Inverse Wave Fault Identification for Lightning-Triggered Grid Protection
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Solution Overview
Problem
Existing fault detection methods in high and medium voltage DC or AC grids struggle to accurately identify and classify lightning-induced faults, particularly due to the stochastic nature of lightning strikes and the inability to model their current waveform, leading to potential non-detection or inappropriate protection actions.
Innovation Solution
A transient-based method that measures voltage and current at specific locations in the grid, uses an inverse physical wave propagation model to estimate the initial voltage waveform at the fault location, and iteratively adjusts to classify faults, allowing for precise identification and control of protection actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fault detection methods are used in HVDC grids, then the protection system can operate, but it cannot accurately identify lightning-induced faults due to the stochastic nature of lightning strikes and inability to model their current waveform
Solution Approach 1:
The patent inverts the traditional approach by not trying to model the lightning current waveform directly, but instead using the measurable voltage waveform and applying an inverse physical wave propagation model to estimate the initial voltage waveform at the fault location. This inversion strategy allows accurate fault identification without needing to model the stochastic lightning current.
Solution Approach 2:
The patent introduces an inverse physical wave propagation model as an intermediary between the measurable voltage waveform and the fault characteristics. This intermediary model enables the transformation of measurable quantities into meaningful fault information without directly modeling the unpredictable lightning current.
2Productivity
If selective fault clearing strategy is implemented to minimize grid impact, then only the faulty component is isolated, but the protection algorithm must operate extremely fast (less than a millisecond) which makes telecommunication unsuitable
Solution Approach 1:
The patent performs preliminary action by using the inverse physical wave propagation model to estimate the initial voltage waveform and determine fault characteristics in the very first milliseconds after fault occurrence. This preliminary analysis enables immediate selective tripping decisions without requiring time-consuming communication or iterative calculations.
Solution Approach 2:
The patent replaces the mechanical/telecommunication-based protection systems with a physics-based computational approach using inverse wave propagation models. This substitution enables ultra-fast local decision-making at the measurement point without relying on external communication infrastructure.
3Reliability
If breaking modules are triggered before faulty component identification to ensure fast protection, then the grid is protected from damage, but a large part of the grid is deenergized which is non-selective and minimizes grid impact
Solution Approach 1:
The patent implements feedback by continuously monitoring the voltage waveform and using the inverse physical wave propagation model to provide real-time fault characterization. This feedback loop enables the protection system to make informed selective tripping decisions immediately, ensuring both grid protection and minimal disruption by isolating only the faulty component.
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 method effectively distinguishes between different types of faults, such as pollution, vegetation, and direct lightning strikes, enabling targeted protection actions and minimizing unnecessary system disruptions by accurately locating and characterizing faults, even in the presence of stochastic lightning events.
Implementation Method 1
measuring voltage and current at a specific location in the said power system of at least one travelling wave due to a suspected fault
Implementation Method 2
estimate initial voltage waveform at fault location by using an inverse physical wave propagation model applied to the measurements concerning the at least one travelling wave
Data Source
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AI summary
The invention concerns a transient-based method for controlling protection actions in an electric power transmission and/ or distribution system having at least one current transmission line comprising the following steps : - measurement (10) of voltage and/or current at a specific location in the said power system of at least one travelling wave due to a suspected fault having occurred on a current transmission line, - estimate (20) initial voltage waveform at fault location by using an inverse physical wave propagation model applied to the measurements concerning the at least one travelling wave, and taking into account the distance between said specific location and the fault location, - identification and classification (30) of the fault in function of estimated initial voltage waveform at fault location, - control (40) of protection actions in function of the fault classification.