Ferroresonance Detection via Amplitude Threshold Filtering

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Solution Overview

Problem

Detecting ferroresonant oscillations in electrical systems is challenging due to their non-linear and chaotic nature, requiring high computing capacity and complex algorithms, which complicates reliable detection and differentiation from other faults.

Innovation Solution

A method that filters digital voltage measurement values using a low-pass filter to determine an amplitude value for half an oscillation period, comparing it to a threshold value to generate a resonance signal, thereby simplifying the detection process and reducing computational demands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wavelet analysis or fuzzy logic methods are used to detect ferroresonant oscillations, then detection reliability is improved, but device complexity and computing capacity requirements increase significantly

Engineering Contradiction:
Improvedetection reliabilityVSAvoidalgorithm complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential feature for ferroresonance detection - the amplitude of filtered voltage measurements during half oscillation periods - while discarding complex frequency domain analysis. By focusing solely on amplitude threshold comparison after simple filtering, the method achieves reliable detection without wavelet decomposition or fuzzy logic classification, thereby reducing algorithm complexity while maintaining detection effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of analyzing frequency components to detect ferroresonance (conventional approach), the patent inverts the approach by filtering the voltage signal and analyzing amplitude characteristics in the time domain. This inversion from frequency-domain analysis to time-domain amplitude comparison simplifies the computational requirements while preserving detection reliability

Inventive Principle:
Principle #13The other way round (Inversion)

2Measurement precision

If complex algorithms are used to distinguish ferroresonance from other faults, then measurement precision is improved, but computing capacity requirements increase

Engineering Contradiction:
Improvefault differentiation precisionVSAvoidcomputing capacity
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by focusing analysis only on specific characteristics - the amplitude of filtered voltage measurements during half oscillation periods - rather than analyzing all signal features. This localized approach to amplitude comparison provides sufficient precision for fault differentiation while minimizing computing capacity requirements by ignoring irrelevant signal aspects

Inventive Principle:
Principle #3Local quality

3Device complexity

If simple threshold comparison is used without filtering, then device complexity is reduced, but measurement precision deteriorates due to noise and non-linear characteristics

Engineering Contradiction:
Improvedetection method simplicityVSAvoidamplitude measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by filtering the voltage measurements before amplitude comparison. The digital filter removes noise and prepares the signal in advance, ensuring that subsequent amplitude threshold comparison is performed on clean, reliable data. This preliminary filtering step maintains measurement precision while keeping the overall detection method simple and computationally efficient

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for efficient detection of ferroresonant oscillations with lower equipment and computing requirements, stabilizing the electrical system and preventing false alarms or damage by generating a resonance signal only when multiple consecutive amplitude values exceed the threshold.

Implementation Method 1

ferroresonant oscillations (also referred to as 'breakdown oscillations') can occur in electrical systems

Methodology Applied
Scientific EffectFerroresonance: Resonance

Implementation Method 2

ferroresonant oscillations are often triggered when the iron core of the voltage transformer becomes saturated

Methodology Applied
Scientific EffectMagnetic flux saturation: Magnetic Saturation

Data Source

PatentEP3080885B1Method and device for generating a resonance signal indicating the presence of a ferroresonant oscillation in an electrical system
Publication Date: 2018.06.27 SIEMENS AG
  • EP3080885B1 patent drawingFigure 1
  • EP3080885B1 patent drawingFigure 2
  • EP3080885B1 patent drawingFigure 3

AI summary

The invention relates to a method for generating a resonance signal indicating the presence of a ferroresonant oscillation in an electrical system (10), in which digital measured voltage values are detected, which indicate a voltage present at a measurement point (19) in the electrical system (10), and the sequence of the digital measured voltage values is monitored for the presence of a ferroresonant oscillation in the electrical system (10), and the resonant signal is generated when a ferroresonant oscillation is present. To be able to make a decision about the presence of a ferroresonant oscillation in the electrical system (10) with comparatively low outlay on equipment, in particular with low demands on the computing capacity of a device carrying out the method, the digital measured voltage values according to the invention are filtered by means of a digital filter to form filtered measured voltage values; in relation to such filtered measured voltage values, which describe half an oscillation period of the voltage, an amplitude value indicating the amplitude during this half oscillation period is determined; the amplitude value is compared with a threshold value; and the resonance signal is generated if the amplitude value exceeds the threshold value. The invention further relates to a correspondingly designed device.