Beidou clock synchronization server (satellite time service) applies smart street light system
Beidou clock synchronization server (satellite time service) applies smart street light system
In the actual application of street lights, there will be control, detection and safety issues, including street lights that cannot be adjusted in time according to actual conditions (weather sudden changes, major events, festivals), and the switch lights cannot be adjusted. LED lights cannot be dimmed. Achieve secondary energy saving; the basis for failures mainly comes from reports by inspectors and complaints from citizens. It lacks initiative, timeliness and reliability, and cannot monitor the running status of street lights in the city in real time, accurately and comprehensively. The management department lacks the ability of unified dispatching, and can only make adjustments based on the distribution cabinets one by one, which not only takes time and effort, but also increases the possibility of human error. The equipment is easy to lose and the fault cannot be located, and it is impossible to accurately find the stolen cable and the lamp holder. Theft and disconnection, once the above situation occurs, will bring huge economic losses and at the same time affect the normal life of citizens and travel safety.
At present, the national level has issued the "Guiding Opinions on Promoting the Healthy Development of Smart Cities", pointing out that a number of distinctive smart cities will be built in 2020 to achieve convenient public services, refined urban management, livable living environments, and infrastructure Intelligent and so on. The internal demand for cost reduction and efficiency enhancement and refined operation also drives the construction of smart street lights to reduce manual inspection costs, reduce economic losses due to safety issues, and improve control accuracy, comprehensiveness, and unified scheduling. Compared with other control technologies, NB-IoT technology can meet the above requirements well, realize the intelligent control of street lights, promote the construction of smart cities, and meet the internal management needs of cost reduction, efficiency increase and refined operation.
1. The development status of
street lamps Street lamps start from incandescent lamps and have gone through the stages of gas discharge lamps and LED lamps. The energy consumption is gradually reduced and the degree of intelligence is continuously improved. At present, the luminous efficiency of LED street lamps can reach 160lpw, which is more than 90% energy-saving than incandescent lamps, and 50%-70% energy-saving than high-pressure sodium lamps, and has a lifespan of more than 50,000hrs. It can be controlled by PLC or zigbee technology.
In recent years, my country's urban construction has shown rapid growth. As part of the urban infrastructure construction, urban road lighting has also developed rapidly. According to data from the National Bureau of Statistics, from 2007 to 2015, the number of urban road lighting in the country increased from 13.95 million to 24.23 million. The average compound growth rate reached 7.14%. In terms of the use types of urban road lighting street lamps, according to the different sources of road lighting street lights, they can be divided into high-pressure sodium lamps, LED street lamps, energy-saving street lamps, and new xenon street lamps.
According to the light source, sodium lamps account for the largest proportion, followed by LED lamps, and other lamp types account for a relatively small proportion.
According to statistics on Ag81 key cities, including all municipalities, provincial capitals, and cities under separate planning, the total number of intelligent monitors is the largest, reaching 21,826 points, which are Ag3 times, 6.8 times, and 6.8 times for time control, light control and anti-theft monitoring points. 9.2 times.
In the use of urban road lighting monitoring systems, the "three remote" system is the most commonly used, accounting for 64%; followed by the "five remote" system, accounting for 23%; the "four remote" and GPRS systems account for 5% and 8% respectively.
2. Problems in the intelligent evolution of street lamps The
monitoring and management methods are relatively extensive. The traditional "three-remote" system can only achieve loop-level collection and control. It cannot monitor the operation of a single lamp in real time and accurately. When a lamp failure occurs, it cannot be fed back to the monitoring center in time, and it cannot realize intelligent monitoring and refined management. In addition, it is impossible to track and analyze the fault handling in real time, which affects the assessment and decision-making judgment of lighting production management.
Energy consumption is too large. The lack of flexible and effective energy-saving control methods makes it difficult to reconcile the contradiction between excessive lighting and insufficient lighting (i.e. run according to the urban image illuminance in the first half of the night, and run with energy-saving illuminance in the second half of the night), and can not achieve on-demand lighting, which is effective under the premise of ensuring the quality of lighting Reduce lighting energy consumption.
The operation and maintenance efficiency is low and the cost is high. At this stage, the fault detection mechanism of lighting facilities mainly adopts manual inspection mode. The workload is huge, and there may be blind spots. The operation and maintenance efficiency is low, and it is difficult to realize active services and ensure service quality. In the maintenance process, the procurement of materials is also lacking science. According to the evidence, improper material stocking will cause capital occupation, and materials cannot be refined management.
The safety of facilities is difficult to guarantee. The lack of real-time supervision measures, and the frequent theft or damage of lighting cables and other facilities have caused direct economic losses to the lighting management department, seriously affected the normal operation of urban lighting, and brought security risks. Lack of effective management of facility resources. The resource management of urban lighting facilities basically stays in the era of manual ledger, lack of information technology, the number of facilities resources is unclear, and the status is unclear, which is not conducive to operation and maintenance.
The benefits of the smart street lamp solution to street lamps are obvious. However, the traditional non-intelligent sodium lamps are still the mainstay of urban street lamps in my country, and there is great resistance to intelligent transformation: 1: LED street lamps cost higher. l2 Replace the sodium lamp with LED lamp and upgrade it intelligently. It will take several months to transform the whole city. 3. Replacing sodium lamps with LED lamps saves energy and money, and also increases the workload. Usually, three people are required for street lamp repair, one for driving, one for repair, and one for on-site maintenance. Although great progress has been made, LED lights for street lights still have shortcomings, such as not strong enough penetrability, difficult to illuminate in haze weather; scattering ability is worse than sodium lights, and the irradiation range is small.
3. Comparative analysis of technology selection of NB-IoT technology in intelligent street lamp control.
Currently, group control is mainly adopted. With the continuous improvement of street lamps' requirements for refined control and the accelerating process of smart city construction, some cities have begun to adopt single control . Intelligent street lamp single control mainly adopts two-hop and one-hop systems. The two hops are calculated and converged through the FAN network and then connected to the platform, and one hop directly communicates with the platform through the WAN.
Two hops: The municipal street light management takes the road section as the unit, and each road section is equipped with a power distribution cabinet. The section electrical parameter collector and the gateway are usually integrated and deployed in the power distribution cabinet. Expand applications that require edge computing on street light poles, such as W, security monitoring, and advertising screens. At present, the FAN network mainly adopts PLC and ZigBee/RF technology.
One jump: Single lamp fault location, single lamp switch, dimming does not require local centralized calculation and control. Discrete extended applications are directly connected to the network, without the need for local centralized calculation and control. The one-hop network makes the entire street lamp network simpler. The business side only needs to pay attention to the application layer standards and can quickly access equipment from different manufacturers.
The two-hop scheme is divided into two types: PLC and Zigbee/RF technology. At the same time, it is equipped with GPRS technology to realize street lamp control. One-hop schemes are mainly LoRa and NB-IoT. After comparative analysis, it is found that the entire street lamp network is simple in one hop, and the business side only needs to pay attention to the application layer standards, which can quickly access equipment from different manufacturers, and at the same time, the NB- IoT technology is even better.
At present, in the field of urban public lighting single-lamp intelligent monitoring, cable carrier communication is the mainstream direction of the underlying communication technology, accounting for about 90% of actual applications; ZigBee technology also has certain applications, accounting for about 10% of the market share; others Technology is less applied. In the field of long-distance transmission, most of them currently use GPRS technology, and technologies such as NB-IoT will gradually increase in the future.
From a cost perspective, NB-IoT has the lowest technical cost, including construction costs, operating costs, and average annual costs. From a technical point of view, NB-IoT is more suitable for street lamp control because of its wider coverage, larger capacity, and guaranteed communication quality.
4. Smart street lamp NB-IoT expansion strategy
4.1 aggregation
Establish a model pilot effect. In conjunction with street lamp houses, street lamp manufacturers, and terminal system solution providers, operators provide terminal subsidies to promote smart street lamp manufacturers to carry out terminal transformation and create NB-IoT demonstration application projects.
Promote the convergence of the street lamp industry. Through aggregating module suppliers, street lamp manufacturers, platform providers, system integrators, street lamp management, etc., build industry alliances, form industry standards, reduce the cost of smart street lamp manufacturing, smart chip modules, etc., and strive to promote the maturity of the street lamp industry. Low tariffs attract users to quickly expand the use of street lights in a short time.
4.2 Seize the initiative
Based on pipelines, we will vigorously promote platform-level content so that street lights can become carriers of smart cities and smart transportation based on intelligence. The operator’s resource advantages should be used to promote and publicize the demonstration results, seize the opportunity, and compete for the right to speak on the intelligent street lamp platform.
4.3 Broaden your mind and enrich service content
Utilize the unique advantages of street lamps and combine the characteristics of NB-IoT technology to expand street lamp services. For example, turn street lights into environmental weather stations, add sensors such as PM2.5, temperature and humidity to the smart gateway, and broadcast comprehensive city information such as local weather and environment on the street light carrier.
5. NB-IoT technology monitoring system for smart street lights
Road lighting is an indispensable road traffic safety facility in people's lives. Traditional road lighting adopts a fixed management mode of centralized power supply (lit at night, closed during the day), which has many disadvantages: (1) The brightness of street lights cannot be adjusted according to the changes in the flow of people, vehicles, and weather around; (2) It cannot be set remotely Lighting mode and revised parameters; (3) Failure to automatically report the fault and locate the specific location of the fault. In order to save power and facilitate people's travel, it is necessary to upgrade and transform the traditional street light control system. The Narrowband Internet of Things (NarrowBandInternetThings, referred to as NB-IOT) technology has become an important branch of the Internet of Everything. It is based on a cellular network, a communication technology developed by the 3GPP organization, using the licensed GSM and LTE frequency bands, and using the existing 4G base station. And related equipment, no need to rebuild the network. NB-IOT technology has the following advantages: (1) Wide coverage. Relying on the networks of the three major operators to achieve national coverage. (2) In-depth coverage. (3) Low power consumption. Based on these advantages, the NB-IOT technology can be applied to the street lamp monitoring system to monitor the running status of the street lamp and its related equipment, and realize efficient, intelligent and scientific management. The NB-IOT technology is applied to the intelligent street lamp monitoring system, so that every street lamp is connected to the network and has a unique ID identification code. In this way, the system can monitor and manage the street lights in real time, effectively improve the efficiency of system operation, save power, and meet the requirements of the development and construction of smart towns.
5.1 Network architecture of intelligent street lamp monitoring system
The intelligent street lamp monitoring system based on NB-IOT technology includes perception layer, network layer and application layer. The perception layer consists of a separate street lamp control module and NB-IOT terminal. Each street light on the road is equipped with a street light control module. The street light control module manages the switch of the street light, is responsible for data collection and monitoring the running status of the street light. It communicates wirelessly with the NB-IOT terminal through the NB-IOT network; NB -IoT terminal uploads the data information collected by the street light control module to the NB-IOT base station, and then sends the management commands of the mobile phone or monitoring center in the application layer to the street light control module, and manages and monitors the street lights in the perception layer. The network layer is composed of NB-IOT base station and Internet network. The Internet-net network mainly uses the 4G LTE platform to transmit the data information of the perception layer to the application layer in real time, and at the same time transmit the control commands of the application layer to the perception layer. Figure 1 shows the network architecture of the intelligent street lamp monitoring system.
Figure 1 Block diagram of the network architecture of the intelligent street lamp monitoring system
5.2 System hardware design
(1) Street light control module: The block diagram of the street light control module is shown in Figure 2. The street lamp control module is the core component of the perception layer. It monitors and manages the street lamp scene. It is mainly composed of a microcontroller, NB-IOT module, GPS positioning unit, information acquisition module, detection circuit and drive circuit. Each street light control module is set with a unique ID code to facilitate the identification of different street lights. The GPS positioning unit can locate the specific location of the street light and provide a detailed address for the monitoring and maintenance of the street light. The NB-IOT module realizes the communication between the street light control module and the NB-IOT terminal. The street lamp control module sends the street lamp field data information collected by the information collection module to the NB-IOT terminal through the NB-IOT module, and receives various control commands from the application layer through the NB-IOT terminal. The information acquisition module is mainly composed of temperature and humidity sensors, light sensors, vehicle flow sensors and pyroelectric infrared sensors. The temperature and humidity sensor collects the temperature and humidity of the surrounding environment, the light sensor collects the intensity of light, the vehicle flow sensor collects the traffic flow on the road, and the pyroelectric infrared sensor collects the pedestrian flow on the road. The detection circuit detects the power quality of the power supply of the system, the voltage and current of the street lamp, and the running state of the street lamp. The drive circuit is used to control the switch and brightness adjustment of the street lamp.
Figure 2 Block diagram of street lamp control module structure
(2) NB-IOT terminal: NB-IOT terminal adopts industrial-grade 32-bit ARM9 series chips, supported by embedded real-time operating system, and can be connected to the street light control module in large capacity, and communicate with the street light control module by wireless Information and Communication. At the same time, it is equipped with wired RS485 and RS232 serial communication to receive the data information collected by the street light control module and the status parameters of the street light operation, and transmit the control commands issued by the monitoring center. According to the number of street lights and the actual control requirements of the system, through calculation and analysis, the number and location of NB-IOT terminals are reasonably planned, so that each NB-IOT terminal can communicate with the street light control module connected to it.
(3) NB-IOT base station: As 4G communication network base stations are more distributed and the signal coverage is wide, using the existing 4G communication base station to plan and set up NB-IOT network base stations can make the signal coverage wider and the transmission capacity stronger. The NB-IOT base station is deployed on the existing base station, and the street lamp field data information is transmitted to the monitoring center through the 4G network of the three major operators. At the same time, the NB-IOT base station will control the received monitoring center The command reaches the street light control module.
5.3 Monitoring center software design
The application layer of the monitoring system is mainly composed of mobile phones, monitoring centers and alarm devices. The monitoring center is the core of the application layer. It is a human-computer interaction platform for the perception layer to process data, manage status, handle faults and manage energy consumption. Through the monitoring AP on the mobile phone, the staff can monitor and manage the operation of street lights anytime and anywhere.
The monitoring center is the human-computer interaction window between the staff and the remote monitoring system, which can directly reflect the data collection situation of the entire system and the running state of the street lights. Therefore, its design must meet the control requirements, and also take into account the real-time and operability of the entire system Sex and stability. The functional block diagram of the monitoring center software is shown in Figure 3. Data processing realizes data collection, storage, query and report output printing. Data collection mainly collects temperature and humidity, light intensity, traffic flow, traffic flow, and street lamp voltage, current, power and other parameters; data storage mainly stores on-site data information; data query can quickly query historical data. State management realizes the setting of system parameters, street lamp control mode, street lamp mode setting, street lamp dimming mode setting and running status query. The street lamp control mode can adopt automatic control mode, latitude and longitude mode, holiday mode and temporary mode; street lamp mode can be set for different single street lamps, street lamps in a certain section and street lamps in a certain area; street lamp dimming mode can be set according to the vehicle Traffic and people flow automatically turn on the relevant street lights, and you can also set different percentages of the PWM switch street lights according to the time period, or realize the fully-on, half-on, or fully-off street lights according to the collected natural environment information. Fault handling realizes automatic monitoring of faults, locking of fault location information and automatic alarms, and informs the staff in the form of SMS. Energy consumption management realizes remote meter reading, energy consumption statistics of each road section and system, and energy consumption can generate curve reports according to time for analysis by staff.
Figure 3 Block diagram of functional modules of the monitoring center software
to sum up
A set of intelligent street lamp monitoring system based on NB-IOT technology is designed. The system uses street lamp control module to collect field data information, and then uses NB-IOT terminal to transmit field data to the network layer via wireless network. The network layer uses the NB-IOT base station and 4G network to upload data information and issue control commands. The intelligent street lamp monitoring system based on NB-IOT technology realizes four major functions: data processing, status management, fault handling and energy consumption management, which meets the real-time, automation and IoT requirements of the Internet of Things street lamp control system, and improves the street lamp The intelligentization of the lighting monitoring system improves the management level and technical service level of the system, and can play a role in the construction of energy-saving and environmentally-friendly green towns.