Power battery and energy storage battery -Lithium - Ion Battery Equipment

Do you understand the difference between power lithium-ion battery BMS and energy storage battery BMS? -Lithium - Ion Battery Equipment

1. Application scenarios of large-scale energy storage systems

New energy power plants, wind power or solar power plants, in order to achieve the purpose of stabilizing output power fluctuations, more and more power plants are beginning to be equipped with energy storage systems.

Independent energy storage power stations, with the reform of the power system gradually entering people's field of vision, independent energy storage power stations that make a living by reselling electricity have gradually emerged.

Microgrid, a small power supply and distribution network that includes distributed power sources, power loads, energy storage systems and grid management systems within the system. In order to ensure the continuity and stability of the load, each microgrid will be equipped with an energy storage system.

2. The difference between energy storage battery management system (ESBMS) and power lithium battery management system (BMS)

The energy storage battery management system is very similar to the power lithium battery management system. However, the power lithium battery system is in a high-speed electric vehicle, and there are higher requirements for the battery's power response speed and power characteristics, SOC estimation accuracy, and the number of state parameter calculations.(Lithium - Ion Battery Equipment)

The scale of the energy storage system is huge, and the difference between the centralized battery management system and the energy storage battery management system is obvious. Here, only the power lithium battery distributed battery management system is compared with it.

2.1 The position of the battery and its management system in each system is different

In the energy storage system, the energy storage battery only interacts with the energy storage converter at high voltage, and the converter takes power from the AC grid to charge the battery pack; or the battery pack supplies power to the converter, and the power passes through the converter It is converted into AC and sent to the AC grid.

For the communication of the energy storage system, the battery management system mainly has an information interaction relationship with the converter and the dispatching system of the energy storage power station. On the one hand, the battery management system sends important status information to the converter to determine the high-voltage power interaction; on the other hand, the battery management system sends the most comprehensive monitoring information to the dispatching system PCS of the energy storage power station.

The BMS of an electric vehicle has an energy exchange relationship with the motor and the charger at high voltage; in terms of communication, it has information interaction with the charger during the charging process, and has the most detailed communication with the vehicle controller in the entire application process. Information exchange

Electric Vehicle Electrical Topology

2.2 The hardware logic structure is different

For energy storage management systems, the hardware generally adopts a two-tier or three-tier model, and the larger scale tends to be a three-tier management system. The power lithium battery management system has only one centralized or two distributed, and basically there will be no three-tier management system. Condition. Small cars mainly use a centralized battery management system.

From the function point of view, the first layer and second layer modules of the energy storage battery management system are basically equivalent to the first layer acquisition module and the second layer main control module of the power lithium battery. The third layer of the energy storage battery management system is a new layer on this basis to deal with the huge scale of the energy storage battery.

Mapped to the energy storage battery management system, this management capability is the computing power of the chip and the complexity of the software program.

2.3 The communication protocol is different

The energy storage battery management system basically adopts the CAN protocol for internal communication, but its external communication mainly refers to the energy storage power station dispatching system PCS, which often uses the Internet protocol format TCP/IP protocol.

Power lithium batteries, the electric vehicle environment where they are located all adopt the CAN protocol, but the internal CAN is used between the internal components of the battery pack, and the vehicle CAN is used to distinguish between the battery pack and the whole vehicle.

2.4 Different types of batteries used in energy storage power stations lead to large differences in management system parameters

For safety and economic considerations, energy storage power stations often use lithium iron phosphate when choosing lithium-ion batteries, and some energy storage power stations use lead-acid batteries and lead-carbon batteries. The current mainstream battery types for electric vehicles are lithium iron phosphate batteries and ternary lithium-ion batteries.

Different battery types have huge differences in their external characteristics, and the battery model cannot be used universally at all. The battery management system and battery parameters must have a one-to-one correspondence. The same type of batteries produced by different manufacturers will have different detailed parameter settings.

2.5 Threshold setting tends to be different

Energy storage power stations have more space and can accommodate more batteries. However, some power stations are located in remote locations, and transportation is inconvenient. Large-scale replacement of batteries is more difficult. The expectation of the energy storage power station for the battery cell is to have a long life and not to fail. Based on this, the upper limit of its operating current will be set relatively low to prevent the battery from working at full capacity. The energy characteristics and power characteristics of the battery cells should not be particularly high. It is important to look at the cost performance.

The power lithium battery is different. In the limited space of the vehicle, the battery is finally installed, and it is hoped to maximize its capabilities. Therefore, the system parameters will refer to the limit parameters of the battery, and such application conditions are harsh to the battery.

2.6 The number of state parameters required to be calculated by the two is different

SOC is a state parameter that is calculated by both. But until today, the energy storage system does not have a unified requirement, what state parameter calculation capability is required for the energy storage battery management system. In addition, the application environment of energy storage batteries has relatively abundant space and a stable environment, and small deviations are not easy to be perceived in large systems. Therefore, the computing power requirement of the energy storage battery management system is relatively lower than that of the power lithium battery management system, and the corresponding single-string battery management cost is not as high as that of the power lithium battery.

2.7 It is better to apply passive equalization conditions to the energy storage battery management system

Energy storage power stations have very urgent requirements for the balance capability of the management system. The scale of the energy storage battery module is relatively large, and multiple strings of batteries are connected in series. The large voltage difference of the individual cells will cause the capacity of the entire box to decrease. The more batteries connected in series, the more capacity will be lost. From the perspective of economic efficiency, energy storage power stations must be fully balanced.

And because passive equalization can be more effective in ample space and good heat dissipation conditions, and a relatively large equalization current is used, and there is no need to worry about the problem of excessive temperature rise. Low-cost passive equilibrium can flex its muscles in energy storage power stations.



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