Among small wind power plants, batteries are one of the important auxiliary devices. The battery plays an important role in storing electrical energy and stabilizing voltage in the DC power supply system.
First, the determination of battery capacity
Whether the battery capacity allocation is reasonable or not directly affects various technical and economic indicators of wind power generation. The capacity selection is small, and the surplus power generated when there is a lot of wind is not fully stored. The capacity selection is too large, one increases the investment; the second battery may be in a state of charge dissatisfaction for a long time, which will affect the efficiency and service life of the battery. Table 1 shows the investment of batteries in wind power generation equipment.
Generally, conventional charging is a "two-stage constant current charging". This method does not waste power, and the charging time is short, which is advantageous for prolonging the service life of the battery, and it is also much easier to calculate the battery capacity. The case of wind power is different from conventional charging.
Since the wind speed often changes, the current output by the motor is large and small, sometimes not, so the battery charging current and the required charging time are difficult to determine. For this practical situation, we use the following two calculation methods to determine the configuration battery capacity.
1. The balance calculation method.
The calculation steps are as follows:
a. According to the wind speed data provided by the local meteorological department, the wind speed from the initial working speed of the wind turbine to the different wind speeds within the range of the stop wind is counted separately for ten days.
b. According to the P=f(V) characteristic curve and wind speed data of the selected wind turbine, calculate the amount of electricity that can be emitted by the machine, and plot the annual power generation process curve. Figure—The annual power generation process line of the ED1.5~100 fan of Shangdu Muji Plant based on the wind speed data of the Inner Mongolian Right Rear Banner. It is calculated that the annual power generation of the aircraft is 276 degrees under local wind conditions. From the process line, it is seen that the power generation of each tenth varies greatly, with the most late 19 degrees in late April, and the lowest in late February is only 0.95 degrees, which is nearly 20 times different, indicating that it is necessary to configure the storage battery for energy storage adjustment.
According to the telecom condition, C calculates the electricity consumption by ten days, and gives the annual electricity consumption process line. The dotted line in the drawing shows.
d. Compare the power generation and power consumption process lines to determine the required battery capacity by generating electricity with less power than the period with the largest difference in power consumption (the shaded portion in the figure). The largest difference in the figure is 2. 3 degrees. Need to configure 2300 volt-hour battery, the actual choice of 12 volts 48 ampere battery 4 pieces. The total capacity is 2304 VA.
2. Empirical calculation
According to our pilot experience, in the wind conditions of the Chayouhouqi and Shangdu areas, the following formula can also be used to easily estimate the required battery capacity. In the formula: Q - the required battery capacity (Ah);
P——load power (watts);
T——hours of daily electricity;
U - standard battery voltage (typically 12 volts);
n——Battery reserve cycle factor; (determined according to wind conditions, generally takes 3~8 days)
K——discharge control coefficient, (take 0.75~0.8)
The above formula considers: 1 rated power of the electrical equipment, 2 local meteorological conditions, that is, the average time of no wind period, 8 in order to prevent overdischarge of the battery, the discharge should be controlled to a certain extent.
For example, in the case of the Chayouhouqi, a 100-watt machine is installed for three households to use electricity. Each household is equipped with a 12-volt 15-watt bulb and an average of 5 hours per day to calculate the required battery capacity. (The reserve coefficient is taken as 6 and the discharge control coefficient is taken as 0.8).
Choose 6 l 2 volt 48 ampere batteries with a total capacity of 288 ampere hours.
When determining the standard battery, it must be noted that the capacity of the storage oil group should be able to safely accept the maximum current intensity Imax output by the wind turbine.
Second, the battery operation mode
1. Fully charged. That is, the fan is installed centrally, centralized charging, and the battery is dispersed to the household, and two batteries of each household are rotated and used.
Wind power is subject to wind, especially for small fans. In the village, the wind is small, the wind turbines must be installed outside the village, and the rural areas where there are difficulties in wiring, Haote, is suitable for this way. Fans can be installed on sites with better wind energy to take full advantage of wind energy. The battery can be used to ensure full filling. weakness is:
1 More batteries are needed, which increases investment and electricity costs.
2 battery use efficiency is low (about 40%).
3 The battery has frequent charge and discharge rotation and short service life.
4 often carrying the battery back and forth to cause trouble to the user, and easy to damage the battery; careless handling, the electrolyte is easy to leak,
Will cause the battery to run out of liquid or burn out clothes.
2. Semi-floating operation mode. It is the working mode of fan (DC power generation) and battery parallel supply. When no electricity is used (daytime), the fan generates electricity to charge the battery; when there is no wind, the battery supplies power to the load; when there is wind, the fan generates electricity to float the battery and supply power. This method is mostly used for 1~3 households in a single machine. The capacity of the configured raspberry battery is small, and the investment is correspondingly reduced. The life of a semi-floating battery is generally longer and fuller, and the battery efficiency is about 50%.
3. Full float filling system. The battery is centrally installed in the charging room, and the battery pack and the wind power generator are connected in parallel to the load circuit, so that the battery is always charged in a small current. When the fan supplies power to the load, the voltage fluctuation caused by the wind speed fluctuation plays a stable role through the battery pack, ensuring normal power supply. This type of operation has a longer battery life than the above two methods, and the required battery capacity is greatly reduced, the power efficiency is improved, and the battery maintenance is simplified, and the efficiency of the entire power supply device can reach 60-70%. It is used in this way to check the right rear flag Hanbula wind power station.
Third, the type of battery selection
There are many types of batteries. At present, wind power is commonly used in lead-acid batteries. After the battery is filled, after 30 minutes, the liquid temperature is 15 ° C, and it is not necessary to perform initial charging. It is very advantageous to use electricity immediately in remote areas where the wind turbine has just been installed and does not have the initial charging conditions. The disadvantage of this type of battery is its large size and weight, which is inconvenient to handle. The aluminum-acid batteries sold in the market are mostly used for starting batteries for motor vehicles. The structure and manufacturing characteristics of the plates are not suitable for use in the charging and discharging conditions of wind power generation. The short life is usually only about 2~3 years. In a large-capacity wind power station, it is best to use a fixed acid-proof explosion-proof lead storage battery, which has a large capacity and a low electro-hydraulic specific gravity (about 1.21 at 15 ° C), reducing the plate and Corrosion of the separator can prolong the evaporation time, as well as anti-leakage measures, reducing the discharge to the ground.
Alkaline batteries are small in size. It is light in weight and has a service life of up to 15 years. It is also used in small quantities in our district. Alkaline battery life is 5-7 times longer than acid battery, but its price is several times higher than that of acid battery. From an economic point of view, we believe that it is more advantageous to use a lead-acid battery in small-scale wind power generation.
Fourth, the reasons affecting the service life of the battery
1. During the charging process, as the charging time increases, the battery electromotive force E also increases accordingly. At the end of charging, if the terminal voltage V is constant and the battery electromotive force E reaches the same value as V charge, that is, the battery internal resistance Y pool also drops to a small value, then the I charge should also be small. This is the correct charging method for the battery itself.
In the charging of wind power, there is no stable continuous charging current for a long time, and it cannot be charged according to a certain charging rate. Instead, the size of the wind dominates the level of the charging voltage, and even the current will occur at the end of charging. Large, not only to lose more power from the generator, but also because the electro-hydraulic boiling is too strong, the gas is too high, the temperature of the electro-hydraulic is too high, the battery plate active material is impacted and accelerated to fall off, thereby reducing the battery life.
2. Due to the lack of relevant knowledge of the user, the correct use and maintenance of the battery is poor, the degree of charge and discharge is not well mastered, and the phenomenon of overcharge and discharge is often caused, and the distilled water is not added in time, causing partial plate vulcanization. Or do not pay attention to the liquid temperature when adding liquid (when injecting a new battery), so that the temperature of the battery liquid rises very high, resulting in excessive bubbling and boiling, speed of movement, kinetic energy increases, the sealing glue is broken, resulting in active material of the plate Premature shedding, these are the main reasons for life.
3. The battery manufacturing quality is poor, its structure and electrical performance are not suitable for the requirements of wind power generation conditions, but also reduce the service life.
Fifth, the correct use and maintenance of the battery
In small wind power generation, the battery cost accounts for 24 to 46% of the total cost, and the annual depreciation expense accounts for more than 50% of the total cost. This is due to the high battery price and short service life. Therefore, it is an important issue to strengthen the use and maintenance of the battery and prolong its life. Computational analysis shows that the battery life is extended by one year, and the cost per kWh can be reduced by more than 0.13 yuan.
In order to improve the efficiency of battery use and extend its life, the following points must be achieved in use:
1. To understand the characteristics of lead-acid batteries, strictly in accordance with the provisions of the product manual for use and maintenance
2. Electro-hydraulic must be prepared with chemically pure sulfuric acid and qualified distilled water. In cold places, the specific gravity of the liquid temperature should be 1.285 at 15 °C.
3. The battery level should be 10-15 mm above the plate. When used, it is found that distilled water is added in time when the liquid level is too low.
4. Before wiring, strictly check whether the positive and negative signs of the battery are correct and whether the single cell has reverse polarity.
5. Before using the battery for the first time, it is best to charge it for 3~4 hours, which will be more favorable for its performance. Non-dry batteries must be charged before they can be used.
6. The electro-hydraulic temperature should be kept at around 20 °C, even if the electro-hydraulic temperature does not exceed 35 °C during charging. Pay special attention to antifreeze in winter. According to the data, when the temperature of the electro-hydraulic is within the range of 10 to 35 °C, the capacity of the battery increases or decreases by 0.8% of the rated capacity for each increase or decrease of 1 °C.
7. After filling, it will not be used within 12 hours, or it will be idle for a long time after use. It must be charged according to the regulations and then resumed. Source: tede.cn
8. Always screw on the filler plug, but make the vent clear, so that the vapor can escape. Keep the battery dry and clean and avoid self-discharge outside the battery.
9. When the electro-hydraulic specific gravity drops to 1.175, stop using it and charge it immediately.
10. Wire clamps of the same material as the battery should be used. If copper material clamps are used, a thin layer of Vaseline or butter should be applied to prevent corrosion.
11. It is strictly forbidden to place metal objects and tools on the battery to prevent short circuit between the poles.
12. There is no open fire in the charging room and electrical equipment that can generate electric spark to prevent fire.
Reduced, improved power efficiency, simplified battery maintenance, the entire power supply equipment efficiency can reach 60-70%. It is used in this way to check the right rear flag Hanbula wind power station.
Sixth, the type of battery selection
There are many types of batteries. At present, wind power is commonly used in lead-acid batteries. After the battery is filled, after 30 minutes, the liquid temperature is 15 ° C, and it is not necessary to perform initial charging. For the remote installation of the wind turbine, there is no remote charging condition
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