Aircraft Turbogenerator Phase Isolation for Faster Emergency Shutdown
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Solution Overview
Problem
The existing aircraft turbogenerator shutdown procedure is slow, leading to prolonged rotation and current supply, which increases the risk of overheating and potential fires due to the lack of load on the electric generator after disconnecting healthy phase groups.
Innovation Solution
The control device maintains healthy phase groups connected to their electrical subnetworks to maintain a load on the electric generator, allowing the gas turbine to slow down more efficiently, and optionally disconnects them after a predefined condition is met or increases electrical power consumption to facilitate faster shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all phase groups are disconnected from electrical sub-networks when a short circuit is detected, then fault propagation to the electrical network is prevented, but the gas turbine deceleration time becomes very long (several tens of seconds) and the electric generator continues to supply current causing overheating risk
Solution Approach 1:
The electrical network is divided into multiple electrically disconnected sub-networks, and the generator is divided into multiple phase groups. When a short circuit is detected in one phase group, only that specific phase group is disconnected from its associated sub-network, while other healthy phase groups remain connected to their respective sub-networks. This segmented approach allows fault isolation without completely shutting down the generator, thereby maintaining load on the generator for faster deceleration.
Solution Approach 2:
The disconnection action is applied locally only to the faulty phase group and its associated sub-network, rather than globally to all phase groups. The isolation device associated with each phase group can independently disconnect that phase group from its associated sub-network. This localized approach prevents fault propagation while maintaining operation of healthy phase groups, enabling the generator to continue providing braking torque.
2Reliability
If all phase groups are disconnected from electrical sub-networks when a short circuit is detected, then fault propagation is prevented, but the electric generator loses its load and therefore loses braking torque to decelerate the gas turbine
Solution Approach 1:
The system segments the generator into multiple phase groups and the electrical network into multiple sub-networks. When a short circuit occurs in one phase group, only that phase group is disconnected, while healthy phase groups remain connected to their respective sub-networks. This segmentation allows the generator to maintain load through healthy phase groups, preserving braking torque while isolating the fault.
Solution Approach 2:
The healthy phase groups act as intermediaries that maintain the electrical load on the generator during fault conditions. By keeping healthy phase groups connected to their sub-networks, they continue to provide the electrical burden necessary for generator braking, while the faulty phase group is isolated through its isolation device.
3Loss of time
If the generator continues to supply current during long shutdown time, then the isolation procedure is completed, but local heating occurs which could cause fire in the electric generator
Solution Approach 1:
By segmenting the generator into phase groups and disconnecting only the faulty phase group, the system maintains operation of healthy phase groups. This keeps the generator loaded and decelerating, significantly reducing the time during which overheating could occur, thereby mitigating fire risk.
Solution Approach 2:
The invention rushes through the shutdown process by maintaining generator load through healthy phase groups. The generator decelerates much faster because it continues to drive a loaded electrical system rather than running unloaded, thereby quickly passing through the dangerous overheating period and reaching the stopped state sooner.
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 approach reduces the risk of overheating and fire by maintaining a load on the electric generator during shutdown, enabling faster deceleration of the gas turbine and preventing electrical and thermal insulator fires.
Implementation Method 1
a permanent magnet electric generator designed to be mechanically driven by the gas turbine and having groups of phases respectively connected to the electrical sub-networks
Implementation Method 2
the electrical generator no longer has a load and therefore no longer provides braking torque to decelerate the gas turbine. Thanks to the invention, the healthy phase group(s) remain connected to their respective sub-networks, which makes it possible to maintain a load for the electrical generator and therefore to brake the gas turbine.
Data Source
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AI summary
This electromechanical installation (100) for an aircraft comprises: - an electrical network (102) comprising electrical subnetworks (104, 106); - a turbogenerator (118) comprising a gas turbine (120), an electricity generator (122) with permanent magnets having phase groups (126, 128) respectively connected to the electrical subnetworks (104, 106), and, for each phase group (126, 128), an isolation device (134, 136); and - a control device (140) designed to detect a short circuit in at least one of the phase groups, each phase group in which a short circuit is detected being described as defective and each other phase group being described as healthy, and, in response to the detection of the short circuit, to disconnect this defective phase group (126, 128) from its associated electrical subnetwork (104, 106) and to command the shutdown of the gas turbine (120). The control device (140) is also designed, in response to the detection of the short circuit, to keep each healthy phase group (126, 128) connected to its electrical subnetwork (104, 106).