Gas Turbine Controller Transient Grid Event Recovery
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Solution Overview
Problem
Power generation systems face challenges in maintaining balance during transient grid events, leading to overreactions and potential shutdowns due to misinterpretation of frequency deviations, which can affect turbine dynamics and result in unnecessary fuel shutdowns.
Innovation Solution
Implementing an exciter controller with input and output interfaces, processors, and memory to recognize transient grid events by sensing frequency changes, calculating power differences, and determining shaft acceleration rates, allowing for controlled prepositioning of the gas turbine to avoid trips and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the turbine controller attempts to restore balance by controlling shaft speed during transient grid events, then the power generation system can respond to frequency deviations, but the system may overreact and cause unnecessary fuel shutdowns
Solution Approach 1:
The controller prepositions the gas turbine in advance of the transient event by detecting frequency deviations and predicting upcoming events. This preliminary action allows the turbine to be prepared for the transient condition without overreacting, thereby maintaining stability while avoiding unnecessary shutdowns
Solution Approach 2:
The system continuously monitors grid frequency and provides feedback to the controller. This feedback mechanism enables the controller to distinguish between normal frequency variations and actual transient events, preventing overreaction and unnecessary fuel shutdowns while maintaining system stability
2Speed
If the turbine controller reacts quickly to frequency changes, then the system can maintain balance during transient events, but the controller may misinterpret frequency deviations and cause overreactions
Solution Approach 1:
The controller performs preliminary detection and prediction of transient events by monitoring frequency deviations before they fully manifest. This allows the system to prepare appropriate responses in advance, ensuring both quick response and accurate interpretation of frequency changes
Solution Approach 2:
The controller acts as an intermediary between the grid frequency variations and the turbine response. It processes frequency deviation signals, distinguishes between normal variations and actual transient events, and generates appropriate control commands, thereby preventing misinterpretation while maintaining fast response
3Power
If the controller increases active power output to compensate for frequency drop, then the system can restore balance, but the electrical power may exceed system limits causing flame out
Solution Approach 1:
The controller prepositions the gas turbine by detecting frequency drops and predicting the need for increased power output. This preliminary action allows the turbine to gradually increase active power output within safe limits, compensating for frequency drops without exceeding system capacity and causing flame out
Solution Approach 2:
The controller dynamically adjusts the active power output based on real-time frequency conditions and system capacity limits. This dynamic control ensures the turbine increases power output sufficiently to compensate for frequency drops while preventing excessive power that would cause flame out, maintaining both balance and continuous operation
Data Source
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AI summary
A method of controlling a power generation system following a transient grid event, and a system and controller to control the power generation system are described. The method includes sensing a rate of change of electrical frequency at terminals of a generator, determining a rate of change of shaft line acceleration, and identifying the transient grid event based on the rate of change of shaft line acceleration. The method also includes triggering an action to recover from the transient grid event when the rate of change of electrical frequency exceeds a first specified value and the rate of change of shaft line acceleration exceeds a second specified value for a specified duration.