Segmented Energy Storage SOC Control for Grid Services
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Solution Overview
Problem
Traditional energy storage devices for photovoltaic systems are not optimized to utilize their full capacity for grid services, leading to underutilization of energy storage capabilities, especially in low and high state of charge ranges, which affects service life and operational efficiency.
Innovation Solution
An electrical accumulator system with distinct capacity ranges for grid feed, self-consumption, and exclusive grid feed, coupled with a central control device that manages energy distribution across these ranges to provide network services, allowing for the economical use of previously unused capacity for short-time network services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy storage devices operate exclusively in medium state of charge ranges (e.g., 20-50% SOC) to preserve service life, then reliability is improved, but productivity deteriorates due to underutilization of available capacity for grid services
Solution Approach 1:
The state of charge range is segmented into multiple distinct capacity ranges (first, second, third ranges) with different functions. The first range (low SOC) and third range (high SOC) are specifically allocated for grid feed services, while the second range (medium SOC) is reserved for self-consumption and grid feed. This segmentation allows the system to utilize the full capacity spectrum for grid services without compromising the battery's service life, as each segment serves its designated purpose.
2Productivity
If energy storage capacity is fully utilized for grid services including low and high state of charge ranges, then productivity is improved, but reliability deteriorates due to potential negative impact on service life
Solution Approach 1:
Different quality requirements are applied to different parts of the state of charge spectrum. The first and third capacity ranges are optimized for grid feed operations with appropriate SOC thresholds, while the second capacity range is optimized for self-consumption and grid feed with different SOC thresholds. This local quality approach ensures that each region of the SOC spectrum is used in a manner that balances grid service provision with battery longevity.
3Adaptability or versatility
If distinct capacity ranges are defined for different purposes (grid feed, self-consumption), then adaptability is improved, but device complexity increases due to multiple control parameters
Solution Approach 1:
The control system dynamically adjusts the state of charge thresholds for the first, second, and third capacity ranges based on operational conditions, grid service requirements, and battery status. This dynamic adaptation allows the system to flexibly allocate capacity among different purposes while managing complexity through adaptive control rather than rigid fixed thresholds, enabling versatile energy distribution strategies.
Data Source
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AI summary
The storage (1) has first and second released state of charge (SOC) regions (3, 5) provided for a power supply, a third released SOC region (4) provided for internal consumption and the power supply, and two blocked regions (6, 7). A control device adapts an actual charge state of the storage such that a fixed positive or negative energy quantity is provided for the power supply for a fixed time window at a fixed time of the storage. The first SOC region amounts to 10 % to 40 % of a capacity of the storage. The second SOC region amounts to 80 % to 90 % of a capacity of the storage. Independent claims are also included for the following: (1) an energy storage-power plant (2) a method for operating an energy storage.