What is the difference between energy storage battery BMS and power battery BMS?

1. Application scenarios of large-scale energy storage systems

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

Independent energy storage power stations have gradually entered the field of vision with the reform of the power system, and independent energy storage power stations that resell electricity for a living have emerged.

Microgrid, the system contains a distributed power supply, power load, energy storage system and a small power supply and distribution network of the power grid management system. In order to ensure the continuity and stability of the load, each microgrid is equipped with an energy storage system.

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

The energy storage battery management system is very similar to the power battery management system. However, the power battery system is on the high-speed electric vehicle, and has higher requirements on the power response speed and power characteristics of the battery, the SOC estimation accuracy, and the number of state parameters.

The energy storage system is very large, and the centralized battery management system and the energy storage battery management system are quite different. Here, only the power battery distributed battery management system is compared with it.

2.1 The battery and its management system are different in their respective systems.

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

The energy storage system communication, battery management system mainly has information interaction relationship with the converter and the energy storage power station dispatching system. On the one hand, the battery management system sends important state 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 electric motor and the charger at a high voltage; in communication, there is information exchange with the charging machine during the charging process, and the vehicle controller has the most detailed in all application processes information exchange.

2.2 Hardware logic structure is different

In the energy storage management system, the hardware generally adopts a two-layer or three-layer mode, and the larger scale tends to a three-tier management system.

The power battery management system has only one layer of centralized or two distributed, and basically does not have three layers. Small cars mainly use a centralized battery management system. A two-layer distributed power battery management system, as shown below.

From the function point of view, the first layer and the second layer module 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 battery. The third layer of the energy storage battery management system is an additional layer based on this, to cope with the huge scale of energy storage batteries.

A less apt analogy: The optimal number of subordinates of a manager is 7 people. If the department has been expanding and there are 49 people, then only 7 people choose a team leader, and then a manager is appointed to manage the 7 team leaders. Beyond personal abilities, management is prone to confusion.

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 Communication protocols are different

The energy storage battery management system and the internal communication basically adopt the CAN protocol, but it communicates with the outside. The external mainly refers to the storage power station dispatching system PCS, which often adopts the Internet protocol format TCP/IP protocol.

The power battery, the electric environment of the electric vehicle is in the CAN protocol, but the internal CAN is used according to the internal components of the battery pack, and the whole vehicle is used to distinguish between the battery pack and the whole vehicle.

2.4 The types of batteries used in energy storage power stations are different, the management system parameters are different.

For reasons of safety and economy, energy storage power stations often use lithium iron phosphate when selecting lithium batteries, and some lead storage batteries and lead carbon batteries are used in other energy storage power stations. The current mainstream battery types for electric vehicles are lithium iron phosphate batteries and ternary lithium batteries .

The difference in battery type has a huge difference in external characteristics, and the battery model is completely unusable. The battery management system and the battery parameters must have a one-to-one correspondence. The same type of batteries produced by different manufacturers will not have the same detailed parameter settings.

2.5 threshold setting tends to be different

The energy storage power station is richer in space and can accommodate more batteries. However, some power stations are located in remote areas, transportation is inconvenient, and large-scale replacement of batteries is a difficult matter. The expectation of the energy storage power station is that the battery life is long and should not be faulty. Based on this, the upper limit of the operating current will be set lower, and the battery will not be operated at full load. The energy characteristics and power characteristics requirements of the cells do not need to be particularly high. Mainly look at the price.

The power battery is different. In the limited space of the vehicle, the battery is hard to install, and it is hoped that its ability will be maximized. Therefore, the system parameters will refer to the battery's limit parameters such application conditions are bad for the battery.

2.6 The number of state parameters required to calculate is different

The SOC is a state parameter that both need to be calculated. But until today, the energy storage system does not have a unified requirement, which state parameter calculation ability is necessary for the energy storage battery management system. In addition, the application environment of the energy storage battery, the space is relatively abundant, the environment is stable, and the small deviation is not easily perceived by humans in a large system. Therefore, the computing capacity requirement of the energy storage battery management system is relatively lower than that of the power battery management system, and the corresponding single string battery management cost is also not high.

2.7 Energy storage battery management system application passive equilibrium conditions are better

The requirements of the energy storage power station to balance the management system are very urgent. The size of the energy storage battery module is relatively large, with multiple batteries in series, and the large single voltage difference will cause the capacity decline of the whole box. The more batteries in series, the more capacity it will lose. From the perspective of economic efficiency, energy storage power stations need a sufficient balance.

And because of the abundant space and good heat dissipation conditions, passive equalization can be more effective, and a relatively large equalizing current is used, so there is no need to worry about excessive temperature rise. A low-cost passive balance can make a big difference in energy storage power stations.

The page contains the contents of the machine translation.