Battery Energy Storage System with Asset Switching for Frequency Response
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Solution Overview
Problem
The existing battery systems for frequency response in power grids are costly due to the requirement for oversized energy storage to meet the 30-minute energy storage and discharge demands, leading to inefficient use and high costs.
Innovation Solution
A method and system that utilize a storage battery to monitor its state of charge and switch on alternative assets when the SoC falls below a low or rises above a high threshold, allowing these assets to provide balancing services, reducing the battery's capacity requirements and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery systems are designed to meet 30-minute energy storage and discharge demands, then regulatory requirements are satisfied, but battery capacity must be oversized leading to high costs
Solution Approach 1:
The system divides the balancing service provision into two segments: the battery handles rapid frequency response (EFR) for immediate imbalances, while alternative assets (generators or loads) provide sustained power adjustment for longer-duration frequency deviations. This segmentation allows the battery to be smaller since it only needs to cover the initial response period until alternative assets can take over.
Solution Approach 2:
Alternative assets act as intermediaries that bridge the gap between the battery's limited capacity and the grid's sustained power adjustment needs. The controller coordinates between the battery and alternative assets, transferring the balancing responsibility from the battery to alternative assets when frequency deviations persist beyond the battery's optimal discharge/charge duration.
2Productivity
If battery capacity is increased to meet extreme response demands, then frequency response capability is improved, but battery degradation accelerates and lifespan reduces
Solution Approach 1:
The battery performs only the necessary partial action of providing rapid initial frequency response rather than sustaining full-power discharge/charge for extended periods. The controller monitors battery state of charge and transfers to alternative assets before the battery is fully depleted or overcharged, avoiding excessive action that would accelerate degradation.
Solution Approach 2:
The controller continuously monitors battery state of charge and frequency deviations, using feedback to determine when to switch between battery and alternative assets. This feedback mechanism ensures the battery operates within optimal state of charge ranges, preventing deep discharge or overcharge conditions that would reduce lifespan.
3Reliability
If the battery operates continuously to provide balancing services, then frequency regulation is maintained, but the battery experiences increased degradation
Solution Approach 1:
The system extracts the sustained power adjustment function from the battery and assigns it to alternative assets. The battery is taken out of continuous operation and only engaged when rapid frequency response is needed, reducing its operational cycle count and degradation while alternative assets handle the bulk of sustained balancing services.
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 approach reduces the battery's capacity needs, lowers costs, and extends its lifespan by using supplementary assets to handle extreme responses, maintaining regulatory reserve requirements while minimizing battery degradation.
Implementation Method 1
A battery system arranged to store charge that is used in balancing electricity supply with demand
Data Source
AI summary
A battery energy storage system for use in providing balancing services to an electrical power distribution network is set to monitor the state of charge (SoC) of a storage battery (26). If the SoC is within an optimal range (48), the balancing service is provided solely by charging and discharging the battery. If the battery SoC falls below a predetermined low threshold (52), a first non-battery asset is operated to increase power supplied to the network. Similarly, if the battery SoC rises above a predetermined high threshold (50), a second non-battery asset is operated to provide the balancing service. With this arrangement, requirements on the energy storage capacity of the battery are reduced. For the system to meet balancing service regulatory requirements, the battery need only remain capable of charging or discharging beyond each threshold (50, 52) for a period of time that covers that taken for the respective asset to reach operational capacity.