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in the context of building a new power system, the distribution system has been given a new role and mission. it not only has to complete the basic task of providing users with high-quality electricity supply, but also will assume important responsibilities such as a large number of distributed wind and solar renewable energy access platforms, a key integration platform for diversified massive information data, and an energy and power trading platform involving multiple stakeholders.

how to develop the power distribution system with high quality in the future? what are the characteristics of the power distribution system development? what needs to be improved in my country's power distribution system? focusing on the above questions, the reporter of china energy news interviewed wang chengshan, an academician of the chinese academy of engineering and a professor at the school of electrical automation and information engineering of tianjin university.

in recent years, the reform and development of my country's power system has received great attention.in 2021, the country officially proposed the development goal of "building a new power system with new energy as the main body."in 2022, my country further proposed the important policy of "developing distributed smart grids".in 2023, the country once again emphasized the urgency of "accelerating the construction of a new power system that is clean, low-carbon, safe, sufficient, economical and efficient, coordinated in supply and demand, flexible and intelligent."in february this year, the key task of "promoting the intelligent transformation of power grid infrastructure and the construction of smart microgrids" was proposed.all these indicate that the importance of power system development has been elevated to a new level.

behind this series of measures is my country's firm pursuit of achieving the "dual carbon" goal and energy transformation. for the power system, it is mainly reflected in the changes on the power supply side and the load side. in recent years, my country's wind and solar power generation has developed rapidly. three years ago, my country proposed a goal of 1.2 billion kilowatts of wind and solar installed capacity by 2030, which was achieved ahead of schedule at the end of july this year. looking ahead to 2030, wind and solar installed capacity is expected to reach 2.5 billion to 3 billion kilowatts. the speed of change and development is far beyond expectations, bringing new challenges and opportunities to the development of the power system.

the power system consists of power generation, transmission, and distribution. as a key infrastructure for safely and efficiently distributing electricity to thousands of households, the distribution system covers a variety of forms, including super-large urban power grids, rural power grids, and microgrids. according to statistics, more than 80% of power outages are caused by failures in the distribution system, which makes the reliability of the distribution system an important factor affecting user experience and has therefore received widespread attention.

wang chengshan believes that "looking into the future, both the development of distributed renewable energy and the acceleration of transportation electrification cannot be separated from the support of the distribution system. at the same time, new technologies such as artificial intelligence and big data have broad application prospects in the field of distribution systems."

wang chengshan said that my country's power distribution system is equipped with hundreds of millions of smart meters, which have the ability to upload data in minutes. the data collected by these smart meters are integrated with the data collected by various terminals in the power distribution system to form a huge data set. in-depth mining and analysis of these data can provide valuable reference information for government decision-making, power distribution system planning, construction, operation and maintenance.

when talking about the development characteristics of the future power distribution system, wang chengshan believes that the power distribution system will present four major characteristics:low carbonization, distribution, decentralization and digitalization.low carbonization means that a large amount of renewable energy will be connected to the distribution system. at the same time, the distribution system will support terminal energy consumption with a high electrification ratio, serving the improvement of energy efficiency and low carbonization of energy consumption in the whole society.this not only includes electric energy substitution, such as the development of electric vehicles, but also involves the mission and responsibility of the distribution system in improving the overall energy efficiency of the whole society.distribution and decentralization emphasize changes in the structure, operation mode, and market mechanism of the distribution system, while digitalization is an important means to improve the intelligence level and efficiency of the distribution system, and is also the key to the development of various new business models related to the distribution system.

wang chengshan said that in some provinces, the number of distributed photovoltaic systems easily reaches hundreds of thousands or even millions, which is in sharp contrast to the large capacity and small number of traditional thermal power plants. due to the distributed nature of power sources, the corresponding control measures also need to be distributed, and the energy storage configuration also needs to consider the distributed characteristics, and the distribution system grid structure also needs to adapt to it. in the future, the operation and management of the distribution system cannot completely rely on uploading all information and issuing instructions to solve operation control problems. this approach is inefficient and difficult to achieve, and must rely on local processing and distributed solutions to meet the challenges.

decentralization will be a major change in the form and mechanism of the distribution system. traditional distribution systems are passive or have few sources, and electricity flows one-way from high voltage to low voltage, which requires unified management and operation by the upper power grid. however, in the future, there will be a large number of distributed power sources in the distribution system, as well as a large number of new energy storage systems. a region or a district can completely constitute a local distribution system with strong autonomy, or form a microgrid. this means that these local area networks or microgrids do not have to rely entirely on the unified management and regulation of the superiors, thereby achieving decentralization. the purpose is to achieve local consumption of distributed energy as much as possible and avoid large amounts of power being sent back to the upper power grid. as the number and overall scale of distributed power sources increase, this will become an important means to solve related problems.

"decentralization is necessary in terms of network structure and operation mode, as well as in terms of operation mode and market mechanism." wang chengshan believes that the current market mechanism of the power distribution system is still in its infancy, and issues such as wall-to-wall power sales and point-to-point transactions are still under discussion. in the future, with the increase in the scenarios of local production, local trading and local utilization of electric energy, a decentralized market model is expected to be realized.

wang chengshan said that digitalization is an important development trend in the current power industry. in the past, the technical level of the distribution system was low, mainly because information could not be uploaded effectively, which made it impossible to use some advanced technical means. today, with the economic solution of communication problems and the deployment of a large number of smart meters, the situation is different. "we can build a new distribution system architecture through transformation and upgrading on the basis of the original distribution system, and cover a layer of information network on this basis to achieve timely upload of data. this change involves many technical issues, such as new sensor technology, advanced communication technology, edge computing technology, and the application of internet of things technology, big data technology, and artificial intelligence technology." these technologies are expected to truly realize the full utilization of user-side resources, truly achieve supply and demand interaction, and vehicle-network interaction, and create conditions for the development of new formats such as virtual power plants.

in wang chengshan's view, the grid structure of the power distribution system will undergo major changes in the future.its evolution reflects the development of distribution systems in serving social goals.initially, as long as power was available, there was a high tolerance for power outages.subsequently, society has put forward higher requirements on the reliability, efficiency and quality of power supply.in the future, emphasis will be placed on intelligent, green and customizable power supply services, and users can choose highly reliable power supply or green energy according to their needs.

"when considering future load growth, we face an important question: whether to increase investment and improve the power supply capacity of the distribution system by traditional means such as transformer or line capacity increase, or to increase efforts to tap the power supply potential of the existing distribution system." wang chengshan analyzed that in fact, the asset utilization efficiency of the existing distribution system has not been fully utilized. there are two main reasons: first, according to the current grid design principles, it is necessary to reserve a backup for possible faults. for the hand-in-hand connection method of two 10kv feeders, each feeder can only carry 50% of the load under normal circumstances, so that when one feeder fails, its load can be transferred to another feeder, and the feeder that takes over the load will not be overloaded; second, when the distribution system is constructed, whether it is the structure, conductor cross-section or substation capacity selection, it is based on the maximum load throughout the year. however, the maximum load may account for less than 5% of the time throughout the year, and the load is far lower than the maximum load value most of the time, which causes the idleness of distribution assets in normal times. the former requires changes in the structure of the distribution system, focusing on strengthening the interconnection between feeders. the latter needs to effectively reduce the maximum load through means such as supply and demand interaction, which can be achieved through guidance of electricity price mechanisms and other means. "if the asset utilization rate can be increased from 30% to 60%, the power supply capacity of the distribution system will be doubled."

the distribution system is a major asset-heavy infrastructure. over the past two decades, my country has invested hundreds of billions of yuan in the construction of the distribution system every year, which has greatly improved the equipment level and power supply reliability of my country's distribution system. however, compared with the transmission system, the distribution system has many types of equipment, a large number of equipment, and involves thousands of households, so there is still a lot of room for improvement in the technical level. especially in the context of my country's energy transformation, it is difficult to achieve the expected goals by building a distribution system in accordance with traditional investment methods. it is necessary to implement major changes in construction, operation, and market mechanisms through technological innovation to build a new distribution system to meet the needs of achieving my country's "dual carbon" goals. it must be pointed out that major changes in the distribution system require a long process and the joint efforts of the whole society to achieve the goal.