Design and Implementation of Intelligent LED Street Light Energy Saving Control System

introduction

The current global energy consumption has increased dramatically and the energy shortage is extremely scarce. The power shortage has endangered our lives. Saving energy has become a very urgent issue. As a new type of green light source, LED lighting has the advantages of energy saving and environmental protection, small size and long life. It is bound to be the development trend of ordinary lighting in the future.

In this paper, the intelligent street lamp lighting control system designed for LED lighting is applied to the road lighting. Therefore, it is difficult to feedback the various status of the street lamp in the existing road lighting control system, the problem of not switching the street lamp in time, and the low energy utilization rate. improve.

1 system overall design

1.1 Overall Design Block Diagram The overall design block diagram of the system is shown in Figure 1. This article consists of 51 MCUs as the central module, power supply module, monitoring environment module, constant current source drive module, parameter setting and display module.

1.2 The power supply module uses a three-terminal regulator integrated circuit. After the transformer is stepped down, it is bridge-rectified and filtered, and then the DC power supply is obtained through the three-terminal regulator.

1.3 LED monitoring environment module

1.3.1 Ambient light and dark change sensor environment light and dark change sensor mainly detects whether the intensity of light should switch the street light. The system uses photodiode and op amp comparator as the sensor for photometry and fault detection. The photodetection sensor circuit is shown in Figure 2. When daylight rays enter the glass window of the photodiode, the carriers of the PN junction are excited to generate electron-holes, ie, photocarriers. Under the action of an electric field, photocarriers participate in conduction, forming a reverse current much larger than the dark current, called photocurrent. At this time, the +5V voltage flows through the photodiode, and when the input voltage drops to the threshold voltage of the inverter 74HC04, the inverter flips, the P2.1 port of the microcontroller reads high level, and the MCU controls the LED street light to be turned off. When there is low light or no light (at night), because the dark resistance of the photodiode is very large, the input voltage of the inverter is relatively high, so that its output is low, and the MCU controls the LED street light.

1.3.2 Traffic condition detection sensor uses infrared sensor to automatically adjust the street light

When the vehicle reaches the infrared sensor receiving range, the LED street light is on. When the vehicle is out of range, the LED street light is off, and the whole system control circuit is the same, thereby improving energy utilization and saving power.

1.3.3 Sound and light alarm sound and light alarm device is the sound of buzzer and LED

The basic device for light alarms. When the LED street light in a branch of the system is not bright, it is judged that the street light is faulty. The method of detecting by the photosensitive sensor is used in the system to detect whether the LED street light is on or off, thereby determining whether there is a fault. When there is a fault, the single-chip microcomputer drives the buzzer to alarm and simultaneously emits the corresponding diode, and displays the address number of the current fault street light through the LED digital tube, so as to make timely adjustment.

1.4 Constant power drive LED circuit The first is to avoid the drive current exceeding the maximum rated value, affecting its reliability; the second is to obtain the expected brightness requirements, and to ensure the consistency of each LED brightness and chromaticity. In this case, the LED constant current source drive module is used to ensure energy-saving operation.

This paper chooses constant-current driving LED lighting with high cost performance and improved performance. Since the luminous stability and efficiency of LED are closely related to its temperature, uninterrupted running time and its own parameters, its luminous efficiency will decrease as the temperature increases. If the "constant temperature" circuit is used to ensure the performance of the LED itself, the hardware cost is high and the stability is degraded. In this paper, a constant current driving circuit (Fig. 3) is adopted. This circuit has the advantage of keeping the light intensity (optical power) of the LED output constant, thereby eliminating the fluctuation of the light source and improving the energy utilization rate.

In Figure 3, I1, R1, R2, Rf, R4, and C1 form an I-V conversion circuit. The output voltage is proportional to the LED's light intensity output and is fed back to the op amp. The A2 and NPN transistors form the V-I converter, which performs the difference between the given signal UG and UP. The difference signal drives the LEDs, keeping the intensity of the LED output constant, thus improving energy efficiency.

1.5 parameter setting and display module

The modification and setting of the current date and time; the setting of the street light working mode; the detection of the street lamp fault and the display of the corresponding unit fault, the address number of the fault street light, and the fault alarm display function.

2 system software design

The system program flow is: after the system is initialized, it enters the default working mode of the street light. The default working mode of the system is to detect the ambient light and dark switch mode, and determine whether to turn on the LED street light according to the ambient light intensity. When entering the setting mode for setting, the set mode includes: setting of output power, setting of date and time, setting of working mode, alarm and display of corresponding unit failure. After the setting is completed, wait for the input of the external detection signal, judge the reception as the normal switch street light signal, environmental monitoring signal, traffic condition signal, the MCU processes the corresponding signal, then controls the switch street light, and accumulates the street light switch time, and displays it through the LED digital tube. When there is a fault, the single-chip microcomputer drives the buzzer to alarm and simultaneously emits the corresponding diode, and displays the address number of the current fault street light through the LED digital tube, so as to make timely adjustment.

3 functional test

The system can automatically turn on and off the light according to the light and dark changes of the environment. When the day is bright, the light is off. When the environment is getting darker, the night light is on. Moreover, the lighting state of the street lamp can be automatically adjusted according to the traffic situation, that is, when the pedestrian vehicle comes, the light is turned on, and after the light is turned off, each street light is like this, which greatly saves electric energy. The system has a clock function, which can set the time for displaying the switch lights, and can control the entire branch or each street light to turn on and off the lights on time. When the street lamp fails, it can sound and light alarm in time, and display the address number of the fault light on the LCD.

The test results show that the output power of the street lamp driving power supply can be automatically reduced according to the set requirements within the specified time. The power can be set and adjusted within the range of 10% to 100%, and the adjustment error is less than 2%, which realizes the intelligent control of the street lamp. , saving electricity and human resources.

4 Conclusion

In order to solve the problem that the lighting control method and management method of the urban street lighting system are backward and the technical content of the used lamps is low, this paper adopts energy-saving and environmentally-friendly LED lights as the light source, adopts scientific and effective detection and control technology, and realizes the running time timing display. The constant current source drives the LED street light, switches the street light according to traffic conditions, fault detection and alarm display, etc., which saves energy resources, reduces system running cost, and has high cost performance, which has practical significance.

references:
[1] Yang Bangwen. New sensor practical book [M]. Beijing: Mechanical Industry Press, 2005.
[2] Luo Hairong. Research Status and Development Trend of Light Emitting Diodes [J]. Semiconductor Optoelectronics. 1996 Vo117(4): 299~303.
[3] Gao Jixiang. Analog Electronic Technology (Second Edition) [M]. Beijing: Publishing House of Electronics Industry, 2007.

About the Author:
Chen Bin, born in 1981 in Xinle City, Hebei Province, Shijiazhuang Information Engineering Vocational College, Master, Instrument Automation.

Edit: Sophy