Features of new power system with new energy as the main body

1. Morphological characteristics

1, a high proportion of new energy wide access

The core feature of the new power system is that new energy occupies a dominant position and becomes the main form of energy. With the proposal of China's carbon peak and carbon neutral goal, the proportion of new energy in primary energy consumption continues to increase, accelerating the replacement of fossil energy. In the future, the installed capacity of China's power supply will maintain steady and rapid growth, showing a "landscape leader, multi-source coordination" power generation will be the fastest growing power type in China, about 60% by 2060, and the sum of power generation will reach about 35%. Posture. In the total installed capacity of power supplies, the extensive access of onshore wind power and photovoltaic new energy in the future will also show a centralized and distributed trend. Large-scale scenery bases in Northwest, North and Northeast, hydropower bases in southwest, offshore wind power bases in eastern coastal areas, and distributed power sources adapted to local conditions and in considerable quantities and nearby, jointly alleviate the problem of reverse distribution of resources in China.

The extensive access of new energy in the future will also show the characteristics of intelligent flexibility, friendly grid-connection, efficient and environmental protection. Improve intelligence and flexibility through energy storage, AC/DC networking and multi-scenario integration; Through "wind, water and fire storage" multi-energy complementarity, cluster scheduling, meteorological big data power generation prediction, generalized virtual synchronization technology, improve the friendly grid-connection and active support performance; Improve efficiency and reliability through new wind energy capture and large impeller, new photovoltaic cells, digital intelligent operation and maintenance, and environmentally friendly materials; And build flexible thermal power units, natural gas and hydrogen storage peaking power station, heat storage and energy storage power station peaking power system.

2. Highly resilient power grid allocates resources flexibly and reliably

The new power system needs to solve the problems of strong uncertainty (i.e., randomness and volatility) and vulnerability under the high proportion of new energy access, and give full play to the power grid's ability of large-scale resource allocation. The future power grid will show the form of AC and DC long-distance transmission, regional grid interconnection, main network and micro-grid interaction.

Uhv AC and DC long-distance transmission has become an important means of clean energy allocation. The distributed power supply is connected in layers according to voltage level to achieve on-site consumption and balance. The rapid development of energy storage and demand side response, is expected to 2060 demand response scale is expected to reach about 360 million kilowatts, energy storage installed capacity will reach about 420 million kilowatts, the two will become the future power system important flexibility resources, to ensure the new energy consumption and system safe and stable operation. New generation scheduling system. It mainly includes:

1) From the traditional top-down scheduling mode, it has evolved into the "source network load and storage" whole-network coordinated scheduling mode;

2) From the traditional individual experience judgment to the intelligent scheduling of data-driven AI decision-making;

3) From the passive protection triggered by a single point of failure to the active defense of power iot global awareness in advance prevention;

4) Evolution to agile response (millisecond level) that combines power electronics with modern communications;

5) The core of highly resilient power grid lies in the establishment of rich scheduling and adjustment resources for new power electronic devices such as network coordination, data-driven, active defense, intelligent decision-making, composite power flow control and dynamic capacity increase.

6) From the slow response of traditional electromechanical action (second level) frequency modulation resources are insufficient to have flexible power supply, energy storage, demand-side response, and wide frequency oscillation suppression;

7) The foundation of the traditional high-elastic power grid is to build the power Internet of things with the interconnection of everything. Based on sensing devices such as Internet of Things intelligent sensing, edge computing fusion gateway, intelligent terminal and security chip, the whole process of data can be measured, collected and transmitted, and all kinds of terminals and devices can plug and play, secure access, and the Internet of everything; Fast data upload through modern communication networks such as 5G/ optical fiber/Internet of Things; Through artificial intelligence, big data and other advanced algorithms, based on the cloud platform to achieve intelligent power generation, intelligent scheduling, intelligent operation and maintenance of the whole scene and the whole chain intelligence.

3, highly electrified terminal load multiple interaction

In the future terminal energy consumption structure, the level of electrification continues to improve, and electric energy has gradually become the most important energy consumption variety. According to the forecast of relevant agencies, the dominant position of 2025 fees, the proportion of electric energy in terminal energy consumption is expected to reach about 45% and 70% in 2035 and 2060. Around to meet the people's yearning for a better life, the wide application of electric energy replacement, electric vehicles, clean heating, rooftop photovoltaic, household energy storage equipment and smart home electricity load is developing in a diversified direction.

In the context of the energy Internet, the new model of both consumers and producers has changed the form of energy and power services, and demand side response, virtual power plants and distributed transactions have become more and more new choices for users. Under the new consumption of energy Internet, in addition to universal services, green power, customized services, high-quality power supply, accurate metering, and value-added services of power big data have become new needs of users.

4, infrastructure multi-network integration digital empowerment

The energy Internet being built in our country is a technological path to promote the energy revolution. At the physical level, the energy Internet needs to build a comprehensive energy network that is based on a new generation of power systems and interconnected with many fields such as natural gas, transportation, and construction.

On the production side, various types of energy need to combine their own characteristics, give play to their strengths, carry out interconnection and complement each other's advantages; On the transmission side, the smart grid interconnects with the heat pipe network, natural gas pipe network and transportation network to coordinate scheduling;

On the consumption side, electric cooling, hot gas and water are integrated energy supply. Power Internet of Things has become a key link in network security. Construction of "security chip - terminal authentication - data trust - network encryption - application key" At the information layer, the power network is gradually integrated with the modern communication network to jointly build an active global network security protection system of the information physical society, and create an open and secure iot network with holographic panoramic perception, efficient information processing, data digital security, convenient and flexible application.

At the data level, the power industry carries out digital transformation and builds a dynamic electric power digital ecology. Power big data serves social governance and economic development, enables digital grid platform, and cultivates new electric power digital industry; Connecting with the industrial Internet, serving the digital government and smart city; Docking the resources of all links of the energy value chain, giving play to the advantages of mutual benefit and symbiosis among enterprises, and building an industrial chain cooperation platform and a new energy power ecology.

In general, the core feature of the new power system in the future is that new energy plays a dominant role. At the same time, around to meet the people's yearning for a better life, the wide application of electric vehicles, clean heating, roof PV, home energy storage, smart home and electric energy replacement has made the electricity load develop in a diversified direction. In the face of major changes at both ends of the source and load, the function and form of the power grid also need to carry out profound changes. In order to promote the strategy of energy revolution, the implementation of carbon peak by 2030 and 2060 to build a "clean, low-carbon, safe and efficient" new power system. This historic task is of great significance.

Ii. Mission and Challenge

To carry the crown, must bear its weight, to hold the rose, must bear its pain. The new power system bearing the high hopes of the Party and the state is not only a historical mission, but also a major challenge. The existing power system is not a simple energy system, and the construction of a new power system that ADAPTS to the wide access of a high proportion of new energy and evolves to a higher stage in a linear development mode has a big difference between the two. To sum up the essential technology, its evolution process is three points:

(a) The evolution of technology from the existing power system to the new power system

1. From a deterministic system to a strongly uncertain system

First, the power supply side has strong uncertainty. China's power supply structure will be dominated by traditional thermal power units and gradually evolve into new energy units in the future. In the future, the installed capacity of wind power and photovoltaic power generation will show a continuous upward trend, and it is expected that the sum of the installed capacity of the two will reach about 60% in 2060, and the sum of the power generation will reach about 35%. The existing conventional thermal power, hydropower or nuclear power output shows a certain regularity and controllability; However, the output of new energy such as wind power and photovoltaic has strong uncertainty and uncontrollability in multiple time and space.

Secondly, the load side has strong uncertainty. In the future, electric energy will gradually become the most important energy consumption in the years after electricity will replace coal in the dominant position in terminal energy consumption. The existing power load changes relatively regularly, and the operation mode of the entire power system is relatively fixed. For example, when planning the power system, it can be predicted by selecting the load curve of typical days or hours in different seasons. Under high electrification, the load structure is diversified, the random distribution of electric behavior such as electric vehicle charging and electric heating, and the active characteristics of the user side are prominent, which will aggravate the unpredictability of the load. At present, the peak-valley difference of China's power grid load is gradually increasing.

Thirdly, power flow has strong uncertainty. When less new energy is connected to the grid, the operation mode of the traditional power system is relatively fixed due to the regularity of load phase pairs. In the high ratio new energy power system, the "boundary conditions" of power system operation will be more diversified due to the large uncertainty in the source and load end. The power flow of the link line of the transmission network may vary greatly with the output fluctuation of new energy (even two-way flow), and the distributed new energy and virtual power plants of the distribution network will also change the power flow.

2. The evolution from electromechanical equipment to power electronic equipment

The grid-connection, transmission and consumption of new energy have introduced more power electronic equipment at the source-net-load end, and the power system has shown a significant trend of power electronization. Therefore, the basic characteristics of the power system will change from the electromechanical steady-state process dominated by the rotating motor to the electromagnetic transient process dominated by the power electronic equipment. The existing thermal power, hydropower and other traditional units use synchronous motor, with strong mechanical inertia, so the power system has a large time constant (second - minute level), the system frequency to power frequency (50 Hz). Power electronic devices have low inertia, low short circuit capacity, weak immunity and multi-time scale response, resulting in a smaller time constant (millisecond level), wider frequency domain (hundreds of Hertz), and more complex security domain. Multiple factors such as electromechanical transient and electromagnetic oscillation of the system interact with each other under various disturbance situations. For example, the current transient voltage support in the new energy base, the high/low voltage crossing shutdown of the wind turbine connected to the grid, broadband oscillation, and the failure of multi-feed DC commutation are all specific manifestations of the power electronic system.

3. Evolution from a single power system to an integrated energy system

Energy Internet needs to build a comprehensive energy network based on the new energy power system and interconnected with natural gas, transportation, construction and other fields. Therefore, the existing power system will be interconnected with the heat network, natural gas network and transportation network to form a comprehensive energy system. Moreover, the storage and transmission of natural gas and hydrogen energy will be deeply integrated with the power system and play an important role in peak regulation.

(2) The deficiency of the existing power system technology system

Under the existing technical conditions, the new energy output uncertainty is strong, with randomness, volatility, anti-peak regulation characteristics, "extremely hot no wind", "late peak no light", "large installed capacity, small power" has become the industry drawbacks. The evolution from the existing power system to the new power system will face important technical challenges. The existing technical system is not enough to support the construction of the new power system in the future. The main shortcomings are as follows:

(1) Insufficient overall coordination of power supply and grid planning. The construction of supporting power supply at the sending end lags behind and the carrying capacity of the receiving end is insufficient. The power grid structure can not fully meet the needs of large-scale resource allocation and distributed extensive access.

(2) The power system balance capacity is seriously insufficient. New energy units do not have the same power grid security and stability support capacity as traditional power units, and the ability to withstand power grid disturbance is low. The existing flexible power supply adjustment capacity of thermal power transformation and pumped storage is insufficient, which can not fully meet the needs of system peak regulation and frequency regulation in the case of high proportion of new energy access.

(3) Insufficient regulation and control capacity of the power system. There have been some safety problems in the system operation, such as insufficient dynamic reactive power support, insufficient frequency regulation and stability, excessive short-circuit current, and interweaving of traditional synchronous stability and new form stability. In addition, the "weak scheduling" or "no scheduling" characteristics of a large number of emerging distributed generation causes the difficulty of coordinated operation control of power systems to increase continuously. Due to the "data chimney", the foundation of the "generation - grid - user" degree system has not been fully established.

(4) Insufficient support capacity of electric power equipment. Facing the characteristics of the new electric power system, the adaptability of the existing power transmission and transformation equipment needs to be upgraded, and it needs to develop in the direction of more agile, more intelligent and higher carrying capacity. In particular, the overload bearing capacity of existing power electronic devices for power systems is low, which physically determines the vulnerability of equipment and systems, and it is urgent to improve the level of devices. In addition, the practical level of large-capacity energy storage systems needs to be improved, and cost, safety and efficiency are still the main obstacles to the large-scale promotion of energy storage.

(5) The basic theoretical system of the power system needs to be improved. The problem that the traditional power system technology system does not adapt to the development of large-scale new energy and power electronic equipment gradually appears. At the planning level, the concept and method of power quantity balance and capacity adequacy should be transformed from the current deterministic thinking to the probabilistic thinking. At the operational level, it is necessary to deeply grasp the dynamic characteristics of power electronics and improve the means of system analysis in complex environments.

 Scientific and technological innovation is the scientific road and inevitable choice to build a clean, low-carbon, safe and efficient energy system and a new power system.

Third, technical path

Scientific and technological innovation is the scientific road and inevitable choice to build a clean, low-carbon, safe and efficient energy system and a new power system.

At present, the scientific and technological revolution and industrial transformation are changing with each passing day, and the fields of energy Internet, digital energy, and power Internet of Things are developing in depth. Energy production and consumption technologies represented by renewable energy generation, distributed power supply, microgrid, energy storage and electric vehicles are accelerating the evolution of the traditional power industry to the new energy power system. Digital Internet technologies represented by big data, cloud platforms, the Internet of Things, mobile communications, artificial intelligence, and blockchain are driving the global industrial economy to evolve into a digital economy. The equipment manufacturing technology represented by power electronics, intelligent sensing, superconductivity and graphene materials is endless. Therefore, with the continuous emergence of various new technologies and development and utilization methods, new energy power system equipment technology is facing the possibility of continuous innovation and breakthrough and major demand.