DC Breaker H-Bridge Current Control for HVDC Fault Interruption
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Solution Overview
Problem
Current DC breakers in high-voltage direct current (HVDC) power transmission systems face challenges in efficiently disconnecting fault points due to conduction losses and increased facility dimensions, particularly when dealing with large fault currents, which are exacerbated by the need for high-capacity semiconductor circuit breakers and H-bridge circuits.
Innovation Solution
A DC breaker design that incorporates a mechanical disconnection switch, a mechanical circuit breaker in series, a parallel circuit with a semiconductor circuit breaker and a reactor, and an H-bridge circuit that controls current flow through output voltage management, allowing for efficient fault current breaking without arcs and reducing facility dimensions and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a semiconductor circuit breaker is connected in series to perform fast-speed breaking, then the fault current breaking speed is improved, but conduction loss occurs causing reduction of power transmission efficiency
Solution Approach 1:
The breaker function is segmented into two independent parts: a mechanical circuit breaker for normal current interruption and a semiconductor circuit breaker for fast fault current breaking. This segmentation allows each component to optimize for its specific function, with the mechanical breaker handling steady-state operations without conduction losses and the semiconductor breaker providing rapid fault response when needed.
Solution Approach 2:
An H-bridge circuit acts as an intermediary between the power transmission line and the parallel-connected breakers. This intermediary controls current distribution dynamically, directing fault current to the semiconductor breaker for fast interruption while maintaining normal current flow through the mechanical breaker, thereby eliminating conduction losses during normal operation.
2Reliability
If a semiconductor circuit breaker with large-current capacity is used to break increasing fault current, then the fault current breaking capability is improved, but the facility dimension and costs increase
Solution Approach 1:
The current breaking function is segmented between mechanical and semiconductor breakers, allowing the semiconductor breaker to be sized for fast fault interruption rather than continuous high-current carrying capacity. The mechanical breaker handles the bulk of current transmission duties, enabling the semiconductor components to be more compact while maintaining adequate fault breaking capability.
Solution Approach 2:
The semiconductor circuit breaker is designed to handle only the transient fault current portion rather than the full continuous current. By providing excessive fast-breaking capability for fault conditions while relying on the mechanical breaker for normal current flow, the system achieves reliable fault protection with reduced semiconductor component size and cost.
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 proposed DC breaker achieves fast-speed fault current disconnection with reduced conduction losses and costs, enhancing power transmission efficiency and reliability by utilizing the mechanical disconnection switch and semiconductor circuit breaker in parallel, while the H-bridge circuit manages current flow effectively.
Implementation Method 1
the H-bridge circuit controls a current flowing through the mechanical circuit breaker by an output voltage control
Implementation Method 2
a parallel circuit which is connected in parallel with the mechanical disconnection switch and the mechanical circuit breaker, and which includes a semiconductor circuit breaker that changes a supply or a breaking of a current of the DC power transmission system, and a reactor connected in series to the semiconductor circuit breaker
Implementation Method 3
which includes a plurality of switching elements and a capacitor
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4~5
AI summary
A DC breaker 1 includes a mechanical disconnection switch 2 provided at a power transmission line 100, a mechanical circuit breaker 20 connected in series to the mechanical disconnection switch 2, and a parallel circuit 3 connected in parallel with the mechanical disconnection switch 2 and the mechanical circuit breaker 20. The parallel circuit 3 includes a semiconductor circuit breaker 4 that changes a supply or a breaking of the current from the power transmission line 100 to the parallel circuit 3, and a reactor 55 connected in series to the semiconductor circuit breaker 4. An H-bridge circuit 5 which connects one point between the mechanical disconnection switch 2 and the mechanical circuit breaker 20 to one point between the semiconductor circuit breaker 4 and the reactor 55 is provided. The H-bridge circuit 5 includes an H-bridge unit 50 including a plurality of switching elements 51 and a capacitor 53. The H-bridge circuit 5 controls the current flowing through the mechanical circuit breaker 20 by an output voltage control.