Grid-side energy storage stations are facilities installed within power systems to store and release electrical energy. These facilities are typically located at key points in the grid, such as power plants, substations, or near power consumption points. The main purpose of grid-side energy storage stations is to enhance the flexibility and efficiency of the power system. By storing excess energy generated during low-demand periods and releasing it during peak periods or power shortages, these stations help balance grid load, improve energy utilization efficiency, reduce energy costs, and increase the integration of renewable energy sources.
The Role of Batteries in Grid-side Energy Storage
Batteries play a crucial role in grid-side energy storage stations, acting as the core components that store and release electrical energy. The type, performance, and configuration of batteries significantly impact the efficiency, reliability, and economic viability of the entire storage system. Selecting the appropriate type and configuration of batteries is essential for the design and operation of grid-side energy storage stations. This article will detail key considerations for battery selection to help you choose the most suitable batteries for your needs.
Principles for Battery Selection
1.Flexible Configuration and Easy Installation: The energy storage system should be flexibly configurable and easily expandable. Additionally, the construction period should be short without excessive special requirements. Lithium batteries can achieve various combinations, meet high working voltage and large working current requirements, and are easy to install and maintain.
2.Long Cycle Life, High Safety, and Reliability: The cycle life of energy storage batteries significantly impacts the reliable operation of the system. Long cycle life reduces the need for battery replacement, saving operating costs and improving system economic efficiency. The batteries used in energy storage systems should have a lifespan of at least 12 years and a cycle life of over 6000 cycles at a 90% depth of discharge. Safety is paramount; the system must remain safe even in extreme conditions, preventing explosions, fires, or other hazards.
3.Good Fast Response and High Charge/Discharge Efficiency: The intermittent operation of battery storage systems requires excellent start-up characteristics. Lithium batteries must quickly switch between charge and discharge states, requiring fast response times. Improving energy conversion efficiency during storage helps enhance overall system efficiency, and high charge/discharge efficiency reduces system costs.
4.Good Environmental Adaptability and Wide Operating Temperature Range: The chosen batteries should function effectively across a broad temperature range and adapt to various environmental conditions.
5.Cost Appropriateness: Cost is a crucial factor in battery selection, affecting the feasibility of large-scale deployment. Batteries should be cost-effective without compromising performance.
6.Avoidance of Used and Overstocked Batteries: Batteries used should not be repurposed or have production dates exceeding three months, ensuring reliability and longevity.
Types of Batteries
- Lead-acid batteries
- Lead-carbon batteries
- Lithium iron phosphate batteries
- Sodium-sulfur batteries
- Flow batteries
Comparing Battery Types
From the application level, these batteries can all reach the hundred-megawatt scale. In terms of performance, lithium iron phosphate batteries and sodium-sulfur batteries have high energy density and charge/discharge efficiency. However, sodium-sulfur and vanadium flow batteries are not yet fully industrialized, have limited supply channels, and are expensive.
Considering operational and maintenance costs, vanadium flow batteries require pumps for fluid control, increasing operational costs. Lithium and lead-carbon batteries have lower maintenance costs. In terms of the cost per kilowatt-hour (the present value of project costs over the lifecycle power output), lead-acid (carbon) and lithium iron phosphate batteries are comparable. However, lead-acid (carbon) batteries are not suitable for deep charge/discharge cycles, have low discharge rates, and shorter cycle life.
Battery Form Selection
Lithium iron phosphate batteries come in three main types based on casing: aluminum-shell prismatic, soft-pack aluminum plastic film, and cylindrical. The primary differences lie in the casing material, with each having its advantages and disadvantages.
Choosing the Right Capacity
Large-capacity energy storage projects should opt for batteries with relatively high capacity to improve power density, reduce space requirements, and minimize the number of parallel and series circuits, which helps mitigate the capacity degradation caused by the weakest cell (the “bucket effect”). It is recommended to select battery cells with a capacity of over 280Ah, as they meet the mainstream standards and advanced technology criteria.
Key Performance Parameters
|
Item |
Specification |
|
Type |
Lithium Iron Phosphate |
|
Packaging Form |
Prismatic Aluminum Shell |
|
Nominal Voltage |
3.2V |
|
Nominal Capacity |
≥280Ah (0.5C) |
|
Operating Voltage |
2.8V~3.6V |
|
Cycle Life |
≥6000 cycles (at 80% capacity) |
|
Operating Temperature |
Charge: 0~+45℃, Discharge: -20~+45℃ |
|
Internal Resistance |
0.18±0.05mΩ |
|
Self-Discharge Rate |
<3.5% per month |
Conclusion
Selecting the most suitable battery involves balancing technical performance, economic factors, and environmental impact. Each battery type has unique strengths and limitations, and no single battery excels in every aspect. Therefore, it is essential to consider specific application scenarios and requirements to make the best choice.
As technology advances, new battery technologies will continue to emerge, offering more options. Regardless, our goal remains the same: to improve the performance of grid-side energy storage stations, enhance energy efficiency, and contribute to the development of a clean, sustainable energy system.
