Transient Fault Detection in Electrical Networks

Solution Overview

Problem

Existing fault detection devices in three-phase networks face challenges in rapidly and reliably identifying transient faults, particularly in overhead networks, due to high capacitance values and the intermittent nature of faults, which can lead to delayed detection or failure to detect faults before they resolve on their own.

Innovation Solution

A method and device that determine the frequency of the current signal in a multiphase network by polynomial approximation using three consecutive values, comparing it to the natural frequency to identify faults, allowing for rapid and reliable detection of both transient and non-permanent faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional threshold-based fault detection methods are used, then the detection device can identify faults in three-phase networks, but the detection is delayed or fails for transient faults due to requiring significant sampling or computation periods

Engineering Contradiction:

Improvefault detection reliabilityVSAvoiddetection response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention extracts only the essential information needed for fault detection by using a simplified frequency determination method based on three consecutive current values. Instead of processing entire current waveforms or using complex computational algorithms, the method extracts frequency information from minimal data points (three consecutive current measurements), enabling rapid fault detection without requiring significant sampling periods or complex computations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the detection parameter from traditional threshold-based current or voltage measurements to frequency determination. By calculating the frequency of the current signal using three consecutive values and comparing it to the natural frequency, the method achieves faster and more reliable transient fault detection. This parameter change allows detection within a single current period rather than requiring multiple periods for conventional methods.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If threshold-based detection methods with significant sampling periods are used, then detection accuracy can be maintained, but transient faults occurring between sampling periods cannot be detected

Engineering Contradiction:

Improvefault detection accuracyVSAvoiddetection speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The invention performs preliminary frequency determination using three consecutive current values at the beginning of each current period. This preliminary action allows the system to identify frequency deviations indicative of transient faults before the current period ends, enabling detection within the same period rather than waiting for the next sampling period. This preliminary frequency assessment ensures both accuracy and speed in detecting transient faults.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If complex computational algorithms are used for fault detection, then detection reliability can be improved, but the computation time increases preventing detection of transient faults

Engineering Contradiction:

Improvefault detection reliabilityVSAvoidcomputation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The invention extracts only the essential information needed for fault detection by using a simplified frequency determination method based on three consecutive current values. Instead of processing entire current waveforms or using complex computational algorithms, the method extracts frequency information from minimal data points (three consecutive current measurements), enabling rapid fault detection without requiring significant sampling periods or complex computations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces complex computational algorithms with a mathematical formula-based frequency determination approach. By using the relationship between three consecutive current values and the natural frequency to calculate the actual frequency, the method substitutes complex signal processing and computational algorithms with a straightforward mathematical calculation that can be performed rapidly, achieving both reliability and speed.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10228406B2Detecting a fault, in particular a transient fault, in an electrical network

Publication Date: 2019.03.12 SCHNEIDER ELECTRIC IND SAS

AI summary

In order to determine the occurrence of a fault, notably transient, in an electrical distribution network, a method and a device are developed based on the determination of the frequency (f) of the current signal circulating in a phase of the network. Notably, the difference between the determined frequency (f) and the natural frequency (f0) of the network is compared to a threshold.