Keywords: ZigBee; communication module; wireless technology; power distribution system; power management
0 Introduction With the gradual development of smart grid construction worldwide, the intelligent management of distribution systems as users of smart grids is becoming more and more important. At present, the user-end distribution management system will consider a mixed networking method of multiple communication technologies to overcome some of the deficiencies inherent in the existing technology. Among them, industrial Ethernet, GPRS, and CDMA are used as remote communication networks; wireless short-range communication, carrier waves As a short-range communication network, that is, the communication method within the last 1 km. ZigBee technology, as an emerging short-range, low-rate wireless network technology, is a good short-range communication method. It has many advantages, such as low power consumption, high reliability, and ad hoc network functions, etc., so that it can have a lot of room for development in short-distance communication. Therefore, the wireless automatic meter reading system based on ZigBee technology has become a hot spot. This article mainly introduces a ZigBee technology wireless module and its application in factory power distribution management system based on ZigBee wireless network.
1 Features of ZigBee technology
ZigBee wireless technology is characterized by low power consumption, low cost, low data rate, short distance, and high communication reliability. Its network topology mainly supports three types of self-organizing wireless networks, namely, star structure, mesh structure, and cluster tree structure, especially the mesh structure, which has strong network robustness. And system reliability. This makes ZigBee technology play a huge role in the wireless meter reading system with low power consumption, low cost, low data rate and strong reliability.
At present, other communication methods used in the energy management system, such as low-voltage power line carrier (PLC) and RS485 wired communication, have various disadvantages. Table 1 lists the comparison between ZigBee and other communication technologies. From Table 1, it can be seen that the advantages of ZigBee technology are obvious. ZigBee technology is a very ideal communication method in the power management system. It is suitable for some short-range wireless energy management system communication means, such as office buildings, office buildings, dormitory buildings, factories and other wireless energy management systems, especially suitable for energy management systems in old buildings with difficult wiring.
Table 1 Comparison of ZIGBEE and other information technologies
PLC | RS485 | ZigBee Wireless | |
Network construction difficulty | simple | difficult | simple |
One-time investment | small | general | Larger |
Operation and Maintenance | difficult | difficult | easily |
Communication speed | low | high | high |
reliability | difference | general | it is good |
real time monitoring | Can't | can | can |
2 Design of ZigBee wireless module [1]
The ZigBee wireless module is the main component of the ZigBee wireless power distribution management system. It acts as a communication link in the entire network. It is responsible for connecting the communication of all meters in the network to facilitate the upload of data to the main station (ie. Power Management Center).
The ZigBee wireless module designed in this paper adopts a rail-mounted installation method, which can be easily installed on a 35mm standard rail, which enables the module to be flexibly installed in various distribution boxes and distribution cabinets. The appearance side view is shown in Figure 1.
Figure 1 ZigBee module side view
ZigBee wireless modules are divided into two categories. Among them, the module that converts ZigBee signals to RS485 signals is called ZigBee acquisition module, which is responsible for communication with the following meters; and the module that converts ZigBee signals to Ethernet signals is called ZigBee network terminal, which is the entire The initiator of the ZigBee network, that is, the central node in the ZigBee network. The technical parameters of the ZigBee wireless module are as follows: 1) AC220V input; 2) Operating frequency range is 2.41GHz ~ 2.48GHz, RF channel is 16, receiving sensitivity is -94dbm, transmit power is -27dbm ~ 25dbm; 3) Mesh network Mesh network to realize the function of self-organizing network. The addressing mode adopts IEEE802.15.4 / ZigBee standard address. The maximum network capacity in the same one is 255; 4) The ID and network channel of the wireless network can be configured to expand the network capacity.
The principle block diagram of the ZigBee wireless module is shown in Figure 2, which is mainly composed of the switching power supply part, the ZigBee wireless transmission part and the interface conversion part. The switching power supply circuit part mainly adopts TOP221Y (TOPSwitch) of the American PI company, and uses a flyback power conversion circuit to convert AC power to DC power; the wireless transmission part mainly uses MC13213 chip, which is a second-generation ZigBee chip of freescale, with internal MCU chip and wireless transceiver; power amplifier uses SKY65336, which can support up to 20dbm power amplification function.
Figure 2 ZigBee communication module
3 Application based on ZigBee distribution management system
The ZigBee distribution management system is of great significance for improving the efficiency of electric energy utilization, achieving energy saving and emission reduction, and reducing production costs, and for the utilization of distributed energy. Real-time detection and measurement, data collection, summary analysis, vertical and horizontal comparison, etc. of each link of the power system, especially the key energy-consuming equipment, to find the unreasonable use of electrical energy, improve and optimize through manual intervention or automatic control Energy-using equipment to improve the efficiency of the use of electrical energy. Moreover, the design of the ZigBee wireless network makes the design of the entire user-end power management system more flexible and more convenient, without the need to lay additional communication cables, reducing labor costs. In addition, communication with smart furniture can also be established, which can more easily control the electricity load, which has achieved the effect of a low-carbon economy and a saving society.
Figure 3 is a system block diagram based on the ZigBee distribution management system. The entire system consists of a ZigBee network terminal and several ZigBee collectors. The ZigBee network terminal is the coordinator of the entire ZigBee network (ZigBee central node). It is the initiator of the entire ZigBee network. It 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 collecting data and network routing in the ZigBee network. Each ZigBee collector can connect up to 32 meters on the 485 bus. All meters and master station software in the system use MODBUS-RTU communication protocol to communicate [2].
Figure 3 Based on ZigBee distribution management system
At present, the distribution management system based on ZigBee wireless network is implemented in an instrument manufacturing enterprise in Jiangyin, Jiangsu. The system adopts the principle of sub-metering of electrical energy, monitors the various processes in the production process and the electricity consumption of each electrical circuit of the factory, and displays the statistics in the form of reports or curves. The entire ZigBee wireless network distribution management system uses 21 wireless modules, and the used meter counts as 82 [3] [4].
Figure 4 is the communication block diagram of the ZigBee wireless network distribution management system. It lists in detail the models and monitoring circuits of 82 meters. The main monitoring objects are the power consumption of the switch cabinets and control cabinets. The power consumption of each technological process in the production process, the power consumption of each production line, the power consumption of the office and the power consumption of each air-conditioning circuit, etc. Through these statistical analyses, managers can fully understand the energy consumption of the entire plant, find out unreasonable energy consumption factors through statistical analysis, and put forward reasonable rectification opinions and measures.
Figure 4 ZigBee wireless network communication diagram
Figure 5 is the power distribution diagram of the incoming circuit of the plant. The parameters shown on the figure are the power parameters of each loop collected by the master station software through the ZigBee wireless network. Figure 6 is the distribution diagram of K1 cabinet among the distribution cabinets of several main distribution cabinets in the factory area. The figure shows the power parameter values ​​of each circuit of the K1 distribution cabinet in detail, which is convenient for the administrator to understand the power consumption of the plant in more detail.
Figure 5 Distribution diagram of incoming circuit
Figure 6 K1 cabinet power distribution diagram
Figure 7 shows the specific values ​​of the parameters of the incoming circuit in a certain period of time. It records the three-phase voltage, current, active energy, non-functional energy, power factor, and frequency parameters of the incoming circuit in detail. The electrical energy of each circuit in the whole plant area is summarized as shown in Figure 8, which records the power consumption of each circuit in a certain period of time, including the total electrical energy and branch electrical energy of each circuit's cabinet.
Figure 7 Various parameters of the incoming circuit within a certain period of time
Figure 8 Summary of power in each circuit
Through the establishment of a ZigBee wireless network distribution management system, the system monitors the entire production process, analyzes the energy consumption of the company's annual production meters, and analyzes the electrical energy used to produce each meter this year. And through process energy consumption analysis, analyze the specific electricity consumption of each process year, and find out the links with higher energy consumption based on these information, so as to formulate energy saving plans for the coming year. Through the energy-saving measures adopted by the system every year, the annual average production energy consumption of the meter is reduced year by year, and the effect of energy saving and emission reduction is finally achieved.
4 Summary Based on the ZigBee wireless network distribution management system, the networking mode is more flexible, and effectively reduces the workload of wiring, and solves the problems of high wiring difficulty, high cost, and difficult upgrade and maintenance brought by the wired communication method.
The system performs sub-metering of electrical energy for the entire plant or the entire building, detailed statistics of the energy consumption of each sub-item, and can also analyze the annual energy consumption of each sub-item in the form of a report in terms of the total energy consumption, so that the company can understand the annual The energy consumption by item provides a basis for formulating energy saving measures in the future, so as to achieve the effect of energy saving and consumption reduction.
The article comes from: "Software Industry and Engineering", Issue 1, 2011.
references
[1] Shanghai Ankerui Electric Co., Ltd. Product Manual. 2010.08 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 Electric Power Measurement Digital Instruments. China Electric Power Press, 2007
About the Author:
Yu Jing, female, undergraduate, engineer of Wuhan Ankerui Electric Co., Ltd., the main research direction is intelligent power monitoring and power management system
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