Gas Turbine Engine Generator Load Management
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Solution Overview
Problem
Small gas-turbine engines face challenges in managing transient electrical loads due to the inability to control the rate of change of these loads, leading to potential engine instability and inefficiency, as conventional methods either require oversized engines or rely on engine electronic control to anticipate and manage loads, which may not be effective for rapid changes.
Innovation Solution
A method and system that incrementally increase the electrical output of a generator powered by a gas-turbine engine, using a pulse width modulator to modify the mark-to-space ratio of control signals, allowing the engine to maintain an acceptable surge margin and accommodate increasing loads dynamically, without prior knowledge of load size, by adjusting engine parameters and using energy storage devices if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large surge margin is applied to engine design to accommodate engine power off-takes and degradation, then engine reliability is improved, but engine efficiency deteriorates and weight increases
Solution Approach 1:
The invention dynamically adjusts the surge margin based on actual generator load conditions rather than using a fixed large margin. The controller monitors generator output and modulates engine parameters in real-time, allowing the surge margin to vary from small (when load is stable) to large (when transient loads are detected), thereby improving efficiency while maintaining reliability
Solution Approach 2:
The invention changes engine operating parameters dynamically in response to detected transient loads. When a transient load is detected, the controller adjusts parameters such as fuel flow, valve timing, or compressor blade angles to increase the surge margin temporarily, then returns to optimal efficiency parameters when the transient condition passes
2Reliability
If the engine is oversized to effectively power through transient loads, then engine reliability is improved, but engine efficiency and weight increase
Solution Approach 1:
The invention detects transient loads before they fully impact the engine and takes preliminary action by preemptively adjusting engine parameters to prepare for the incoming load. This allows a properly sized engine to handle transients effectively without needing to be oversized, as the engine is proactively prepared for the load change
3Reliability
If conventional engine electronic control is used to manage loads, then engine reliability is improved, but the system cannot effectively respond to rapid transient loads
Solution Approach 1:
The invention implements a feedback control system that continuously monitors generator load conditions and automatically adjusts engine parameters in response. The controller detects transient loads through changes in generator output and feeds this information back to modify engine operation, creating a closed-loop system that responds rapidly to load changes without requiring manual intervention or pre-mapping
4Productivity
If the generator output is increased rapidly to meet electrical load demands, then electrical productivity is improved, but engine stability deteriorates
Solution Approach 1:
The invention uses periodic modulation of the generator output rather than continuous rapid increases. By cycling the generator load in controlled periodic increments and allowing the engine to adjust between cycles, the system achieves high electrical productivity while maintaining engine stability through rhythmic rather than sustained high-stress operation
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 enables the generator to supply electrical loads at a sustainable rate, maintaining engine stability and efficiency by ensuring the engine operates within acceptable conditions, even during rapid load changes, without the need for oversized engines or pre-mapping of load handling strategies.
Implementation Method 1
using a pulse width modulator to modify the mark-to-space ratio of control signals
Implementation Method 2
an electricity generator powered by torque from the engine
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method of operating an engine and an electricity generator powered by torque from the engine is provided. The engine has a working line which is a locus of operating points of the engine as the engine is throttled. The method includes increasing an electrical load on the generator. The method further includes repeatedly performing the steps of: (i) detecting the working line position of the engine; (ii) determining if the detected working line position is sufficient or insufficient to allow the engine to provide additional torque to power the generator while maintaining engine operation within a predetermined range of acceptable engine operating conditions relative to the detected working line position; (iii) when the determination at step (ii) is that the engine operating condition is insufficient, modifying operational parameters of the engine to adjust the position of the working line to allow the engine to provide the additional torque while maintaining engine operation within the predetermined range of acceptable engine operating conditions; and (iv) increasing the electrical output from the generator by an amount such that the engine provides the additional torque. The steps are repeated until the electrical output of the generator matches the electrical load.