Research on building a new power system framework with new energy as the main body

I. Introduction

The proposal of the goal of carbon peak and carbon neutrality is a major strategic decision of the state, which bears on the sustainable development of the Chinese nation and the building of a community with a shared future for mankind. In the process of clean and low-carbon energy consumption, electricity occupies the dominant position of the energy system, and the development of the power system is facing a difficult task. Considering the endowment of various types of non-fossil energy resources in China and the technical economy of development and utilization, vigorously developing new energy is an inevitable choice. Building a new type of power system with new energy as the main body is not only an inevitable requirement of energy and power transformation, but also an important way to achieve the goal of carbon peak and carbon neutrality.

Energy and power industry technology capital intensive, there is a high degree of path dependence, technical route trial and error cost is very high. The construction of a new power system with new energy as the main body is a complex systematic project, which should be carried out in advance, a comprehensive analysis of the changes and challenges brought by the change of power production structure to the power system, an in-depth study of the path of low-carbon power transformation and major issues in the transformation process, and strive to form a broad consensus on key issues such as technical form and technical direction.

In view of this, this paper starts from the aspects of primary energy, power supply, network, load, balance mode, etc., studies the profound changes that will take place in the material and technical basis of the power system, and discusses the direct challenges faced by the future development of the power system from the aspects of reliable power supply, new energy consumption, and safe operation of the grid. This paper expounds the connotation, construction principles and ideas of the new power system, divides the development stages of the new power system, and puts forward strategic development suggestions in order to provide basic reference for the medium and long term development of the power industry.

2. Changes brought about by power system transformation

The process of achieving the goal of carbon peak and carbon neutrality in the power system is accompanied by the transformation and upgrading of the traditional power system to the new power system with new energy as the main body, and the relevant material base and technological base continue to undergo profound changes.

The first is a change in energy characteristics. The main body of primary energy in the power system changes from fossil energy that can be stored and transported to wind and solar energy resources that cannot be stored or transported and are related to meteorological environment, and the primary energy supply faces high uncertainty.

The second is the power supply layout and function changes. According to the distribution of wind and solar energy resources in China, the development of new energy will be centralized and decentralized, and the overall access location of the power supply will become more remote and deeper. In the future, as the main power source, new energy will not only be the main provider of electric power, but also have a considerable degree of active support, regulation and fault crossing and other "network" capabilities; Conventional power functions are gradually shifting to regulation and support.

The third is the change of network scale and form. The overall pattern of load center transmission in the eastern central region of the large clean energy base in the western and northern regions remains unchanged, and the scale of the grid will be further expanded in the near future. The form of power grid has changed from AC-DC hybrid power grid to microgrid and soft and direct power grid.

The fourth is the change of load structure and characteristics. Energy consumption is highly electrified and demand for electricity continues to grow. Distribution network is active, multi-energy flexible conversion, "production and consumption" widely exist, load from a single power to power generation/power integration direction change, regulation support capacity is enhanced.

The fifth is the change of power grid balance mode. Both the supply and demand sides of the new power system are faced with greater uncertainty, and the power balance mode has shifted from the power generation/power consumption balance of "source with load" to the balance in a larger space and a larger time scale in which energy storage and multi-energy conversion participate in the buffer.

The sixth is the change of power system technology foundation. The power grid connection technology has changed from AC synchronization to power electronics, and the synchronous operation mechanism of AC power system has changed from physical characteristics to human control algorithm. The microsecond switching process is introduced in power electronic devices to analyze and recognize the transition from electromechanical transient to electromagnetic transient. Operation control changes from centralized continuous control of large capacity homogenized units to discrete control of wide area massive heterogeneous resources. The fault defense system is transformed from the independent "three lines of defense" to the active and comprehensive defense system that extensively mobilizes the controllable resources of source network, load and storage.