Multi-Port Hybrid DC Circuit Breaker With Shared Breaking Branch
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Solution Overview
Problem
The high investment cost of direct current circuit breakers in complex power grids is a bottleneck due to the high cost of breaking switches formed by connecting power electronic devices in series and parallel, and existing multi-port circuit breakers have high through-flow loss and do not adequately address bus fault protection for both common buses.
Innovation Solution
A multi-port hybrid direct current circuit breaker design with through-flow branches, reversing branches, and a breaking branch, utilizing fast mechanical switches and diode bridge arms, along with a bus fault protection branch and auxiliary energy consumption branch, to share an expensive breaking switch and reduce semiconductor count, enhancing fault protection and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple power electronic devices are connected in series and parallel to form breaking switches, then the fault current breaking capacity is improved, but the investment cost increases significantly
Solution Approach 1:
The breaking switch is designed as a multi-port device that can protect multiple incoming and outgoing lines simultaneously. A single breaking switch with multiple ports replaces what would traditionally require multiple separate breaking switches, thereby maintaining fault current breaking capacity while significantly reducing the number of devices needed and the overall investment cost
Solution Approach 2:
Multiple breaking functions for different lines are merged into a single multi-port breaking switch. The breaking switch integrates multiple breaking chambers and control mechanisms into one unified device, allowing it to handle fault current from multiple lines through a single device rather than requiring separate devices for each line
2Device complexity
If a multi-port direct current circuit breaker is adopted to share a breaking switch, then the number of circuit breakers is reduced, but the through-flow loss increases
Solution Approach 1:
The multi-port breaking switch is segmented into multiple independent breaking chambers, each equipped with its own fast mechanical switch. This segmentation allows current from different lines to be interrupted independently through dedicated chambers, reducing the through-flow path length and minimizing energy loss compared to a single integrated chamber design
Solution Approach 2:
Fast mechanical switches are introduced as intermediary devices between the power electronic components and the breaking chambers. These fast mechanical switches can rapidly open to interrupt current flow, reducing the duration and magnitude of through-flow losses while coordinating with the multi-port breaking switch to maintain system protection
3Speed
If power electronic devices are used to form breaking switches, then the breaking speed is improved, but the cost of the breaking switch increases
Solution Approach 1:
The design hybridizes power electronic switching with mechanical breaking. Power electronic devices (IGBTs or MOSFETs) perform the initial current commutation and transfer at high speed, then fast mechanical switches complete the physical interruption. This combination achieves rapid breaking speed while reducing reliance on expensive all-electronic breaking switch designs
Solution Approach 2:
The breaking process utilizes parameter changes in the power electronic devices to transition from conducting to blocking state. By controlling the switching parameters of IGBTs/MOSFETs and coordinating with mechanical switch timing, the system achieves rapid current interruption with optimized cost-performance balance
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 design reduces the number of semiconductors in the current path, lowers through-flow loss, improves economic efficiency, enhances bus fault protection, and maintains rapid on/off capabilities for rated and fault currents, while reducing the need for nonlinear resistors and improving reliability.
Implementation Method 1
a first fast mechanical switch and a one-way commutation switch which are connected in series
Implementation Method 2
each of the at least two reversing branches includes a diode upper bridge arm and a diode lower bridge arm which are connected in series in the same direction
Implementation Method 3
the breaking branch includes a one-way breaking switch and a nonlinear resistor which are connected in parallel
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed are a multi-port hybrid direct current circuit breaker and a control method thereof. The circuit breaker includes at least two through-flow branches, at least two reversing branches and a breaking branch; each through-flow branch includes a first rapid mechanical switch and a one-way commutation switch which are connected in series; one ends of the through-flow branches are interconnected to form a direct current bus; each reversing branch includes a diode upper bridge arm and a diode lower bridge arm which are connected in series in the same direction; the other end of each through-flow branch is correspondingly connected to an intermediate point of each reversing branch to form a port; the breaking branch includes a one-way breaking switch and a nonlinear resistor which are connected in parallel; the breaking branch and the reversing branches are connected in parallel to form a first common bus and a second common bus.