The traditional low-voltage distribution control method mainly uses low-voltage switch control cabinets composed of circuit breakers, contactors, fuses, control relays, transformers, and various analog pointer instruments (ammeters, voltmeters, power meters, energy meters) to achieve functions such as distribution control, protection, and monitoring. This traditional switchgear is mainly operated manually, and if computer intelligent management is required, power transmitters and microprocessors are needed to achieve it. Due to the extensive use of power transmitters, there are disadvantages such as high cost, complex wiring, simple functionality, low accuracy, and poor reliability. The development of modern industrial technology has put forward higher requirements for the reliability and intelligent management of low-voltage distribution systems. The widespread application of microprocessor technology and the significant improvement of computer system reliability have led to the rapid development of intelligent low-voltage electrical components, and the emergence of intelligent low-voltage electrical management systems.

1、 Basic composition principles of the system

The intelligent low-voltage distribution system maximizes the use of technological achievements in the digital age. It is based on existing circuit breakers, contactors, relays, etc., combined with new intelligent power instruments, monitoring modules, on-site and back-end monitoring devices, network I/O, to achieve real-time monitoring of electrical parameters such as voltage, current, active power, reactive power, power factor, frequency, and power of the main distribution circuit and each branch, and to control and monitor the opening and closing of control appliances. At the same time, in conjunction with communication networks and various sophisticated remote monitoring software, the "four remote" functions of the low-voltage distribution system can be achieved: (1) telemetry: real-time collection of various electrical parameters, display and analysis, and generation of reports. (2) Remote signaling: Real time monitoring and control of the operating status of electrical appliances, prompting fault and alarm information, recording and printing. (3) Remote control: Control the corresponding electrical actions, record the time, type, and object of operation, etc. (4) Remote adjustment: Set the operating parameter values and fault alarm protection values of each intelligent module.

(1) Monitoring host. The monitoring host obtains information from the protection and monitoring intelligent devices and on-site intelligent devices through communication and data acquisition front-end machines, and issues control instructions. The protection and monitoring intelligent devices and on-site intelligent devices realize the protection and measurement functions of the power distribution equipment. The monitoring host completes functions such as graphic monitoring, report generation, curve analysis, and system management.

(2) Communication and data acquisition front-end machine. The communication and data acquisition front-end machine is used to communicate with the underlying field devices and achieve real-time data acquisition, as well as interface with the factory DCS system. The communication protocol related to equipment and systems involved in the compatibility engineering of communication and data acquisition front-end machines.

(3) On site intelligent devices. On site intelligent devices complete functions such as low-voltage switch on/off data acquisition (remote communication), analog data acquisition (telemetry), switch operation (remote control), switch protection, motor protection, as well as power collection and switch on/off position data acquisition (remote communication).

(4) Communication network. It is a critical part of the system. It is like the neural network of the entire monitoring system, with each part of the system connected through a communication network. Under the premise of ensuring reliability and anti-interference ability, the communication medium uses shielded twisted pair cables or optical fibers.

2、 Main characteristics of intelligent low-voltage distribution system

The intelligent low-voltage distribution system is composed of intelligent components with communication functions for low-voltage switchgear, which are connected to the computer system network through digital communication to achieve automation and intelligence in the operation and management of low-voltage switchgear in substations. The system can achieve real-time data collection, digital communication, remote operation and program control, protection setting management, event recording and alarm, fault analysis, various reports, and equipment maintenance information management. In response to the characteristics of low-voltage electrical systems directly facing control terminals, with multiple devices, wide distribution, and complex on-site conditions, as well as the strong electromagnetic and harmonic interference generated by frequent operation and fault tripping of the system and equipment, the intelligent monitoring system should be able to achieve an object-oriented operation mode with strong anti-interference ability. The main control functions are completed by intelligent components at the equipment layer, forming a network integrated fully distributed control system to meet the requirements of real-time, fast, and reliable system operation. The low-voltage intelligent components in the system can generally be divided into functions such as power quality monitoring, switch protection and control, and motor control. Due to the application of fieldbus technology, intelligent components in the system can operate independently without relying on computer networks, greatly improving the real-time and reliability of system operation, meeting the needs of low-voltage electrical equipment operation management and factory production process control.

(1) Intelligentization. The low-voltage distribution system consists of low-voltage distribution switches equipped with intelligent measurement and control protection devices with communication functions, such as network power instruments, microcomputer reactive power compensation control devices, microcomputer motor protection devices, etc

Through digital communication and computer system network connection, achieve automation and intelligence in the operation and management of switchgear in distribution stations. The implementation of intelligent distribution systems can effectively ensure the reliability and quality of power supply, provide guarantees for continuous automated production, facilitate the rational arrangement of production plans, optimize load distribution, save electricity costs and maintenance costs. Compared to traditional distribution systems, intelligent distribution systems have the following advantages: digitalization

This is the fundamental characteristic that distinguishes intelligent measurement and control protection devices from traditional instruments. Due to the use of high-speed microprocessor chips and high-precision analog-to-digital conversion chips, all measured parameters on site are processed digitally, greatly improving measurement and protection accuracy, reducing product dispersion, and also greatly enhancing real-time performance, stability, and reliability.

(2) Multifunctional. The intelligent measurement and control protection device has overcome the weakness of traditional components with single functions, integrating multiple functions such as measurement, control, and protection, completely replacing conventional components such as pointer type electricity meters, transmitters, signal lights, relays, etc., and greatly reducing secondary wiring inside the cabinet, making the system more compact, time-saving, fast, and convenient to install and debug.

(3) Networking. Intelligent measurement and control protection devices generally have digital communication interfaces, which are interconnected with computer systems through networks. They can achieve real-time data collection, data processing, data storage, digital communication, remote operation and program control, protection setting management, event recording and reporting, fault analysis, various reports, and equipment maintenance information management on monitoring computers, realizing unmanned and remote monitoring of power distribution systems. This is also an important function that traditional methods cannot achieve.

With the continuous development of information technology and the increasing demand of enterprises for the combination of automation and transmission and distribution systems, the intelligent design of low-voltage distribution systems conforms to the trend of scientific and rational use of power energy, energy conservation and consumption reduction, and is an inevitable development trend. The intelligent low-voltage distribution system is developing towards miniaturization and multifunctionality in China. The continuous development and application of fieldbus technology will gradually improve the compatibility of intelligent low-voltage electrical products on the network and the reliability of system operation.

But intelligent low voltage配電系統There are numerous manufacturers and different system configurations, but the functions of the system should be the same and similar. Engineering designers should propose detailed technical parameters and system functional requirements based on the specific design characteristics of the project. The selection principles of standardization, progressiveness, compatibility and expandability shall be adhered to in the design.