2 The new Solar street lamp controller The conventional controller controls the charging/discharging of the battery. When the overcharge point is reached, the solar panel is disconnected from the battery; when the over-discharge point is reached, the connection between the battery and the load is cut off. Achieve protection of the battery.
The use of conventional controllers in street lighting systems has the potential to cause this: due to insufficient sun exposure during cloudy days, the nights are still used at maximum load. In this way, after a few days, the battery will be over-discharged, which will cause the street lights to be turned on at night. The feeling for people is that although solar street lights have the advantages of environmental protection, they are not reliable, and they are not reliable. It will not be used for a long time.
Bureau, water volume/area ratio calculation, performance prediction, etc. have exerted great practical value. In addition, in the engineering bidding, the system also plays a certain role in enhancing the amount of tender information and the accuracy of the data.
+2- In practice, it is found that because the meteorological data database is usually quite large (even in Mb), it brings certain difficulties to the realization of basic functions such as data loading, query and processing, which makes the user wait longer. Especially when the computer performance is low, the waiting time will be longer. In addition to improving algorithms, optimizing code, and using snapshot tables, we have also taken the approach of opening up memory blocks by dynamically allocating a certain amount of storage space in the computer's memory for temporary storage of updated data. Since the memory is read faster than the hard disk space, the execution speed is also responsive. However, this approach also has the disadvantage of sacrificing memory space and affecting the operation of other applications. Therefore, it is recommended that when designing other solar application software systems, the above factors should be carefully weighed to improve the overall performance of the software.
As a research and development specialized solar system auxiliary design software, the current work of this system is only preliminary, and there are still many aspects to be further improved in the future. For example, considering the particularity of meteorology in the low latitudes of the south and the cold latitudes in the north, the selection of rainfall parameters, relative humidity, atmospheric pressure, etc. should also be considered in the selection of meteorological parameters. In addition, from the perspective of long-term development, the use of medium- and high-temperature solar energy in the future will require more abundant meteorological parameters.
In today's informationization, the final development direction of the solar meteorological data database query system will be single-machine combat, and gradually move toward a networked strong array. One of the more typical service modes is the three-layer 6eb structure consisting of network protocols TCP/IP, S, and ASP, as shown.
Up to now, the design and development of solar energy professional software in China is still progressing slowly, especially the self-developed solar professional software is relatively rare, and compared with some well-known foreign software (such as Fchart, etc.), there are still quite a lot of domestic software. Compared with the current situation of the rapid development of China's solar industry, it is very uncoordinated. However, we believe that as long as we continue to work hard and explore, we will one day occupy a place in the field of solar system auxiliary design software.
The new Solar Street Light controller we developed uses the battery residual capacity control method to control the discharge process of the battery. The theory it is based on is a mathematical model of the relationship between residual capacity (SOC) and terminal voltage during discharge of a battery based on electrochemical principles: a constant of voltage change, 0.1 to 0.2; b is an electrochemical polarization term constant , 0.1~0.15; c is the internal resistance polarization term constant, 0.08~0.15; Vr is the static voltage (V) of the battery charging initial or discharge end; SOC is the state of charge of the battery or the capacity at any time, (I) I is the charging current or discharging current, (A); T is the actual temperature; DOD is the battery discharge depth, (K); K is the temperature coefficient, the temperature changes by 1, the percentage change of the capacity, (K).
The solar street lamp system composed of the new controller is a closed-loop adaptive control system, which can automatically adjust the output load power or working time according to the measured battery residual capacity (SOC), effectively preventing the battery from being over-discharged, thereby greatly Extend the service life of the battery and improve the reliability of the system.
The cycle life of the battery is closely related to the depth of discharge of the battery. The valve-regulated lead-acid battery has a cycle life of more than 1500 when the depth of discharge (DOD) is 20K. When the depth of discharge is 50K, the cycle life will be reduced to About 500 times, when the depth of discharge is 80K, the cycle life will be only about 200 times.
It is the relationship between battery discharge depth and cycle life.
It can be seen that the cycle life when the discharge depth is below 20K is that the discharge depth is more than three times that of 50K, and the discharge depth is more than five times that of 80K. Controlling the battery to work as much as possible in a shallow discharge state (SOC > 50K) will help to extend the life of the battery. The control flow chart of the single lamp system and the dual lamp system is as follows.
3 hardware design program According to the functional requirements of the system, we use the single-chip design of the solar street light controller, the circuit principle is as shown.
(1) It can be seen from the figure that the core of this controller is a piece of AT89S52 single chip. This single chip is low cost, low power consumption, high performance, easy to expand, and has 8K program memory. The calculation and control of SOC are completed by this chip.
The chip has a temperature sensor and A/D conversion function, and the converted serial data communicates with the CPU through onewire ("wire"). The measurement temperature ranges from -55= to +125=. The solar cell has two functions, one is to charge the battery, and the other is as a photosensitive element, which can be judged whether it is dark or too bright, so that the solar street light can be automatically lit when it is dark. And the function of automatically turning off the lights at dawn.
The design of the control channel, the microcontroller uses optocoupler isolation for the control circuit of the charging and discharging power MOFFET tube. At the same time, the switch of the two AC lamps adopts the bidirectional thyristor as the switching component, and the optocoupler is also isolated between the thyristor and the single chip microcomputer. The output channel adopts the optical isolation technology to improve the reliability and anti-interference ability of the system.
4 New solar street light controller features high reliability: Since the controller uses the battery residual capacity control method to control the load, it can ensure that the battery does not over discharge, thus ensuring that the street light is bright every night to make up for the previous solar street light system due to the yin The battery causes insufficient charging of the battery, which causes the battery to be over-discharged and cannot properly illuminate the street lamp. Long life: ensure that the battery is in the shallow discharge state to the maximum extent, that is, the discharge depth is generally not more than 50D, which can greatly extend the service life of the battery.
Automatic switch control: This controller uses the light-sensitive characteristics of the solar panel to always ensure that it lights up when it is dark, and at the same time in the program rate and working time, in order to make the street lamp reliable one by one! Dual flexibility of work and battery but discharge: The controller can be set up in several combinations: single/double, two AC, one AC, one DC, two DC, one AC, one DC Charge control: Pulse width modulation control.
Table 1 Recording time Single lamp system Battery voltage V Dual lamp system Battery voltage V Weather conditions February 2nd sunny February 3rd sunny February 4th sunny February 6th clear February 9th sunny February 10th sunny February On the 11th, cloudy and cloudy February 12, the secretary-general of the Ministry of Science and Technology, the chairman of the China Solar Energy Society, the editor of the solar energy journal, Mr. Shi Dingqi, and the president of the World Wind Energy Association, D+.p+ebenmaegaad, held a cordial talk in Beijing (Chang Mianzeng Photography). 1 channel solar battery, 1 channel battery; output control: 2 channels of DC (any one of which can be connected to the inverter), 2 channels of AC; solar cell maximum input current: 20A; suitable for 12V or 24V battery; DC output: single channel 10A; AC output: 220V/80. 5 test results In order to verify the protection of the new solar controller to the battery, we used this new solar street light controller to configure two solar street light systems, specifically after the battery of the single lamp system was emptied It is put into operation again; the dual-lamp system, which should be equipped with a 120-solar battery, is only equipped with a 50p solar cell.
Pool: 12V/65AH (on January 29, the battery voltage is 9.63V, which is the venting state); new solar controller: 1; DC energy-saving lamp: 11 (designed to work an average of 10 hours a day).
Battery: 12V/76AH (on January 29, the battery voltage is 12.90V, which is full state); new solar controller: 1 set; AC energy-saving lamp: 18+9 (designed for an average of 10 hours per day for double lights).
From February 2nd to February 12th, the streetlights automatically light up before the test record every evening.
The test data is shown in Tables 1 and .
The test results analyzed that the single-lamp system battery was 9.63V on January 29, which was lower than the over-discharge voltage of 10.8V, and the remaining capacity was 0H. The system was installed. After 3 days of operation, to 9:30 on February 2, the battery The voltage is 11.86V. In the next few days, the controller keeps the system in the lowest load operation state, the battery voltage is gradually increased, the remaining capacity is gradually increased, and the remaining capacity is restored to over 90%. At this time, the controller controls the street lamp system to be fully loaded. Work (10 hours of work per night), more energy used at night, less energy during the daytime sunshine, and the remaining capacity of the battery is gradually reduced, and finally reach equilibrium, staying between 6-8 hours per night.
The dual lamp system performs just the opposite. The battery is 12.90V on January 29, the remaining capacity is greater than 90%, the system is installed, after 3 days of full load (double light working 10 hours per night), after 17:30 on February 2, the battery voltage has dropped. For 12.59V, the system automatically reduces the load and working time in the next few days, and drops to 11.99V at 9:30 on February 9th. The remaining capacity has dropped below 50%. At this time, the controller keeps the system at the lowest load. In order to make the system work in the greater than out state, since most of the daytime is cloudy on the 10th and 11th, the recovery is not very obvious, but the basic guarantee is equal to the output.
6 Conclusion 6.1 From the results of the two systems, the controller controls the use of the load according to the remaining capacity of the battery, so as to ensure that the nightly lighting, and the remaining capacity of the battery is not less than 50%. 6.2 The controller has ideal adaptive function. Even if the configuration of the solar street light system is unreasonable (small horse-drawn cart), after using the controller, after a few days, the power and working time of the street light have been automatically adjusted to the best state of the system in this season. And to ensure that the lights are on every night and the battery is not discharged.
6.3 This new solar street light controller can also be used in stand-alone photovoltaic systems and photovoltaic household power systems. The company can program the control of the discharge process according to user requirements.
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