Electric Field Intensity Monitoring for Single-Phase Ground Fault Detection
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Solution Overview
Problem
Existing methods for single-phase ground fault detection in low-current grounding distribution networks face challenges due to high impedance fault paths, noise interference, and low accuracy, particularly in distinguishing between three-phase imbalance and single-phase ground faults, and are unreliable due to dependence on electromagnetic voltage transformers and complex signal processing.
Innovation Solution
Monitoring changes in electric field intensities of three-phase feeders to detect single-phase ground faults by identifying consistent electric field intensity changes, eliminating the need for electromagnetic voltage sensors and reducing ferromagnetic resonance, and using local signal acquisition to improve reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic voltage transformers and complex signal processing are used for fault detection, then measurement capability is improved, but device complexity and reliability deteriorate due to ferromagnetic resonance and noise interference
Solution Approach 1:
The patent extracts and utilizes the electric field signal component from the composite signal, separating it from the complex electromagnetic environment. By focusing specifically on electric field intensity changes rather than processing entire voltage signals through complex transformations, the method isolates the fault detection mechanism from sources of noise and ferromagnetic resonance, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent replaces the mechanical/electromagnetic sensing system (electromagnetic voltage transformers) with an electric field sensing approach. This substitution eliminates the ferromagnetic resonance issues inherent in traditional electromagnetic transformers and simplifies the sensing mechanism, reducing device complexity while improving reliability by removing vulnerable components
2Reliability
If traditional fault detection methods are used, then detection capability is maintained, but reliability deteriorates due to inability to distinguish between three-phase imbalance and single-phase ground faults
Solution Approach 1:
The patent applies local quality by monitoring electric field intensity changes at specific phases rather than analyzing overall system characteristics. During a single-phase ground fault, only the faulted phase exhibits significant electric field intensity changes, while other phases remain relatively stable. This localized monitoring approach enables reliable distinction between single-phase ground faults and three-phase imbalance conditions, improving both reliability and measurement precision
Solution Approach 2:
The patent exploits the asymmetric nature of single-phase ground faults, where only one phase experiences significant electric field intensity changes. By comparing electric field intensity changes across different phases and looking for asymmetric patterns, the method reliably distinguishes single-phase ground faults from symmetric three-phase imbalance conditions, enhancing fault detection reliability and accuracy
3Measurement precision
If impedance-based fault path analysis is used, then fault detection is performed, but detection accuracy deteriorates due to high impedance causing weak fault signatures
Solution Approach 1:
The patent changes the detection parameter from current or voltage (which are weak during high-impedance faults) to electric field intensity. Electric field intensity changes provide a prominent signature even during high-impedance single-phase ground faults, as the electric field distribution in the vicinity of the fault changes significantly. This parameter change improves both measurement precision for detecting weak faults and reliability of fault detection
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
The method enables rapid, accurate, and reliable detection and location of single-phase ground faults, reducing false positives and improving the stability of the power grid by utilizing electric field and current signals in a frequency division manner, providing a prominent fault signature.
Implementation Method 1
monitoring changes of electric field intensities of three-phase feeders in a distribution network
Implementation Method 2
utilizing electric field and current signals in a frequency division manner
Data Source
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AI summary
An method for single-phase ground fault detection based on electric field induction is provided, which includes that: changes of an electric field intensity of three-phase feeders in a distribution network is monitored; and when the changes of the electric field intensities of the three-phase feeders are consistent with a preset electric field intensity change condition, it is determined that a single-phase ground fault occurs in the distribution network. An device for single-phase ground fault detection based on electric field induction and a storage medium are further provided.