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Xiho
Jun 20 2025
Why must energy storage systems abandon the constant current mode? The four major demands of the power system reveal the core of standardized design.
The national standards GB/T 36276-2023 and GB/T 44026-2024 clearly require that energy storage systems must adopt a constant power charging and discharging mode, the core of which is derived from the underlying needs of power grid dispatching. As a key regulating unit of the power system, the energy storage system must accurately match four major logics:
1. Match the power system dispatching language
The power grid dispatch uses power (MW) and energy (MWh) as the command units. The energy storage system adopts constant power mode to directly respond to the command and ensure the stability of power output/absorption. If the constant current mode (in ampere-hour capacity) tested by the battery factory is used, it will be out of touch with the power system demand.
2. Avoid parameter confusion risk
The power system needs to unify the design and test standards. The constant current mode will cause the capacity, efficiency and other parameters of the energy storage system to deviate greatly from the actual working conditions. For example, lithium batteries dynamically adjust the current under constant power, which is closer to the grid fluctuation scenario.
3. Optimize energy efficiency and stability
In constant power mode, the energy efficiency of energy storage batteries such as lithium batteries is greater than 93% (far better than lead-acid batteries). Constant current testing will cause capacity calculation distortion due to voltage platform fluctuations, while the constant power operation of the energy storage system ensures grid connection stability.
4. Meet the national standard hard indicators
The new national standard forces prefabricated cabin energy storage systems to support constant power mode, requiring power deviation ≤1% and response time ≤100ms. This standardization enables the energy storage system to seamlessly adapt to the power system and improve overall compatibility.
Additional note: Although constant power may cause the battery capacity to be slightly lower than the constant current and constant voltage mode (lack of constant voltage supplementary power), for the power system, the power control accuracy is much higher than the absolute capacity. Therefore, the energy storage system needs to focus on the national standard constant power operation, continuously optimize the energy storage battery technology, and ensure the efficient and safe dispatch of the power system.
Additional note: Although constant power may cause the battery capacity to be slightly lower than the constant current and constant voltage mode (lack of constant voltage supplementary power), for the power system, the power control accuracy is much higher than the absolute capacity. Therefore, the energy storage system needs to focus on the national standard constant power operation, continuously optimize the energy storage battery technology, and ensure the efficient and safe dispatch of the power system.
