TBEA: Renewable energy integration into the flexible DC transmission system Still Necessary Further Explore Large-Scale

Beijing International Wind Energy Conference and Exhibition (CWP 2021) will be held at the Beijing New International Exhibition. “Flexible DC Transmission System”

As one of the largest annual events in the global wind power industry, this wind energy event, attended by more than a hundred speakers and thousands of representatives at home and abroad, once again landed in Beijing.

With the theme of “Carbon Neutrality-New Opportunities for Wind Power Development”, the conference lasted four days, including the opening ceremony, keynote speeches, summit dialogue, innovation theater, and “International Mature Wind Power Market Development Trends and Investment Opportunities”.

15 sub-forums on different topics such as the development trends and investment opportunities of the emerging wind power market”, “Intelligent Operation and Maintenance Forum of Wind Power Equipment”, “Carbon Peak Carbon Neutralization and Accelerating Energy Transition”. You can see the App live broadcast of this conference.

Among them, the offshore wind power development forum was grandly held on October 19 . Sheng Junyi, deputy chief engineer of TBEA New Energy Co., Ltd., attended the meeting and delivered a speech.

The following is the full text of the speech:

Good afternoon everyone! It is a great honor to share with you this afternoon the exploration of flexible DC transmission system solutions for large-scale new energy access. Before I talk about the PPT, let me tell a short story. In fact, everyone knew about the AC/DC dispute between Faraday and Edison. In the end, Faraday won. In our daily life, we use DC power from household appliances, televisions, and computers. We convert AC power into DC. In new energy, photovoltaic itself is a DC.

We need to convert it into AC, and use it through boosting. Grid this way. Like wind power, DC is still mostly seen in daily life. Why hasn’t DC been developed? 

The first is related to the setting of power equipment and components. With the current development of new energy, many DC technologies including component technology, transmission technology, and conversion technology have achieved qualitative breakthroughs. Therefore, in the future large-scale new energy transmission, new energy can be delivered in a larger amount and farther. For there are only two lines at sea, the cost is also lower, and the conversion pile is more flexible.

Today’s sharing is divided into three parts. The first part is the necessity of the DC transmission scheme. The second part is about the necessity of a few more typical new energy scenarios. I will give you a brief introduction. . The third is a report on the company’s research results on flexible DC transmission that we have done from 2013 to now.

As the world’s largest energy producer and consumer, China resources and energy are concentrated in the west and north, while electricity consumption is concentrated in the south east coast. The special resource endowment makes China must establish a long-distance, cross-regional dispatch of super energy channels , UHV power transmission highways can transport huge amounts of electrical energy thousands of miles away, which is a key technology to measure the level of a country’s power equipment.

DC transmission currently includes conventional DC transmission and flexible DC transmission. Compared with conventional DC transmission, flexible DC transmission can realize the integration of weak grids, four-quadrant control of power, low harmonic emission, power supply and black start capability for the power system, high dynamic performance, small footprint, no replacement Phase failure problem.

However, it is precisely because of its high cost and high technical content that flexible DC transmission HVDC is still at the commanding heights of the industry.

Flexible DC transmission has various application scenarios, which can realize multi-terminal DC power supply, asynchronous interconnection, large-scale deep-sea offshore wind power DC transmission, and power supply for isolated islands and offshore platforms.

For AC power transmission, conventional DC power transmission and flexible DC power transmission, the large-scale integration of new energy sources and the use of flexible DC power transmission technology are currently the preferred technical solutions.

The second is the exploration of flexible DC transmission system solutions for large-scale new energy integration.

2021 is the first year of China’s 14th Five-Year Plan. The Party Central Committee and the State Council are standing on the height of “promoting high-quality development internally and building the image of a responsible major country externally” and have made a series of major decisions and deployments in response to climate change.

Striving to achieve carbon peaks by 2030 and carbon neutrality by 2060 is a major strategic decision made by the Party Central Committee after careful consideration. It is related to the sustainable development of the Chinese nation and the building of a community with a shared future for mankind. For us, flexible DC transmission system solutions for large-scale new energy integration still need to be explored in depth.

Realize the problems of grid connection and transmission of new energy, improve the stability of the grid, provide part of the electricity load with new energy transmitted by the flexible DC transmission system, and transform the existing lines into flexible DC transmission technology. Sending new energy power directly to the load center and using green power for industrial upgrading will become the trend of future development.

For the flexible DC solution for large-scale new energy access, we analyze from the following four scenarios. First of all, for the ±250kV/1GW integrated source-network-load-storage scenario, we designed a flexible DC transmission system topology that integrates source-network, load-storage, and sends the new energy power of the large base directly to the load center, using green power for industry Upgrading will become the trend of future development.

This solution can solve the problem of large-scale new energy grid connection and transmission, and improve the stability of the grid. It can also provide part of the electricity load with new energy delivered by the flexible DC transmission system.

For this solution, the flexible straight system solution can be based on the following parameters, with a rated power of 1GW, a DC voltage of ±250kV, a pseudo-bipolar system, a half-bridge module, and a 4500V/3000A crimping IGBT for the power device.

Realize the seasonal and reasonable consumption of new energy in the northwest and northern regions, improve power transmission capacity, strengthen the interconnection of new energy local grids with central and southern China, improve the controllability of grid operation, reduce the risk of safe and stable operation of the grid, and adopt flexible direct parallel technology The solution realizes back-to-back interconnection, which can isolate areas with more new energy from the large power grid and maintain the stability of the regional power grid.

For the ±420kV/1.125GW new energy local power grid and the large power grid back-to-back interconnection scenario, we designed a dual-channel topology, using flexible direct parallel technology to achieve back-to-back interconnection, which can isolate areas with more new energy from the large power grid , Maintain the stability of the regional power grid.

This scheme can realize the reasonable seasonal consumption of new energy in the northwest and northern regions, and improve the power transmission capacity. Strengthen the interconnection of new energy local power grids with central and southern China, improve the controllability of power grid operation, and reduce the risk of safe and stable operation of the power grid.

For this solution, the flexible straight system solution can be based on the following parameters, rated power 1.125GW, DC voltage ±420kV, using pseudo-bipolar system, half-bridge module topology, and power devices using 3300V/1500A welded IGBTs.

Aiming at the large-capacity power transmission scenario of the new energy local grid of ±500kV/3GW, we designed the LCC-MMC hybrid hierarchical DC access outbound topology structure.

The use of hierarchical DC access technology can effectively disperse new The effective integration of energy and electric energy can meet the requirements of power transmission and realize local grid isolation.

This scheme can realize the large-capacity power transmission of new energy local power grids. In addition, existing lines can be transformed into flexible DC transmission technology.

For this solution, the flexible straight system solution can be based on the following parameters, with a rated power of 3GW, a DC voltage of ±500kV, a symmetrical bipolar system, a half-bridge module topology, and a 4500V/2000A crimping IGBT for the power device.

New energy local power grid large-capacity power transmission solution: For the ±500kV/1.5GW new energy local power grid large-capacity power transmission scenario, we also designed the LCC-MMC hybrid hierarchical DC access external transmission topology. In areas where new energy is intensive, especially in the west and northwest, the construction of flexible and direct power grids in the region can satisfy the stability of cross-regional power transmission and ensure the stability of the regional system.

This scheme realizes the stability of new energy grid connection and improves the power transmission capacity. In addition, it can also take advantage of the power transmission economy and adopt the UHV flexible DC transmission scheme.

For this solution, the flexible straight system solution can be based on the following parameters, with a rated power of 1.5GW, a DC voltage of ±500kV, a symmetrical bipolar system, a half-bridge module topology, and a 4500V/2000A crimping IGBT for the power device.

The third is TBEA flexible DC valve technology.

TBEA can not only provide a complete set of flexible DC transmission solutions, but also provide flexible DC converter valves, converter transformers, reactors, AC and DC high-voltage wall bushings, cables, transformers, high-voltage switches and other key equipment.

The following mainly introduces the flexible DC converter valve products and technology of TBEA for all leaders.

In 2015, the ±320kV/1000MW power module developed by TBEA passed the experiment. In 2016, TBEA put forward the technology of “Overhead flexible DC transmission system DC fault-free ride-through control” for the first time in the world. In 2017, TBEA successfully developed the world’s first UHV flexible DC transmission converter valve. In 2018, TBEA won the bid for the China Southern Power Grid Wudongde project. In 2020, the Wudongde project went into production smoothly.

The picture on the left is the actual photo of the valve hall of the converter valve, and the picture on the right is the actual photo of the valve tower of the converter valve. As the core electrical equipment of the flexible DC transmission system, the converter valve must comply with strict operating procedures during its manufacturing, testing, transportation, engineering site assembly, debugging and operation to ensure the stable and reliable operation of the entire flexible DC transmission system.

In 2016, TBEA put forward the technology of “Overhead flexible DC transmission system DC fault-free ride-through control” for the first time in the world. In 2017, TBEA successfully developed the world’s first UHV flexible DC transmission converter valve. In 2018, TBEA won the bid for the China Southern Power Grid Wudongde project.

The national level has repeatedly reported on the strength of the TBEA flexible DC product development and testing in this project! Up to now, the flexible transmission industry has authorized 115 patents and software works related to converter valves and valve control systems, including 52 invention patents, 49 utility model patents, 6 software works, and 8 appearance patents.

Through years of research and development and precipitation, the intellectual property rights of TBEA’s flexible straight industry have been fruitful, and more than 100 patents and software copyrights have been accumulated.

With compact and lightweight power modules, valve sections, and valve towers, TBEA provides a complete set of solutions and equipment for flexible DC transmission and regional grid interconnection with voltage levels of ±10kV～±800kV and capacity levels of 10MW～8000MW.

TBEA can provide complete sets of solutions and equipment for flexible DC transmission and regional grid interconnection with voltage levels ranging from ±10kV to ±800kV and capacity levels ranging from 10MW to 8000MW for the State Grid Corporation, China Southern Power Grid Corporation, and local power companies.

Our ±800kV/3000MW flexible DC transmission valve control system is composed of 9 panel cabinets, including dual redundant 2 main control panels, 6 pulse distribution panels, and 1 auxiliary function panel.

Flexible straightening research and development experimental prototype platform-±10kV/5MW non-locking overhead flexible straightening experimental platform.

TBEA has built a ±10kV/5MW overhead flexible straight prototype, which can perform various tests such as DC fault ride-through, step-down operation, and start-up. In Xi’an Industrial Park, TBEA has built a ±10kV/5MW overhead flexible straight prototype, which can perform various tests such as DC fault ride-through, step-down operation, and start-up. In addition, in the Xi’an Industrial Park, TBEA has also built an LCC+4-terminal VSC five-terminal flexible straightforward research and development experimental prototype platform.

Thank you for listening, thank you for your long-term support and help to TBEA. The development and progress of TBEA are inseparable from the strong support of the party, the state, autonomous regions, the power industry, energy industry, manufacturing, and all sectors of society. I hope you can provide valuable suggestions for our development (HVDC)

That’s all for today’s sharing, thank you everyone!