Power Electronic Tap Changer Module Overvoltage Protection
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Solution Overview
Problem
Existing power electronic tap changer modules struggle to maintain undisturbed power flow during long-term overvoltage or open circuit conditions, as standard transient voltage suppressors are limited to short-time protection and require additional components like fuses or circuit breakers, which can lead to internal arc-faults and reduced component lifespan.
Innovation Solution
A power electronic tap changer module with an overvoltage triggering circuit and thermally protected MOV or TVS diodes, along with a pair of diodes in reverse polarity, automatically triggers the nominal valve to reduce voltage to a safe level, eliminating the need for external measurements and additional components, and ensuring continuous power flow by rating the oversized valve for short-circuit current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard transient voltage suppressors (MOV, TVS diodes) are used for overvoltage protection, then short-time overvoltage is mitigated, but long-term overvoltage protection is unavailable and component lifespan is reduced
Solution Approach 1:
The protection function is segmented between two types of valves: oversized valves rated for short-circuit current provide long-term overvoltage protection, while standard valves handle nominal operations. This segmentation allows each component to be optimized for its specific function, with oversized valves having higher voltage withstand capability for sustained periods.
Solution Approach 2:
The invention changes the voltage rating parameter of specific valves (oversized valves) to be higher than standard valves, enabling them to withstand long-term overvoltage conditions. This parameter change allows the system to differentiate between short-term surge protection needs and long-term overvoltage tolerance requirements.
2Reliability
If oversized power electronic components are used in all tap changer modules to withstand short circuit current, then short circuit protection is ensured, but economic efficiency decreases due to unnecessary oversizing
Solution Approach 1:
Oversized power electronic components are applied locally only to specific tap changer modules that require short-circuit withstand capability, rather than uniformly to all modules. This local quality approach ensures that only necessary components are oversized, reducing overall system cost while maintaining required protection levels.
Solution Approach 2:
The tap changer system is segmented into different valve types: oversized valves for short-circuit protection and standard valves for nominal operation. This segmentation allows cost optimization by applying expensive oversized components only where absolutely necessary for safety and reliability.
3Reliability
If circuit breakers or fuses are activated to protect against long-term overvoltage, then overvoltage damage is prevented, but power flow is interrupted and internal arc-fault risk increases
Solution Approach 1:
The oversized valves are designed to inherently withstand long-term overvoltage conditions without requiring external protection devices like circuit breakers or fuses. This self-service capability eliminates the need for protective devices that would interrupt power flow, allowing continuous operation even during overvoltage events.
Solution Approach 2:
The oversized valves provide beforehand cushioning by being pre-designed with sufficient voltage and power ratings to absorb and withstand long-term overvoltage energy dissipation. This prior cushioning prevents the need for reactive protection measures that would disrupt power flow.
4Ease of manufacture
If standard valves are used without oversizing, then cost is reduced, but the valve cannot withstand long-term overvoltage or open circuit conditions
Solution Approach 1:
The valve population is segmented into two categories: standard valves for cost-effective nominal operation and oversized valves for critical short-circuit and long-term overvoltage protection. This segmentation achieves cost reduction while maintaining necessary reliability through strategic placement of oversized components.
Solution Approach 2:
Specific valves are selected with changed parameters (higher voltage and power ratings) to handle exceptional conditions, while most valves maintain standard parameters for cost efficiency. This selective parameter change optimizes the balance between cost and reliability.
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 solution provides reliable protection against short-circuit, overcurrent, and long-term overvoltage conditions without disrupting power flow, reducing the size and footprint of power electronic elements and eliminating the need for additional components, while maintaining reliability and economy.
Implementation Method 1
standard transient voltage suppressors are used like: MOV (Metal Oxide Varistor) device or TVS diodes (Transient Voltage Suppressor diodes)
Implementation Method 2
a pair of diodes with reverse polarity
Implementation Method 3
a transformer (4) having a primary winding (3) and a secondary winding (5)
Data Source
Figure 1~2
Figure 3~4
AI summary
The subject of the invention is a power electronic tap changer module (1') for transformer (4) using power electronic elements connected to sections of a primary winding (3) of the transformer. The power electronic tap changer module (1') is equipped with valves (V1'...VN') having a pair of a thyristor or transistors connected with a controller (7) and the valves (V1'...VN') are connected in series with the fuses (F1... FN), respectively. The module (1') is equipped with an additional oversized tap line (LX) having an oversized valve (VX) rated for short circuit current, which valve is connected with an overvoltage triggering circuit(11), The oversized valve (VX) is equipped with a pair of thyristor or transistors connected with a thermally protected voltage suppressing device (13).