Fault Detection in Three-Phase Distribution Networks

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Solution Overview

Problem

Existing methods for detecting faults in electrical distribution networks, particularly in radially operated medium voltage networks, are inefficient and often damage the system due to the need for time-consuming and manpower-intensive test measurements, and struggle with accurately localizing faults in compensated networks.

Innovation Solution

A method and system for detecting faults in three-phase electrical distribution networks by determining zero sequence, phase, and filtered currents, comparing their directions, and signaling faults based on threshold exceedances, utilizing fault detector control units and arrangements along the network to provide reliable and efficient fault detection and location.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If test measurements are performed to locate faults, then fault location information can be obtained, but the process requires a lot of effort and manpower and is time-consuming

Engineering Contradiction:

Improvefault location accuracyVSAvoidtime for fault detection

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual test measurements with an automated electronic detection system that uses current sensors and signal processing algorithms to automatically locate faults, eliminating the need for manual intervention and significantly reducing detection time

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system enables self-diagnosis of the electrical distribution network by automatically detecting and locating faults without requiring external manual testing, allowing the network to identify its own problems through embedded sensors and processing units

Inventive Principle:

Principle #25Self-service

2Measurement precision

If test measurements are performed to locate faults, then fault location information can be obtained, but the process requires a lot of manpower

Engineering Contradiction:

Improvefault location accuracyVSAvoidmanpower required for fault detection

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Inventive Principle:

Principle #25Self-service

3Measurement precision

If circuit breakers are closed during test measurements, then fault location measurements can be performed, but the electrical distribution system may be damaged

Engineering Contradiction:

Improvefault location accuracyVSAvoidsystem damage risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system applies preliminary filtering and signal processing to isolate and identify fault signatures before taking any action, allowing fault detection without requiring circuit breakers to be closed, thus preventing potential system damage

Inventive Principle:

Principle #9Preliminary anti-action

4Device complexity

If centralized measurements are used for fault locating, then fault distance can be estimated, but the ability to localize faults to the right branch is limited

Engineering Contradiction:

Improvemeasurement system structureVSAvoidfault branch localization accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the electrical distribution network into multiple monitored zones with distributed measurement points, allowing precise identification of which specific branch contains a fault by comparing measurements from different locations rather than relying on a single centralized measurement point

Inventive Principle:

Principle #1Segmentation

5Measurement precision

If distributed measurements are used for fault locating, then faulty branch recognition is improved, but the system requires disconnector stations with appropriate measurements and remote control capability

Engineering Contradiction:

Improvefaulty branch recognition accuracyVSAvoiddisconnector station requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a universal fault detection algorithm that can be implemented at any measurement point in the network, allowing the same core technology to identify faults regardless of location, thereby reducing the need for specialized equipment at specific disconnector stations

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11428726B2Method and apparatus for detecting faults in a three-phase electrical distribution network

Publication Date: 2022.08.30 EMTELE AUTOMATION OY

AI summary

A method for detecting faults (4) in a three-phase electrical distribution network comprising determining a zero sequence current (21 C), a first phase current (21A) and a second phase current (21 B) at a location of the three-phase electrical distribution network, determining first filtered currents (22) by removing a frequency component from the determined currents corresponding to a fundamental frequency of the electrical distribution network through filtering out said frequency component, determining directions of the first filtered currents during a first time period (23), and comparing said directions (24) relatively to each other, and, if at least one of the determined directions is opposite with respect to at least one of the other two determined directions, signaling a detection of a fault (25).