The technology breakthroughs behind Huawei’s next-generation Smart-String Grid-Forming ESS Platform

Features such as its industry-leading round-trip efficiency (RTE), high-precision state of charge (SOC) control and cell-to-pack optimisation are achieved across multiple disciplines, Zheng says, “including electrochemistry, electrical engineering, electronics, thermodynamics, control technology, and prediction technology.”

“Huawei’s comprehensive control over the overall solution achieves 93.1% efficiency on the low-voltage side of the PCS at 25°C ambient temperature, with the SOC precision reaching 2.5% at both ends and 3% in the plateau,” Zheng says.

The integrated design covers full cell-to-pack thermal management, liquid-cooling systems and high-voltage silicon carbide (SiC) switching architecture. The setup offers unique performance advantages for long-duration energy storage (LDES) applications over other products on the market.

“We adhere to the string architecture and adopt an optimiser for each pack and a controller for each rack. These refined and effective management methods address electrochemical inconsistency, especially inconsistency in the battery lifecycle,” Zheng explains.

“In our next-generation solution, the AC voltage is increased to 1000 V AC for the first time based on SiC components. This reduces system loss and improves efficiency. Our unique, intelligent, distributed cooling technology increases the heat dissipation area. In addition, the high RTE, high consistency, high SOC level, and high availability improve the solution’s throughput by more than 10% compared with conventional solutions.”

While the technology is sophisticated, installation and logistics are designed to be as simple as possible, according to Steve Zheng. In the example of a 1GWh BESS plant, LUTERRA Smart String Grid-Forming ESS Platform reduces delivery time by at least 30%, balance of plant (BOP) costs by at least 20%, and the footprint by 1 square metre for every megawatt-hour installed, compared to conventional solutions.

Zheng says these results are achieved with Huawei’s patented through-busbar architecture, which enables flexible installation, capacity expansion, and adaptive C-rates for charging and discharging throughout the project’s lifecycle.

Grid-forming for stable inverter-based electricity grids

As regular readers of Energy-Storage.news will be aware, grid-forming technologies and their associated applications have grown hugely in importance for enhancing the stability of electricity grids across the world.

Historically, grid frequency and voltage have been established as byproducts of the rotating mass of thermal generation turbines. As these largely fossil-fuel-based assets are replaced or outnumbered by variable renewable energy (VRE) sources, a new challenge arises in maintaining system stability.

Fortunately, inverters equipped with GFM capabilities can provide the same inertia, short-circuit ratio (SCR) and other essential functions such as black start capability. GFM is a perfect fit for BESS, and countries and regions, including the UK, Australia and China, are actively deploying grid-forming resources.

Within Europe, Germany’s four transmission system operators (TSOs) launched a long-term inertia service market earlier this year, for which GFM BESS assets are eligible, while the European association of TSOs across 36 countries, ENTSO-E, has drafted technical guidelines for grid-forming requirements.

“Grid-forming technology is key to maintaining the stability of a power grid that integrates a high proportion of renewable energy. The technology has evolved from individual equipment to arrays and power plants,” Steve Zheng says.

Huawei has defined six grid-forming capabilities: inertia, short-circuit level, Primary frequency regulation, Power oscillation damping, black start and on/off-grid switching in virtual synchronous generator (VSG) mode.

“We believe that the breakthrough of grid-forming technology at the plant level is critical,” Zheng says.

In the example of a 100MW BESS plant, there will be thousands of power electronics devices that must run in GFM mode.

“It is technically challenging to ensure that these devices work together to stabilise the power grid through the collaboration of hardware and software,” Zheng says, referring to the example of The Red Sea project.

Huawei’s technology has also been used in large-scale grid-forming projects in other countries, including Germany, Bulgaria, the Philippines and China.

Huawei’s product roadmap strategy focuses on array and system-level optimisation

The company has developed the industry’s largest GFM energy storage solution, optimised for BOP at the system level. The strategy behind that product roadmap choice was to focus not just on the power and energy density of a single BESS container, but on the power and energy density of a full array or power plant.

“Only when the array solution is optimal can the entire plant be optimal. A single container is not a true energy storage system; cells alone do not make an energy storage system,” Zheng says.

The Smart String Grid-Forming ESS Platform’s design features a dual-stage 1000Vac high-voltage platform. This grid-forming storage system can resolve critical front-of-the-meter (FTM) operational challenges across utility renewable plants and C&I storage deployments, even as power systems impose increasingly stringent grid-support requirements on energy storage assets.

“When it comes to architecture, we believe that the dual-stage solution offers superior grid safety compared to the conventional single-stage solution,” Steve Zheng tells us.

First, under high-voltage ride-through (HVRT) conditions, inrush current will flow back and forth between the power grid and the PCS. Especially when the battery SOC is low, this may cause battery insulation failure or even severe safety issues.

Second, during low-voltage ride-through (LVRT), a certain constant active power is required to help the power grid recover quickly. These advantages are not available in the single-stage architecture.”