DC Blocking Component for Transformer Protection
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Solution Overview
Problem
Current solutions for protecting high voltage transformers from geomagnetic-induced currents (GIC) and high altitude electromagnetic pulses (HEMP) are either costly, unreliable, or require significant maintenance and adjustments to power system relays, with no comprehensive system for sensing and controlling potentially damaging DC or quasi-DC currents.
Innovation Solution
A sensing and control system that includes detection components such as harmonic analyzers, shunt resistors, Hall Effect current sensors, and electromagnetic field detectors, which detect harmful signals and control a switch assembly to provide a DC blocking component for protecting high voltage transformers, allowing for remote operation and self-testing to ensure system functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive circuits are used to block DC currents, then protection against GIC is achieved, but the system requires expensive electronics and complex switching mechanisms
Solution Approach 1:
The patent extracts the DC blocking function from complex capacitive circuits with switches and implements it using a simple normally-closed switch that opens only when DC current is detected, eliminating the need for expensive capacitive switching mechanisms while maintaining protection reliability
Solution Approach 2:
Instead of using capacitive circuits that are normally active and require switching to block DC, the patent uses a resistive circuit with a normally-closed switch that is inactive during normal operation and only activates (opens) when DC current needs to be blocked, inverting the operational state
2Reliability
If active components are continuously used to reduce GIC, then protection is maintained, but the system becomes expensive and unreliable due to constant operation
Solution Approach 1:
The patent implements periodic action by using a control system that continuously monitors for DC current and only activates the protective switch opening when DC current is detected, rather than keeping active components continuously operational, thereby reducing complexity and cost while maintaining protection
Solution Approach 2:
The system performs self-service through automatic detection and response to DC current conditions, with the control system autonomously opening or closing the switch based on sensor input, eliminating the need for continuous human intervention or complex control mechanisms
3Reliability
If fixed value resistors are used to reduce DC current, then protection is provided, but the resistor must have high resistance value and only reduces rather than eliminates DC current
Solution Approach 1:
The patent transitions from a static fixed-value resistor to a dynamic switchable circuit that can change state between normally-closed and open positions, allowing complete elimination of DC current rather than just reduction, while simplifying the overall circuit configuration
4Reliability
If sensing and control systems are installed to detect DC currents, then protection capability is enhanced, but the system requires substantial on-site maintenance
Solution Approach 1:
The patent implements feedback through sensors that continuously monitor DC current and provide input to the control system, enabling automatic response without requiring manual inspection or adjustment, thereby reducing on-site maintenance requirements while enhancing detection capability
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 effectively protects high voltage transformers from GIC and HEMP events by blocking DC currents, preventing half cycle saturation, excessive reactive power losses, and grid collapse, while being cost-effective and requiring minimal maintenance, with self-test capabilities ensuring continuous reliability.
Implementation Method 1
Hall Effect current sensors, which detect harmful signals
Implementation Method 2
shunt resistors, which detect harmful signals
Implementation Method 3
A DC blocking component is electrically connected between the transformer neutral and ground
Data Source
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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.