Doubly-fed induction generator power balancing
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Solution Overview
Problem
Multi-shaft gas turbine engines often experience power imbalances between high and low pressure turbines, particularly on hot days when increased power demands require higher air mass flow rates, leading to inefficiencies and reduced performance.
Innovation Solution
A doubly-fed induction generator system is integrated with a multi-shaft gas turbine engine, allowing the first doubly-fed induction generator to operate as both a motor during start-up and a generator during full load operations, and a second generator to balance mechanical power, thereby addressing power imbalances and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compressor increases air mass flow rate to meet high power demands on hot days, then power output is improved, but power imbalance between high pressure turbine and low pressure turbine worsens
Solution Approach 1:
The first generator is designed to perform multiple functions: it can operate as a generator during normal full-load operations to produce electricity, and switch to motor mode during start-up or power imbalance conditions to drive the compressor. This multi-functionality allows the system to maintain power balance while meeting high power demands without requiring separate dedicated devices for each function.
Solution Approach 2:
The system dynamically switches the operational mode of the first generator between generator and motor based on real-time system conditions. During hot day high power demands, the generator can switch to motor mode to provide additional driving torque to the compressor, thereby maintaining power balance between the high pressure and low pressure turbines while still meeting the increased power output requirements.
2Reliability
If a doubly-fed induction generator system is added to balance power, then power balance is improved, but device complexity increases
Solution Approach 1:
Rather than adding a separate dedicated device solely for power balancing, the patent utilizes the first generator to perform both power generation and power balancing functions. By enabling the first generator to operate in both generator and motor modes, the system achieves power balance without requiring additional specialized equipment, thereby limiting the increase in device complexity.
Solution Approach 2:
The first generator serves the system's power balancing needs through its own operational flexibility. The generator monitors and responds to power imbalance conditions by switching to motor mode when needed, effectively self-regulating the power balance without requiring complex external control systems or additional balancing devices.
3Speed
If the first generator operates as a motor during start-up, then start-up speed is improved, but energy consumption increases
Solution Approach 1:
The patent replaces traditional mechanical starting methods (such as mechanical coupling or external starters) with an electrical motor-driven starting system. The first generator, operating in motor mode, provides electromagnetic torque to drive the compressor during start-up, enabling rapid acceleration. This electrical substitution allows for controlled, efficient energy usage during the start-up process while achieving fast start-up speeds.
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
The system enables rapid start-up, increased power output on hot days, improved part load efficiency, and reduced system degradation, while also providing cost savings and a smaller footprint.
Implementation Method 1
a first doubly-fed induction generator in communication with a first shaft of the multi-shaft gas turbine engine, a first rotor of the first doubly-fed induction generator in communication with a converter via a first rotor bus
Data Source
AI summary
The present application provides a doubly-fed induction generator system for a multi-shaft gas turbine engine. The doubly-fed induction generator system may include a first doubly-fed induction generator in communication with a first shaft of the multi-shaft gas turbine engine, a first rotor of the first doubly-fed induction generator in communication with a converter via a first rotor bus, and a first breaker on the first rotor bus. The first doubly-fed induction generator acts as a generator or a motor depending in part upon the position of the first breaker.