Unidirectional DC Breakers for HVDC Switchyard Loss Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage DC switchyards using standard bidirectional semiconductor devices, such as IGBTs, incur significant conduction losses and require a large number of devices due to their inability to block negative voltages, leading to increased costs and inefficiencies.
Innovation Solution
Implementing unidirectional DC breakers in high voltage DC switchyards, which reduce the number of semiconductor devices needed by allowing current flow in only one direction, thereby minimizing costs and losses while maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional semiconductor devices (IGBTs) are used in DC breakers to handle both current directions, then the breaker can block negative voltages and operate bidirectionally, but the number of semiconductor devices increases and conduction losses increase significantly
Solution Approach 1:
The DC breaker is segmented into two functional parts: a unidirectional semiconductor switch section for fast fault interruption, and a bidirectional mechanical switch section for normal bidirectional operation. This segmentation allows each part to be optimized for its specific function, reducing overall losses.
Solution Approach 2:
A mechanical switch acts as an intermediary between the unidirectional semiconductor switch and the bidirectional operation requirement. The mechanical switch handles the bidirectional current flow during normal operation, while the semiconductor switch only handles fast interruption in one direction during faults.
2Adaptability or versatility
If bidirectional semiconductor devices are used in DC breakers, then the breaker can handle both current directions, but the number of semiconductor devices required increases
Solution Approach 1:
The DC breaker is segmented into two functional parts: a unidirectional semiconductor switch section for fast fault interruption, and a bidirectional mechanical switch section for normal bidirectional operation. This segmentation allows each part to be optimized for its specific function, reducing overall losses.
Solution Approach 2:
A mechanical switch acts as an intermediary between the unidirectional semiconductor switch and the bidirectional operation requirement. The mechanical switch handles the bidirectional current flow during normal operation, while the semiconductor switch only handles fast interruption in one direction during faults.
3Loss of energy
If unidirectional DC breakers are used, then the number of semiconductor devices is reduced and conduction losses are minimized, but the breaker can only block current in one direction
Solution Approach 1:
The DC breaker is segmented into two functional parts: a unidirectional semiconductor switch section for fast fault interruption, and a bidirectional mechanical switch section for normal bidirectional operation. This segmentation allows each part to be optimized for its specific function, reducing overall losses.
Solution Approach 2:
The mechanical switch provides multi-functionality by handling both bidirectional current flow during normal operation and assisting the semiconductor switch during fault conditions, enabling the system to achieve bidirectional capability without requiring bidirectional semiconductor devices.
4Ease of manufacture
If unidirectional DC breakers are used, then costs are reduced due to fewer semiconductor devices, but the breaker cannot block negative voltages
Solution Approach 1:
The DC breaker is segmented into two functional parts: a unidirectional semiconductor switch section for fast fault interruption, and a bidirectional mechanical switch section for normal bidirectional operation. This segmentation allows each part to be optimized for its specific function, reducing overall losses.
Solution Approach 2:
A mechanical switch acts as an intermediary between the unidirectional semiconductor switch and the bidirectional operation requirement. The mechanical switch handles the bidirectional current flow during normal operation, while the semiconductor switch only handles fast interruption in one direction during 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 use of unidirectional DC breakers in high voltage DC switchyards results in a substantial reduction of semiconductor devices required, leading to lower costs and conduction losses, without compromising the switchyard's functionality, and allows for efficient fault current limitation and protection.
Implementation Method 1
using semiconductor devices of turn-off type, which may open within a few μs, as switches in such DC breakers
Implementation Method 2
a rectifying member connected in anti-parallel therewith
Data Source
AI summary
A high voltage DC switchyard comprises at least one busbar, at lest two DC lines connected to said at least one busbar through DC breakers comprising a section of at least one semiconductor device of turn-off type and rectifying member in anti-parallel therewith. At least one said DC line is connected to at least one said busbar through a unidirectional said DC breaker, i.e. a DC breaker that may only block current therethrough in one direction.