Pumped Storage System Grid Stabilization via Dynamic Control Mode Switching
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Solution Overview
Problem
Pumped storage systems lack the ability to stabilize the grid during pumping operations due to the inability to adjust supply and demand, leading to inefficiencies in power management.
Innovation Solution
A pumped storage system incorporating a reversible pump turbine, a synchronous motor generator, a frequency converter with bidirectional AC/DC conversion units, and a storage battery, along with a control device that adjusts the guide vane opening based on grid state inputs to manage reactive and active power commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the guide vane opening is controlled depending on the difference in water level between upper reservoir and lower reservoir for efficient pumping, then pumping efficiency is improved, but the ability to adjust supply and demand for grid stabilization deteriorates
Solution Approach 1:
The control system dynamically switches between two control modes: water level difference-based control for pumping efficiency and grid state-based control for supply and demand adjustment. This dynamic adaptability allows the system to optimize for different operational priorities based on real-time conditions, resolving the contradiction between maintaining pumping efficiency and enabling grid stabilization.
Solution Approach 2:
The system changes the control parameter from water level difference to grid state (reactive power and active power commands) when grid stabilization is needed. This parameter substitution allows the same physical system to serve different functional priorities, enabling both efficient pumping and grid adaptability through parameter-based control mode switching.
2Reliability
If the guide vane opening is controlled for power generation amount based on grid state, then grid stabilization is improved, but pumping efficiency deteriorates
Solution Approach 1:
The control system dynamically selects between grid state-based control and water level difference-based control depending on operational requirements. During power generation, grid state control prioritizes stability; during pumping, water level control prioritizes efficiency. This dynamic mode selection resolves the contradiction by allowing each operational phase to optimize for its primary goal.
Solution Approach 2:
The control system periodically switches between different control strategies based on operational phase (power generation vs. pumping). This periodic alternation between control modes allows the system to maintain grid stability when generating power while preserving pumping efficiency when in pumping mode, resolving the contradiction through time-based control strategy alternation.
3Adaptability or versatility
If a frequency converter with storage battery is added to enable bidirectional power conversion and grid control, then supply and demand adjustment capability is improved, but device complexity increases
Solution Approach 1:
The frequency converter with storage battery serves multiple functions: bidirectional AC/DC conversion, reactive power control, active power control, and energy storage. By consolidating these functions into a single integrated system, the patent achieves supply and demand adjustment capability while managing device complexity through multi-functional design rather than separate dedicated systems for each function.
Solution Approach 2:
The storage battery acts as an intermediary energy buffer between the grid and the pump-turbine system. This intermediary component enables smooth bidirectional power flow and decouples the timing of power consumption and generation, facilitating supply and demand adjustment without requiring direct complex control of the mechanical system for each power exchange operation.
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
Enhances grid stability and enables supply and demand adjustment during pumping operations, improving load variation handling and overall grid stability.
Implementation Method 1
water that flows from the upper reservoir to the lower reservoir rotates a pump turbine to rotate a rotor of a generator motor connected to the pump turbine, thereby generating power
Implementation Method 2
the generator motor is driven by receiving power from a system to rotate the pump turbine
Implementation Method 3
a first power conversion unit performing bidirectional AC/DC conversion and connected to a grid; a second power conversion unit performing bidirectional AC/DC conversion and connected to the synchronous motor generator
Data Source
Figure 1
Figure 2
AI summary
A pumped storage system has: a reversible pump turbine (3); a synchronous motor generator (2) directly coupled to a runner shaft of the reversible pump turbine; and a frequency converter (1). The frequency converter has: a first power conversion unit (11) performing bidirectional AC/DC conversion and connected to a grid; a second power conversion unit (12) performing bidirectional AC/DC conversion and connected to the synchronous motor generator; and a storage battery (13) connected between the first and second power conversion units. The pumped storage system further has: a governor (5) for adjusting a guide vane opening of the reversible pump turbine; and a control device (4) for controlling the first and second power conversion units and the governor. The control device has a first frequency converter control unit (41) that controls the first power conversion unit (11) based on a reactive power command and an active power command input externally.