“The wireless communication module adopts ZigBee technology, IEEE802.15.4 protocol, and the communication coverage radius can reach 150m. It can communicate with any street lamp node in its coverage area by self-organizing network and communication. In addition to realizing the object-to-object connection of the street lamp, it also has adjustment The power output of the Electronic ballast (30%～100%) can realize energy saving and green lighting. It can detect the current, voltage, power factor and the working status of each lamp of the power supply line. When rod impact, man-made damage), real-time alarm to the monitoring center and related departments and other functions.
The structure of the road lighting system based on the Internet of Things is shown in Figure 1. By embedding a wireless communication module in each street lamp, making them self-organize the network, accept the command of the control center and feedback the state of the street lamp to the control center; HG-2 control The box uses ZigBee technology to communicate with all street lights on the road under its jurisdiction, and uses GPRS to communicate with the control center. According to the instructions of the control center or the time and daily illuminance, control commands are issued to each street light (street lights on, off, illuminance (power size), etc. ), automatically adjust the power balance of the entire road; the control center is composed of a server, a large-screen Display, and the CenterView central control system software platform. The CenterView central control system software platform adopts a 3D design. The lighting conditions of an entire city, a street, a road, or even a street lamp; mobile computing tools (laptops, PDAs, mobile phones) and street lamp maintenance vehicles can also be remotely measured and remotely controlled through the control center.
3 Wireless communication module
The MCU of the wireless communication module is Freesclae’s MC13213. The MC13213 uses SiP technology to integrate the MC9S08GT master MCU and MC1320x radio frequency transceiver in a 9×9mm LGA package. as shown in picture 2.
The wireless communication module adopts ZigBee technology, IEEE802.15.4 protocol, and the communication coverage radius can reach 150m. It can communicate with any street lamp node in its coverage area by self-organizing network and communication. In addition to realizing the object-to-object connection of the street lamp, it also has adjustment The power output of the electronic ballast (30%～100%) can realize energy saving and green lighting. It can detect the current, voltage, power factor and the working status of each lamp of the power supply line. When rod impact, man-made damage), real-time alarm to the monitoring center and related departments and other functions.
The wireless communication module is also designed for rain, moisture, lightning, and electromagnetic interference, and fully considers the convenience of installation, simple maintenance and recoverability (the two wires are connected to achieve street lamp-level wireless control, and the removal of the two The root wire returns to its original state) and can be embedded in different positions of the street lamp (the bottom of the lamp pole, the inside of the lamp post, and the inside of the lamp shade).
3.2 Communication protocol
The communication protocol of the wireless communication module is as follows: the lighting is numbered according to the order of the road sections, and the “hand in hand” communication between nodes is realized through command forwarding and status return. Command forwarding mechanism: Each node uses a bitmap structure to record which frames have been forwarded (the bitmap can represent up to 256 frames), if the node receives the command frame, it will determine whether the frame has been forwarded by the node, such as If the frame has been forwarded, the frame is discarded (the node only forwards the received command frame and does not modify the content of the frame), thus ensuring the fastest control of a line, and effectively preventing a node failure from affecting the entire line Line work; state return mechanism: after the command frame is sent to the designated node, the designated node will receive the command and return to the state immediately; forwarding rule: only the node number is smaller than the target node number before forwarding, and the state return process is reversed.
3.3 Connection with central monitoring
A transmission communication link is composed of several ZigBee nodes. A cluster node is set in the middle of these nodes (one or more cluster nodes can be set on a road), and its function is to communicate with the control center in GPRS mode (command acceptance and Status return), the cluster node uses Freescale’s 32-bit CodeFire series MCF52223 chip as the control unit, and GTM900B (Huawei GPRS communication module) and EM770W (Huawei WCDMA 3G communication module) as the long-distance wireless communication module. The MCF5222x series are built using the commonly used V2ColdFire core, and the performance is up to 76MIPS (Dhrystone2.1) at 80MHz. The interface functions include: 1 MiniUSB interface, supporting USBOTG function, 3 2-wire serial ports, 1 microphone input interface, 1 HEADSET input/output interface, 1 HANDSET input/output interface, 1 8Ω/16Ω speaker output interface, 1 132*96 dot matrix LED, 1 5*5 key keyboard, support RTC, ADC, PIT&GPT, PWM Etc.; GTM900B and EM770W complete long-distance GPRS communication.
4 Control center software design
The software design platform of the control center is Windows 2003, the development tool is Microsoft Visual Studio 2005, the database uses SQL Server 2005, and it is combined with the geographic information system. After obtaining the characteristic information of the street, building and street lamp position and shape, the design takes the street lamp as the main body. The 3D virtual city dynamically displays the lighting effects of the road on the large screen of the control center, and can observe the lighting conditions of the entire city, the street, and even each street lamp through geometric transformations such as panning, zooming in, and zooming out. The software mainly has 5 functional modules: system settings, intelligent control, power accounting, fault handling and emergency plans. There are four types of areas in the system settings: city, district, street and electric control box; street lights are set with the location, model, production unit, construction unit, maintenance person in charge, installation date, cleaning and maintenance date, etc.; lighting method setting There are full on, full off, single street light on, single street light off, double street light on, double street light off, 1/3 street light on, 1/3 street light off, 1/4 street light on, and 1/4 street light off , Intelligent control and other 11 control methods; time setting can be set according to different cities and different seasons to set different time lighting methods; intelligent control has two aspects: for the road section where electronic street lights are installed, according to seasonal changes and weather conditions, Through real-time sampling of the ambient light intensity, the lighting brightness of the street lights can be intelligently adjusted; at night, especially in the middle of the night, when the traffic of cars and pedestrians is detected to be very scarce, the road lighting brightness should be appropriately reduced without affecting the recognition and reliability. Save electricity consumption; electricity accounting can perform electricity consumption statistics and accounting for the city, district, street, electric control box, and even each street lamp; troubleshooting is to deal with lamp damage, power failure, phase loss, overcurrent, overvoltage, and three For phase imbalance and man-made damage, the fault report will be generated immediately after alarming to the monitoring center; another function of fault handling is to count the lighting rate, failure rate, and failure rate according to road section and time period (year, quarter, month). The efficiency of secondary fault handling (average repair time); emergency plan is to formulate emergency plans for some emergencies. In special circumstances, provide suitable road lighting as much as possible to ensure the safety of people’s lives and property. Figure 3 is one of the operating interfaces of the control center software.
5 Practical application
The road lighting system of the Internet of Things has been installed and tested in a national industrial park since May 2009. The installation environment is 100 street lights on both sides of the same road, and the 100 street lights on the left side of the road are controlled by wireless sensors. , A total of RMB 24600.00 was added. The 100 street lights on the right side of the road adopt the conventional control method (the odd and even numbers are turned on at 18:30-6:30 after midnight). The test results are shown in Table 1.
It can be seen from Table 1 that using the intelligent control of the Internet of Things, through actual tests, the 100 street lights controlled by the Internet of Things can save 15925 kWh of electric energy in 91 days. Under normal circumstances, the entire investment can be recovered within half a year of the product input. . The power consumption reduction has the following factors: the adjustment of the opening and closing time, the control method of the street lamp on the right of the road is to set the opening and closing time according to the season (timing control) and it is full power on and off, and the street lamp on the right of the road is controlled by Ambient light intensity and seasons automatically control the opening and closing time. When it is turned on, because there is still strong ambient light on the road, the street light works in a way of supplementing light, gradually increasing the lighting intensity, and the street light closing control is similar; late night control mode, due to late night time The electricity load of enterprises and residents has decreased, the voltage of low-voltage power grid has increased, and the street lights (right side of the road) under conventional control methods are unusually bright and dazzling, which often causes excessive lighting, which not only greatly increases power consumption, but also leads to the actual service life of lamps and electrical appliances. Rapid decline, a large increase in maintenance and maintenance costs, late-night control mode (on the left side of the road), using reduced power lighting, not only reduces power consumption, but also improves road lighting quality and visual comfort, and extends the actual service life of lamps and electrical appliances; Intelligent control of lighting, for special road sections with schools, densely populated communities, road turns, accident-prone areas, etc., appropriately increase the lighting brightness, and appropriately reduce the lighting brightness for the remaining road sections.
After adopting the intelligent street lamp control of the Internet of Things, it has the advantages of good real-time performance and strong reliability for automatic fault detection and alarm, which greatly reduces the time and labor intensity of manual inspections on a regular basis.
Advanced road lighting can not only enhance the image of the city, improve the efficiency of transportation, reduce traffic accidents, but also save a lot of public electricity consumption. But for most cities, due to the lack of necessary infrastructure (street-level communication links), advanced control methods cannot be realized. The emergence and application of the Internet of Things (Internet of Things) effectively solves the above problems. This article is based on wireless sensor networks. Choose Freesclae’s MC13213 chip to design an embedded wireless communication module to make every street lamp on the entire road network autonomously, using Freescale’s MCF52223 chip, Huawei’s MG323 and EM770W as the remote communication module to realize the street lamp The remote measurement and remote control of the system have high practical application value for saving public resources and building a digital and economical city.