In recent years, the state has vigorously advocated energy conservation and consumption reduction. Most of the traditional street lamp control methods focus on and control the switch state. The laying and maintenance of the line requires a lot of manpower and financial resources. At the same time, whether the street lamp is normal or not can only be done manually. Inspection, these management of street lamps is extremely inconvenient, and it is also easy to cause power loss, so it is necessary to improve the street lamp control system. This paper presents a wireless control street light control scheme based on wireless technology, which realizes automatic monitoring of street lamps, greatly reducing the cost of street lamp management and maintenance, and reducing power loss.
The proposed rapid development of wireless technology has been widely used in various industries. The manual management control method of the traditional street lamp is to connect each street lamp to the management center by wire, which is inconvenient to manage and maintain. Street lamps have some remarkable features, the distance between them should not be too far, otherwise they can not play the role of illumination, while the adjacent street lamps are illuminated at the same time, the bus of each street lamp is in the bus, wireless communication, etc.; Cui Ping (1978-), female, lecturer, Mainly engaged in wireless sensor network research and development.
The brightness of the bus and the network is increased, and the controller is designed with this feature. Each controller of the street lamp detects its light intensity through a photoresistor, determines whether it belongs to the natural light change rule through a filtering algorithm, and then determines the state of the street light switch. At the same time, each controller automatically identifies the working state of the street lamp monitored by the algorithm to determine whether it is Normally, the status of the street lamp is fed back to the management center through the wireless transmission function of the controller. The management center can also transmit the corresponding command to the street lamp at the designated position to perform related control, realize the remote control of the management center, real-time monitoring of the street lamp and timely maintenance of the street lamp. Or replace it.
Photoelectric Properties Photoresistors are electronic components fabricated from semiconductor materials that operate using the photoelectric effect. A voltage is applied to the electrodes at both ends of the photoresistor, and a current is passed therethrough. When exposed to light of a suitable wavelength, the resistance thereof is reduced, and the current is also increased as the light intensity increases, thereby achieving photoelectric conversion; In the range of light intensity that the photoresistor can effectively detect, its current and light intensity are basically linear. The light intensity of the environment where the street lamp is located generally belongs to the range of natural light variation. The illuminance is (0400)K wavelength (0.40.76)>10-6m, and the cadmium sulfide photoresistor can effectively detect the light intensity range between (0 4000)lx. The wavelength is (0-0.8)>10-6m, so the controller uses cadmium sulfide photoresistor as the light intensity detecting component.
Wireless transmission algorithms, whether street lights or residential street lights, are not too far apart from each other. Due to the special nature of street lighting monitoring, the small power consumption of the controller can be neglected. Therefore, the low-power wireless transceiver can be used to carry out the street light in the baton mode. Information transfer, report the status of street lights to the management center, and its working principle is as shown. Obviously, if a street light is lost, the management center can be detected and reported by its own controller or adjacent street light controller.
In each district or street of a city, the street lamp itself has a position label, so it is only necessary to equate the controller number attached to a street lamp with the street lamp itself number. Due to the special nature of streetlight control, the wireless transmission data protocol can be simplified: destination address, source address, status, and verification. The specific provisions are as follows: destination address data transmission destination address, such as the management center, 2 bytes.
The address of the controller that sends the information to the source address, 2 bytes.
The status indicates the status of the street light and the number of times the report was sent, 1 byte. The highest position d7, dd5 is used to indicate the status of the current street lamp and the adjacent street lamp, where d7 indicates the state of the street lamp with a large number, d6 indicates the current street lamp state, and d5 indicates the state of the street lamp with a small number. If a bit is 1, it indicates that the street light is off; otherwise, it is on. Obviously, if the adjacent street lights are normal, d7d6d5=000. The remaining 5 bits are used to indicate the number of times the controller reports the same condition of the street light to the management center. If the street light status changes, the 5 bits are automatically cleared. When d4d3d2d1d0=11111, the current controller does not receive the relevant instructions of the management center, then stops sending data to the management center.
Check the checksum of the transmitted data.
In the wireless transmission process, if a controller receives the same source address, the same state, and the same number of times of data multiple times, the duplicate data can be directly discarded according to the above protocol, so as to avoid repeatedly transmitting the same content.
1.3 Filtering algorithm In the single-chip microcomputer control system, the signal source itself, the sensor, the Power Supply, etc., usually have various kinds of pulse interference. In the street lamp control system, the interference introduced by the instantaneous illumination is prone to occur, and the duration of the interference is uncertain. For example, the lights of the vehicle, the ship, and the aircraft may cause the light to illuminate the test point for a long time because of the terrain, and such interference may easily cause the controller. Misjudgment. If the corresponding measures are not taken, it will inevitably affect the accuracy of the controller. For this reason, the anti-pulse interference average filtering algorithm is introduced in the controller.
The anti-pulse interference average filtering algorithm combines the advantages of median filtering and arithmetic mean filtering, and has a good inhibitory effect on occasional pulse interference. The algorithm principle is to compare the collected n data, and remove the maximum value and The minimum value is then calculated for the arithmetic mean of the remaining n-2 data. Namely: taking the interference of the lamp as an example, in the process of the car leaving the road section from far to near and then leaving the streetlight, the light on the photoresistor is weakened and then weakened, and the process of light intensity is different from the smoothing of natural light. Change, the duration of this interference rarely exceeds 5 min. It is not difficult to find through analysis that the characteristics of this type of interference source are faster, shorter, and the data curve is convex, that is, the data value of the intermediate point is the largest. In response to this feature, the controller selects the way of memory comparison to filter out this interference.
The method is as follows: Pre-define an array containing 30 elements for storing data collected every 10s, and can store data of about 5 minutes. Another variable is used to store the number of times the sampled value is above or below the set value. During the off period of the street light, the collected data is first compared with the set value to see if it is lower than the set value. If it is lower than the set value, the unit for storing the number of times is incremented by one; if there is a higher than the set value during this period, the storage is performed. If the number of times lower than the set value is cleared, if the street is lower than the set value for 29 consecutive times, the street light is turned on and the counting unit is cleared; if the street light is on, if the collected light intensity exceeds the set value, the stored time exceeds the number of times. Add 1 to the unit. If it is continuously higher than the set value 29 times, analyze the stored 29 light intensity data. If the difference between the adjacent elements in the 29 data is equal or close, or the change smoothness is good, it is in line with the natural light intensity. If the law changes, the street light should be turned off; on the contrary, keep the street light on and clear the counting unit.
2 The first hardware manufacturer designed to integrate ZigBee radio frequency (RF) front-end, memory-based microcontrollers for a variety of ZigBee or ZigBee-like wireless network nodes. It uses an 8-bit MCU (8051) with 128kB of programmable flash and 8kB of RAM and also contains up to 14-bit analog-to-digital converters (ADCs). The CPU satisfies the data acquisition, data processing and wireless transceiver functions of the street lamp controller at the same time, and the power consumption is very small.
The detection circuit is usually accompanied by a large common mode voltage. Generally, the common mode rejection ratio of the operational amplifier can reach 80dB. If a measurement amplification circuit composed of multiple integrated operational amplifiers is used, the common mode rejection ratio can reach (100H20) dB. The dual-operation amplifier is connected in series to suppress the common-mode signal of the floating bridge, and the light intensity detecting circuit is as shown. The analog data processed by the operational amplifier is directly sent to the P00 pin of the CC2430 for AD conversion. The controller hardware circuit structure is as shown.
3 software design controller software mainly includes 4 parts of functions: light intensity detection, filtering algorithm, street light switch control and wireless transmission. The wireless transmission function uses timing work, for example, from the normal opening of the street light to the closing of the street light. The design reports the status of the street light to the management center at intervals of 1 mm. Of course, the management center can also check the status of a street light. The software flow is as shown.
(Continued on page 81) The controller sets the light intensity threshold to 40lx when the street light is turned on, and the enclosure has a degree of protection, or NEMA standard. With both requests, you can attach a label that matches this. From the fact that the enclosure can be found to meet the requirements of IP56, it can also be defined to also comply with IP 56 protection. However, an enclosure with an IP56 rating does not necessarily meet the requirements of NEMA 4X in other respects, such as corrosion protection and ice load.
In the figure, A indicates the first protection code corresponding to the IEC, B indicates the second protection code corresponding to the IEC, and the shaded area indicates that the corresponding NEMA protection level is higher than the IEC. 4 Conclusions The enclosure of almost all electrical facilities has protection. Grade, commonly used standard or IEC standard, or NEMA standard. Although the two standards are different, they all have the same intent to protect personal safety and protect equipment safety. Then you should list the meanings and definitions of the protection level codes one by one, compare the common definitions behind them, and compare them in order to grasp their essence and correspondence, and you can handle the housing problems of electrical facilities freely and accurately. It doesn't matter what code it uses.
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