The inconsistency of the battery cells is formed during the production process and deepened during use. The batteries in the same battery pack are weaker and weaker, and the acceleration becomes weaker. However, although there is no completely consistent battery cell, digital technology, power electronics technology and energy storage technology can be integrated, and the controllability of power electronics technology can be used to minimize the impact of lithium battery inconsistency. In response to the problems caused by the inconsistency of the previous analysis, some manufacturers in the market have launched string energy storage systems, which have the characteristics of refined energy management and distributed temperature control, and can prescribe the right medicine:
1.Refined management to increase available capacity
Compared with a traditional PCS that manages more than 1,000-2,000 batteries, the string energy storage system improves the management accuracy of batteries to more than a dozen, and the accuracy is increased by about 100 times. For the series mismatch between battery packs, the optimizer design is used to realize the individual charge and discharge management of each battery pack. When a battery pack reaches the set threshold, the battery pack is bypassed, and other battery packs can continue to charge and discharge without affecting each other, maximizing the use of battery capacity.
At the same time, each battery cluster is equipped with an intelligent cluster controller to avoid the impact of battery inconsistency caused by direct parallel connection, so that the charge and discharge current of each cluster can be precisely controlled, and the error can be within 1%. In this way, the parallel mismatch between clusters is avoided, the independent charge and discharge management between battery clusters is truly realized, the generation of circulating current is eliminated, and the capacity and safety of the system are further improved.
2) Distributed temperature control to extend the life of the energy storage system
Traditional energy storage containers are equipped with 1-2 centralized air conditioners, using longitudinal air ducts for heat dissipation. The length of the air ducts is about 6 meters to 12 meters. Due to the long heat dissipation channels, the temperature of each battery pack and battery cluster cannot be guaranteed. consistency.
The string energy storage adopts cluster-level distributed heat dissipation, and uses distributed air conditioners instead of centralized air conditioners. Each battery cluster can dissipate heat independently and evenly. temperature difference. At the same time, the patented tree-shaped bionic cooling air duct is cleverly used in the battery pack, and by adjusting the length and distance of the air ducts of each battery cell, the cooling capacity of each battery cell is as consistent as possible, reducing the temperature inconsistency of each surface of each battery cell sex.
Battery inconsistency is the root of many problems in current energy storage systems. However, due to the chemical characteristics of the battery and the influence of the application environment, the inconsistency of the battery is difficult to eradicate. Through the controllability of power electronics and digital technology, the string energy storage system greatly weakens the system's requirements for battery consistency, can greatly increase the available capacity of the energy storage system, and improve system security.