Earth Grid Integrity Detection Using Off-Frequency Current Injection
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Solution Overview
Problem
Existing systems for detecting electrical grounding inter-grid integrity between buried earth grids are inefficient, as they often require high current injection, which can cause equipment damage and safety threats, and typically require shutting down electrical substations or process plants for testing, making it difficult to assess integrity while the system is in service.
Innovation Solution
A system utilizing a current injection device that modifies input current to an off-grid frequency and amplitude, combined with a measuring device and bypass conductors, allows for the detection of inter-grid connectivity integrity without high current injection, enabling assessment while the system is operational by measuring voltage drops and resistance before and after connecting bypass conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high current is injected to detect earth grid damage, then detection capability is improved, but equipment safety deteriorates and tripping occurs
Solution Approach 1:
The patent changes the frequency parameter of the test current from power frequency (50/60 Hz) to a different frequency. This allows the test current to be distinguished from normal operating currents and enables detection without injecting high amplitude currents that would cause tripping or equipment damage. The frequency transformation is achieved using a frequency converter that converts power frequency current to a different frequency for testing purposes.
Solution Approach 2:
The patent introduces a frequency converter as an intermediary device between the test current source and the earth grid. This intermediary transforms the current characteristics (frequency) before injection, enabling safe testing by preventing direct high-current injection that would cause harmful effects while still allowing integrity detection through the transformed current signal.
2Measurement precision
If high current testing is performed, then fault detection is improved, but system availability deteriorates requiring shutdown
Solution Approach 1:
By changing the frequency parameter of the test current, the system can perform testing during normal operation without causing protective relay tripping. The frequency-converted test current coexists with power frequency operating currents, enabling continuous operation and maintaining system availability while achieving fault detection capability.
Solution Approach 2:
The patent enables continuous testing and operation by using frequency-converted currents that do not interfere with normal power system operation. The earth grid can be tested while the substation remains in service, maintaining continuous productive operation without shutdowns or interruptions to the electrical system.
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 system accurately detects inter-grid integrity without disrupting the electrical grid, avoiding equipment damage and allowing for real-time assessment of faulty connections, enabling prompt repairs without shutting down operations.
Implementation Method 1
a frequency converter that modifies an input current with grid frequency into an input current with off-grid frequency
Implementation Method 2
a measuring device that is connected between the first reference riser and the second reference riser to measure a voltage drop and resistance
Implementation Method 3
a current unit that regulates the input current with off-grid frequency into a variable amplitude input current with off-grid frequency
Data Source
AI summary
A system for detecting an electrical grounding inter grid integrity between the earth grids includes a current injection device 108 that provides the low amplitude input current with off-grid frequency to the first earth grid 102 to detect the electrical grounding inter grid integrity between the first earth grid 102 and the second earth grid 104. The system includes a measuring device 106 that is connected to a first reference riser 112A and a second reference riser 112B to measure a drop in voltage or resistance between the first earth grid 102 and the second earth grid 104. The system includes a first bypass conductor 114 that is connected between the first earth grid 102 and the second earth grid 104 to transmit the input current with off-grid frequency to the second earth grid 104 when the electrical grounding inter grid connectivity is damaged.