Adaptive Overcurrent Protection Using Incremental Current Supervision

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Solution Overview

Problem

Existing ultra high-speed fault detection techniques in electric power systems may mistakenly identify non-fault events as faults, leading to unnecessary protective actions, and there is a need for improved supervision to differentiate between faults and other events like switching events to ensure system security and stability.

Innovation Solution

The implementation of a supervision element using incremental currents and a time-varying threshold based on system conditions to differentiate between faults and switching events, allowing for adaptive overcurrent protection that balances speed and security in electric power systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If ultra high-speed fault detection techniques are used, then fault detection speed is improved, but false identification of non-fault events as faults increases

Engineering Contradiction:

Improvefault detection speedVSAvoidfault identification accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent introduces an intermediary supervision element that acts as a mediator between the ultra high-speed fault detection and the protective action. This supervision element analyzes incremental quantities and compares them against thresholds to verify whether a detected event is truly a fault before triggering protection, thereby preventing false tripping while maintaining fast detection speed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The supervision element implements a feedback mechanism where the output of the fault detection is fed back into a verification process. The supervision element continuously monitors incremental quantities and uses this feedback to confirm or reject the fault detection signal, ensuring that protective actions are only taken for genuine faults.

Inventive Principle:

Principle #23Feedback

2Reliability

If conventional overcurrent protection is used, then system security is maintained, but unnecessary protective actions occur due to misidentification of switching events

Engineering Contradiction:

Improvesystem securityVSAvoidprotective action accuracy

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent employs dynamic thresholds for the supervision element that adapt based on system conditions. Rather than using fixed thresholds, the supervision element adjusts its criteria for identifying faults dynamically, allowing it to distinguish between normal switching events and actual faults more accurately, thereby reducing unnecessary protective actions while maintaining system security.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The supervision element changes the parameters used for fault detection by analyzing incremental quantities (changes in voltage and current) rather than absolute values. This parameter transformation allows the system to detect the distinctive signature of faults versus switching events, improving protective action accuracy.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If fast fault clearing is implemented, then power system stability is improved, but discrimination between faults and switching events becomes more difficult

Engineering Contradiction:

Improvepower system stabilityVSAvoidfault discrimination difficulty

Core Design Contradiction:

Stability of the object's compositionVSDifficulty of detecting and measuring

Solution Approach 1:

The supervision element performs preliminary analysis of incremental quantities before triggering protective actions. By pre-processing and analyzing the characteristics of voltage and current changes in advance, the supervision element can quickly distinguish faults from switching events, enabling fast fault clearing while maintaining accurate discrimination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional mechanical or conventional electrical protection mechanisms with a supervision element based on incremental quantity analysis. This substitution enables faster and more accurate discrimination between faults and switching events by using computational analysis of electrical parameters rather than conventional protection methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10522995B2Overcurrent element in time domain

Publication Date: 2019.12.31 SCHWEITZER ENGINEERING LABORATORIES INC

AI summary

The present disclosure pertains to systems and methods for supervising protective elements in electric power systems. In one embodiment, a system may be configured to selectively enable a protective action an electric power system. The system may include a data acquisition subsystem receive a plurality of representations of electrical conditions associated with at least a portion of the electric power delivery system. An incremental quantities module may calculate incremental quantities from the plurality of representations. The system may be configured to detect an event, to determine an incremental quantities value during the event, and to determine a time-varying threshold. The incremental quantities value during the event may be compared with the time-varying threshold, and a protective action module may be enabled to implement a protective action when the value of the incremental quantities value during the event exceeds the time-varying threshold.