As the green hydrogen industry develops in the direction of large-scale and high-efficiency, the importance of hydrogen power supply as a key power conversion device in the electrolysis of water hydrogen production system is becoming increasingly prominent.

How should the green hydrogen project choose the hydrogen power supply? Industry insiders believe that this depends on the needs of the owner, including the project scale, initial investment, later operating costs, and the adaptability of different electrolyzers.

 

From the perspective of the current market application technology, hydrogen production power sources can be roughly divided into two categories: thyristor (SCR) power sources and insulated gate bipolar transistor (IGBT) power sources. Thyristor hydrogen production power source technology is mature and low-cost; while IGBT hydrogen production power source is more friendly to the power grid and has a higher system comprehensive conversion efficiency, and is becoming a hot track in the industry.

Comparison of Technical Routes

In the renewable electricity hydrogen production network, the hydrogen production power source plays the role of receiving power from the grid and supplying power to the hydrogen production electrolyzer. Its main function is to convert AC/DC into DC power that can be used for hydrogen production by electrolyzing water.

A complete hydrogen production power source mainly includes a rectifier cabinet, a transformer, a control system, a cooling system and auxiliary equipment. The rectifier cabinet is the core place for current conversion. The core of the rectifier cabinet is the power module, which can be divided into SCR or IGBT power semiconductor devices. The hydrogen production power source mentioned in the industry actually refers to the thyristor rectifier cabinet and the IGBT rectifier cabinet.

In the chlor-alkali hydrogen production industry, the thyristor rectifier cabinet has a history of more than 40 years of application. Due to the similarity in power parameters between the chlor-alkali electrolyzer and the alkaline hydrogen production electrolyzer, the thyristor rectifier cabinet can be directly applied to the hydrogen production industry under a stable power environment.

Thyristor-controlled hydrogen power sources use digital circuits to control the conduction of thyristors to achieve rectification. They can meet the working environment under high voltage and high current conditions, and their power can usually reach MW level. The advantages of thyristor-controlled hydrogen power sources are mature technology, low cost of single equipment, and applicability to high-power scenarios. At present, Sinopec Xinjiang Kuche, Huadian Damao Banner, Yuanjing Chifeng and other green hydrogen projects have adopted thyristor-controlled hydrogen power sources.

Technically speaking, there are also some challenges when thyristor power sources are applied to renewable energy hydrogen production scenarios. Because thyristor power sources are limited by the characteristics of their own semi-controlled power electronic devices, thyristors can control conduction but cannot be turned off, and can only be turned off by relying on the shutdown of the power grid. Its grid-side current has high harmonic content and poor friendliness to the power grid, which affects the grid connection of renewable energy hydrogen production systems; its dynamic response speed is slow and cannot quickly match the volatility of renewable energy; and in green hydrogen projects, special rectifier transformers, on-load voltage regulators, SVG/SVC, water cooling devices, etc. are required, and the comprehensive investment cost is high and the comprehensive system conversion efficiency is low.

At present, my country's green hydrogen projects often need to rely on part of the power grid for support, and cannot achieve completely off-grid hydrogen production for the time being. With the traditional grid-connected access method, the power grid company often helps hydrogen production enterprises to bear part of the power peak load responsibility, thereby ensuring that the front-end volatility and intermittent renewable energy are combined with the safety and stability required by the back-end chemical production. Therefore, the friendliness of the hydrogen production power source to the power grid is crucial.

Compared with thyristors, IGBT has more precise switching control, higher switching frequency, less corresponding harmonics, and higher power quality. At the same time, it also has reactive power compensation capability, which can replace the reactive power compensation device on the 35kV side. In addition, its supporting equipment is also less, and the system's comprehensive conversion efficiency is higher.

Of course, there are some development bottlenecks in IGBT hydrogen power supply. Compared with thyristors, the monomer cost of IGBT hydrogen power supply is higher, which is 3-5 times the price of thyristor hydrogen power supply. Moreover, as an emerging technology route, the stability and project adaptability of IGBT hydrogen power supply need to be further verified.

At present, in hydrogen production demonstration projects, the application of IGBT hydrogen power supply shows a certain upward trend. Some projects also use a combination of thyristors + IGBT. Some industry insiders analyzed that the project owner adopted a combination of thyristors + IGBT, mainly from a cost perspective. Currently, the two technical routes are still under development, and the final choice still depends on the needs of the owner, which includes project scale, initial investment, later operating costs, adaptability of different electrolytic cells, floor space, maintenance requirements and other indicators, and different owners will also have different focuses.

IGBT power supply has greater development potential

Due to its greater technical advantages in renewable energy hydrogen production systems, IGBT hydrogen production power supplies have gradually become a popular track in the industry. Companies such as Sunshine Hydrogen, CRRC Times, VEIChuang Electric, Xuji Electric, Narada Power, Huichuan Technology, Hopewind Electric, Leidong Zhichuang, Inbo New Energy, Kangpin Electric, Edison Technology, and Zhongke Zhihuan have all targeted the IGBT technology route and seized the hydrogen production power supply track.

Among them, Sunshine Hydrogen PWM hydrogen production power supply adopts IGBT fully controlled power devices, and its market performance is very outstanding. In August this year, Sunshine Hydrogen won the bid for the Zhongneng Songyuan Hydrogen Energy Industrial Park (Green Hydrogen Ammonia Alcohol Integration) demonstration project, and will provide 16 sets of PWM hydrogen production power supplies for the project. So far, the scale of its PWM hydrogen production power supply bid has exceeded 400MW, and it has been applied in demonstration projects such as the Inner Mongolia Shenneng Northern Photovoltaic Hydrogen Production Project, the Hubei Yangtze Power Green Electricity and Green Hydrogen Demonstration Project, and the Da'an Wind and Solar Green Hydrogen Synthesis Ammonia Integration Project.

Now more and more companies are pouring into the field of IGBT hydrogen production power supplies and obtaining batch orders, which also shows the industry's recognition of this technical route. With the entry of many enterprises, the price of IGBT hydrogen power supply has dropped. According to Gaogong Hydrogen and Electricity, the price of 1,000 standard cubic meters of IGBT hydrogen power supply of some leading enterprises has dropped from the original 1.2 to 1.5 million yuan to less than 1 million yuan.

In addition, the disadvantage of the initial investment cost of IGBT hydrogen power supply can also be compensated by comprehensive cost. According to Guo Xiaolong, marketing manager of the hydrogen production division of Inbo New Energy, IGBT power supply does not require additional configuration of SVG/SVC or on-load voltage regulators and other detuning and power factor improvement equipment, and can replace the 35kV side reactive compensation device, reducing investment maintenance costs and work losses. By comparing the conversion efficiency of 1,000 standard square meters of systems, they found that the IGBT power supply system is 0.7% more efficient than the thyristor power supply system. According to this efficiency, each hydrogen production system works 8,000 hours per year, and the electricity bill is calculated at 0.4 yuan, which can save 110,000 yuan in electricity bills per year.

With the large-scale development of the green hydrogen industry, IGBT power supplies still have room for further development in the hydrogen production power supply track. Recently, the Yongli Hydrogen Production Plant of the first phase of the Ningdong Renewable Hydrogen Carbon Emission Reduction Demonstration Zone of the State Energy Group successfully produced green hydrogen. This is also the first case in China where a hydrogen production station using all IGBT power supplies has been put into operation. It is reported that this project includes 500,000 kilowatts of photovoltaic power and 120,000 kilowatts of hydrogen production photovoltaic power. The new energy grid connection point is 33 kilometers away from the hydrogen production station, which is a typical weak power grid system. The project team has continuously overcome the stability problems of hydrogen production power supplies in weak power grid environments with characteristics such as low inertia, weak stability, weak anti-interference and random output, and the adaptability problems of grid voltage drop caused by transformer closing excitation inrush current. Li Haidong, general manager of Leidong Zhichuang, said that the current hydrogen production power supply industry has just started, and it will take some time to accumulate operating data for the matching between the battery tank and the power supply, including the definition of the operating condition boundary. With the increase of demonstration projects and the gradual improvement of industry awareness, the design optimization of IGBT hydrogen power supply will be further improved, thus more effectively supporting the development of hydrogen production from renewable energy; at the same time, the market demand for verified IGBT power supply is expected to further expand, and manufacturers will promote the large-scale production of IGBT hydrogen power supply industry through technology upgrades, which will also drive the production cost of individual products to further reduce.

Overall, thyristor hydrogen power supply has received good orders, but IGBT hydrogen power supply has stronger protection for the power grid and is more adaptable to power grid energy fluctuations. With the emergence of high-power electrolyzers and weak grid-connected or purely off-grid hydrogen production scenarios, IGBT hydrogen power supply is expected to have a broader application space.