0 Preface
Before the 1980s, China's public lighting equipment was generally in the traditional grid power supply and manual management mode. The running state of street lamps was mainly realized by means of patrol and patrol. The disadvantages of this model are high cost and low automation. Intelligent management such as automatic detection and dimming such as local control and remote monitoring cannot be realized. The response to the fault is slow, and there are factors such as inconvenience of lighting and even safety hazards due to the failure to repair in time.
From the late 1980s to the early 1990s, China began to research and put into use the street lamp monitoring and management system. The technology has gradually developed, and intelligent implementation of line management and dimming control has been realized. The street lamp has strong monitoring capability and can quickly implement the system. Data acquisition, data analysis, system control according to the conditions specified by the program, fault condition judgment to locate faults, reduce the cost of the street lamp system, improve the monitoring capability and automation level of the system, thereby achieving rapid recovery of faults and reducing faults. Time, improve the reliability of power supply lighting and system management level.
The centralized intelligent power supply LED lighting system discussed in this paper is a management mode that emerged in the context of the widespread popularity of LED street lamp products and the relatively mature intelligent lighting system. This mode is aimed at LED street lights around several branches. Supply DC power, achieve safe, reliable and stable power supply and secondary energy saving through intelligent management. The Guangdong Institute of Product Quality Supervision and Inspection has undertaken the drafting of the local standard “centralized power supply LED intelligent lighting interface†in Guangdong Province. Some preliminary research has been carried out for this purpose, and the industry is invited to provide valuable opinions.
First, the characteristics and advantages of centralized lighting LED street light intelligent lighting control system
(1) Comparison of centralized power supply of LED street lamps with traditional power supply systems
LED lamp
(1) Traditional AC-powered LED lamps
LED luminaires are directly connected to the AC grid. On the one hand, they are greatly affected by the grid. For example, the EMC impact of the grid on the luminaires and the lightning strikes transmitted by the grid; on the other hand, each LED luminaire needs EMC, rectification, power factor correction, Filter, power drive, inverter buck, steady voltage output or re-stable output to the LED source. The luminaire control device has complex circuits, many components, and high lamp cost. And relatively speaking, security and EMC issues are more prominent. These make LED luminaires less reliable and affect life (such as components such as electrolytic capacitors that withstand grid voltages in luminaires).
(2) High voltage DC powered LED lamps
The LED luminaire is connected to the DC output of the power module of the control cabinet. On the one hand, it is basically unaffected by the EMC influence of the AC grid on the luminaire and is not affected by lightning strikes transmitted from the AC grid side (of course, it is also necessary to resist lightning strikes on the DC line.) On the other hand, each LED luminaire can eliminate the need for EMC, rectification, power factor correction, filtering, power drive, inverter buck and other circuits and components. The simple constant voltage type requires only a small number of auxiliary components, and is directly output to the series LED light source, or a constant current circuit to output a constant current to the series LED light source. In this way, the circuit of the luminaire control device is very simple, the reliability is very high, and the life can be long, which is very advantageous for the road and tunnel lighting engineering using harsh environmental conditions. The complex intelligent DC LED lamps also need to be equipped with intelligent receiving control circuit and internal intelligent control protocol program. The components of the lighting control device are slightly more, the circuit is slightly more complicated, and the lighting cost is slightly higher. However, compared with similar intelligent AC LED lamps, it is still much simpler, more reliable, and has a longer life, which is still very beneficial for road and tunnel lighting projects.
2. Control cabinet
(1) Traditional AC-powered LED lighting control cabinet
The high-pressure sodium lamp street lamp control cabinet generally controls dozens of high-pressure sodium lamp street lamps. The early simple control cabinet manually switches the high-pressure sodium lamp streetlight manually; the slightly more complicated energy-saving high-pressure sodium lamp street lamp control cabinet manually converts the transformer to reduce the power in the middle of the night; It has the ability to accept remote control for uniform automatic switching or dimming control of all high-pressure sodium lamp street lamps or LED lamps, or to individually and intelligently control each LED lamp.
(2) Concentrated high voltage DC power supply LED lighting control cabinet
First, the control cabinet generally controls dozens of LED lamps. First, the grid AC power is converted into a high voltage DC voltage output to the LED lamps, and the control cabinet contains an intelligent control circuit module to enable remote control, thereby controlling the power module adjustment. The output DC voltage is used to uniformly switch and dim all LED lamps, or the sophisticated intelligent control system can individually and intelligently control each intelligent LED lamp.
Second, the power module of the control cabinet can be divided into a single high power power module or a combination of multiple low power power submodules. The DC output of multiple low-power power sub-modules can be divided into parallel output and unified output. Since the unified output mode in parallel can make one of the power sub-modules fail, the hot backup power sub-module immediately accesses the output line, which can ensure the reliable operation of the system under the same power output, and the number of backups of the power sub-module Minimized to a minimum. However, the technical requirements are high, for example, the error of the DC output voltage of each power sub-module should be as small as possible. The DC output voltage can be divided into high voltage DC such as 300V (output high voltage can reduce wire line loss and improve overall system efficiency), or safe low voltage such as 120V or less (lines and lamps are more safe for human body electrical safety, but equivalent load The line loss of the lower wire will be much larger, and the heat of the line itself is much higher and the cost is high).
3. Line
(1) Traditional AC power supply line
Single-phase three-wire (hot, neutral, and ground), or three-phase five-wire (three live, neutral, and ground) power lines.
(2) Concentrated high voltage DC power supply line
First, the input end of the control cabinet needs to be connected to the AC power supply grid, which can be divided into single-phase AC input or three-phase AC input. A three-phase AC input can balance the grid load and is a good way. The output DC power supply line can be three lines (for the positive, negative and ground lines of 120V high voltage DC), or two lines (corresponding to the positive and negative poles of ≤120V DC, and meet the requirements of safety extra low voltage). If there is another AC power supply grid access point in the adjacent LAN of the same intelligent lighting project, the power line of the original AC power grid can be used as the DC output line in the LED intelligent lighting system transformation, otherwise additional wiring is required for output DC power supply. line. In the same way, the same is true for new projects. This point is that public building intelligent lighting systems are easier to implement than street lighting intelligent lighting systems, but there are many other issues to consider.
4. Intelligent Control Protocols and Approaches
(1) Between the remote computer and the control cabinet
At present, there are many secondary development protocols based on the Internet, but there is no special unified.
(2) The mobile phone passes between GPRS and the control cabinet
It is only used for system maintenance personnel to set up individual data and receive feedback information. It is technically unrealistic to perform comprehensive, fast and continuous single-lamp control on the system. More importantly, from the perspective of public safety, for public lighting such as street lights, tunnel lights and large buildings, system maintenance personnel should not be allowed to control the mobile phone at will.
(3) between the control cabinet and each fixture
The LED voltage of the control cabinet is controlled to adjust the output DC voltage to automatically switch or dim all the LED lamps. At this time, no intelligent control protocol is required between the control cabinet and each lamp. At this time, the lamp has the lowest cost and the most reliable. , but can not control a single fixture).
(4) Agreements and approaches between the main control equipment and the lamps
For intelligent systems that can be individually controlled for each luminaire, there must be control protocols and pathways between the main control unit and each luminaire. The intelligent control method between the control cabinet and each single lamp can be equipped with another control line, or AC carrier, or DC carrier, or wireless Zigbee. If you need to individually control each LED street light, the most commonly used intelligent control protocol There are two kinds of DMX512 and DALI.
DMX512 has many control nodes, fast speed and long transmission distance, but it can only transmit in one direction (if fault diagnosis feedback is needed, other measures need to be taken up), and the protocol does not specify specific instructions and procedures. The system signal distribution has many points. The use of points is uncertain and other factors. Therefore, the systems and luminaires of various enterprises are difficult to interchange and generalize from a control point of view. It is only suitable for lighting projects where the company has a long warranty period or a high reliability and long life of lamps and systems. Therefore, from the above analysis, DAX512 is very suitable for centralized power supply DC intelligent lighting, especially in tunnel lighting engineering applications.
DALI can be transmitted in both directions, with comprehensive function definition and program flow, and there are consecutive protocol addresses between the lamps. However, DALI control lamps are not many, slow, and the transmission distance is not far. Although there are many well-defined control functions and instructions, it is easy to interchange and generalize the systems and lamps of various enterprises from the perspective of control. However, the internal protocol procedure is complicated, which is used in lighting projects that do not require multiple control functions, such as road lighting, which is overkill and leads to high cost of lamps. Therefore, it is not suitable for road lighting including tunnel intelligent lighting.
(2) Advantages and disadvantages of centralized DC power supply LED intelligent lighting control system
All luminaire control devices (commonly known as drive power) do not require the "AC-stable DC" conversion function, but are replaced by multiple high-power power modules concentrated in the control cabinet, which makes the power module highly reliable and long. Longevity, high quality, and high efficiency in luminaires and systems, and reduced overall system cost.
The control device (drive power) circuit of the luminaire can be very simple, the components can be few, the cost of the luminaire is low, and more importantly, all the luminaires can have no driving power, and the driving power source is separated from the LED luminaire, so that the heat generation of the luminaire is reduced, and the driving power is simultaneously The ambient temperature of the device itself is greatly reduced, which makes the reliability of the lamp very high, the life can be long, and there is no power factor problem, so the power line loss is reduced. These are very beneficial for the harsh environment of street lighting and tunnel engineering.
The disadvantage is that in streetlight applications, unless there is another AC grid power supply access point every few kilometers, in addition to the original AC power grid power line, a separate DC output power line is required. Similar problems exist in indoor applications. In addition, if it is necessary to further intelligently control each luminaire separately, unless the carrier is used (there is an AC carrier mode, it is not suitable in the centralized DC power supply mode; there is a DC carrier mode, but currently there are fewer dedicated ICs), or wireless Communication, otherwise an additional dedicated control line is required.
It can be seen from the above that the biggest advantage of the centralized DC-powered intelligent lighting control system is that the LED lamps can be made very simple, and are easily interchangeable in structure, so that they have the advantages of low cost, high reliability and long life. For professional management applications such as roads and tunnels, if another adjacent control cabinet with several kilometers apart has another AC power grid access point and is allowed, the original can be directly used in the retrofit of the LED street light intelligent lighting system. The power line of the AC power supply grid is changed to a DC output line, which reduces wiring troubles and costs. Otherwise, additional wiring is required for the output DC power supply line, which is a problem to be solved, that is, its biggest drawback.
For indoor applications, considering that other home appliances such as refrigerators must use AC, for indoor home lighting, unless the newly built building is separately embedded with a dedicated DC line for lighting, the centralized DC-powered LED intelligent lighting control system can be implemented. It is very convenient to carry out, but it is also necessary to consider, more importantly, DC LED lamps and DC LED lamps should be strictly ensured from the structure and can not be mixed with current AC lamps and AC lamps, otherwise it will easily lead to major safety problems.
Therefore, from all aspects, the centralized DC-powered intelligent lighting control system is most suitable for professional applications such as tunnel lighting applications.
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