Liquid Braking Resistor for Rapid Grid Overfrequency Limiting
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Solution Overview
Problem
The increasing integration of renewable energy sources in electrical energy transmission networks leads to rapid and unpredictable frequency fluctuations, posing challenges in maintaining frequency stability, particularly during periods of high energy feed-in or load changes, which can result in network instability and potential blackouts.
Innovation Solution
A braking resistor arrangement that quickly converts excess electrical energy into heat using a liquid, such as water, to absorb energy surpluses, thereby stabilizing network frequency by rapidly activating a power switching device to manage electrical current through electrodes and controlling the liquid's temperature to prevent boiling, allowing for efficient and reliable energy absorption without the need for frequent maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional generators with rotating mass are used to stabilize frequency, then frequency stability is improved, but response speed to rapid frequency changes is insufficient
Solution Approach 1:
The patent replaces the mechanical rotating mass of conventional generators with an electrical-braking system consisting of a braking resistor, power switching device, and control unit. This electrical system responds instantaneously to frequency deviations without the inertia limitations of mechanical systems, achieving both rapid response and frequency stability.
Solution Approach 2:
The patent introduces a power switching device and control unit as intermediaries between the grid and braking resistor. These components detect frequency deviations and rapidly switch the braking resistor into the circuit, enabling quick response to frequency changes while maintaining system stability through controlled energy dissipation.
2Reliability
If pumped-storage power plants are used for energy withdrawal, then frequency stability is improved, but response speed is too slow for rapid frequency increases
Solution Approach 1:
The patent replaces the slow mechanical pumping process with an electrical braking system that can be activated within milliseconds. The power switching device rapidly connects the braking resistor to the grid, providing immediate energy absorption capability without the mechanical response delays inherent in pumped-storage systems.
3Reliability
If batteries are used for energy storage, then frequency stability is improved, but system complexity and cost significantly increase
Solution Approach 1:
The patent utilizes the phase transition of liquid resistive material from liquid to vapor state. When excessive energy is fed into the grid, the material transitions phase to absorb the energy, providing a simple, passive mechanism for frequency stabilization without complex control systems or expensive battery infrastructure.
Solution Approach 2:
The patent employs a simple, inexpensive liquid resistive material that can be easily replaced. The system uses basic electrical components (resistor, switch, controller) rather than expensive batteries, achieving frequency stabilization through a cost-effective, low-complexity approach where the consumable material is replaced periodically.
4Reliability
If liquid resistors are used to absorb energy, then frequency stability is improved, but control precision is reduced when liquid boils
Solution Approach 1:
The patent incorporates a control unit that continuously monitors the state of the liquid resistive material and the grid frequency. Based on this feedback, the control unit adjusts the power switching device to regulate current flow, ensuring the liquid operates within optimal temperature ranges and maintains precise control over energy absorption while preventing uncontrolled boiling.
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 braking resistor arrangement effectively stabilizes network frequency by quickly absorbing excess energy, preventing rapid frequency increases and maintaining network stability, even in small or isolated grids, while being cost-effective and low-maintenance, thus reducing the risk of blackouts and extending the service life of rotating equipment.
Implementation Method 1
The braking resistor arrangement converts electrical energy into heat and can thus, as a quickly switchable load, draw excess energy from the power grid
Implementation Method 2
the power switching device is designed to conduct electrical current through the liquid via the electrodes
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to a braking resistance arrangement for limiting a frequency rise in an electrical supply system, having a housing that is at least partially fillable with a liquid, a first electrode and a second electrode, wherein during operation of the braking resistance arrangement the electrodes have different electrical potentials and the electrodes enter the liquid, characterized in that a protection device is provided for detecting a frequency rise in the electrical supply system, and in that the braking resistance arrangement is configured such that an electric current flows through the liquid via the electrodes in the event of a frequency rise, with the liquid heating. Further, the present invention relates to an overfrequency protection arrangement and to a method for limiting a frequency rise in an electrical power supply system.