Circuit Breaker Zero-Crossing Detection Noise Immunity

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Solution Overview

Problem

Existing methods for controlling circuit breaker opening and closing fail to minimize noise impact during zero-crossing detection, leading to potential delays and malfunctions, especially in substation environments with high noise levels.

Innovation Solution

A method and device that integrate signal processing to detect changes in signal signs, set a zero-crossing reference, and control the circuit breaker based on the absolute value of the signal integral over a period, ignoring noise-induced abnormalities to prevent delays and ensure accurate phase matching without noise impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional zero-crossing detection is used in noisy substation environments, then the circuit breaker can operate, but noise causes detection errors leading to delays and malfunctions

Engineering Contradiction:

Improvereliability of zero-crossing detectionVSAvoidnoise impact on detection

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary signal processing mechanism between the noisy input signal and the zero-crossing detection. This includes filtering stages and reference signal generation that mediate the detection process, allowing accurate zero-crossing identification despite noise. The intermediary processing converts the noisy signal into a cleaner reference signal for comparison.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements feedback mechanisms where the detected zero-crossing information is fed back to adjust the detection threshold and reference signals. This feedback loop continuously optimizes the detection parameters based on the actual signal conditions, improving reliability in noisy environments by adapting to varying noise levels.

Inventive Principle:

Principle #23Feedback

2Speed

If fast switching semiconductor devices are used to reduce operating delay, then switching speed improves, but noise generation increases and detection accuracy decreases

Engineering Contradiction:

Improveswitching speed of circuit breakerVSAvoidprecision of zero-crossing detection

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent segments the control system into distinct functional modules: a semiconductor switching unit for fast operation and a separate signal processing unit for accurate detection. This segmentation allows each module to optimize its function independently - the semiconductor device focuses on speed while the signal processing module focuses on detection precision, resolving the contradiction between speed and accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediary signal conditioning circuit is introduced between the fast-switching semiconductor device and the zero-crossing detector. This intermediary stage filters the high-frequency switching noise generated by the semiconductor device before it reaches the detection circuit, allowing fast switching to proceed while maintaining detection accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If noise filtering is applied to improve detection accuracy, then detection precision improves, but operating delay increases

Engineering Contradiction:

Improveprecision of zero-crossing detectionVSAvoidoperating delay of circuit breaker

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary signal processing and reference signal generation in advance, before the actual zero-crossing detection is needed. By pre-filtering and preparing reference signals during normal operation, the system avoids time-consuming filtering operations at the moment of detection, thus maintaining both precision and speed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional analog filtering mechanisms with digital signal processing techniques. Digital filtering can be implemented with minimal time delay compared to analog RC circuits, allowing the system to achieve high detection precision without significant operating delay through computational rather than physical filtering.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3399533B1Method and device for controlling opening/closing of circuit breaker

Publication Date: 2020.10.21 HYOSUNG HEAVY IND CORP

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AI summary

A method for controlling the opening/closing of a circuit breaker of the present invention includes: a signal inputting step for receiving an input of a signal; a sign change detecting step for detecting a sign change of the signal; a zero crossing reference setting step for setting a zero crossing reference when there is the sign change; a one period integrated value comparing step for checking whether an absolute value of a one period integrated value obtained by integrating the signal for one period from the zero crossing reference exceeds a reference value; a detected phase comparing step for determining whether a detected phase is identical to a set phase; and a circuit breaker opening/closing step for controlling the opening/closing of a circuit breaker when the absolute value of the one period integrated value does not exceed the reference value and the detected phase is identical to the set phase.