Application scenarios of large-scale energy storage systems
More and more power plants are equipped with energy storage systems to smooth out fluctuations in output power, such as new energy, wind power or solar power.
Along with the reform of electric power system, the independent energy storage power plant comes into people’s sight gradually, and the independent energy storage power plant which sells electric power for a living appears gradually.
Micro-grid, a small power supply and distribution network consisting of distributed power supply, power load, energy storage system and power grid management system. In order to ensure the continuity and stability of the load, each micro-grid will be equipped with energy storage system.
The Top 7 differences between energy storage battery management system (ESBMS) and Power Battery Management System (BMS)
Energy Storage Battery Management System, and Power Battery management system is very similar. But the power battery system is in the high-speed electric vehicle, which requires higher power response speed and power characteristics, SOC estimation accuracy, and more state parameters.
Energy storage system scale is very large, centralized battery management system and storage battery management system is obviously different, here only take the power battery distributed battery management system and its comparison.
1. The location of the battery and its management system is different in each system
In an energy storage system, the battery only interacts at high voltage with the storage converter, which draws power from the alternating current grid to charge the battery pack, or the battery pack supplies power to the converter, electrical energy is converted into alternating current by a converter and sent to an alternating current network.
The communication and battery management system of the energy storage system are mainly related to 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 PCS, the dispatching system of the energy storage plant.
Basic topology of energy storage system
The BMS for electric vehicles, at high voltage, has an energy exchange relationship with both the motor and the charger; in communication, there is an information exchange with the charger during the charging process, and in all applications, has the most detailed information interaction with the vehicle controller.
2.The hardware logic structure is different
In energy storage management system, the hardware generally adopts two-layer or three-layer model, and the larger scale tends to three-layer management system.
Power Battery management system, only one-tier centralized or two-tier distributed, there is no basic three-tier situation. Small cars are mainly used in a layer of centralized battery management system. A two-tier distributed power battery management system.
From the function point of view, the first layer and the 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 Battery. The third layer of the storage battery management system is an additional layer to cope with the huge scale of the storage battery.
A not-so-apt analogy. The optimal number of subordinates for a manager is seven. If the department keeps expanding and there are 49 people, then seven people have to choose a team leader and appoint a manager to manage the seven team leaders. Beyond personal ability, management is prone to confusion.
To an energy storage battery management system, this management capability is the chip’s computing power and the complexity of the software program.
3. Communication protocols are different
CAN protocol is used in the communication between the storage battery management system and the internal, but it is used in the communication with the external, which mainly refers to the storage power station dispatching system PCS, and TCP/IP protocol is used in the communication between the system and the external.
Power Battery, where the environment of electric vehicles are based on the CAN protocol, only according to the battery pack internal components between the use of internal CAN, battery pack and vehicle between the use of vehicle CAN to make a distinction.
4.The parameters of the management system vary greatly with the types of cells used in the energy storage power station
Energy storage power stations for safety and economic considerations, the choice of lithium batteries, often choose lithium iron phosphate, more energy storage power stations use lead-acid batteries, lead-carbon batteries. At present, the main battery types of electric vehicle are lithium iron phosphate battery and lithium ternary battery.
Different types of battery, its external characteristics vary greatly, the battery model can not be universal. The battery management system and the cell parameters must be a one-to-one relationship. Different manufacturers of the same type of cell, its detailed parameter settings will not be the same.
5.The tendency of threshold setting is different
Energy storage plants, space is more abundant, can accommodate more batteries, but some power plants are located in remote, transportation inconvenience, large-scale replacement of batteries, it is more difficult. Energy storage power plant to the expectation of cell life is long, do not fail. Based on this, the upper limit value of the operating current will be set relatively low, not allowing the cell to work at full load. For the energy characteristics and power characteristics of the cell requirements do not need to be particularly high. Mainly look at the cost-effective.
The power battery is different, in the limited space of the vehicle, it is not easy to install the battery, hope to play its ability to the extreme. Therefore, the system parameters will refer to the battery limit parameters, such application conditions for the battery is harsh.
6.Both require different number of state parameters to be calculated
SOC is a state parameter that needs to be evaluated for both. However, until now, there is no uniform requirement for energy storage system, which state parameters must be able to calculate energy storage battery management system. In addition, the energy storage battery application environment, the space is relatively abundant, the environment is stable, the small deviation is not easy to be perceived in the large system. As a result, the computational capability of the battery management system is relatively lower than that of the power battery management system, and the corresponding single-string battery management cost is not as high as that of the power battery.
7.Energy storage battery management system application of passive equalization conditions are better
It is very urgent for energy storage power station to balance the management system. The larger the scale of the battery module, the more the battery series, the larger the single voltage difference will cause the capacity of the whole box, the more the battery series, the more the loss of capacity. From the point of view of economic efficiency, it is necessary to balance the energy storage power station.
Due to the sufficient space and good cooling conditions, the passive equalization can play a better role, the use of a larger equilibrium current, do not have to worry about excessive temperature rise. Low-cost passive equilibria can play a big role in energy storage plants.