Smart grid, providing strong power support

In recent years, China's power system has accelerated its transition towards accommodating large-scale, high-proportion new energy sources. Facing challenges in the low-carbon energy transition, networking, grid supplementation, and chain strengthening of infrastructure have become inevitable choices. In the future, distributed smart grids will be further developed, focusing on key technologies and business models to promote more coordinated development of generation, grid, load, and storage.

On May 25, the DC back-to-back grid project in the Guangdong-Hong Kong-Macao Greater Bay Area officially went into operation, expected to support "West-to-East Power Transmission" with electricity not less than 188.3 billion kWh this year; on June 30, the largest pumped storage power station in East China — Zhejiang Changlongshan Pumped Storage Power Station — was fully commissioned, acting as a giant "power bank" to undertake grid peak regulation and valley filling tasks; on July 1, the 2080-kilometer-long Baihetan to Jiangsu UHV DC project was put into operation...

Since the beginning of this year, China's power infrastructure construction has been progressing in an orderly manner. The 11th meeting of the Central Financial and Economic Affairs Commission pointed out the need to strengthen network-type infrastructure construction in transportation, energy, water conservancy, etc., focusing on networking, grid supplementation, and chain strengthening to improve network efficiency. As an important driver of economic operation and a key link in energy transition, how is the progress in networking, grid supplementation, and chain strengthening in the power sector? What should be the key focus areas going forward? The reporter conducted interviews.

The foundation for power supply security continues to be solidified, making networking, grid supplementation, and chain strengthening of infrastructure inevitable choices.

In recent years, China's power infrastructure has maintained moderately advanced development, accelerating the transition of the power system towards accommodating large-scale, high-proportion new energy sources.

Installed power capacity and the scale of "West-to-East Power Transmission" continue to expand. Currently, China's total installed power generation capacity exceeds 2.4 billion kilowatts, with wind, photovoltaic, hydropower, and biomass power generation capacities ranking first in the world for consecutive years; 33 AC and DC UHV lines have been built nationwide, with "West-to-East Power Transmission" exceeding 290 million kilowatts.

Rural power supply security has significantly improved. By 2020, all counties nationwide were connected to the large power grid, and villages within the large grid coverage were supplied with power. Rural power supply capacity and reliability have continuously improved.

Power technology innovation capabilities have rapidly improved. China has established a complete manufacturing industry chain for clean energy equipment including hydropower, nuclear power, wind power, and solar power. In the first half of the year, China's photovoltaic product exports totaled about 25.9 billion USD, a year-on-year increase of 113.1%.

Although the foundation for power supply security continues to be solidified, supply tightness still occurs in some periods and regions. During the 14th Five-Year Plan period, China's electricity load and consumption are expected to continue growing, requiring further strengthening of power supply security capabilities; meanwhile, in the low-carbon energy transition process, challenges include the new power system still being in its early development stage and insufficient adaptability to large-scale, high-proportion new energy grid integration and consumption. To address these shortcomings, networking, grid supplementation, and chain strengthening of power infrastructure have become inevitable choices.

A relevant official from the National Energy Administration introduced that for power infrastructure construction, networking mainly includes developing UHV transmission channels; grid supplementation mainly includes optimizing and improving the backbone grid layout, strengthening urban distribution network upgrades and resilient local grid construction, developing distributed smart grids, and improving power infrastructure in rural and remote areas; chain strengthening mainly includes enhancing the safety and intelligence level of power infrastructure, making the power system more flexible and intelligent, and promoting coordinated interaction among generation, grid, load, and storage. "Accelerating networking, grid supplementation, and chain strengthening of power infrastructure is an inevitable requirement to ensure national energy security and to achieve carbon peak and carbon neutrality goals on schedule."

Focusing on networking, grid supplementation, and chain strengthening as key construction priorities also helps leverage investment-driven growth. In June, the State Grid announced a power grid investment exceeding 500 billion yuan this year, reaching a historic high, expected to drive social investment of over 1 trillion yuan.

Improving the intelligence level of the power grid to ensure reliable, stable, and low-cost power supply.

In Taiping Town, Xinxing County, Yunfu City, Guangdong Province, a "white house" stands prominently. This is the "smart brain" of the Southern Power Grid's 10kV distributed grid — an energy storage switch station, which can flexibly switch the distributed grid between shutdown, grid-connected operation, and off-grid operation modes, and also acts like a large "power bank" capable of storing 2 megawatts of electricity. It is reported that last year, this "generation (hydropower)–grid–load–storage" medium-voltage distributed grid was built locally, enabling full consumption of small hydropower and reducing about 43% of hydropower curtailment.

The 11th meeting of the Central Financial and Economic Affairs Commission proposed developing distributed smart grids. How should distributed smart grids be understood? What role do they play?

A relevant official from the National Energy Administration introduced that distributed smart grids are based on the power grid platform, improving grid intelligence to actively adapt to the development of large-scale distributed new energy.

On the generation side, they can support distributed power sources connecting to the grid, meeting electricity demand nearby, and continuously providing reliable power supply to users.

Du Zhongming, president of the Electric Power Planning and Design Institute, introduced that China's new energy development and utilization show a pattern of both centralized and distributed approaches. The "large clean energy bases + large power grid" approach mainly solves the problem of "power coming from afar," but long-distance transmission faces constraints such as investment costs, land, and environmental factors. To promote large-scale, high-proportion new energy development, reliance on distributed power sources is also needed to fully leverage their advantage of being close to loads and consuming power nearby, achieving "power taken from nearby."

On the load side, they can support various load entities such as electric vehicle charging stations, new energy storage, and virtual power plants, meeting diversified "plug-and-play" access needs.

"New energy output has characteristics of intermittency, volatility, and randomness. As the proportion of new energy increases, maintaining power system balance becomes increasingly difficult, and the lack of flexible regulation resources in the traditional grid becomes prominent," said Du Zhongming. Through fine regulation of user electricity consumption by distributed smart grids, it is equivalent to creating another "power plant," which will become a key means to ensure reliable, stable, and low-cost power supply in the new power system.

"Currently, it is the peak electricity price period; it is recommended to charge before the low-price period at 12 o'clock." At 10 a.m., Mr. Zhang, a teacher at the Hangzhou Advanced Research Institute of the University of Chinese Academy of Sciences, originally planned to charge his electric vehicle and saved about 70% of the electricity cost by following the charging app's suggestion. Last year, the State Grid Hangzhou Power Supply Company launched a "photovoltaic-storage-charging integrated" smart collaborative project on campus, including distributed photovoltaics, energy storage stations, 3 fast charging piles, 20 slow charging piles, and a photovoltaic-storage-charging intelligent control system.

Data provided by the National Energy Administration shows that in recent years, China's distribution network structure has been further optimized, intelligence levels have significantly improved, and distributed power acceptance capacity has steadily increased, fully ensuring flexible access of various distributed power sources exceeding 100 million kilowatts.

Developing distributed smart grids also requires efforts in key technologies, business models, and other aspects.

Experts interviewed believe that developing distributed smart grids requires joint efforts in improving key technology "hardware" and business model "software" among other aspects.

At the key technology level, Du Zhongming believes it is urgent to study coordinated control technologies that adapt to massive distributed power sources and diverse load access, intelligent grid dispatching and operation technologies, as well as key technologies for the digitalization and intelligence enhancement of distributed smart grids.

As of the end of June this year, the national stock of pure electric vehicles reached 8.104 million, and the installed capacity of distributed photovoltaic power generation was 127 million kilowatts, equivalent to the installed capacity of more than five Three Gorges power stations. "The charging load of electric vehicles is highly random; photovoltaic power generation during the day can meet most of the electricity demand, but there is no output at night. Coupled with a surge in electric vehicle charging load, the power balance and the safe and stable operation of the system during the evening peak will face great challenges." Du Zhongming suggests building a technical support system integrating distribution and electricity use to open up the "last mile" connecting the distribution network to users.

At the business model level, it is necessary to improve the pricing mechanism and market rules for "wall-separated electricity sales" (i.e., market-based transactions of distributed generation). "'Wall-separated electricity sales' help promote the local consumption of renewable energy, but the current standards for 'grid usage fees' are still unclear. How to balance the demands of all trading parties and grid companies, and improve the electricity price mechanism that supports self-generation and self-use as well as local utilization of distributed clean energy generation, requires further exploration," said Du Zhongming.

A relevant official from the National Energy Administration told reporters that next, the National Energy Administration will, guided by the construction of a new type of power system, promote the upgrading of the form, technology, and functions of the traditional power grid, significantly enhance the power supply guarantee and flexible interaction capabilities of distributed smart grids, and achieve more coordinated development of sources, grids, loads, and storage.

First, leverage planning roles to strengthen the formulation and top-level design of distributed smart grid planning. Second, in areas with good demand response resource conditions and abundant new energy generation resources, support distributed smart grids and promote the consumption of distributed new energy power through demand response tailored to local conditions. Third, accelerate research on distributed smart grid technologies by gathering forces from research institutes, universities, and enterprises to achieve breakthroughs in core technologies.