Analysis of the superiority of solar streetlights using complementary solar and commercial power
The world economy has not yet emerged from the financial crisis today The climate change is getting worse and worse. How to reduce energy consumption, reduce emissions, and use clean and recyclable energy issues has been highly valued by various countries. China's new energy industry has entered a stage of rapid development, new technologies have continued to advance, and scale has been expanding. Especially in the solar industry, the domestic market is widely used in the fields of hot water, power generation, street lighting, etc. The use of non-renewable energy such as low oil and coal, all in the country, for rural road lighting, all adopt solar power supply mode. After several years of investment, it has been popularized nationwide, but the problem has also appeared: The countryside has less than two-thirds of the light per year; 2 the battery has a short life. To this end, a more reliable solution is proposed to improve the service life of the battery and ensure reliable nighttime lighting effects.
Foreword: Energy is an important material basis for the development of the national economy and people's lives. In the past, energy based on fossil fuels such as coal, oil and natural gas. Body
The system has greatly promoted the development of human society. With the rapid decline of non-renewable energy sources, countries are gradually recognizing the importance of energy to human beings, and more aware of the damage to the environment and ecosystems in the process of conventional energy utilization. Countries have begun to manage and alleviate the deteriorating environment according to national conditions. And put renewable, non-polluting, clean energy development and utilization in an important position, especially solar energy. In order to save energy, the state now strongly advocates the use of solar energy as an energy supply scheme for street lighting. Due to the high cost of solar streetlights, it has brought great difficulty to the promotion and popularization. The state has applied the one-time paving method to the local government for construction. Subsidies, rural lighting projects across the country have now been fully popularized.
However, after several years of application, there are two common problems:
First, due to the use of solar panels in the sunny day to generate electricity and store in the battery for night lighting, in many rural areas in China, smog and cloudy time account for more than one-third of the year. Time, the battery storage energy is low, the lighting effect is not up to the requirement; secondly, the battery has a serious impact on its service life due to overcharging and discharging process, it has to replace the new battery within 5 years, and some places must be replaced in only 3 years. The replacement of a batch of batteries has caused serious waste of resources and also affected the nighttime illumination of rural roads.
2 Solution
Change the original power supply scheme, supplementing each other with light energy and electric energy The street lighting method has far-reaching significance for the improvement of the current solar street lighting system. The principle is to use solar cell power generation as the main street lighting system supplemented by ordinary 220V AC power. With this power supply scheme, the photovoltaic battery pack and battery capacity can be designed to be smaller, basically the daytime sunshine, the same day The solar battery is used to simultaneously charge the battery, and when it is dark, the battery discharges to light the load LED.
In rural areas where there are basically more than two-thirds of fine weather throughout the year, there are more than two-thirds of the time in the year. Using solar energy as lighting energy, the remaining time is supplemented by commercial power, which not only reduces the one-time investment of solar photovoltaic lighting system, but also has significant energy saving and emission reduction effect. It is an effective method for promoting and popularizing solar LED street lighting at the present stage. One. In the past, solar street lamps were powered by batteries. Due to frequent charging and discharging cycles, and overcharge or deep discharge often occurred, battery performance and cycle life became major problems. The valve-regulated sealed lead-acid battery has the advantages of no maintenance, no hydrogen and acid mist discharged into the air, good safety, and low price, and thus is widely used. Battery overcharge, overdischarge and battery ambient temperature are all important factors affecting battery life, so it is important to take protective measures in the controller. And in the actual use process, the battery life is significantly shortened, only used less than 5 years, in other words, the solar LED lighting system installed 4 years ago, all have the problem of replacing the battery, how to improve its service life is a An urgent problem to be solved. In the complementary street lighting system of light energy and electric energy, LED street lamps are powered by solar energy and commercial power complementary controllers.
Because the sun varies greatly with the weather, when the sun is strong during the day, the solar panel charges the battery; the battery at night Power the load. On cloudy days, the load power is taken from the battery, and when the battery discharge voltage drops to the minimum allowable limit, it is automatically converted to the mains supply. When the system works, the output voltage of the solar panel and the voltage of the battery are detected in real time, and according to the different conditions of the respective voltage values, the solar battery is controlled to charge the battery, and the LED is controlled according to the set street lamp time control or light control mode. Whether the street light is on, and the power supply mode is properly switched between the battery and the mains. How to judge whether the weather is good or bad? How to judge whether to use battery or power supply? This requires a reasonable control switching device to implement, first to timely track the charging voltage and discharge voltage of the battery, and timely determine the day when the sun is shining, after the sun sets, the storage state of the battery: voltage and watts Does it meet the night use standard?
In addition, in the days when the sun is not bright enough, it is also necessary to accurately determine the battery charging situation: voltage and current and power When the battery supply voltage is low to the specified value, it must be switched to the mains supply in time to ensure the night lighting effect of the street light. The use of optoelectronic complementary technology can improve reliability and reduce cost. It is the best choice for solving solar LED street lighting. The matching relationship between battery capacity and solar panel capacity is calculated according to the LED street lamp load. The solar street light controller utilizes accurate discharge control corrected for battery discharge rate characteristics. The discharge end voltage is a control point corrected by the discharge rate curve, which eliminates the inaccuracy of the simple voltage control overdischarge and conforms to the inherent characteristics of the battery, that is, different discharge rates have different final voltages. The series PWM charging main circuit is used to reduce the voltage loss of the charging circuit by nearly half compared with the charging circuit using the diode. The charging efficiency is 3%-6% higher than that of the non-PWM, which increases the power consumption time. At the same time, the crystal timing control is used, and the timing control is accurate. The potentiometer adjustment control set point is canceled, and the flash memory is used to record each working control point, so that the setting is digitized, and the error of accuracy and reliability of the control point due to the potential deviation, temperature drift, etc. of the potentiometer is eliminated. Using digital LED display and settings, all settings can be done in one click, making it extremely easy and intuitive to use.
3 application examples
Dalian Ludao Electromechanical Automation Co., Ltd., since 2009 Several hundred ordinary solar street lamps have been installed in the exchange island community of Dalian Changxing Island National Economic Development Zone. In recent years, hundreds of batteries have been replaced one after another. The main problem is that the batteries are not working properly. Some rural areas are foggy and cloudy all year round. The street lamps are not able to guarantee the nighttime lighting due to the solar panels. After consultation with the local authorities, the solar street lamps in some areas will be reconstructed, and the complementary power supply modes of light energy and electric energy will be used. The transformation has been completed so far, the original solar plates have not been replaced. The original battery voltage and current detection, according to the voltage and power, automatically switch between solar and commercial power, whether it is sunny or cloudy, the night lighting effect has been improved, so far, no replacement.
4 Conclusion
This proposal is based on our company's solar streetlights and the city for many years. Some problems found in the construction and maintenance of circuit lights, for this reason, put forward some of their own ideas, I believe it will have a certain guiding significance. The traditional solar LED controller does not consider the main problem of battery life. It does not use real-time and effective control for overcharging and over-discharging. Especially on cloudy days, it mainly relies on battery discharge to ensure illumination, which greatly increases the burden on the battery. At the same time, it lacks detection and protection links, reduces the service life, adopts the method of supplementing light energy and electric energy, and reasonablely controls the excessive use of the battery, which will be well promoted in practical applications.