Generator Emergency Mode Switching for Cooling Failure
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Solution Overview
Problem
Isolated electrical grids on ships or offshore platforms face downtime due to cooling device failures in generators, particularly those with high-temperature superconductor windings, leading to overheating and inability to maintain nominal voltage, necessitating additional emergency power supplies which are space and cost-intensive.
Innovation Solution
A method to switch generators from normal operation to emergency operation, reducing excitation current to a lower value suitable for secondary sub-networks, allowing continued power supply without additional emergency power sources, and reverting to normal operation once the winding cools down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the generator continues to operate with full excitation current after cooling device failure, then the generator can maintain nominal voltage for the first sub-network, but the excitation winding overheats and causes generator failure
Solution Approach 1:
The excitation current is dynamically adjusted based on the operational state. In normal operation, full excitation current is supplied to maintain nominal voltage. Upon cooling device failure detection, the system automatically reduces the excitation current to a reduced level, allowing continued operation without overheating. This dynamic adaptation resolves the contradiction between maintaining voltage and preventing overheating.
Solution Approach 2:
The system changes the operational parameters of the generator by switching from nominal voltage operation to reduced voltage operation. The excitation current parameter is modified from its normal value to a reduced value, which changes the output voltage from nominal to reduced level. This parameter change allows the generator to continue operating safely while avoiding the overheating that would occur at full excitation current.
2Reliability
If additional emergency power supply devices are provided to compensate for cooling device failure, then network downtime is prevented, but space and cost increase
Solution Approach 1:
The generator serves itself in emergency mode by automatically switching to reduced excitation current operation when cooling device failure occurs. This self-service capability eliminates the need for separate emergency power supply devices, as the generator can maintain partial operation independently. The system handles its own emergency situation without requiring additional complex infrastructure.
Solution Approach 2:
The generator is designed to perform multiple functions: it can operate in normal mode supplying the first sub-network at nominal voltage, and in emergency mode supplying the second sub-network at reduced voltage. This multi-functionality allows the same generator to provide power under different conditions without requiring separate dedicated emergency power supplies, thereby reducing system complexity.
3Temperature
If the generator is switched to reduced excitation current operation, then overheating is prevented and operation continues, but the output voltage decreases from nominal to reduced level
Solution Approach 1:
The generator operates dynamically in two distinct modes: normal operation with full excitation current and nominal voltage output, and emergency operation with reduced excitation current and reduced voltage output. The system transitions between these modes based on cooling device status, allowing flexible adaptation to maintain temperature control while providing appropriate power levels for different operational conditions.
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
Minimizes network downtimes and eliminates the need for additional emergency power supplies by enabling continued operation of generators in emergency mode with reduced excitation current, allowing for potential repair of cooling devices and resumed cooling, thus maintaining network stability.
Implementation Method 1
the generator has a cooling device for cooling the excitation winding
Implementation Method 2
the generator feeds current into the first sub-network
Data Source
Figure 1
AI summary
During the operation of a generator (10) in an electrical system (1), particularly in a stand-alone system, such as an onboard power supply system on a ship or an offshore platform, wherein the electrical system (1) comprises a first subsystem (2) having a first rated voltage (UN1) and at least one second subsystem (3) having a second rated voltage (UN2), wherein the first rated voltage (UN1) is higher than the second rated voltage (UN2), wherein the generator (10) has a field winding (11) which, in a normal mode of the generator (10), in which it supplies current to the first subsystem (2), has a first field current applied to it which matches the first rated voltage (UN1) of the first subsystem (2), and wherein the generator (10) comprises a cooling device (12) for cooling the field winding (11), the aim is to keep down-times or impairments in the electrical system (1) in the event of failure of the cooling device (12) as low as possible without the need for additional emergency power supply devices. The invention allows this by virtue of the generator (10) being switched, following failure of the cooling device (12), from the normal mode to an emergency mode, in which it supplies current to the second subsystem (3), wherein in the emergency mode the field winding (11) has a second field current applied to it which is lower than the first field current and which matches the second rated voltage (UN2) of the second subsystem (3).