NARI: Pioneer of energy interconnection technology and equipment

China Energy Storage Network News : At the end of 2016, the world's first 200kV high-voltage DC circuit breaker, a golden "giant", was successfully put into operation in the five-terminal flexible DC transmission system in Zhoushan, Zhejiang. As the manufacturer of the product, Purui Engineering Co., Ltd., a subsidiary of NARI, has made a significant contribution to the historic breakthrough of China's high-end DC equipment technology.

"Zhoushan DC circuit breaker is based on a hybrid of ultra-high voltage mechanical switches and cascaded full-bridge modules, which can cut off a fault current of up to 15 kiloamperes generated by a 200kV high-voltage DC transmission line within 3 milliseconds," said the person in charge of the Puri project. This speed is a hundred times faster than "the blink of an eye". In this way, the world's century-old power problem of "one converter station has an operating fault, other stations will stop with it, and the fault cannot be quickly isolated" has been completely solved.

Over the years, with a sound management mechanism, an ever-optimizing innovation system and a professional R&D team, NARI Group has shown more than one "weapon" in the field of power grids. Now, with the major development opportunities of building a global energy internet, NARI Group has strengthened the R&D of global energy internet technology and major equipment, and a series of new achievements have been born.

Make power transmission more efficient

UHV technology is an important support for the construction of energy internet. my country and many other countries in the world have vast territories, and the distance between energy centers and load centers is far. "Electricity comes from afar, and it is clean electricity." UHV transmission has become the preferred solution for long-distance and large-scale transmission of clean electricity with its large transmission capacity and low loss. State Grid Corporation of China is making every effort to promote the construction of UHV transmission channels and accelerate the construction of the "four cross and seven direct" UHV project.

The converter valve is the heart of the UHV DC project. With the careful "polishing" of NARI, the converter valve with the Chinese label has been transformed and applied in major projects after several optimization and upgrades. In May 2016, the ±1100kV converter valve was "born" to fully support the Changji-Guquan project with the highest voltage level, the largest transmission capacity and the longest power transmission distance in the world. At the same time, the UHV series compensation device developed by NARI with completely independent intellectual property rights helped the Ximeng-Shandong UHV project to be completed and put into operation.

In terms of emergency response to UHV faults, last summer, the "large-scale source-grid-load friendly interactive system" independently developed by NARI changed the situation of "one-size-fits-all power outage" due to power outages or power grid emergencies during peak hours, and reduced the emergency response time from minutes to milliseconds. The receiving end of the Jinsu UHV, Jiangsu Power Grid, became the first beneficiary.

Not only in China, but also in the international market, NARI is writing a new chapter in the manufacturing of UHV core high-end equipment in China. On the other side of the earth, in Brazil, which is world-famous for football and samba dance, the ±800kV Belo Monte Hydropower Station transmission project is under construction in full swing; in Nanjing in the cold winter, at the NARI Relay Protection Research Institute, every detail of the converter valve, DC control protection system, DC measurement and other equipment is being repeatedly verified. "The Belo Monte Phase II project in Brazil is the first time that NARI and China's UHV technology have gone abroad." Every member of the project team is very clear about their mission.

Making the grid run smarter

Flexible DC transmission is an important equipment for building smart grids. Compared with traditional methods, flexible DC transmission has strong advantages in island power supply, capacity expansion and transformation of urban distribution networks, AC system interconnection, large-scale wind farm grid connection, etc. NARI is the only equipment supplier in China that can provide complete sets of core products for flexible DC transmission. From the Nanhui wind farm project in the prosperous city of Shanghai, the five-terminal flexible DC transmission project in Zhoushan, Zhejiang, the city of thousands of islands, to the flexible DC project in Xiamen, the garden on the sea; from DC converter valves, DC control and protection systems to DC circuit breakers, the "NARI" brand has witnessed the growth of each major project.

During the peak summer period this year, the unified power flow controller (UPFC) effectively alleviated the uneven distribution of power flow and increased the power supply capacity of Nanjing's main urban area by 200,000 kilowatts. This flexible AC transmission device, independently developed by NARI and known as the "intelligent navigation system" of the power transmission channel of the power grid, has been operating stably in Nanjing West Ring Network for a year. In November 2016, the world's highest voltage level and largest capacity 500 kV UPFC Suzhou Southern Power Grid Demonstration Project started construction. NARI Group provided it with a complete set of equipment including UPFC control and protection system, converter valve and valve cooling system, thyristor high-speed bypass switch and electronic transformer.

Behind first-class technologies and products, there must be an innovative model that is guided by market demand, based on major projects, and focused on breakthroughs in key areas. At present, NARI Group is accelerating the layout of strategic emerging industries, and is conducting in-depth research in the fields of intelligent power distribution, large power grid system protection, drones and inspection robots, new generation communication technology, energy storage, etc., to fully support the future development of smart grids.

Make energy use greener

The vision of building a global energy internet is to meet global electricity demand in a clean and green way. However, compared with synchronous generators such as thermal power, new energy power generation such as wind power and photovoltaic power generation do not have the ability to inertial frequency regulation, autonomous voltage regulation, and provide inertial damping. Large-scale grid connection will affect the stability of the power grid. At the end of last year, the world's first high-power photovoltaic virtual synchronous machine successfully developed by NARI Group was successfully connected to the grid in the Zhangbei wind, light, storage and transmission demonstration project, which enabled the photovoltaic power source to have output characteristics close to those of thermal power units, effectively solving the compatibility problem between distributed power sources and power grids, and filling the gaps in new energy grid connection support technology at home and abroad. At present, relying on virtual synchronous machine technology, NARI is building a full range of wind, light and storage industry chains.

In addition, NARI has made a breakthrough in wind power pumped storage joint optimization technology, and the results have been applied to the Inner Mongolia power grid. As a precedent for the joint operation of pumped storage and large-scale wind power in China and even in the world, it has realized a new model of intensive wind power utilization in the region using energy storage, greatly improving the power grid's ability to absorb large-scale wind power.

Port shore power is an important measure to implement the "two substitutions". Ships moored at the port shut down their own auxiliary generators and rely on the port's shore power supply facilities to provide power to the ships to meet the power needs of the ships while in port. In this way, it is no longer a dream for ships on rivers, lakes and seas to use clean electricity. When the bulk carrier of Shanghai Puyuan Shipyard sailed into Nantong Port, Jiangsu Province and connected to the shore-based power supply system, the noise disappeared, the sky was blue and the clouds were white, and the port was quiet. This was the first megawatt-class shore power system developed by NARI at work. "Our products are also widely used in Nanjing, Taizhou, Yancheng and other places, and we just settled in Zhuhai not long ago." said the person in charge of NARI Agricultural Power Supply Company.

2016年，南瑞集团主导编制的电动汽车电池更换系统及智能电网调度支持系统4项国际标准正式发布，显著提升了我国在电动汽车充换电及智能调度领域的国际话语权和竞争力。

Fruitful results and remarkable achievements. In the new stage of my country's in-depth implementation of the "Belt and Road" strategy and the promotion of international production capacity and equipment manufacturing cooperation, NARI is facing the challenges of technological breakthroughs and equipment upgrades, and fully supports the construction of the global energy Internet with cutting-edge technology and high-end equipment.