Hydraulic Turbine Variable Speed Control for Efficiency
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Solution Overview
Problem
Existing methods for operating hydraulic turbines are constrained by fixed speed operations, leading to inefficiencies and limited adaptability, with look-up table methods being inaccurate due to manufacturing deviations from prototype characteristics.
Innovation Solution
A method and system that adjust the rotation speed of hydraulic turbines based on a speed adjustment quantity and change ratio, using a perturb and observe approach to track maximum efficiency operation points in real-time, allowing for variable speed operation and improved energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed speed operation is used to match rated power frequency, then the synchronous generator can operate at rated conditions, but the efficiency of hydropower generation decreases significantly
Solution Approach 1:
The patent implements variable speed operation of the hydraulic turbine by decoupling the turbine rotation speed from the fixed grid frequency. The turbine can rotate at optimal speeds to maximize efficiency, while the generator uses power electronic converters to convert the variable frequency output to fixed frequency for grid connection. This dynamic operation allows the turbine to adapt to different hydraulic conditions and operate at peak efficiency points.
Solution Approach 2:
The patent changes the operating parameters of the hydraulic turbine from fixed speed to variable speed. By adjusting the rotation speed parameter according to the hydraulic head and power requirements, the system can track the maximum efficiency operating points. The generator frequency is changed from directly coupled to the turbine speed to being converted through power electronics, enabling independent optimization of turbine efficiency and grid synchronization.
2Productivity
If look-up table method based on Hill Chart is used for maximum power efficiency tracking, then the turbine rotation speed can be determined, but the computational accuracy decreases due to manufacturing errors
Solution Approach 1:
The patent implements a feedback mechanism where the actual efficiency of the hydraulic turbine is continuously calculated based on real-time operating parameters (flow rate, head, power output, and rotation speed). This actual efficiency feedback is used to dynamically adjust the operating point and track the maximum efficiency curve. The system compares the actual efficiency with the target efficiency and adjusts the turbine speed accordingly, eliminating the need for pre-stored look-up tables and their associated accuracy issues.
Solution Approach 2:
The system performs self-adjustment by continuously monitoring its own performance and automatically optimizing its operating parameters. The control system calculates the actual efficiency in real-time and uses this information to self-correct any deviations from optimal operation, making the system adaptive to manufacturing variations and changing conditions without requiring external calibration or pre-programmed data.
3Productivity
If variable speed operation is implemented, then the energy savings and turbine life time increase, but the device complexity increases due to additional control systems
Solution Approach 1:
The patent uses power electronic converters that serve multiple functions: they convert the variable frequency output from the turbine to fixed frequency for grid connection, control the active and reactive power output, protect the generator from overcurrent and overvoltage conditions, and enable bidirectional power flow. This multi-functionality reduces the need for separate dedicated devices for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent replaces traditional mechanical speed regulation mechanisms (such as governor systems and mechanical governors) with electronic control systems. Instead of using mechanical devices to physically adjust the turbine speed or generator characteristics, the system uses power electronic converters to achieve speed variation and power control electronically. This substitution simplifies the mechanical structure while adding electronic control capabilities.
Data Source
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AI summary
A method (100, 300), system (900) and apparatus (1000) for operating a hydraulic turbine. A speed adjustment quantity for the hydraulic turbine and a corresponding change in flow quantity are obtained (110, 310). A rotation speed of the hydraulic turbine is adjusted based on the speed adjustment quantity. A change ratio of the flow quantity with regard to the speed adjustment quantity is determined based on the speed adjustment quantity and the corresponding change in flow quantity (120, 320). An adjustment manner in which the rotation speed is further adjusted is determined based on the determined change ratio of flow quantity (130, 330).It enables the hydraulic turbine to track a maximum efficiency operation point under a given power order and water head in real time at a low cost.