Superconducting Fault Current Limiter with Tertiary Winding for Bus Voltage Stability
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Solution Overview
Problem
Conventional Superconducting Fault Current Limiters (SFCLs) fail to effectively suppress bus voltage drops during faults, leading to instability and economic costs in power systems due to the inability to separate faulty sections and stabilize power supply.
Innovation Solution
The proposed SFCL includes a primary winding, secondary winding, and tertiary winding around an iron core, with a superconductor connected to one of the windings, and switches to separate faulty sections and stabilize power supply by generating resistance and controlling magnetic coupling, allowing for stable power delivery during faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SFCL with two coils is used to limit fault current, then fault current is limited by generating resistance in HTSC, but bus voltage drops occur during faults
Solution Approach 1:
The patent divides the single SFCL system into two separate systems: one SFCL dedicated to fault current limitation and another SFCL dedicated to bus voltage support. This segmentation allows each system to independently perform its specific function without interfering with the other, thereby resolving the contradiction between fault current limitation and voltage maintenance
Solution Approach 2:
The patent makes the second SFCL system multi-functional by enabling it to perform both fault current limitation and bus voltage support simultaneously through a switching mechanism. During faults, the switch connects the second SFCL in series to limit fault current, and after fault clearance, the same system switches to parallel connection to support bus voltage, thus achieving multiple functions with a single system
2Reliability
If HTSC generates resistance to limit fault current, then fault current is reduced, but power supply stability deteriorates during faults
Solution Approach 1:
The patent prepares a second SFCL system in advance that can be quickly deployed for power supply support after fault clearance. The switching mechanism is pre-configured to enable rapid transition from fault current limitation mode to voltage support mode, ensuring stable power supply restoration without manual intervention
Solution Approach 2:
The switching mechanism acts as an intermediary between the two operational modes (fault current limitation and voltage support). It seamlessly transitions the second SFCL system between series and parallel connections, mediating the change in system configuration to maintain power supply stability during and after faults
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 solution effectively limits fault currents and prevents bus voltage drops by separating faulty sections and ensuring stable power supply, enhancing system stability and reducing economic costs.
Implementation Method 1
Before a fault occurs, a High Temperature Superconductor (HTSC) maintains zero resistance in a superconducting state
Implementation Method 2
when a fault occurs, and the current flowing through the HTSC exceeds a threshold, resistance is generated in the HTSC
Implementation Method 3
magnetic coupling between two coils (a primary winding and a secondary winding) wound around the same core
Implementation Method 4
magnetic flux components generated by the two coils cancel each other
Implementation Method 5
a second switch connected in series to the tertiary winding and configured to be shorted so as to stably supply power when the fault current is generated
Data Source
AI summary
Disclosed herein is a Superconducting Fault Current Limiter (SFCL) for suppressing a bus voltage drop in an electric power system. A primary winding, a secondary winding, and a tertiary winding are wound around an identical iron core, and a superconductor is connected to any one of the primary winding and the secondary winding. A first switch is connected to any one of the primary winding and the secondary winding and is configured to be opened so as to separate a faulty section when a fault current is generated and to be shorted when the fault current is eliminated. A second switch is connected in series to the tertiary winding and is configured to be shorted so as to stably supply power when the fault current is generated and to be opened when the fault current is eliminated. According to the present invention, there are advantages in that a fault current is limited using magnetic coupling between two coils that are connected in a non-isolated type (in parallel or in series) or in an isolated type and in that a faulty section is separated using a switch and power is stably supplied to a section, in which a bus voltage drop has occurred due to the fault current, using a tertiary winding and a switch connected thereto, thus improving the stability of the system and obtaining economic effects.