Modular Frequency Converter for Pumped Storage Speed Control
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Solution Overview
Problem
Existing pumped storage systems face challenges in achieving wide speed control ranges at low additional costs, particularly in decentralized systems, due to the high cost of high-performance frequency converters, which limits efficiency and scalability.
Innovation Solution
A modular frequency converter unit with multiple frequency converters connected in parallel, allowing for scalable and cost-effective speed control of the motor-generator machine over a wide range, enabling efficient operation in both pump and turbine modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-performance frequency converter is used to achieve wide speed control range, then speed control capability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The frequency converter is divided into multiple independent modules (first frequency converter module, second frequency converter module, etc.), each handling a portion of the total power. This segmentation allows using multiple lower-power, cost-effective converters instead of one expensive high-power converter, while achieving the same total power capacity and wide speed control range through parallel operation.
2Device complexity
If the motor-generator machine operates at constant speed directly connected to the power grid, then device complexity is reduced, but efficiency during turbine operation deteriorates
Solution Approach 1:
The system transitions from constant speed operation to variable speed operation by introducing frequency converter modules that dynamically adjust the motor-generator's speed according to load conditions. This dynamic speed adjustment enables the pump turbine to operate at optimal efficiency points across varying loads, significantly improving energy efficiency during turbine operation while maintaining acceptable device complexity through modular converter design.
3Ease of manufacture
If speed control is limited to narrow range around rated speed, then manufacturing cost is reduced, but productivity and adaptability deteriorate
Solution Approach 1:
The frequency conversion system is segmented into multiple parallel modules, each capable of independent operation. This modular architecture enables wide speed control range by combining the capabilities of individual modules, achieving high productivity and adaptability across different operating conditions without requiring a single expensive high-performance converter, thus maintaining cost-effectiveness.
4Adaptability or versatility
If a customized solution is developed for each decentralized plant location, then adaptability to different boundary conditions is improved, but manufacturing cost increases
Solution Approach 1:
The modular frequency converter design creates universal building blocks that can be configured in different numbers and arrangements to meet various power requirements. Instead of customizing entire systems for each location, the same standardized modules can be universally applied across different decentralized plants, with adaptability achieved through flexible combination of modules rather than custom design, significantly reducing manufacturing costs while maintaining versatility.
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 solution allows for efficient operation across a wide speed range, reducing load shocks, increasing output, and enabling compact, economically viable decentralized systems with improved control behavior and reduced manufacturing costs.
Implementation Method 1
a frequency converter unit for speed control or regulation of the motor-generator machine
Implementation Method 2
electrical energy is generated from the potential energy of the pumped water
Implementation Method 3
electrical energy is generated from the potential energy of the pumped water
Data Source
Figure 1~3b
Figure 2
AI summary
The invention relates to a pumped storage plant (1) comprising a pump-turbine (5), which can be switched between pump operation and turbine operation and which has several pump-turbine modules (8), which are connected to each other in the flow direction and which are connected to a common shaft (7), and comprising a motor-generator machine (6), which is coupled to the shaft and which is connected to a frequency converter unit (9) for controlling the speed of the motor-generator machine (6) in an open-loop or closed-loop manner, wherein the frequency converter unit (9) has a modular design having a plurality of frequency converters (10) connected in parallel.