Shang Xinjian, Shen Xiaobo, Zhou Yong 1 Background 1.1 Theft of lighting cables In recent years, lighting cable theft has become increasingly rampant. According to the online survey, the statistics on cable theft losses reported in various cities over the years are shown in Table 1. It can be seen that the theft of the lighting cable caused huge economic losses to the country. 1.2 Social hazards caused by the theft of lighting cables In addition to direct economic losses, the theft of lighting cables has brought great social harm to urban security. (1) Public security and traffic safety are affected: street lights are out of power in large areas, and cars are driving on the roads. On average, they encounter darkness every few minutes. More than 90% of such power failures are caused by theft of cables. In the case that the street lights are not bright, the probability of occurrence of potential traffic accidents and theft cases will rise, and the resulting social security problems are also emerging. (2) Life safety is threatened: the cutting port of street lamp cable and many exposed wire ends are charged. If passers-by pass by or touch these wires, the possibility of electric shock is extremely high. In severe cases, they may even be electrocuted. . (3) Self-security is threatened: In addition to threatening the personal safety of residents, burglary people may experience electric shocks during the theft. There have been many instances of casualties in the theft of substation equipment and high-voltage power lines. 1.3 Development trend of lighting cable theft In recent years, due to the price increase of non-ferrous metals, the scale of cities has increased, the number of migrants has increased, and the theft of lighting cables has accelerated. According to statistics, in 2003, the total loss of street lamp cable in Hangzhou was 800,000 yuan, and in 2008 it was 2.88 million yuan. In 2005, the direct loss due to cable theft was as high as 5 million yuan. The trend of theft of lighting cables is shown in Figure 1. It can be seen that the loss caused by the theft of the cable increases by more than 30% every year, which becomes a huge heart disease in the hearts of every lighting management personnel. 1.4 It is imperative to adopt corresponding technical measures. At present, the situation of urban street lamp cable theft has been deteriorating. The management department is helpless. It is necessary to adopt corresponding technical measures and measures to curb the spread of this trend and adopt the lighting cable anti-theft alarm technology. It is a better anti-theft solution by monitoring the street lamp in real time for real-time monitoring, detecting abnormalities in time, reducing or even preventing the loss caused by cable theft. 2 The current technology and lighting cable speciality At present, some manufacturers in China have produced corresponding lighting cable alarm system, trying to solve this problem. These products use power carrier communication or cable detection methods for theft detection. However, these techniques have a high rate of false positives or are unreliable due to the following characteristics of the lighting cable. (1) The lighting line is energized after lighting at night, and the power is turned off after the daylight is turned off, requiring all-weather burglar alarm; (2) Each light source of the street lamp cable is connected with tens of micro-method compensation capacitors in parallel, and the traditional power carrier signal strength is The distance is exponentially decreasing, which makes the power carrier communication very unreliable; (3) The self-extinguishing phenomenon occurs before the end of the high-pressure sodium lamp (always on and off, separated by several minutes), resulting in unstable cable current; (4) The lighting cable is buried in the ground. After long-term work, it is caused by rainwater and moisture. (5) The failure of the lighting equipment itself often leads to partial light-off, and the current changes greatly. It is difficult to distinguish whether the cable is stolen or extinguished according to the current. 3 A new lighting cable anti-theft technology In order to solve these problems, we have designed a new lighting cable anti-theft alarm system. It is a combination of traditional anti-theft technology, wireless alarm technology, power electronics technology, computer data processing technology, multimedia technology and cable detection technology. It has both alarm function and line status detection function. The false alarm rate is extremely low, and the function of remote alarm is added. The system is divided into two levels: the monitoring front end and the monitoring center. Monitoring front-end: including several cable anti-theft hosts (referred to as "hosts"), each with a number of cable anti-theft ends (referred to as "ends"). The host is set in the monitoring front end and has a wireless communication unit (default is GSM communication). The main unit is connected to the low voltage outlet of the power cable, and the number of ends is determined by the number of outlets on the low voltage side. The end is connected to the host of the monitoring terminal through the power carrier (the distance is not more than 3000m), and the single detector is connected to one of the low-voltage outlets to detect the condition of the line. In Figure 2, only one host and one end are shown. Monitoring Center: It consists of communication processing front-end machine, computer host and related software. The monitoring center computer collects the working status of each point through the wireless network (public network), realizes data recording and management, and performs data statistics. Once an abnormal situation is found, the fault can be located in time, and the status quo is reported to relevant personnel, and the management personnel can Actively query the monitoring front-end operation information anytime, anywhere. The alarm signal has different forms (light, sound, mobile phone SMS alarm), which can be submitted automatically or submitted according to the preset scheme. At the same time, the monitoring center has the function of sending short messages. After setting the mobile phone number of the on-duty personnel, the alarm message can be sent to these numbers during the alarm so that the relevant personnel can rush to the scene in time. 4 Comparison of this system and Other schemes The system has the function of anti-theft when turning on and off. The comparison between this technology and the existing domestic technology is shown in Table 2 and Table 3. It can be seen from the table that the scheme has the characteristics of moderate cost, high accuracy and low false positive rate. 5 Conclusion This system has been tested in lighting and functional lighting systems. It has repeatedly issued cable burglary alarm signals. After the rushed to the scene, the staff prevented the thieves from stealing and saved huge economic losses for the country. .
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