Submarine Branching Unit Fault-Tolerant Power Control
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Solution Overview
Problem
In submarine cable systems, when a ground fault or open fault occurs on the power feeding paths, the switching circuit cannot operate, preventing the switching control of the power feeding path, which disrupts the supply of electric power to the submarine branching unit.
Innovation Solution
A submarine branching unit with a switching circuit, control circuit, and connection circuit that allows power to be received from a different power feeding path, enabling the switching of power feeding paths even when the primary path is faulty by connecting the control circuit to a sea earth when power is not available from the primary path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground fault or open fault occurs on the power feeding path, then the switching circuit cannot operate, but the submarine branching unit still needs to maintain power supply and switching control capability
Solution Approach 1:
The control circuit is connected to both the first power feeding path and the second power feeding path in advance, establishing multiple power supply routes before faults occur. This preliminary configuration enables the system to switch power sources quickly when faults happen, maintaining both reliability and operational capability.
Solution Approach 2:
The control circuit acts as an intermediary that can receive power from either the first or second power feeding path. This intermediary structure allows flexible power source selection and switching control even when one power feeding path experiences ground faults or open faults.
2Reliability
If the switching circuit is disconnected from the faulty power feeding path, then the fault is isolated, but the control circuit also loses power supply
Solution Approach 1:
The power feeding paths are segmented into a first power feeding path and a second power feeding path, allowing independent fault isolation. When a fault occurs in one path, only that segment is affected while the other segment remains operational and can supply power to the control circuit.
Solution Approach 2:
The system changes the power supply parameter by switching from a single power feeding path to an alternative power feeding path when faults occur. This parameter change enables the control circuit to maintain power supply while isolating faulty segments.
3Reliability
If a single power feeding path is used, then the device complexity is reduced, but the system cannot withstand ground faults or open faults
Solution Approach 1:
The second power feeding path serves multiple functions: it acts as a standby power source, provides fault tolerance, and enables switching control capability. This multi-functional design justifies the increased complexity by delivering significant reliability improvements.
Solution Approach 2:
The second power feeding path serves as a cushioning backup that is prepared in advance to handle ground faults or open faults. This prior cushioning configuration ensures the system can withstand faults without losing power supply or control capability.
Data Source
AI summary
In order to enable switching control over power-feeding paths even in the event of a ground fault or an open fault in a power-feeding path, the submarine branching unit is provided with: a switching circuit which switches multiple power-feeding paths formed among a first through a third power-receiving ports; a control circuit which receives power from a power-feeding path formed between the first power-receiving port and the second power-receiving port and controls the switching circuit; and a connection circuit which connects the control circuit between the third power-receiving port and a sea-earth when no power is supplied to the control circuit from the power-feeding path formed between the first power-receiving port and the second power-receiving port.