Hitachi Energy delivers the first 66 kV WindSTAR transformer with natural ester for offshore wind applications

Tackling the challenges associated with the clean energy transition requires ambition and technology leadership. New solutions must be developed to pursue a sustainable energy future where renewable energy sources perfectly integrate and support the efficiency, reliability, and flexibility of the power grid.

COP28 agreement is a historic milestone with the consensus to triple renewable energy capacity by 2030. This ambitious goal aims to advance the vision of a carbon-neutral future. Wind energy has emerged as a critical technology for reducing emissions, becoming more affordable and accessible in recent years.

To translate this aspiration into concrete action, all stakeholders in the energy sector must collaborate to accelerate the clean energy transition. Notably, the progress made last year is encouraging, showing a substantial growth in offshore wind capacity with an impressive 11 gigawatts (GW) added to the grid.

At Hitachi Energy, sustainability is at the heart of our Purpose. We actively co-create pioneering solutions that shape the energy system, supporting the global transition toward carbon neutrality.

During the early 2010s, as offshore wind power started gaining prominence, Hitachi Energy introduced WindSTAR™ Transformers, as part of its OceaniQ™ portfolio. They are an ideal solution for offshore wind turbines that has evolved to suit both fixed and floating applications, including the latest generation turbine developments with increased power ratings. These transformers were meticulously developed following wind energy standards, like APQP4Wind¹, with a design process involving prototyping and type-testing of each new design based on application and customer requirements.

Over the past 14 years since the first prototype, more than a thousand WindSTAR units have been installed worldwide. They feature over 20 distinct designs tailored to withstand the challenging conditions of operation in both fixed and floating offshore wind turbines. Their compact, lightweight design enables them to handle the vibrations, sudden movements, and fluctuating electrical loads inherent in wind power generation.

WindSTAR Transformers are designed for energy efficiency and utilize biodegradable insulating fluids. Initially launched with a voltage capacity of up to 33 kilovolts (kV), these transformers have now doubled their voltage capability to 66 kV. This enhancement allows them to be deployed in larger, more powerful wind turbines, resulting in reduced electricity losses and greater cost-effectiveness for wind farms.

Just few weeks back, Hitachi Energy’s transformer factory in Zhongshan, China, delivered the company’s first 66 kV WindSTAR transformer with natural ester to be used in Chinese waters. Noteworthy, this unit is the first WindSTAR transformer to use natural ester as insulation fluid. The pilot project represents a significant milestone, facilitating enhanced integration of renewable energy sources and further elevating the overall sustainability of the transformer.

Using biodegradable fluids as an insulation medium enhances safety and reduces environmental consequences (in the event of leakage) reducing the carbon footprint of the transformer. Specifically, the insulating fluid employed in this transformer is a plant-based natural ester with almost 100 percent biodegradability, which is a marginal improvement compared to the already high biodegradability performance of synthetic ester and a very relevant improvement compared to mineral oil.

This solution, manufactured for the first time in China, offers an additional option that complements the choices available to all our customers. Leveraging our TrafoStar global technology platform, this innovation can be replicated in other power transformer factories worldwide, enabling customers everywhere to contribute to a more sustainable future.

Additionally, WindSTAR transformers are also prepared for floating applications. In this environment, wind turbines are affixed to floating structures, enabling electricity generation in water depths where fixed-foundation turbines are impractical.

The advent of floating wind farms holds immense promise as it significantly expands the sea area available for offshore wind energy projects, particularly in countries with limited shallow waters.

By harnessing floating applications, vast regions of previously untapped ocean can be unlocked for renewable offshore wind power generation and Hitachi Energy stands as the partner of choice, offering comprehensive solutions from the nacelle to the point of connection.