Author: Lian Kun -BESS Solution Manager of Huawei Southern Africa Digital Power

With the rising integration of renewable energy sources, power grids are increasingly influenced by high proportions of renewables and power electronic equipment. The grid-forming energy storage system (ESS) is crucial to addressing these challenges. However, as large-scale energy storage projects proliferate, safety concerns have intensified, becoming a significant bottleneck in the industry's development.

Sub-Saharan Africa's regulatory framework for energy storage is varied from country to country and is still evolving. The absence of comprehensive safety standards can lead to inconsistent practices among manufacturers and operators, increasing safety risks during installation and maintenance. One of the primary safety concerns is the risk of fire associated with lithium-ion batteries, with incidents reported globally, including in South Africa. The potential for thermal runaway poses serious risks, especially in densely populated areas where safety protocols may not be rigorously enforced.

A major safety incident can have lasting repercussions, potentially influencing the trajectory of the entire industry. Given that an ESS typically has a service life of 10 to over 20 years, ensuring its safe, stable and high-quality operation under various conditions is essential. Thus, addressing ESS safety while meeting market demands is a critical challenge for the industry.

Huawei Digital Power leverages its extensive experience in power electronics and digital technologies to develop the industry-leading Smart String Grid-Forming ESS. This system mitigates inconsistencies and uncertainties associated with lithium batteries through advanced power electronics control. Huawei has established end-to-end technical capabilities in ESS safety, covering materials, battery cells, applications and lifecycle management. By adhering to comprehensive safety principles from cell to grid, Huawei minimises the risk of thermal runaway and enhances active safety through intelligent diagnosis via the battery management system (BMS).

Active Safety from Cell to Grid

ESS safety is not only about cell safety, but covers end-to-end safety protection from battery cells, battery packs, battery racks and systems to the power grid.

Cell Safety

Huawei collaborates with battery cell vendors to define safety specifications for all scenarios, validating them through rigorous testing. Over 100 tests ensure that battery cells do not catch fire, explode, leak, or experience thermal runaway under extreme conditions.  These tests have verified that Huawei's ESS outperforms samples from other vendors and exceeds industry standards.

Safety design: The cell-level isolation design adopts a thermal insulation layer (patented materials with an ultra-high temperature resistance of over 400 °C) between battery cells to stop heat transfer.

Safety testing: Cycle tests are conducted to simulate the real situation of battery cells in a battery pack, outputting more accurate parameters.

Pack Safety

Battery packs, being the core of an ESS, employ protective measures to prevent thermal runaway.

Smart cooling algorithm for rapid cooling: Activates when abnormal temperatures are detected, cooling battery packs by 20 °C a minute.

Positive pressure oxygen blocking and directional smoke exhaust: The battery pack enclosure is constructed from a patented metal (able to withstand 1 538 °C), ensuring high reliability and airtightness. It features a directional smoke relief valve and a patented smoke exhaust duct achieving pack-level smoke extraction and reducing fire risks.

Cross-linked polymer insulation: This patented insulation material can resist electrolyte corrosion for more than 1 000 hours, ensuring that the leaked electrolyte does not spread to other battery packs.

Rack Safety

The six protective measures for each battery rack consist of four-level active protection and two-level passive protection, reducing the risk of battery overcurrent for electrical safety.

Four-level active protection includes BMU overcurrent protection, contactor protection, rapid disconnection switch on the DC side, and DC/AC overcurrent protection.

Two-level passive protection includes circuit breakers and fuses.

System Safety

At the system level, four protective measures—detection, exhaust, suppression and relief, are interconnected to provide comprehensive protection.

Detection: Multiple sensors, such as smoke detectors, heat detectors, humidity sensors, water sensors and carbon monoxide (CO) sensors, are deployed to detect the internal environment and trigger the release of gas extinguishant.

Exhaust: Each cabin is equipped with a proactive smoke exhaust function. If combustible gases are detected in a battery cabin, the exhaust fan is activated, creating immediate extraction.

Suppression: The perfluorohexanone gas extinguishant and water spray cooling solutions are used to prevent heat from spreading, suppressing potential risk escalation.

Relief: The battery cabin door adopts the directional explosion relief design, with 3 m2 large pressure relief panels that are positioned 2 m above the ground, ensuring quick pressure relief and personal safety.

Grid Safety

Huawei’s new power conversion system employs a two-stage architecture that prevents power back feed during high voltage ride-through, safeguarding both the ESS and the grid. This architecture maintains battery voltage stability, even at low states of charge, and dynamically adjusts bus voltage to ensure stable power output.

Risk Warning and Proactive O&M

As the capacity of the energy storage plant grows, the volume of information to be collected also increases. Typically, operations and maintenance (O&M) personnel respond only after receiving alarms, and the system does not support proactive maintenance. Huawei Digital Power offers an end-to-end, multi-dimensional intelligent diagnosis system. It collects data from battery cells, battery packs, battery racks, and the entire ESS to provide a comprehensive evaluation of the ESS's operating status across five dimensions: consistency, charge and discharge, health, O&M management, and troubleshooting management.

Huawei has also developed fault warning technologies that collect data from battery cells and modules, analysing it over 8 000 times daily. This system identifies over ten types of safety risks and generates advance warnings, effectively mitigating risks associated with battery abuse, short circuits and low consistency.

The energy storage industry is evolving rapidly and safety remains paramount for its sustainable development. Huawei Digital Power is committed to investing in quality and safety, providing comprehensive multidimensional ESS protection. This dedication supports the healthy growth of the energy storage sector and contributes to establishing clean, low-carbon, safe and efficient new power systems.

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