Dyness Knowledge | Brief analysis of AC Block solution

Standard & Poor's definition of AC Block is a container-based AC and DC integrated solution that integrates both batteries and PCS, but this definition is obviously inaccurate. Because many current container energy storage solutions integrate PCS and batteries, but in these solutions, the integrated box is divided into two parts: the battery compartment and the electrical compartment. Multiple clusters of batteries are connected in parallel in the battery compartment, and a MW-level centralized PCS or a MW-level PCS system integrated with string PCS is used in the electrical compartment. This type of solution can only be regarded as a DC Block. Moreover, the AC Block solution should not be limited to container-type energy storage systems. In fact, standard cabinet-type energy storage (such as Dyness DH200F 100kW/215kWh energy storage system) can also realize AC Block-like structures through multiple parallel machines. AC Block should be a topology structure in which a single string PCS or PCS module manages a single cluster or even a single module battery.

So what is the significance of AC Block?

The first is to use string PCS to replace centralized PCS. There are currently relatively few centralized PCS manufacturers on the market, and only a few leading companies can provide relatively reliable centralized PCS solutions. Energy storage companies have little room for choice and poor bargaining power. Moreover, the standardization of energy storage systems can be further improved. The string PCS has been pre-assembled at the factory before transportation, and the junction box communication test and capacity test of PCS and DC side batteries have been completed. In the later operation and maintenance, faults are isolated between each string PCS. When a fault occurs, other PCSs can be kept running and the faulty PCS can be repaired and replaced separately, reducing the impact of the faulty PCS on the overall availability of the energy storage system.

DC Block connects multiple clusters of batteries in parallel in the battery section, which will lead to imbalance between battery clusters. Over time, some of the parallel battery clusters will have insufficient actual output. The other part of the battery cluster is used beyond the rate, causing the "barrel" effect. AC Block can achieve precise management at the cluster level, and PCS corresponds to the battery cluster one-to-one to achieve higher charge and discharge capacity, thereby extending the life of the system and increasing the discharge capacity throughout the life cycle. AC Block can effectively solve the circulation problem, improve DC side capacity utilization, and avoid capacity loss caused by circulation.

In addition to the above mentioned, AC Block combines standard cabinet and modular design, which can effectively reduce the space required for energy storage system deployment, making it very suitable for sites with limited space. AC Block+ string PCS can bring higher conversion efficiency and energy storage system availability, and further improve grid friendliness. AC Block can mix old and new batteries between clusters and replenish power in installments. Of course, the AC Block solution also has the problem of high short-term investment costs and high potential for cost reduction in the long term. Moreover, AC Block requires energy storage system suppliers to have stronger PCS integration and integration capabilities.

Author: Ven Li

Dyness Digital Energy Technology Co., LTD

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