Introduction to Small Wind Turbine

First, the use conditions of small wind turbines

Small wind turbines should be used in areas with abundant wind resources. That is, the annual average wind speed is above 3m/s and the annual effective wind speed of 3-20m/s is above 3000h. The annual average effective wind energy density of 3-20m/s is above 100w/m2. When choosing to use wind turbines, we should know well and avoid blindness, so as to make full use of local wind resources, maximize the efficiency of wind turbines, and achieve higher economic benefits. 

It should be pointed out that in areas with abundant wind resources, it is best to choose the wind turbine whose rated wind speed is consistent with the local optimal design wind speed. If we can do this, it is of great significance both in the choice of wind turbines and in the economic significance of utilizing wind resources. Wind tunnel test proves that the conversion power of wind wheel is proportional to the cube of wind speed, that is to say, wind speed has the greatest influence on power. For example, if a wind turbine with a rated wind speed of 8m/s is installed in an area where the optimal design wind speed is 6m/s, the rated annual output power of the wind turbine is only 42% of the original design output power, that is, the rated output power of the wind turbine is 58% lower than the design value. If the rated design wind speed of the selected wind turbine is higher, then its rated power output effect is more unsatisfactory. However, it must also be pointed out that the rated design wind speed of the wind generator is low, the diameter of the wind wheel and the motor should be increased, and the cost of the whole machine should be increased correspondingly. The economics of the manufacturing and the product are not worth it. 

Second, The General Requirements For The Use Of Small Wind Turbines 

At present, small wind turbines are using batteries to store energy, household appliances are provided by batteries. Therefore, the general principle of electricity is that the battery can be replenished by the wind turbine in time after discharge. That is to say, the amount of energy in the battery is roughly equal to the amount of energy used by the appliance (generally measured in days). 

The following is an example to illustrate this problem: a wind turbine is used in a region with a rated wind speed output power of 100W. If the rated wind speed of the region is blown for 4h in a day, the energy output and stored in the battery of the fan is 400Wh a day. Considering that the conversion efficiency of lead battery is 70%, the actual available energy of user electric appliance is 280Wh. If the appliance used by the user has: 

(1) Two 15W bulbs, using for 4h, the energy consumption is 120Wh; 

(2) A 35W TV set, using 3h, the energy consumption is 105Wh; 

(3) A 15W tape-recorder, which can be used for 4h, consumes 60Wh. 

The total energy consumption above is 285Wh. 

In this way, the total daily energy consumption of electrical appliances exceeds the energy provided by wind turbines by 5Wh, which is the so-called "pay more than you spend" electricity; This kind of income does not pay the electricity, will make the battery in the state of loss of power. If you often use electricity for a long time, it will cause serious power loss and damage of the battery and shorten its service life. 

The above example assumes the power consumption of the wind turbine under the rated wind speed. In fact, due to the variability and intermittency of wind, the wind varies in both size (wind speed) and blowing time (wind frequency). Therefore, when using electrical appliances, we should do more electricity when the wind condition is good, and less electricity when the wind condition is bad. This requires the user to summarize the experience carefully when using. 

In addition, where conditions exist, a kilowatt diesel generator set can be provided for users to supplement and charge the battery when the wind condition is poor, so that the battery can provide uninterrupted power. 

Three, The Reasonable Matching Of Small Wind Turbine 

The electricity produced by a small wind turbine is first stored by a storage battery, which then supplies electricity to electrical appliances. Therefore, it is necessary to carefully and scientifically consider the reasonable matching between the power of wind turbine and the capacity of battery and the storage of energy in the quiet wind period. At present, small wind turbine and battery capacity are generally in accordance with the input and output equal, or input is greater than the output of the principle of matching. That is: 

100W wind turbine matching 120Ah battery (60Ah2 pieces); 

200W wind turbine matching 120-180Ah battery (60 or 90Ah2); 

300W wind turbine matching 240Ah storage (120Ah2); 

750W wind turbine matching 240Ah battery (120Ah2 pieces); 

1000W wind turbine matches 360Ah battery (120Ah3). 

Practice has proved that: if the matched storage battery capacity does not meet the requirements of wind turbine energy, the following problems will occur: 

(1) When the capacity of the battery is too large, the energy from the wind turbine cannot guarantee sufficient power for the battery in time, resulting in the battery is often in a state of loss of power. Shorten the battery life. In addition, the capacity of the battery, the price and the use of the cost increases, to the economy also caused unnecessary waste. 

(2) the capacity of the battery is too small, so that the battery is often in the state of overcharging. If the wind turbine is stopped because of sufficient electricity, the efficiency of the wind turbine will be seriously affected. Battery long-term overcharging will cause early damage to the battery, shorten the service life. 

In addition, the reasonable matching of small wind turbines and the matching of electrical appliances is also a content that can be ignored. In the selection of electrical appliances should also be in accordance with the battery and wind turbine matching principle. That is, the energy consumed by the optional appliances should match the energy output of the wind turbine. But it should be pointed out that the emphasis of the matching index is "energy", not confused with power. In the selection of electrical appliances, we must also pay attention to the requirements of electric suppression, at present, the small wind turbine distribution box is equipped with 12V, 24V and TV special socket, user use, to select the corresponding socket for the voltage value required by electrical appliances, the TV should be specially plugged in the TV socket. 

If an AC power device is used, an inverter that meets the power requirements must be prepared to convert the DC current of the battery into AC power of 220V and 50Hz.