1. Problems of rural power grid automation in rural power grid transformation and construction (1) Selection problem: The automation technology content is not high; some emerging companies cannot guarantee good after-sales service, and the products have not been tested and certified by national authoritative departments. (2) Single function: The expansion and interface of the system have not been considered. (3) Weak technical strength: The number of maintenance personnel of county-level dispatch automation system is smaller and the technical level is lower than that of urban power grid dispatch personnel. (4) Advanced dispatch system and backward management system coexist. 2. A new generation of dispatch automation system suitable for rural power grid (1) System design goal: The new generation of power grid dispatch automation system should take into account the impact of Internet/Intranet technology on power companies. In the design and development, it should be based on SCADA function, with DA/DMS, AM/FM/GIS, MIS and other subsystems as extended functions, and be a networked, multi-functional system with an integrated platform. ① Hardware aspect of the system: The latest and most reliable microcomputer hardware technology should be given priority as the hardware platform of system workstations and servers. If conditions permit, the latest RISC or UNIX workstation system can also be used. ② Software aspects of the system: The operating system of the dispatch automation system adopts the new generation Microsoft Windows NT/2000; the database adopts high-performance commercial relational databases, such as MS SQL Server, Oracle, Sybase, etc., to make the system software configuration standard and standardized; the system output format adopts excellent tools such as Microsoft Office Excel, making the reporting system more convenient and easy to use; the software structure adopts a network distributed client/server model. (2) System design principles: ① Stability: For the dispatch automation system applied to rural power grids, stability is the top priority. Outdated systems increase the difficulty for technicians to master and may even render the system ineffective; ② Practicality: Adhere to the principle of simple, clear and convenient human-computer dialogue and be able to complete information sharing between the dispatch system and the MIS system; ③ Easy maintenance: The hardware design and selection of the system should be universal and the software design of the system should have remote maintenance function; ④ Advanced; ⑤ Expandability; ⑥ Scalability: According to the needs of user application systems and investment status, the system should be able to flexibly select hardware and software configurations and have the characteristics of cross-hardware platforms. The scale of the system can be selected from single machine to multiple machines, single model to multiple models; ⑦ Flexibility: Most of the functional modules that make up the system should be able to be "installed and used"; ⑧ Security: The system hardware adopts redundant design to ensure uninterrupted and reliable operation of the system; The operating system, database and application software operation levels meet the strict security operation requirements. (3) System functional specifications: The function of the new generation of power grid dispatch automation system should be based on SCADA function, expand DMS function, and realize a new generation of power grid dispatch automation system integrating SCADA/DMS, dispatch management and power energy billing. (4) System hardware structure: ① The hardware architecture of the dispatching system adopts a dual-network redundant distributed structure, and important nodes adopt dual-machine backup to ensure the reliability of real-time system operation; ② To ensure the reliability of system data communication, a dual network structure can be adopted. Automatic switching and network load balancing can be realized, and a single network failure will not affect the normal operation of the entire system. (5) System software platform: ① The future rural power grid dispatch automation system should be a unified platform based on SCADA; ② The system should adopt a distributed, multi-means data acquisition system; ③ A network communication management system based on TCP/IP should be adopted; ④ The system should adopt a database system that organically combines real-time and commercial databases; ⑤ The system should have a powerful graphics system; ⑥ The system should also have a WEB interface with the MIS system and related output capabilities. (6) System reliability indicators: The reliability should be formulated in accordance with the "County-level Power Grid Dispatch Automation Function Specification (DL/T 635-1997)" and with reference to the requirements of the original "County-level Power Grid Dispatch Automation System Practical Acceptance Rules" of the State Power Corporation Rural Electrification Department. Considering the improvement in the performance and reliability of computers and related supporting systems and equipment in recent years, higher requirements should be placed on the reliability of the system. We suggest that the annual availability rate of the rural power grid dispatching system should reach 99.95% at the current stage. Considering the relatively weak technical personnel in rural power systems, the dispatching automation system should have remote maintenance functions. (7) Typical system structure: A typical rural power grid dispatching automation system should have the following structure: dual front-end machines, dual dispatching machines, dual servers, dual networks, and a system with remote maintenance, dispatching management, MIS information system and analog screen interface. 3. Communication methods of rural power grids (1) Traditional communication mode: In the traditional dispatching system, real-time data transmission is carried out using power line carrier, audio cable, wireless spread spectrum, microwave, optical fiber and other methods. In recent years, with the development of communication technology, microwave, wireless spread spectrum, optical fiber and other communication methods have gradually entered the power industry, and some communication methods have even become the mainstream of the power industry. (2) Developing Communication Methods: With the development of technologies and equipment such as power grid dispatch automation, distribution network automation, and substation automation, the construction of mature, stable, and high-performance communication systems has become inevitable. Therefore, in the construction of power communication systems, the structure and development direction of the power communication network should be considered, and the professional network and the public telephone network should be organically connected to form a stable and reliable power communication system with each party fulfilling its responsibilities. The following methods are for reference only: Table 1 ① For regions with abundant funds, optical fiber should be used as the backbone network and backbone channel, while power line carrier, communication cable, microwave, and wireless spread spectrum should be used as communication branches to save investment. ② For regions with developed public telephone systems, administrative and dispatch business communications can use the public telephone network; for communication methods that do not require long-term channel occupation and have a small amount of data, such as dial-up access and remote meter reading, the public telephone network should also be used, and time-division multiplexing communication methods should be adopted. ③ For the transmission of various real-time data that requires uninterrupted communication and long-term channel occupation, a dedicated data communication network should be established. Generally, fiber optics, carrier waves, communication cables, and wireless spread spectrum can be used. When setting up, a comprehensive demonstration should be conducted from the aspects of technology and funding. ④ For areas with inconvenient transportation and difficulty in setting up wired communication lines, wireless communication can be considered as the main means of data communication, and wireless spread spectrum communication and other inexpensive and effective communication means should be given priority. ⑤ When selecting communication equipment, factors such as advanced technology, operational reliability, product performance-price ratio and functional scalability should be considered. When building a rural power communication network, expansion space should be reserved while meeting the current communication system requirements to avoid the trouble of repeated investment and construction caused by system development. 4. Construction mode of substations in rural power grids (1) Construction of substation automation system: The so-called substation automation system is a comprehensive automation system that uses microcomputer technology to combine the secondary equipment of the substation (including control equipment, signaling devices, measuring instruments, protection devices, automatic devices, remote control devices, etc.) to achieve information sharing and implement automatic monitoring, measurement, control and coordination of the substation. Substation automation systems can collect relatively complete data and information. After high-speed calculation and judgment by the main control unit, they can conveniently monitor and control the operation of various equipment in the substation and complete the operation of related equipment. Its main features are: integrated functions, microcomputer structure, distributed installation, screen-based operation monitoring, and intelligent operation management. Main functions: monitoring and control, microcomputer protection, automatic safety devices, automatic voltage and reactive power control, data communication and system self-diagnosis functions, etc. Structure of substation automation systems: Various forms of system structures have their own characteristics to adapt to the needs of the site. The best system structure should be selected according to local conditions and based on the principles of practicality, reliability and stability. The selection of substation automation systems can refer to Table 1: (2) Construction of unmanned substations: In the transformation and construction of rural power grid substation automation, the principles of economy, practicality, stability and reliability should be followed, and the appropriate substation secondary microcomputer integrated automation device should be selected according to the actual situation of the specific configuration. The transformation of old substations or the construction of new substations can refer to the following models. For distribution substations and 10kV switching stations, if the renovation is based on an existing station, it can generally be carried out in the following two ways: Option 1: Retain the original protection devices and directly install a distributed measurement and control device integrating remote signaling and remote control in the equipment bay. The telemetry part uses AC sampling units or smart energy meters for centralized data collection. Option 2: For community substations and box-type substations, due to their small scale and simple wiring, a "centralized" substation main control system is more suitable for the needs of substation renovation and construction. For newly built substations, it is recommended to use an object-oriented distributed substation main control system with integrated monitoring and protection functions; multi-rate multi-function energy meters can also be used to communicate with the main control CPU module via fieldbus to collect outgoing load and related data. In addition, for distribution network switching stations in my country, which are mainly 10kV, it is recommended to use a "four-in-one" intelligent module that integrates the measurement, control, protection and communication interfaces of the feeders, and distribute them to each switch cabinet, which simplifies both investment and construction difficulty. (3) Promotion of unmanned substations in rural power grids: With the improvement of the automation level of rural power grids, unmanned operation of substations is not only feasible but also an inevitable trend in the development of rural power grids. The construction or renovation of substations, by installing microcomputer monitoring and substation automation systems, reduces human error, lowers the probability of errors, enhances the reliability of equipment operation, and simplifies production management. By optimizing the system structure, improving the automation level of substations, reducing the cost of power construction, and promoting the scientific operation and management of rural power grids; at the same time, realizing unmanned operation is also an important technical means to improve the automation level of rural power grids and ensure the safe and economical operation of the power grid. The principle of building unmanned substations is: to adhere to the combination of new construction and renovation, to achieve substation automation and dispatch automation as the foundation, and to improve the safe operation level of the power grid and improve the economic benefits of enterprises.