In order to use current directly, voltage and frequency must be regulated. Voltage and frequency regulators are absolutes in wind energy conversion to electricity. Output voltage tends to naturally fluctuate due to varying torque input to the generator. Vibration shutdown controls are crucial to the long life of any medium to large size wind plant. Most quality systems utilize solid state controls to sense vibration or imbalance by applying the brakes automatically at the critical point.
Controls open up many options to the owner of a wind system.
The controls can tie the system into the utility grid directly, or feed direct to a load, can run AC current when there is an immediate need for it, and automatically switch to the DC storage bank when there is no AC load. The owner can leave the wind system unattended for long periods of time because monitoring of voltage, frequency and RPM is all provided for in the control box. The inverter takes the DC output from the battery storage system and through a conversion process changes the waveform to alternating current at the desired voltage and frequency. Depending on the overall requirements and uses of the wind system, either, none, some or all of the power is inverted to AC Since all inverters use up some power to operate themselves, only those appliances which operate solely on AC should operate through the inverter. There are three basic categories of inverters available and each differs widely in cost and efficiency ratings.