Transformer Protection Sensing for DC and Harmonic Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solutions for protecting high voltage transformers from geomagnetic storms and electromagnetic pulses (GIC/HEMP) are either costly, unreliable, or require substantial maintenance, and lack a comprehensive sensing and control system to effectively manage damaging DC or quasi-DC currents and harmonics.
Innovation Solution
A sensing and control system that includes detection components like harmonic analyzers, shunt resistors, Hall Effect current sensors, and electromagnetic field detectors, coupled with a controller that opens a switch in a protection circuit to block DC currents and harmonics, and features self-test procedures to ensure functionality, all housed in a shielded enclosure to prevent electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive circuits with switches are used to block DC currents, then transformer protection is improved, but system complexity and cost increase due to expensive electronics and relay readjustment requirements
Solution Approach 1:
The patent extracts the DC blocking function from complex capacitive circuits with switches and isolates it into a simple series-connected capacitor component in the neutral grounding path. This removes the need for expensive electronics and complex control systems while maintaining the DC blocking capability.
Solution Approach 2:
The protection system is segmented into independent functional components: the series capacitor for DC blocking, parallel resistors for energy dissipation, and simple detection circuitry. This modular approach reduces overall system complexity and eliminates the need for coordinated relay settings.
2Reliability
If continuous active components are used to reduce GIC currents, then transformer protection is improved, but cost and reliability worsen due to expensive power equipment and constant operation requirements
Solution Approach 1:
Instead of continuous operation, the system uses periodic detection of DC current conditions followed by activation of the blocking circuit only when needed. The series capacitor provides automatic, event-driven protection rather than requiring continuous active component operation.
Solution Approach 2:
The patent employs simple, inexpensive passive components (capacitors and resistors) that can be easily replaced if needed, rather than expensive active power equipment. These components provide adequate protection without requiring continuous operation or complex control.
3Reliability
If fixed value resistors are used to reduce DC current, then some protection is achieved, but DC current elimination is insufficient and relay readjustment is still required
Solution Approach 1:
The system changes the electrical parameters in the neutral path by introducing a series capacitor that blocks DC while passing AC, and parallel resistors that provide AC grounding. This parameter change achieves complete DC blocking without requiring resistor value adjustments or relay settings changes.
Solution Approach 2:
The series capacitor performs multiple functions simultaneously: it blocks DC currents, maintains AC grounding continuity, and prevents transformer saturation. The parallel resistors provide additional AC grounding and energy dissipation. This multi-functional approach eliminates the need for separate DC blocking and grounding systems.
4Object-affected harmful factors
If shielded enclosures with filters are used to protect against EMP, then electromagnetic protection is improved, but system cost and complexity increase
Solution Approach 1:
The patent introduces filters as intermediary components between the external electromagnetic environment and the sensitive control electronics. These filters selectively block high-frequency EMP signals while allowing normal control and sensing signals to pass through, providing protection without requiring complete shielding.
Solution Approach 2:
Instead of uniformly shielding the entire system, the patent applies electromagnetic protection locally at critical points where control electronics interface with the external environment. This targeted approach reduces the overall complexity and cost compared to comprehensive shielding.
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 provides reliable, cost-effective protection for high voltage transformers by effectively blocking damaging DC currents and harmonics, preventing transformer damage and grid instability, while minimizing maintenance needs and ensuring continuous operation.
Implementation Method 1
Hall Effect current sensors configured to detect damaging DC or quasi-DC currents in the transformer neutral to ground connection
Implementation Method 2
The control system is enclosed in an EMP/IEMI shielded and electrically filtered enclosure
Implementation Method 3
filters positioned along the inner periphery of the shielded enclosure, configured to prevent high frequency, high power electromagnetic signals from entering the shielded enclosure
Implementation Method 4
A DC blocking component is connected in parallel with the switch assembly between the transformer neutral and the ground
Data Source
AI summary
Systems and method for detecting potentially harmful harmonic and direct current signals at a transformer are disclosed. One such system includes a plurality of detection components electrically connected to electrical signal lines leading from one or more connection points on a power grid, and a plurality of threshold detectors, each threshold detector configured to compare an incoming signal from a detection component to a predetermined signal having a threshold. The system also includes a controller receiving an output from each of the plurality of threshold detectors and configured to drive at least one external component in response to receiving an indication from at least one of the plurality of threshold detectors of a detected signal above a threshold.