Abstract : With the rapid development of wireless technology, wireless intelligent management systems have also been rapidly applied. This paper introduces the design of a ZigBee-based wireless communication module, its application in power grid user-end distribution systems, and its role in energy conservation and emission reduction in industrial and mining enterprises.
Keywords : ZigBee; communication module; wireless technology; power distribution system; power management
0 Introduction
With the gradual rollout of smart grid construction globally, the intelligent management of power distribution systems, as users of smart grids, is becoming increasingly important. Currently, user-side power distribution management systems often consider using a hybrid networking approach with multiple communication technologies to overcome some inherent shortcomings of existing technologies. Industrial Ethernet, GPRS, and CDMA are used for long-range communication networks; wireless short-range communication and carrier waves are used for short-range communication networks, i.e., communication within the last kilometer. ZigBee technology, as an emerging short-range, low-speed wireless network technology, is an excellent short-range communication method. It has many advantages, such as low power consumption, high reliability, and self-organizing network capabilities, giving it significant potential for development in short-range communication. Therefore, wireless automatic meter reading systems based on ZigBee technology have become a hot topic. This article mainly introduces a ZigBee wireless module and its application in a factory power distribution management system.
1. Characteristics of ZigBee technology
ZigBee wireless technology is characterized by low power consumption, low cost, low data rate, short range, and high communication reliability. Its network topology primarily supports three types of self-organizing wireless networks: star, mesh, and cluster tree. The mesh topology, in particular, offers strong network robustness and system reliability. This makes ZigBee technology extremely useful in low-power, low-cost, low-data-rate, and highly reliable wireless meter reading systems.
Currently, other communication methods used in power management systems, such as low-voltage power line carrier (PLC) and RS485 wired communication, all have various drawbacks. Table 1 compares ZigBee with other communication technologies, and it can be seen from Table 1 that ZigBee technology has significant advantages. ZigBee technology is an ideal communication method in power management systems. It is suitable for implementing short-range wireless power management system communication methods, such as wireless power management systems in office buildings, dormitories, and factories, and is especially suitable for energy management systems in old buildings undergoing renovation due to wiring difficulties.
Table 1 Comparison of ZIGBEE with other information technologies
| PLC | RS485 | ZigBee Wireless | |
| Network construction difficulty | Simple | difficulty | Simple |
| One-time investment | Small | generally | Larger |
| Operation and maintenance | difficulty | difficulty | easy |
| communication speed | Low | high | high |
| reliability | Difference | generally | good |
| Real-time monitoring | cannot | able | able |
Design of 2ZigBee wireless module [1]
The ZigBee wireless module is a key component of the ZigBee wireless power distribution management system. It serves as a communication connector in the entire network, connecting all the electricity meters in the network to facilitate data transmission from each meter to the master station (i.e., the power management center).
The ZigBee wireless module designed in this paper adopts a DIN rail mounting method, which can be easily installed on a standard 35mm DIN rail. This allows the module to be flexibly installed in various distribution boxes and cabinets. Its external side view is shown in Figure 1.
Figure 1. Side view of the ZigBee module
ZigBee wireless modules are divided into two categories. Modules that convert ZigBee signals to RS485 signals are called ZigBee acquisition modules, responsible for communication with the electricity meter. Modules that convert ZigBee signals to Ethernet signals are called ZigBee network terminals, which are the initiators of the entire ZigBee network, i.e., the central nodes in the ZigBee network. The technical parameters of the ZigBee wireless module are as follows: 1) AC220V input; 2) Operating frequency range: 2.41GHz~2.48GHz, RF channels: 16, receiver sensitivity: -94dBm, transmit power: -27dBm~25dBm; 3) Mesh network architecture for self-organizing functionality, addressing using IEEE 802.15.4/ZigBee standard addresses, with a maximum network capacity of 255 nodes within the same mesh; 4) Configurable wireless network ID and network channels to expand network capacity.
The block diagram of the ZigBee wireless module is shown in Figure 2. It mainly consists of a switching power supply, a ZigBee wireless transmission section, and an interface conversion section. The switching power supply circuit mainly uses the TOP221Y (TOPSwitch) from PI (Pi) Co., Ltd., which uses a flyback power conversion circuit to convert AC power to DC power. The wireless transmission section mainly uses the MC13213 chip, which is Freescale's second-generation ZigBee chip, and has an integrated MCU chip and wireless transceiver. The power amplifier uses the SKY65336, which can support a maximum power amplification of 20dBm.
Figure 2 ZigBee communication module
3 Applications based on ZigBee power distribution management system
ZigBee power distribution management systems are of great significance for improving power utilization efficiency, achieving energy conservation and emission reduction, reducing production costs, and utilizing distributed energy. They enable real-time monitoring, metering, data collection, aggregation, analysis, and comparative analysis of power consumption in all aspects of the power system, especially key energy-consuming equipment. This allows for the identification of unreasonable power usage, which can be improved through manual intervention or automatic control, optimizing energy-consuming equipment and increasing power efficiency. Furthermore, the use of a ZigBee wireless network makes the design of the entire user-end power management system more flexible and convenient, eliminating the need for additional communication cables and reducing labor costs. Additionally, it can establish communication with smart home devices, enabling easier control of power load and achieving the goals of a low-carbon economy and a resource-saving society.
Figure 3 is a block diagram of the ZigBee-based power distribution management system. The entire system consists of a ZigBee network terminal and several ZigBee collectors. The ZigBee network terminal is the coordinator (ZigBee central node) of the entire ZigBee network. It is the initiator of the entire ZigBee network and is also responsible for data interaction with the power distribution management center. It mainly uses long-distance communication methods such as Ethernet, GPRS or CDMA. The ZigBee collector plays the role of data collection and network routing in the ZigBee network. Up to 32 meters can be connected on the 485 bus of each ZigBee collector. All meters and master station software in the system communicate using the MODBUS-RTU communication protocol [2].
Figure 3. Based on the ZigBee power distribution management system
Currently, a ZigBee wireless network power distribution management system is being implemented and operated in an instrument manufacturing enterprise in Jiangyin, Jiangsu Province. The system adopts the principle of sub-item metering of electricity, monitors the electricity consumption of each process in the production process and each power circuit in the factory, and displays the statistics in the form of reports or curves. The entire ZigBee wireless network power distribution management system uses 21 wireless modules and 82 meters [3][4].
Figure 4 shows the communication block diagram of the ZigBee wireless network power distribution management system. It details the models of 82 meters and the circuits they monitor. The main monitoring targets include the power consumption of various switchgear and control cabinet input/output circuits, the power consumption of each process flow in the production process, the power consumption of each production line, the power consumption of the offices, and the power consumption of each air conditioning circuit, etc. Through this statistical analysis, managers can fully understand the energy consumption of the entire factory, identify unreasonable energy consumption factors, and propose reasonable rectification opinions and measures.
Figure 4. ZigBee wireless network communication diagram
Figure 5 shows the power distribution diagram of the incoming circuits in the factory area. The parameters shown in the diagram are the power parameters of each circuit collected by the main station software through the ZigBee wireless network. Figure 6 shows the power distribution diagram of cabinet K1 among the main power distribution cabinets in the factory area. The diagram shows the power parameter values of each circuit in cabinet K1 in detail, which helps the administrator to have a more detailed understanding of the factory's power consumption.
Figure 5 Power distribution diagram of incoming line circuit
Figure 6K1 cabinet power distribution diagram
Figure 7 shows the specific values of various parameters of the incoming circuit over a certain period of time. It records in detail the three-phase voltage, current, active energy, non-active energy, power factor, and frequency parameters of the incoming circuit. Figure 8 shows the summary of the electrical energy of all circuits in the entire plant area. It records the power consumption of each circuit over a certain period of time, including the total electrical energy of each circuit cabinet and the branch electrical energy.
Figure 7 shows the parameters of the incoming line circuit during a certain period of time.
Figure 8 Summary of electrical energy in each circuit
By establishing a ZigBee wireless network-based power distribution management system, the system monitors the entire production process, statistically analyzes the annual energy consumption of the company's instruments, and determines the electrical energy used to produce each instrument that year. Furthermore, through process energy consumption analysis, it identifies the specific annual electricity consumption of each process and uses this information to pinpoint energy-intensive stages, thereby developing energy-saving plans for the following year. By implementing energy-saving measures annually based on the system, the goal is to gradually reduce the average annual energy consumption of instrument production, ultimately achieving energy conservation and emission reduction.
4. Summary
The ZigBee wireless network-based power distribution management system offers flexible networking options and effectively reduces cabling workload, solving problems such as high cabling difficulty, high cost, and difficult upgrade and maintenance associated with wired communication methods.
The system performs sub-metering of electricity consumption across the entire factory area or building, providing detailed statistics on the energy consumption of each sub-item. It can also analyze the percentage of each sub-item's energy consumption relative to the total energy consumption each year in the form of reports, so that the company can understand the energy consumption of each sub-item each year, providing a basis for formulating energy-saving measures in the future, thereby achieving the effect of energy conservation and consumption reduction.
References
[1] Shanghai Acrel Electric Co., Ltd. Product Manual. August 2010 Edition.
[2] Guo Dan, Li Junfang. Application of ZigBee wireless network technology in meter reading system [J]. Automation Instrumentation, 2009, (04)
[3] Chen Tang, Power Distribution System and Its Automation Technology [M]. Electric Power Press, 2004
[4] Zhou Zhong, Ren Zhicheng, Principles and Application Guide of Digital Instruments for Power Measurement. China Electric Power Press, 2007.
About the Author
Zhou Zhong (1967-), male, undergraduate, engineer, major research direction is the principle and application of power instrumentation;
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