Looking at the current development trend of nuclear power at home and abroad, large-scale centralized nuclear power plants are still the mainstream, while small and medium-sized nuclear power plants are regarded as a good complement to the current large-scale nuclear power plants. Although small and medium-sized nuclear power plants have not yet reached the stage of large-scale commercialization and practical use, in the long run, centralized nuclear power plants are the mainstay, and moderate development of small and medium-sized nuclear power plants will be an important direction for the future development of nuclear power.

The potential advantages of "backyard nuclear power plant" are obvious

At present, the nuclear power plants in operation in my country are basically large units in terms of design and scale. Compared with these large nuclear power plants with an installed capacity of one million kilowatts, small and medium-sized nuclear power plants are usually designed to supply power to small and medium-sized towns or some large industrial facilities. Small and medium-sized power plants called "backyard nuclear power plants" often do not require much capital, and their safety can also be guaranteed, such as modular small pressurized water reactors and pebble bed modular high temperature gas-cooled reactor power plants.

Small and medium-sized nuclear power plants have many advantages: the total investment of the project is low, which can reduce capital investment and power plant land occupation, and shorten the construction period; good flexibility, less potential safety hazards, and improved energy integration through the cascade utilization of energy. Utilization efficiency; easier to operate, and the ability to locate nuclear power plants in areas closer to cities, saving the cost of long-distance transportation. In addition, the use of clean energy provided by small and medium-sized nuclear power plants to promote combined cooling, heating and power can reduce fossil energy consumption, reduce local pollutant emissions, and maximize energy conservation and environmental protection benefits.

Broad market prospects, diversified customers, good equipment sealing, and continuous energy supply have made some companies fiercely compete in the field of small and medium-sized nuclear power design and development, such as Westinghouse, Areva, China National Nuclear Corporation, Huaneng Group, Toshiba, etc. . At present, the United States, China, Japan and other countries are all committed to the research and development and construction of small and medium-sized nuclear power plants. US President Barack Obama recently proposed to build 500 small nuclear power plants to replace old thermal power units, and plans to invest 453 million US dollars in five years to support the research and development of small modular nuclear power plants; China Huaneng Shidaowan High Temperature Gas-cooled Reactor Nuclear Power Demonstration Project (200MW unit) has been started in December 2012; Japan's Toshiba has proposed that the 10MW small reactor developed by it does not need to be replaced within 30 years, and can provide electricity for about 3,000 households.

However, small and medium-sized nuclear power plants are currently facing some practical problems, such as increased investment per unit of capacity, high technical requirements, and public doubts about the safety of nuclear power. However, with the large-scale deployment of smart grids, small and medium-sized nuclear power plants can overcome the problems faced by their development with the help of this technology, so as to obtain greater development prospects.

Complementing the advantages of coordinated operation with large power stations

In order to meet the demand for electricity in the future social and economic development, the development of nuclear power in my country will still be dominated by large nuclear power units in the medium and long term. In the context of smart grid, the development of small and medium-sized nuclear power plants while developing large-scale nuclear power plants can promote the coordinated operation of centralized power sources and distributed power sources, comprehensively improve power grid performance and achieve diversified services.

After the completion of the smart grid, breakthroughs will be made in the fields of rapid regulation of conventional units, power prediction and dynamic modeling of intermittent energy, and the level of safe, stable and economic operation of the energy base will be improved. Large-capacity energy storage technology will also be popularized and applied, and clean energy power generation, including nuclear power, and its grid-connected operation control capabilities will be significantly improved. Large-scale nuclear power plants have large power supply capacity and can be used for system power supply support, complementing the advantages of small and medium-sized nuclear power plants under the smart grid.

For large nuclear power plants, the use of advanced technologies in the power generation link under the smart grid can promote the intensification of nuclear power development methods, scientific structure and layout, standardization of grid connection, intelligent operation control, and greatly strengthen the power supply support capability. The conventional power grid-plant coordination technology can realize online monitoring of the main equipment operating conditions of large-scale units in main conventional power plants through actual measurement of excitation and speed control system parameters, and effectively cover all aspects of nuclear power plants. The intelligent upgrade of large nuclear power units can effectively improve the coordination level of grid plants, ensure the safety and stability of the system, and realize the optimal allocation of resources.

For small and medium nuclear power plants, it can play a role similar to distributed generation in smart grids. In the future, a large number of distributed clean energy power generation and other forms of power generation will be connected to the power grid, which requires the distribution network to have flexible reconfiguration, power flow optimization, and clean energy acceptance capabilities. The smart grid adopts the simplified interconnection method of "plug and play", which can be seamlessly connected with various power generation methods (including centralized power generation and distributed power generation) and energy storage devices, so as to realize the coordinated operation of centralized power and distributed power. .

Realize flexible consumption, flexible power distribution and unified power distribution

The characteristics of centralized nuclear power development in my country require improving the large-capacity transmission capacity of the power grid, as well as the flexibility of power grid voltage and power flow control. Smart grid provides the feasibility of large-scale nuclear power access and random power grid integration. At the same time, through the smart grid platform, it provides auxiliary services for the integration of clean energy, including nuclear power, to achieve complementation and balance between different energy sources and improve their availability.

In addition to large-scale centralized development and utilization, nuclear power can be directly connected to the regional distribution network by means of decentralized small-scale development. Small nuclear power plants can strengthen the electrical connection between power generation and electricity consumption in the system due to their small power supply capacity and close proximity to loads, so as to meet the requirements of flexible access and nearby consumption of power under smart grids. After the small and medium-sized nuclear power plants are connected to the distribution network, the original radiating distribution network structure becomes a multi-terminal structure with multiple power points, which changes the power flow distribution of the distribution network, and affects the reactive power balance, voltage regulation, and relaying of the distribution network. Electric protection, control, metering and other technologies also put forward higher requirements.

In order to meet the decentralized access requirements of small and medium-sized nuclear power plants, through the comprehensive construction of a practical distribution automation system, an efficient, flexible and reasonable distribution network can be built, with flexible reconstruction and power flow optimization capabilities, and the use of small and medium-sized nuclear power plants in the distribution network. Coordinated operation with the main network and other key technologies to achieve compatible access and unified control of centralized/decentralized energy storage devices and small and medium-sized nuclear power plants. In addition, the use of intelligent power consumption technology to build an intelligent two-way interactive system can realize two-way interaction between the power grid and users, improve user service quality, promote users' rational allocation of electricity consumption, and meet users' diversified needs.