Grid-Forming ESS Powers the "Green Heart" at the Foot of the Balkan Mountains

April in Lovech, Bulgaria, finds spring lingering as the Balkan Mountains shimmer in gold. At the foot of the mountains, a 106 MW PV plant stretches across two square kilometers, where a vast blue ocean of PV modules sparkles under the sun, drawing power from its rays.

There are no rows of densely packed buildings, no thunderous roar of giant machines—only the faint hum of electricity coursing through cables. This is a place designed to harness sunlight, thriving on the energy it receives.

Few would have imagined that behind this quiet harvest of energy once lay a dilemma: the aging local power grid, with its limited capacity, struggled to handle the sudden surges of solar energy. Was Advance Green Energy, the plant's owner, doomed to sigh over "a happiness forever beyond reach"?

Not at all.

A Power Grid Reinforced with "Muscles" and a "Nervous System"

Advance Green Energy, founded in Bulgaria in 2024, is an innovative company dedicated to developing and operating advanced energy facilities in alignment with the European Union's green transition strategy. Nestled in north-central Bulgaria, at the north slope of the Balkan Mountains and along the upper reach of the Osam River, the Lovech site receives 2,100–2,300 hours of sunshine annually—an ideal setting for solar energy projects.

The local potential for renewable electricity is significant: Bulgaria's peak-valley electricity price difference is as high as USD0.09 per kWh, promising strong returns on investments. However, grid stability became a critical constraint; the existing infrastructure was too fragile to support further expansion.

So how could they maximize the returns on renewable electricity? The answer arrived in the form of a "green heart"—Huawei Grid Forming Energy Storage System (ESS) 2.0. In April 2025, the 125 MW/500 MWh ESS was officially connected to the grid, marking Huawei's first grid forming ESS project in Europe.

Unlike conventional ESSs that follow the grid, grid forming ESSs actively reinforce and stabilize it. In scenarios with a high penetration of renewable energy, grid forming ESSs use new technologies to provide the grid with "visible rigidity"—as if equipping it with "muscles" and a "nervous system"—thereby significantly enhancing system stability and safety.

At the Lovech site, the grid forming ESS adopted by Advance Green Energy consists of 111 ESS cabinets (4.5 MWh each), 16 transformer stations, power conversion systems (PCSs), a Smart Power Plant Controller (SPPC), and an energy management system (EMS). Together they form a complete "green heart" beating at the foot of the Balkan Mountains.

Six Core Capabilities of the Grid Forming ESS

One of the most immediate benefits for Advance Green Energy is that the power plant is no longer "picky" about the energy it uses. The previous grid was like a frail body, unable to absorb power from renewable energy sources. Now, Huawei Grid Forming ESS 2.0 responds to shortcircuit currents within 10 ms, completes primary frequency regulation within 200 ms, and even achieves GWh-level black start within 10 minutes. It has become a vigilant "grid guardian," always ready to act.

Huawei Grid Forming ESS 2.0 delivers six capabilities: (1) short-circuit support; (2) inertia support; (3) primary frequency regulation; (4) power oscillation damping (POD); (5) black start; and (6) seamless on/off-grid switching. These capabilities allow the power plant to deliver ancillary services, such as primary and secondary frequency regulation, which in turn amplify its economic returns.

The solution ensures stable performance around the clock and is designed to adapt to future energy architectures, regardless of the SOC and grid SCR. It offers reliable support for the power system and is suitable for various business models.

What truly stands out, however, are the concrete, measurable gains.

Certified by the German Association for Electrical, Electronic & Information Technologies (VDE), the power plant achieved an energy utilization rate of 98.93%, well above the contractual commitment of 90.3%. System efficiency also surpassed expectations, reaching 91.2% versus the guaranteed 87.71%. The payback period, once estimated at three to four years, will now be reached much sooner.

Launched in Bulgaria, Growing Toward Europe

There is no doubt that Grid-Forming ESSs are shaping the future of power grids. As renewables gradually become the main energy source, Grid-Forming ESSs serve as the core support for building new power systems. They enable the grid to shift from passively adapting to renewables to actively embracing and harnessing them, achieving green, stable, and efficient operation.

Huawei Digital Power remains committed to advancing high-quality industry development and pioneering future-oriented Grid-Forming ESS technologies under stricter standards. Across power generation, transmission, distribution, and consumption, Huawei's high-quality products and solutions not only meet demanding environmental requirements but also evolve flexibly to address emerging needs in technology, function, application, and even business model at different stages.

Five years ago, Bulgaria enacted key legislative reforms to allow its first licensed closed energy distribution area. The timely regulatory change, combined with the close collaboration between the government, Advance Green Energy, and Huawei Digital Power, laid the foundation for this large-scale, technologically advanced project.

For Bulgaria, this project is more than a power plant upgrade—it is an experiment exploring the future of energy. Here, solar energy is fully utilized, and the influx of renewables no longer burdens the grid. For Huawei, this represents an important step in deploying Grid-Forming ESSs in Europe, laying the groundwork for developing more business models in the years ahead.

Advance Green Energy's power plant in Lovech now stands as a vital energy hub for the Balkan region and Southeast Europe. As night descends, the plant's ESS gently releases the power captured from the sun, enveloping Lovech in a luminous beauty. This "green heart" beats ceaselessly, pulsing in harmony with the rhythm of Europe's energy transition.