Energy storage battery management systems are very similar to power lithium battery management systems. However, power lithium battery systems in high-speed electric vehicles have higher requirements for battery power response speed and power characteristics, SOC estimation accuracy, and the number of state parameter calculations. Energy storage systems are extremely large in scale, and centralized battery management systems differ significantly from energy storage battery management systems. Here, we only compare them with distributed battery management systems for power lithium batteries.
1. The battery and its management system occupy different positions within their respective systems.
In energy storage systems, the energy storage batteries interact with the energy storage converter only at high voltage. The converter draws power from the AC grid to charge the battery pack; alternatively, the battery pack supplies power to the inverter, which converts the electrical energy into AC power for transmission to the AC grid. Communication between the energy storage system and the battery management system is crucial, requiring the establishment of information exchange relationships with the inverter and the energy storage power station dispatch system. On one hand, the battery management system sends important status information to the converter to determine high-voltage power interaction; on the other hand, the battery management system sends comprehensive monitoring information to the energy storage power station's dispatch system (PCS).
2. Different hardware logic structures
For energy storage management systems, hardware typically employs a two- or three-layer architecture, with larger-scale systems often using a three-layer management system. Power lithium battery management systems generally have only one centralized layer or two distributed layers, with three-layer systems being rare. A single centralized battery management system is crucial for small cars. A two-layer distributed power lithium battery management system... Functionally, the first and second layer modules of an energy storage battery management system are essentially equivalent to the first layer acquisition module and the second layer control module of a power lithium battery. A third-layer energy storage battery management system adds another layer on top of this to handle the massive scale of energy storage batteries.
3. Differences in communication protocols
The internal communication of an energy storage battery management system primarily uses the CAN protocol, but its communication with external systems, especially the power storage station dispatch system (PCS), often uses the TCP/IP protocol. Both power lithium batteries and electric vehicle environments use the CAN protocol, but internal CAN is used between components within the battery pack, while the vehicle CAN is used between the battery pack and the vehicle.
4. The management system parameters vary greatly depending on the type of battery cells used in the energy storage power station.
For safety and economic reasons, energy storage power stations often use lithium iron phosphate batteries when selecting lithium-ion batteries, while some use lead-acid and lead-carbon batteries. Currently, the mainstream battery types for electric vehicles are lithium iron phosphate batteries and ternary lithium-ion batteries. Different types of batteries have significant differences in external characteristics, and battery models are completely incompatible. Battery management systems and cell parameters must correspond one-to-one. The detailed parameter settings for the same type of battery produced by different manufacturers will not be the same.
5. Different threshold setting preferences
Energy storage power stations have relatively large spaces, allowing them to accommodate more batteries. However, some power stations are located in remote areas with inconvenient transportation, making large-scale battery replacement difficult. The expectation for cell-based energy storage power stations is long lifespan and no failure. Based on this, the upper limit of their operating current is set relatively low, preventing the cells from operating at full capacity. The energy and power characteristics of the batteries are unlikely to be particularly high. Price is also important. Power lithium batteries, however, are different. Within the limited space of a vehicle, it is difficult to install batteries, and the goal is to maximize their capacity. Therefore, system parameters are based on the battery's limiting parameters, and such application conditions are detrimental to the battery.
6. The two methods require different numbers of state parameters to be calculated.
State of Charge (SOC) is a state parameter that must be calculated for both batteries. However, to date, there are no unified requirements for energy storage systems, namely, which state parameter calculation functions an energy storage battery management system must possess. Furthermore, energy storage batteries are used in a wider variety of stable environments, making small deviations less noticeable in large systems. Therefore, the computing power requirements of energy storage battery management systems are relatively lower than those of power lithium battery management systems, and the corresponding cost of managing a single battery string is also lower.
