Gas Turbine Fault Detection via N1 Error Accumulation
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Solution Overview
Problem
Existing gas turbine engine fault detection systems are inadequate in accurately identifying uncommanded thrust increases, which can result from mechanical failures or sensor transmission issues, leading to potential safety hazards and operational inefficiencies.
Innovation Solution
A fault detection system that includes a control subsystem with sensors to measure rotational speeds and accelerations, a central processing unit, and a memory to process data and generate a fault detection signal by accumulating errors between requested and target rotational speeds, with threshold limits and reset conditions to prevent false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing fault detection systems are used, then the system structure is simple, but the measurement precision and reliability of fault detection is insufficient
Solution Approach 1:
The fault detection system is divided into multiple independent modules: sensor module for measuring rotational speeds, controller module for processing data, and fault detection module for generating signals. Each module performs a specific function, allowing the system to achieve high measurement precision through coordinated operation of specialized components while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The controller acts as an intermediary between the sensors and the fault detection logic. It receives raw data from sensors measuring rotational speeds, processes this data through comparison with target values, and generates fault detection signals. This intermediary layer enables precise fault detection by coordinating multiple sensor inputs and applying complex detection algorithms without requiring direct complex interconnections between all components.
2Reliability
If fault detection sensitivity is increased to detect all possible faults, then the reliability of fault detection improves, but the number of false alarms increases
Solution Approach 1:
The system continuously monitors rotational speeds and compares them with target values to generate error signals. This feedback mechanism allows the system to detect deviations from normal operation and generate fault detection signals only when actual faults are present. The continuous comparison process provides context about operational state, enabling the system to distinguish between genuine faults and normal variations, thereby reducing false alarms while maintaining high reliability.
Solution Approach 2:
The system changes the detection parameter from simple threshold monitoring to error signal accumulation and comparison with target values. By measuring the difference between actual and target rotational speeds and analyzing this error over time, the system can detect faults with high sensitivity while using the temporal and contextual information from error patterns to filter out false alarms caused by normal operational variations.
3Measurement precision
If multiple sensors are added to improve measurement accuracy, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Multiple sensors are used to measure different aspects of rotational speed (e.g., different shafts or components), and all these sensors serve the universal function of providing input data for fault detection. The controller uniformly processes all sensor inputs using the same error calculation methodology, allowing the system to achieve high measurement precision through multi-sensor coverage while avoiding the complexity of handling completely different measurement systems.
Data Source
AI summary
A gas turbine engine control system is disclosed having a fault detection system capable of detecting a high N1 condition. N1 rotational speed is measured and, in two different locations, subtracted from a target N1 value and a requested N1 value. The resultant error values are scaled by a gain that is scheduled as a function of N2 rotational rate. Each error value is accumulated with separate integrators that have independent maximum and minimum limits. The integrators are reset based upon a number of conditions. A number of additional conditions must also be satisfied for the fault detection system to trigger a fault condition. If the additional conditions are satisfied and the integrators are accumulating values, then a fault condition is set if either or both integrators accumulate a value that reaches a selected limit.