Overvoltage Protection Reset Control via Failure Current Monitoring
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Solution Overview
Problem
Conventional overvoltage suppression devices in variable-speed pumped storage power systems face challenges in efficiently performing reset control without damaging semiconductor elements, leading to increased size, cost, and space requirements due to the need for multiple parallel circuits, especially during grid system failures on the high-voltage side.
Innovation Solution
An overvoltage protection device with a reset control locking condition determination unit that differentiates between high-voltage and low-voltage side failures by monitoring voltage and current conditions, allowing appropriate reset control to prevent damage to semiconductor elements and reducing the number of parallel circuits needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overvoltage suppression device is designed based on the maximum failure current at the time of the grid system failure on the high-voltage side of the main transformer, then the equipment can withstand the maximum failure current, but the size of the equipment increases and the price increases
Solution Approach 1:
The patent changes the design parameter from maximum failure current to a current value that is a predetermined percentage (e.g., 80%) of the maximum failure current. This parameter change allows the equipment to be sized for normal reset control operations rather than worst-case scenarios, reducing equipment size and cost while maintaining sufficient reliability for typical grid system failures.
Solution Approach 2:
The patent introduces dynamic control through the determination unit that dynamically decides whether to permit reset control based on real-time monitoring of failure current magnitude. This dynamic approach allows the system to adapt the equipment's operational state to actual conditions, permitting reset control when safe and preventing it when the failure current exceeds safe thresholds, thereby reducing the need for oversized equipment.
2Reliability
If the number of parallel circuits of the semiconductor element is increased to prevent damage during erroneous reset control, then the equipment is protected from damage, but the manufacturing cost increases and the space requirement increases
Solution Approach 1:
The patent implements a self-protecting control system where the determination unit automatically monitors failure current levels and makes intelligent decisions about permitting reset control. This self-service approach eliminates the need for conservative oversizing of semiconductor elements, as the system autonomously prevents erroneous reset control that would cause damage, thereby reducing manufacturing costs and space requirements.
Solution Approach 2:
The patent employs feedback control by continuously monitoring the failure current magnitude and using this information to dynamically permit or lock reset control. This feedback mechanism ensures that reset control is only permitted when the failure current is within safe thresholds, providing reliable protection without requiring excessive parallel circuits, thus reducing manufacturing cost and space while maintaining equipment safety.
3Productivity
If reset control is performed on the overvoltage suppression device, then the operation of the secondary exciter is resumed and the power system is restored at high speed, but the semiconductor element may be damaged if the joint temperature is too high
Solution Approach 1:
The patent performs preliminary assessment by monitoring the magnitude of the failure current before permitting reset control. By evaluating the failure current magnitude in advance and comparing it against predetermined thresholds, the system determines whether reset control can be safely executed. This preliminary action ensures that reset control is only initiated when conditions are safe, preventing semiconductor damage while enabling high-speed restoration when appropriate.
Solution Approach 2:
The patent replaces physical thermal monitoring of semiconductor joints with an electrical measurement approach, substituting direct temperature measurement with monitoring of failure current magnitude. Since failure current magnitude correlates with the thermal state and safety of semiconductor elements, this substitution enables indirect but effective safety assessment, allowing high-speed reset control decisions without complex thermal sensing while maintaining reliability.
Data Source
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AI summary
An overvoltage protection device of a variable-speed power system according to an embodiment includes a detection unit (27) configured to detect a prescribed phenomenon that occurs when a failure has occurred on the high-voltage side of a main transformer or when a failure has not occurred on the low-voltage side of the main transformer or inside the main transformer or to detect that the prescribed phenomenon has not occurred, and a control unit (L1, L2, F1, F2, SW1, SW2) configured to determine based on a detection result of the detection unit (27) whether control to forcibly release the operation of the overvoltage suppression device (13) is to be permitted to be performed.