4 points let you understand energy storage battery management system

What is energy storage battery management system

First of all, battery management system is a device that cooperates with monitoring the status of the energy storage battery, which generally behaves as a circuit board, or a hardware box.

Component

From the component point of view, energy storage battery management system contains two parts: hardware and software. Hardware includes hardware parts including embedded acquisition circuit, main control circuit and equalization circuit, and electrical equipment such as circuit breakers and contactors. The software part includes the calculation of SOC and SOH of the core, intelligent analysis of the state of the core, etc. The software part includes the calculation of SOC and SOH of the core.

Types

From the perspective of types, BMS is divided into two types: centralized and distributed according to different project requirements. The centralized BMS collects all batteries with one BMS hardware, which is suitable for scenarios with few batteries. The energy storage system generally requires large capacity and high voltage, requiring thousands of single batteries to be combined in series and parallel to form a battery system to meet various functions. Generally, it is a BMS with a distributed architecture. Most of the energy storage battery management system have a three-layer structure because of the large scale of the battery pack. The bottom layer structure is BMU, which is used to monitor each cell in the battery box. Located on the second level is a cluster management unit (BCMU) for each cluster of batteries. The control of the third layer is the BA system, which receives the data of all the cells in the entire stack.

Functional modules

The battery management system for energy storage contains several functional modules, which generally have data acquisition function, operation mode selection function, communication function, alarm function, battery system protection, battery system capacity calibration, SOC estimation function, thermal management function, battery equalization management function, insulation detection function, etc.

The importance of energy storage battery management system

First, the energy storage system has the requirements of deep discharge and long cycle. Especially in the late stage of the battery system, it is more sensitive to the consistency requirements of the battery. Energy storage battery management system is more important for user-side projects, because for the user-side, peak shaving and valley filling in the future will be the main business model for user-side energy storage projects to realize revenue. The consistency of the battery determines the cycle life of the energy storage system, as well as the depth and capacity of each charge and discharge of the energy storage system. Therefore, the energy storage system not only requires batteries to have relatively high consistency, but also requires energy storage battery management system to have relatively strong battery balancing capabilities. Second, the energy storage system’s requirements for cost, longevity, and safety. In terms of energy storage technology,  top 10 energy storage technology manufacturers in China  have made a good performance. More importantly, the energy storage battery management system is in charge of the energy storage system’s whole life cycle. The income and maintenance expenses of the system are, in part, determined by how the BMS ensures the energy storage system operates efficiently throughout its life cycle. The energy storage system’s parallel connection of several locations is generally normal, therefore the anti-circulation design is a unique necessity of the energy storage battery management system . It also experiences significant interference in large-scale energy storage systems, making the BMS’s anti-interference, data processing, and response speed capabilities crucial. For example, a container with 6.88MWh is close to tens of thousands of batteries, and its data volume has reached 15,000 points. At this time, the energy storage BMS is required to have relatively fast data collection and communication capabilities. Use parameter identification to identify the operating state of the battery cell, that is, to judge whether its internal impedance value is within a reasonable range. The health state of the battery can be divided into four categories: healthy state, sub-healthy state, fault warning and fault state by dividing the battery cell parameter grade. In this way, BMS can assist in replacing failing batteries in order to avoid major accidents.

The current problems of energy storage battery management system

Firstly, the core value of BMS is not well understood.BMS is not only a tool to detect data, but also the core of energy storage system to ensure the safety, extend the life of energy storage system and maximize the economic benefits of energy storage. Second, BMS homogenization competition is serious. The market is basically based on mainstream integrated circuit solutions, subject to the influence of the chip industry, the lack of core competitiveness between BMS manufacturers, so homogenization is very serious.For the top 10 energy storage BMS companies in China, strengthening their core competencies is another successful strategy for bridging the competitive gap. Third, the bottleneck of BMS technology still needs to be broken.The profitability of BMS enterprises is relatively weak, resulting in insufficient investment in research and development. In the actual energy storage system BMS application project, some core BMS, SOC algorithm, safety diagnosis, health state diagnosis technology is still mostly stuck in some early algorithms, by the BMS hardware host processing capacity limitations, can not introduce some edge computing, artificial intelligence technology, so recently there has been no major breakthrough in the technical level. However, the development of BMS technology is a necessary prerequisite for the recent development of the energy storage industry. Fourth, the BMS industry standard is not the same, BMS is also a large labor cost work. From the design of the harness, the processing of the harness to the field installation and commissioning, the overall workload is very large. However, the specifications of each manufacturer’s module and single cell, and the protection parameters between each system integrator are also different, so the future of energy storage BMS will still face the problem of incompatible battery modules, single cell capacity, and single cell size.

Future expectations of energy storage battery management system

Hardware and software of energy storage BMS.The core function of the future BMS definitely requires strong arithmetic and algorithms, and powerful algorithms are inseparable from strong hardware capabilities. SOC and SOH values provide the basis for battery equalization, and the accuracy of SOC/SOH calculation will affect the equalization efficiency of the energy storage system. The balance of the energy storage system determines the degree to which the cycle life of the energy storage system is close to the cycle life of the cells. Core functions and difficulties of energy storage BMS.The core function of BMS is not to monitor the number and speed of the BMS, but to diagnose the safety of the battery and predict the risk of thermal runaway, which is based on the strong computing power and algorithm. In other words, whether the BMS can find problems, self-healing problems, and automation will be the key to maximize the value of the BMS in the future. In conclusion, BMS is a very complex system, which needs to consider various failure conditions of the energy storage system and make reasonable protection actions, so that the energy storage system can operate within a reasonable and safe range. At the same time, the hardware and software of BMS is a complementary systemic project, which requires an in-depth analysis of the operating characteristics of the battery cells, starting from the top-level design and fully considering every detail to achieve an efficient and reliable battery management system.