How to Ensure Grid Compliance for Your Green Hydrogen Plant

The green hydrogen industry is rapidly expanding, shifting from prototype development to industrial-scale production, significantly increasing plant output. In Europe and North America, large-scale plants are set to shape the green hydrogen market’s future. As substantial electricity consumers, these plants significantly affect grid stability, necessitating additional regulation.

Project developers and electrolyzer OEMs should anticipate future grid requirements from national authorities and local transmission system operators (TSOs). In countries like Germany and Denmark, facilities exceeding 100MW are expected to face stringent grid requirements, emphasising the importance of planning for thorough grid compliance from the plant’s earliest development phases.

This article explores how project developers and electrolyzer OEMs can address these challenges effectively.

Beyond technical specifications
Grid requirements extend beyond technical specifications; they significantly impact plant design and layout, shaping operational and financial outcomes. Failure to comply often results in no grid permit and, after commissioning, costly retrofits, operational delays, and financial overruns.

“A green hydrogen plant designed to enhance power quality and support grid services can benefit the transmission system operator and the plant’s financial performance. By providing grid services, e.g. reactive power during high-load periods, the plant can earn extra revenue, a factor often overlooked in business case evaluations,” explains Michael Ariel Nielsen, Head of Power-to-X at KK Wind Solutions.

In some instances, TSOs impose power quality standards related to the plant’s point of connection, harmonics, and power factor. Therefore, considering grid compliance during the initial design phase, particularly when choosing the plant’s rectifier technology, can help ensure a faster grid application process and ultimately provide the best cost at the plant level.

Selecting the right rectifier technology from the beginning
Green hydrogen is typically produced through electrical electrolysis, which splits water into hydrogen and oxygen using renewable electricity. This occurs in an electrolyzer system that demands precise and stable AC-to-DC conversion facilitated by the power supply unit, which houses the rectifier.

“Selecting the right rectifier technology is crucial, considering power quality, fault ride-through and recovery (FRT&R) capabilities, future technological advancements, and the overall impact on grid stability. We have seen projects where late attention to grid compliance led to costly installations of additional grid filters to reduce harmonic disturbances in the grid,” says Michael Ariel Nielsen.

Rectifier technologies vary, offering distinct advantages and drawbacks. Thyristor rectifiers are reliable and low-cost but often need harmonic filters and additional power factor compensation to comply with local grid requirements. Diode rectifiers are highly efficient but also require filters and compensation systems. Neither rectifier technology provides active grid support or ancillary services alone.

In contrast, Active Front-End (AFE) IGBT rectifiers deliver superior load control, including fault ride-through and recovery (FRT&R), excellent power quality, and the capability to offer active grid support and ancillary services.

Financial implications and setbacks
Grid compliance has significant financial implications, affecting both capital and operating expenditures. Non-compliance can lead to substantial financial setbacks, as retrofitting systems to meet grid standards is costly and time-consuming.

“Failing to meet grid compliance from the start can result in millions of dollars in unexpected costs. Integrating grid compatibility considerations early in planning is critical,” notes Michael Ariel Nielsen.

Selecting between AFE (IGBT), diode, or thyristor rectifiers presents an economic challenge. It requires balancing the plant’s energy output needs, initial capital investment, and ongoing operating costs. AFE (IGBT) rectifiers are often favoured for hydrogen plants because they meet grid compliance demands and offer precise load control and reactive power supply.

Although AFE (IGBT) rectifiers have slightly higher initial costs, their efficiency and compliance advantages more than justify the investment. Ultimately, the benefits of improved operational efficiency, lower plant-level investments in power factor systems and harmonic filters, and smoother regulatory approval outweigh the upfront costs of AFE (IGBT) rectifiers.

Working proactively with grid requirements
The regulatory landscape for green hydrogen plants is continually evolving, creating risks of delays and cost overruns during development and commissioning. Project developers and electrolyzer OEMs must navigate complex international standards, such as those from the Institute of Electrical and Electronics Engineers (IEEE) and the International Electrotechnical Commission (IEC), along with local TSO codes that require enhanced power quality.

This situation requires ancillary grid services for stability and underscores the necessity of detailed modelling and simulation of a plant’s power supply, including the rectifier and electrolyser, which is crucial for ensuring regulatory compliance and adapting to changes.

Such preparatory work is crucial for maintaining long-term operational efficiency and is undertaken by KK Wind Solutions in collaboration with various stakeholders, including project developers, electrolyzer OEMs, TSOs, and companies specialising in grid feasibility studies, as Michael Ariel Nielsen explains:

“We work closely with customers to anticipate grid compliance issues for green hydrogen plants by creating software models and simulating grid disturbances for steady-state and dynamic power system performance. This approach lets us make timely adjustments and mitigate risks.”

He concludes:

“Grid compliance is not just a technical requirement but a critical success factor for a green hydrogen plant’s operational viability. Prioritising grid requirements and compatibility from the outset ensures regulatory compliance, stable operations and long-term financial viability for your plant.”
 

About KK Wind Solutions
With over 40 years of experience, KK Wind Solutions is a leading systems supplier in the renewable energy industry. We apply our industry-leading grid compliance expertise from the wind industry to green hydrogen, ensuring seamless alignment with grid requirements.