Contradiction:

Improvefault phase identificationVSAvoidalarm false positive rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The alarm generation is segmented into per-phase detection with individual variable pickup timers for each phase. This allows precise identification of which phase experienced the HIF condition while maintaining independent verification for each phase, improving both localization accuracy and reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each phase has its own variable pickup timer and alarm generation logic, allowing the system to treat each phase independently with locally optimized detection parameters. This local quality approach ensures that a false HIF on one phase does not trigger alarms on other phases, improving overall alarm reliability while maintaining precise phase identification.

Inventive Principle:

Principle #3Local quality

4Reliability

If variable pickup timer is used, then false alarm filtering is improved, but response time to actual faults may increase

Engineering Contradiction:

Improvefalse alarm reductionVSAvoidfault response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The variable pickup timer dynamically adjusts the verification window based on the detected HIF condition. The timer duration is optimized to be sufficient for verifying genuine faults while remaining short enough to maintain rapid response capability, balancing false alarm filtering with quick fault isolation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the time parameter of the variable pickup timer based on the specific HIF detection pattern. By adjusting the timer duration and thresholds according to the detected conditions, the system optimizes the balance between filtering false alarms and maintaining rapid response to genuine faults.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10825323B2Systems and methods for relay logic for alarming and tripping for energized downed conductors

Publication Date: 2020.11.03 PPL CORP

AI summary

A method of determining a fault and whether to activate an alarm includes detecting a first high impendence fault (HIF) at a first detection circuit having a first phase and triggering a variable pickup timer. The method further includes monitoring for a second HIF at a second detection circuit having a second phase for a period of time set by the variable pickup timer. The method further includes determining whether to trigger an alarm, wherein the alarm is triggered by the second HIF at the second detection circuit having the second phase being detected during the period of time and the alarm is otherwise not triggered.