Today's light source and lighting technology is not only a simple application of new technologies, technological advances allow us to maximize our visual capabilities, and advanced and reliable lighting control technology is providing amazing control for this visual function. In this new era, artificial lighting has developed into an independent industry, and the status of lighting control systems has received more and more attention.
The start and maturity of commercial projects provides a colorful stage and case for the application of contemporary electrical lighting control systems. Not only the lighting designer's genius imagination, but also the precise and intelligent lighting control system is also indispensable. What is described in this paper is the evolution and technical characteristics of such a system that has long been neglected.
First, the traditional lighting control method
Traditional lighting control methods usually have the following types:
Direct switch control
(1) A rocker-type, pull-wire type, touch type, inductive or other operation type switch installed at the site to perform on-site dispersion or centralized control;
1 Single point control: The most common control method, one switch controls the on/off of one or a group of lamps;
2 Multi-point control: Two or more switches located in different locations jointly control the on/off of one or a group of lamps, which are commonly used in stairwells, corridors, etc.;
Figure 1 Single point control and multipoint control in direct switch control
(2) The miniature circuit breaker in the distribution box directly serves as the control lighting switch, and controls the lighting of the site or a specific area according to the distribution branch;
The main advantages of the direct switch control mode are low cost and convenient maintenance. The disadvantage is that it needs to be manually turned on and off. If the user is not responsible, it is easy to waste electrical energy.
2. Indirect switch control
The lighting control function is achieved by introducing a control device such as a contactor in the lighting circuit (the circuit is schematically shown in FIG. 2). Its main application is in the following occasions:
(1) Since the on-site installed light switch capacity cannot control large-capacity lighting fixtures or the entire set of lamps, the control buttons are installed on site to control by controlling the on/off of the contactors;
(2) Large lighting control system with lighting console, control cabinet and other equipment;
(3) Locations for remote control, such as parking lots, squares, courtyard lighting, etc.;
(4) Lighting for special purposes, such as emergency lighting;
Figure 2 Indirect switch control circuit (the above picture is for general lighting, the figure below is for emergency lighting)
3. Traditional dimming control
In the night lighting control system, there is also a way to control the change of the lighting effect, that is, using a dimming device. The dimming control mode can enrich the lighting effect, but the conventional dimming device has high cost, low efficiency, large volume, and inconvenient operation. It is not widely used because it is very special.
4. Preliminary automatic control
(1) Light control: It consists of photoelectric conversion sensor, intermediate relay, time relay, contactor and so on. It is mainly used for street lighting control, and is also often used for night lighting. Its setting value can usually only be adjusted manually.
(2) Voice control: It is mainly a functional application, and it is only used as a dynamic effect in night lighting.
In the night scene lighting, courtyards, stairwells and non-fire evacuation walkways and other applications with special lighting control requirements, the introduction of light control, voice control, to achieve initial automatic control. This type of automatic control is only a primary, local application.
5. Improved automatic control
A complete automatic control system consisting of light sensors and other sensors, digital-to-analog conversion, central processing unit, electric actuators, etc., in addition to the functions of the above-mentioned system, can also be programmed to set long-term operational state control, such as evening Mode and midnight mode, etc.
For a night lighting control system, partitioning and time-sharing can be performed by pre-classifying according to the normal mode, the weekend mode, the holiday mode, and the major celebration mode. Start at ambient brightness at startup, taking into account different system runtimes in winter and summer. The design of this control system has been characterized by the BA system. However, this kind of system operation depends on the central processing unit, the setting value adjustment is more complicated, and the operation and maintenance work has higher requirements on personnel.
6. Limitations of traditional lighting control methods
As shown in Figure 3, the traditional lighting control methods have the following limitations:
(1) The control function is simple, generally only the switch function. To achieve remote control and centralized control, system wiring becomes more complicated and less reliable;
(2) Mostly rely on manual operation, especially when controlling lighting in large areas and large spaces, operations are cumbersome, and mistakes and omissions are difficult to avoid;
(3) The dimming device and corresponding control device used for non-professional occasions are generally set separately, which affects the performance of the device. It is difficult to implement complicated functions such as scene setting and continuous brightness adjustment;
(4) In the improved indirect switch control mode, if the central processor fails, the lighting control system will be immediately affected.
(5) Construction wiring has a large workload. The huge number of cables is not conducive to maintenance and renovation.
Figure 3 Traditional lighting control technology
Second, intelligent lighting control
1 Introduction
Intelligent lighting control devices have long been ignored, and most buildings still use traditional lighting control methods. As far as contemporary lighting control devices are concerned, there are many new requirements:
(1) It is no longer a simple implementation of area lighting and timed lighting switching. With the improvement of people's quality of life requirements, the lighting control device can also provide control of the lighting time and brightness of the light source to match different applications and atmospheres, providing corresponding lighting scenes, namely suitable light environment, and intelligent management. Functions such as simplification of operation are easy to use.
Figure 4 Control bus and fieldbus in BA system
(2) The installation requirements for modern building electrical appliances are constantly increasing, and the number of wires required is increasing. This not only increases the risk of fire and the workload of the design, but also brings inconvenience and difficulties to future maintenance, maintenance and modification work. Therefore, it is imperative to simplify the work of system wiring.
(3) Promoting “green lighting†provides a new evaluation standard for contemporary lighting design. Designing advanced and reasonable lighting control method is one of the important contents in lighting engineering design. It is an important means to reduce lighting time, reasonable energy saving and improve lighting quality under the condition of ensuring visual conditions and satisfying visual requirements.
In order to overcome the inherent shortcomings of traditional lighting control methods and achieve the requirements of simple design, flexible use, perfect functions, energy saving and huge potential, foreign manufacturers have launched intelligent lighting control devices--event-oriented control bus systems.2, noun
(1) Fieldbus: A “digital, bidirectional, multivariable, multi-point, multi-line communication systemâ€. It uses information technology, microprocessor technology and network technology to realize digital networking between sensors, controllers and actuators. It is the application of communication protocols in field control systems. The current common fieldbuses are LonWorks, BACnet, Profibus, and so on.
(2) Control bus (Controlbus): In the three-layer control structure of the BA system, the control bus belongs to the automation layer and is the hub and bridge connecting the central station and each substation (detail 4). It must ensure the consistency of data transmission between the central station and the substation, and improve the reliability, real-time and accuracy of the system. The control bus can be directly connected to the central station server for real-time access to the database. Its control level is higher than the field bus. Common control buses are Modbus and so on.
(3) Event-oriented: It is called “network variable†in fieldbus technology, which simplifies the design of network communication to parameter setting. This not only saves a lot of design work, but also increases the reliability of communication. In the control bus system, it mainly refers to satisfying certain or certain types of specific functional requirements.
3, new features
(1) Control bus technology:
The control bus was introduced in the 1980s with the introduction of the distributed control BA system. Different from the fieldbus technology formed in the 1990s, the fieldbus technology is mainly oriented to the field of controlled devices, emphasizing the independence of work and the flexibility of configuration. In the modern intelligent lighting control system, in order to facilitate the connection with the upper computer, to ensure the maintainability and operability of the system, most of the mature and reliable control bus is used as the system bus. Table 1 is a comparison of the characteristics of three event-oriented control bus systems (hereinafter referred to as control bus systems), which are commonly used in the domestic market, for lighting control.
Due to the rapid development of the technology of intelligent building control systems, the openness, interoperability of the network and the control of large-capacity nodes through different communication media and different network structures are the development trends of current network control systems. With the advent of the Internet era in the new century, the BA system forms a three-layer structure of the field layer-automation layer-management layer, which corresponds to the Infranet-Intranet-Internet/Control Network-Enterprise Network-Internet Triple Network. The new generation of control bus system will emphasize the seamless integration with various types and layers of networks. In addition to the operation, operation and maintenance of the control bus system by the host computer through the network, the control bus system can directly enter the database of the upper computer. The system integrates management functions and control functions to meet the requirements of the ultra-high-speed information age.
In order to facilitate the promotion, some control bus systems have made their own system communication protocols open-ended, and established professional associations to organize and certify.
(2) Introduction of the dimmer:
Figure 5 Front edge phase control mode (top); trailing edge phase control mode (middle); trigger pulse (bottom)
Incorporating the original independent light control device into the control bus system not only provides a useful function for the system itself, but also makes a drastic change in the traditional lighting control method. Supported by the system bus and in conjunction with other sensor components and control devices, it provides the following features:
1 Dynamically control the illumination and provide the desired light environment with time, sunshine changes, or pre-programming;
2 Minimize unnecessary light flux and achieve good energy saving effect;
3 Through the soft start/soft shutdown function inherent in the dimmer, it can protect and extend the life of the light source and achieve economic return; it can be used with professional lighting control devices or other lighting control systems and other BA systems to achieve system integration;
Therefore, various dimming technologies are increasingly favored by lighting designers, and their use range has expanded from the theater stage to various architectural fields, entering thousands of households. Conventional dimmers use bulky devices such as series resistors or autotransformers. Later dimmers mostly use semiconductor devices for leading-edge phase-controlled triggering of AC mains (for resistive and inductive loads) and trailing edge phase-controlled triggering. Mode (applicable to capacitive load) regulation. The latest product is a dimmer called "Sinusoidal Voltage Converter" (SVC) (Figure 6), which is equivalent to a transformer whose voltage output can be changed. The output voltage no longer causes the waveform. Change, basically eliminate the interference of higher harmonics, more suitable for dimming of gas discharge sources. As the requirements for lighting control devices increase, better performance dimming devices will continue to emerge.
Figure 6 SUV dimmer block diagram
The application of dimmers is of great significance for the promotion of green lighting projects. In this field, the foreign design community has already proposed its own standards. For example, the United States Environmental Maintenance Agency (EPA) convened more than 2,000 lighting equipment manufacturers to sign and promote green lighting plans as early as 1990; the United Kingdom also stipulated that the number of incandescent lamps installed in the entire building should be limited to 10%, or incandescent lamps. The installation capacity is less than 12 watts per square meter, and China's new "Architectural Lighting Design Standards" even stipulates more stringent requirements. This worldwide green lighting revolution has made the application of new types of light sources such as new PL fluorescent lamps, ceramic metal halide lamps and LED lamps more and more widely, and the use of new dimming devices will undoubtedly enable the light control operation of new light sources. More handy to achieve a wider range of lighting control.
Continued: Development of contemporary electrical lighting control systems and their application in commercial projects (2)
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