Electrically Heated Thermal Storage for Gas Turbine Overspeed Control
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Solution Overview
Problem
Current turbine overspeed protections, including mechanical and electrical trip mechanisms, are insufficient to prevent damage to the system and personnel during sudden generator load loss, which can lead to catastrophic overspeed conditions.
Innovation Solution
An electrically heated thermal energy storage system (E-TESS) is integrated with a gas turbine generator system, redirecting generator output to the E-TESS during load loss, providing a continuous load to prevent overspeed by heating compressed gas to drive the turbine, and incorporating a controller to manage system operations for safe shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical and electrical trip mechanisms are used for overspeed protection, then the system has basic protection capability, but the protection is insufficient to prevent damage during sudden generator load loss
Solution Approach 1:
The thermal energy storage system is pre-charged with thermal energy before overspeed conditions occur. When the generator loses load and overspeed begins, the stored thermal energy is immediately applied to the turbine inlet, creating rapid deceleration without waiting for mechanical trip mechanisms to activate. This preliminary preparation of thermal energy enables faster response to overspeed conditions.
Solution Approach 2:
The thermal energy storage system acts as an intermediary between the generator load loss and the turbine. Instead of allowing direct overspeed to occur, the system introduces stored thermal energy as a mediating factor that rapidly adjusts turbine power output, providing a buffer that protects the mechanical trip mechanisms from having to handle extreme overspeed conditions alone.
2Ease of operation
If the generator is disconnected from the electrical grid, then the electrical load is lost causing overspeed, but the system needs to maintain controlled operation
Solution Approach 1:
The control system continuously monitors turbine speed and generator load conditions. When grid disconnection is detected or overspeed begins to occur, the system provides feedback to the thermal energy storage system to discharge stored energy to the turbine inlet. This closed-loop feedback enables the system to respond automatically to load changes and maintain controlled operation during grid disconnection events.
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 E-TESS effectively prevents overspeed by absorbing generator output, allowing a controlled shutdown, reducing the risk of system damage and ensuring personnel safety.
Implementation Method 1
an electrically heated thermal energy storage system configured to receive at a fluid input the pressurized gas flow from the compressor, heat the pressurized gas flow
Data Source
AI summary
A gas turbine generator system configured to be electrically interconnected to an electrical grid via a first circuit breaker. The gas turbine generator system includes a compressor configured to output a pressurized gas flow to an electrically heated thermal energy storage system which outputs a heated and pressurized gas flow to a gas turbine to cause the gas turbine to rotate and drive an electrical generator. The electrical generator outputs electric power to the electrical grid via the first circuit breaker, operating in a normally closed position. There is a controller to detect an opening of the first circuit breaker and to close a first switch, in response to the opening of the first circuit breaker. The first switch is connected to the output of the electrical generator and to the electrical input of the electrically heated thermal energy storage system, connecting the generator to the thermal energy storage system.