GIC Mitigation Switching on Power Transmission Lines
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Solution Overview
Problem
Electric power grids are vulnerable to catastrophic failures due to ground-induced currents caused by geomagnetic storms, which can lead to severe economic and societal consequences, as existing mitigation methods, such as blocking capacitors, are prone to single-point failures and inadequate protection against long-duration geomagnetic events.
Innovation Solution
A system and method that detect DC currents on AC power transmission lines, determine the next zero-crossing point of the AC signal, and use a switch to divert DC currents to ground or a resistive load, effectively removing the DC component while minimizing disruption to the AC power waveform, thereby mitigating ground-induced currents before they integrate and cause damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If blocking capacitors are used to mitigate ground-induced currents, then transformer protection is improved, but system reliability deteriorates due to single-point failure risk
Solution Approach 1:
The patent divides the protection function into multiple independent units distributed along the transmission line. Instead of relying on a single blocking capacitor at the transformer, multiple monitoring devices and switching units are segmented along the line, each capable of independently detecting and mitigating GICs. This segmentation eliminates the single-point failure risk while maintaining transformer protection.
Solution Approach 2:
The patent implements preemptive protection by detecting GICs early in the transmission line and activating switching units before the currents reach the transformer. The system monitors voltage asymmetry and detects DC components beforehand, then activates switches to shunt the GICs to ground before they can integrate and damage the transformer, cushioning the system against potential harm.
2Duration of action of stationary object
If long-duration geomagnetic events occur, then GIC integration increases causing more damage, but existing mitigation methods are inadequate for extended protection
Solution Approach 1:
The patent ensures continuous protection during extended geomagnetic events through persistent monitoring and sustained mitigation. The monitoring devices continuously detect voltage asymmetry and DC components, and the switching units remain ready to activate. This continuous action prevents GIC integration over time, maintaining protection throughout the entire duration of geomagnetic storms regardless of length.
Solution Approach 2:
The system performs preliminary detection of GIC conditions by monitoring voltage asymmetry and detecting DC components before significant current integration occurs. By acting preliminarily and continuously during the event, the system prevents the accumulation of harmful currents over extended periods, addressing the inadequacy of existing methods for long-duration protection.
3Strength
If DC currents are removed from power lines, then transformer damage is prevented, but AC power transmission may be disrupted
Solution Approach 1:
The patent uses periodic switching at the AC voltage zero-crossing points to remove DC currents. The switching units are activated only during the brief moments when AC voltage passes through zero, creating periodic action that eliminates DC components while minimizing disruption to AC power transmission. This timing-based periodic action protects transformers while maintaining productivity.
Solution Approach 2:
The system skips over the harmful DC current components by activating switches only during voltage zero-crossing intervals, allowing the AC power to rush through continuously while the DC components are shunted to ground during these brief skipping moments. This selective skipping removes harmful currents while maintaining overall power transmission continuity.
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 approach provides a cost-effective, resilient, and decentralized method to protect power grids from ground-induced currents, reducing the risk of transformer damage and ensuring continuous power supply by efficiently removing DC currents without impacting the AC power transmission.
Implementation Method 1
a switch that when activated can shunt the signal being transmitted on a transmission line to either ground or to a dissipative circuit
Implementation Method 2
shunt the signal on the transmission line to ground or to a dissipative circuit that can bleed the DC current off the transmission line
Implementation Method 3
detect DC currents on AC power transmission lines, determine the next zero-crossing point of the AC signal
Data Source
AI summary
Systems and methods for mitigating ground induced currents are provided. In one or more examples, the systems and methods can utilize one or more device(s) that can be configured to detect DC currents being induced in and propagated along a power line that is transmitting an AC power signal. In one or more examples the device can be separate the desirable AC power waveform from the undesirable induced DC voltage and determine if the level of induced DC propagating on the power line requires mitigation. In one or more examples, if it is determined that mitigation is required, then the device can be configured to trigger a switch that can be shunt the DC power at the AC waveform zero crossing to a circuit element that is configured to dissipate the undesirable DC current. Filtering can be employed to remove any inadvertent low voltage harmonic distortion. The switch can be triggered during a zero-crossing of the signal to minimize disruption to an end user of the power signal.