Insulation Fault Location Device Using Frequency Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing insulation fault location systems in electrical networks with isolated neutral are cumbersome due to the need for synchronous communication buses, complicating installation and operation, especially in networks with multiple branches and distant derivations.
Innovation Solution
A device that injects alternating current signals at multiple frequencies, including sub-multiples of the natural frequency, to measure fault current and voltage simultaneously, allowing for local determination of leakage impedance without synchronous communication buses, using simultaneous current and voltage measurements and calibration to determine fault impedance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous communication buses are used for fault location measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the synchronous communication function from the measurement system by using the existing power frequency signal as both the injection signal and synchronization reference. This eliminates the need for separate synchronous communication buses while maintaining measurement precision, as the power frequency signal inherently provides the timing reference needed for synchronized measurements across all branches.
Solution Approach 2:
The power frequency signal serves multiple functions simultaneously: it is the injection signal for exciting the network, the synchronization reference for timing measurements, and the carrier for fault detection. This multi-functionality eliminates the need for dedicated communication infrastructure while maintaining system precision.
2Measurement precision
If synchronous communication buses are installed for each branch, then fault location accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The patent removes the requirement for installing separate synchronous communication infrastructure by utilizing the existing power frequency signal. This extraction simplifies installation significantly as no additional communication buses or synchronization equipment need to be deployed across multiple branches, while fault location accuracy is maintained through the inherent synchronization of the power frequency signal.
3Measurement precision
If multiple injection frequencies are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs periodic injection of alternating current signals at the power frequency and its harmonics. This periodic action at multiple frequencies enables precise impedance measurement through frequency-domain analysis while maintaining relatively simple injection hardware that can generate standard power frequency signals and their harmonics.
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
Enables precise and efficient location of insulation faults with reduced architectural complexity and installation requirements, providing reliable impedance measurements even in non-uniform grounding conditions, and is applicable to various power supply configurations.
Implementation Method 1
means for injecting an alternating current signal of a first frequency into the network; the injection means are capable of also injecting, in particular simultaneously, at least one alternating current signal of a second frequency into the network
Implementation Method 2
means for measuring the fault current and means for measuring the fault voltage... allowing for local determination of leakage impedance without synchronous communication buses, using simultaneous current and voltage measurements
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The device (30) has a measurement unit (32) to measure a fault current (Id) with a frequency on an electrical network branch (D), and comprising a detection core (34) surrounding a power supply line of the branch. Another measurement unit (38) measures a fault voltage (Ud) with the frequency on the branch. A determination system (40) determines fault impedance (Zd) of the branch based on the fault current and the fault voltage measured on the branch.