1. Overview According to statistics, lighting electricity consumption accounts for about 12% of China's total electricity generation, which is a significant proportion. A report from the China Illuminating Engineering Society indicates that in 2001, China's total electricity generation was 1,433.25 billion kWh, with lighting electricity consumption reaching 143.325 billion to 171.99 billion kWh, equivalent to about twice the annual generating capacity of the Three Gorges Dam (84 billion kWh). In 2004, total electricity generation was 2,187 billion kWh, with lighting electricity consumption accounting for about 10% of that year's generation, approximately 218.7 billion kWh, equivalent to nearly three times the annual generating capacity of the Three Gorges Dam. Urban public lighting accounts for about 30% of China's lighting electricity consumption, with annual expenditures reaching tens of billions of yuan. In today's context of tight municipal budgets, most cities and regions in China still employ the cost-saving method of switching off streetlights every other lamp, a practice abandoned by some countries in the 1970s. The drawbacks are obvious—not only does it lead to uneven road illumination, creating hidden dangers for public security and traffic safety, but it also fails to prevent the reduction in streetlight lifespan due to increased grid voltage in the latter half of the night. This is not true green lighting and energy conservation. 2. Basic Requirements for Green Lighting 1) High luminous efficiency of the light source, mainly including: high-pressure sodium lamps, metal halide lamps, energy-saving fluorescent lamps, and other gas discharge lamps, as well as new LED light sources. 2) No harmonic pollution to the power grid. This eliminates the feasibility of thyristor phase-shifting voltage reduction for energy saving, and also eliminates the feasibility of using electronic ballasts or energy-saving products with harmonic content exceeding 5%. 3) Energy saving. For HID lamps, this involves improving the power factor and reducing ballast losses; secondly, wide-range dimming of the light source, which not only achieves large-scale and high-proportion energy savings, but also promotes the rational use of the light source, protects eyesight, and protects lighting products and fixtures. 4) No light pollution. 5) Optimized design of lamp distribution and lamp power. 3. Energy-saving principle of HID lamp lighting The highest luminous efficiency of widely used high-pressure sodium lamps is closely related to the voltage supplied to the lamps. This voltage is related to many factors and varies with ambient temperature, reaching as low as 175-185V. Therefore, the energy-saving principle of HID lamps is to reduce the operating voltage of the lamps, allowing them to operate as close as possible to their highest luminous efficiency without affecting visual illumination. 4. Requirements for energy-saving products of HID lamps The green lighting theory of HID lamps points out that under typical urban street light background brightness conditions at night, reducing the voltage can effectively reduce glare intensity, effectively improve lighting quality, improve urban traffic conditions, and save a significant amount of energy and extend the lamp's lifespan several times over. A test report from the American Lighting Technology Association shows that when the lamp voltage exceeds the rated voltage by 10%, the lamp's lifespan is reduced by half; the higher the voltage, the shorter the lamp's lifespan; when the lamp voltage is 90% of the rated voltage, the lamp's lifespan doubles, which is four times longer than when the voltage is 10% overvoltage. Moreover, the illuminance value decreases by only 7% compared to the rated state, which is difficult for the human eye to perceive. The theory of maximum luminous efficacy indicates that the highest efficiency of high-pressure sodium lamps occurs when the lamp voltage is 175–200 V (optimal voltage). Therefore, HID lamp energy-saving products must be able to provide and maintain the optimal voltage for the lamp; this is the requirement for energy-saving products in HID lamps. It includes two aspects: first, the output voltage must be able to reach the relatively low optimal voltage of the lamp (ensuring the HID lamp does not go out); second, it must be able to operate stably near the optimal voltage value, without changing with the mains voltage or load. 5. Main Technical Elements of HID Lamp Energy-Saving Products We know that the essence of the energy-saving principle of HID lamps is voltage reduction and stabilization. For high-pressure sodium lamps used in road lighting, it is difficult to trigger lighting when the supply voltage is below 200 V. Nearly aging HID lamps may require a voltage of 220 V or higher to trigger lighting. HID lamps are very sensitive to current and voltage interruptions; even a few milliseconds of interruption can cause instability and extinguishing of the lamp's arc (some lamps require several minutes to cool down after extinguishing before they can be relit). Therefore, the main technical elements of HID lamp energy-saving products are as follows: 1) Wide range of voltage reduction and stabilization functions. 2) During voltage reduction or stabilization, maintaining continuous current, without impact or overvoltage, ensuring that the HID lamp does not go out, restart, or get damaged. This is a key technology for HID lamp energy-saving products, and it is difficult to achieve this key technology using contact devices (such as relays or contactors) for voltage level switching. 3) Adaptable to different types of HID lamps or mixed HID lamp loads. 4) Adaptable to different environments, different road types, different times, or different requirements of lighting parameters from different people. 6. Main Problems and Analysis of Current HID Lamp Energy-Saving Products Currently, thyristor phase-controlled voltage reduction energy-saving products in HID lighting are gradually being phased out due to harmonic pollution to the power grid. Electromagnetic transformer or inductor voltage reduction energy-saving products are currently the dominant products. The main problems of most electromagnetic lighting energy-saving products are roughly as follows. 1) Failure to meet the energy-saving requirements of HID lamps: For single-lamp control, series inductors are used for voltage reduction to save energy. While this simplifies the control circuit, it makes centralized control of road illumination difficult due to insufficient or excessive voltage reduction. Increasing the number of inductor taps and implementing a voltage regulator circuit inevitably increases circuit complexity and cost, and reduces product reliability. For centralized control, most systems use autotransformers to adjust voltage, making it difficult to dynamically switch gears based on input voltage changes when the HID lamp load is running. Poor power quality during gear switching can easily burn out contactless switches or cause the HID lamp to extinguish, sometimes even damaging streetlights. Consequently, some products only offer fixed output gears or require manual gear switching. Even those using smart chips only automatically switch gears upon power-on, failing to perform gear switching or reliably switch gears while the HID lamp load is running. 2) Some products have lower energy-saving rates, with a maximum energy saving rate of only 10% to 20%. The fundamental reason is that the key technologies of these products are not up to standard. They cannot dynamically switch HID lamps, have a small voltage variation range, and cannot reach the optimal voltage for the lamps, resulting in a low energy saving rate. Energy saving rate is a key technical indicator for measuring energy-saving products; it cannot be too high or too low, and an appropriate value should be considered during the design phase. 3) HID lamps are prone to extinguishing. If the current of the HID lamp becomes discontinuous when the voltage level changes, it can easily cause the HID lamp to extinguish and restart, and may even generate instantaneous overvoltage. If the output voltage after the level switch is low, it will cause the HID lamp to extinguish and cannot be relit under low voltage. 4) HID lamps are prone to damage. Theoretically, as well as from numerous experiments and reports, it can be seen that the lifespan of HID lamps should be significantly increased after using energy-saving products. However, if the HID lamp extinguishes and restarts when the voltage level changes, it will accelerate the aging of the HID lamp and shorten its lifespan. 5) The main reason for the product's inherent unreliability is the failure to meet key technological standards. Theoretically, under inductive loads, as long as the quality of contactless components and key technologies are up to standard, the lifespan of contactless products will definitely be much longer than that of contact products. If contact products or contactless products with inadequate key technologies are used, the inability to accurately detect and judge complex and ever-changing power grid interference signals will lead to poor product reliability. 7. Analysis of Intelligent Lighting Energy-Saving Control System The RZM5 series intelligent lighting energy-saving control system produced by Jiangsu Taizhou Qianjin Electromechanical Manufacturing Co., Ltd. is a relatively ideal intelligent lighting energy-saving control system that meets the requirements of green lighting and is a product recommended by the China Energy Conservation Association. This product has obtained a national patent. The system is described below. 7.1 System Structure The intelligent lighting energy-saving control system consists of a latitude and longitude switch controller using astronomical algorithms, a single-phase or three-phase autotransformer contactless voltage regulation unit, microcomputer street light controller software containing latitude and longitude parameters, and lighting energy-saving control cabinet voltage regulation system parameter setting and monitoring software. Single-phase or three-phase voltage regulating units can communicate with the street light controller. The system's external communication interface comes from the street light controller's communication interface. The computer can communicate with both the street light controller and the voltage regulating units of each phase through this interface, enabling modification and monitoring of all system operating and protection parameters. On the computer side, the microcomputer street light controller software containing latitude and longitude parameters can monitor and modify the street light controller's parameters, and also read the operating status of each phase voltage regulating unit. The voltage regulation system parameter setting and monitoring software in the lighting energy-saving control cabinet can monitor or modify the operating or protection parameters of each phase voltage regulating unit. The latitude and longitude street light controller directly calculates the sunrise and sunset times based on astronomical algorithms to control the street light switching. In addition, it also has light control, and can remotely control street light switching via wired networks, GPRS, or CDMA wireless networks; it can achieve independent control of multiple circuits; it allows for convenient viewing or modification of relevant parameters via computer; and it enables remote control or centralized monitoring via network. The single-phase or three-phase autotransformer contactless voltage regulation unit solves the technical problem of high-intensity gas discharge lamps' high-reliability dynamic switching in current electromagnetic technology's multi-lamp centralized control. It ensures that HID lamps do not extinguish during voltage level switching, improves maximum energy saving rate, and significantly extends the lamp's lifespan. Simultaneously, it fully utilizes the intelligent features of the product to meet various special circumstances of lighting energy saving. Various operating parameters can be conveniently viewed or reset remotely via computer serial port or network to adapt to different environments or specific needs of different personnel. 7.2 Technical Principles 7.2.1 Circuit Principle Block Diagram of the Latitude and Longitude Switching Light Controller [ALIGN=CENTER] The circuit principle block diagram of the latitude and longitude switching lighting controller using astronomical algorithms is shown in Figure 1. [/ALIGN] 7.2.2 Control Method of the Latitude and Longitude Switching Light Controller Using Astronomical Algorithms The controller is equipped with a real-time clock integrated circuit, and the running date and time are consistent with the current actual time. A high-performance microcontroller is used as the controller. Users can configure the controller to automatically adjust according to daylight and nighttime, or to switch the lights on and off at fixed times each day. In addition, it can control the lights via light, manual control, and network control. These light-on signals are determined by an OR relationship to determine the final light-on signal. This signal controls the relay or contactless switch to connect or disconnect the power supply to the street light through the drive circuit, thus completing the multi-functional intelligent control of the street light. When the street light is turned on, if it needs to be temporarily turned off, it can be forcibly turned off by sending a command via a switch or remotely on the controller. The device has multiple circuits for light-on/off control. Each circuit can be set to have two light-on/off times, so it can be combined into lighting schemes such as all-night light control, half-night light control, and two independent controls per day. Each circuit has the same function, so it can control street lights in multiple circuits. The astronomical algorithm used by the light-on/off controller is based on Kepler's three laws of planetary motion and Newton's law of universal gravitation, rather than ordinary approximation algorithms. Approximation algorithms have large calculation errors, sometimes differing by more than 10 minutes. After actual testing, the calculation error of this product does not exceed 3 seconds within 100 years. 7.2.3 Circuit principle block diagram of the voltage regulator unit The circuit principle block diagram of the voltage regulator unit is shown in Figure 2. 7.2.4 Technical Principle of the Voltage Regulator Unit: The microcontroller compares the current voltage and current of the lighting load detected by the true RMS linear sampling circuit module with the set voltage and current values ​​to determine whether the current voltage or current is normal or abnormal. If it is normal, it calculates the appropriate voltage level and sends a trigger signal for the corresponding level at the zero point. After electrical isolation and amplification, this signal drives the contactless switch to the specified level. Simultaneously, the microcontroller measures and calculates the internal temperature and compares it with the set temperature protection value. If parameters such as voltage, current, or temperature are abnormal, the microcontroller issues corresponding fault indication signals and alarms, automatically cutting off the output or bypassing it. Under power-on conditions, various operating parameters can be remotely viewed or reset via the communication interface. 7.3 Product Features The RZM5 energy-saving product series uses a new high-speed microprocessor as its core, continuously sampling parameters such as voltage and current, and dynamically adjusting the transmission voltage with high reliability through a contactless switch. The product integrates automatic light switching control, manual bypass control, automatic bypass control, rapid test control, voltage calibration control, status indication control, and automatic delay energy-saving timer, and has the following features: 1) High efficiency and energy saving: The RZM5 series products achieve energy savings of up to 20% to 50%. 2) Automatic light switching: Based on the latitude and longitude of different locations and the changing patterns of the Earth's rotation and revolution, the system uses astronomical algorithms to automatically and accurately calculate the local daylight and darkness times, automatically correcting the daily light-on and light-off times, avoiding the hassle of manual correction and light-on/off control. 3) Integrated GPS measurement software: Through the GPS interface, local latitude, longitude, time, and other parameters can be read. 4) The system can output the continuous light-on/off times for any consecutive number of days to a computer, allowing managers to have a clear understanding of the light-on/off times. 5) Employs dual intelligent energy-saving control technology, allowing for convenient energy-saving level settings while ensuring relatively stable illuminance even under significant mains voltage fluctuations. 6) Contains a small phase-controlled adjustment circuit, thus eliminating high-order harmonics and helping to suppress them in the power grid, making it a typical environmentally friendly energy-saving product. 7) Effectively extends lamp life by more than 2 times, significantly reducing maintenance costs and workload. 8) High-voltage control adopts contactless switching, using a unique algorithm to ensure accurate, fast, and reliable switching without any voltage or current surges, greatly improving product lifespan and reliability. This solves the problems of contact switching and the large current surges, instantaneous overvoltages, or lamp outages that occur during switching in some products, significantly enhancing product lifespan and reliability. 9) Features automatic protection and automatic bypass identification functions. 10) Each phase is independently adjustable, allowing for 100% unbalanced loads. 11) Monitors the operating status of each phase at all times, taking timely protective actions or automatic bypass, greatly improving product reliability and safety. 12) Various operating parameters can be flexibly and conveniently set according to the actual needs of local illumination. 13) Various operating parameters such as voltage, current, and time can be adjusted under load without interrupting power. 14) Remote and centralized control can be easily performed, and the operating parameters of the equipment can be remotely configured. 15) The system can bypass operation via a manual bypass switch on the panel. 16) Each phase has audible and visual alarm indicators for easy and quick maintenance. 17) Applicable to all gas discharge lamps: high-pressure mercury lamps, metal halide lamps, high-pressure sodium lamps, fluorescent lamps, etc. 18) The control system can be used with street light transformers; only a few taps need to be added to the street light transformer. 8. Application Case of Intelligent Lighting Energy-Saving Control System Taizhou Qianjin Electromechanical Manufacturing Co., Ltd.'s RZM5 series centralized control intelligent lighting energy-saving control system for HID lamps is a multi-functional switch controller with astronomical algorithms, using autotransformer and contactless switch technology for voltage reduction and stabilization. It features a wide range of voltage reduction and stabilization functions, enabling immediate transition from one steady state to another during gear switching or voltage stabilization without instantaneous overvoltage or voltage oscillation. The current is continuous and surge-free, ensuring HID lamps do not extinguish or restart. It automatically adapts to different types of HID lamps or mixed HID lamp loads, and all parameters can be modified or viewed by the user (via serial port, wired network, or wireless network), fully meeting the energy-saving requirements of HID lamps. The product has been used in multiple cities, starting with road lighting and residential lighting in Taizhou, Jiangsu Province, where it has been used for over a year. Despite weathering storms, no problems have occurred. Daily meter readings show that, without changing the original half-night and full-night (all-night) lighting operation modes, the average energy saving rate is 38.5% compared to not using the energy-saving control cabinet. If all lights are used in full-night mode, the energy saving rate will be even higher. 9. Conclusion Energy saving in lighting is of great significance. The Ministry of Construction and the National Development and Reform Commission, in their "Opinions on Strengthening Urban Lighting Management and Promoting Electricity Conservation," clearly stated that energy-saving technologies should be vigorously promoted to improve electricity utilization efficiency. With the aim of saving energy, protecting the environment, and promoting health, we should actively promote green lighting, implement urban green lighting demonstration projects, improve urban lighting quality, and strive to improve the urban living environment. I sincerely hope that everyone will exchange energy-saving technologies and experiences through various channels, introduce good energy-saving products, learn from each other's strengths, cooperate in production, accelerate urban green lighting work, and jointly contribute to building a conservation-oriented society.