WIND ENERGY SYSTEMS - Cd3wd

Chapter 6—Asynchronous Generators 6–4
– Field modulated generator
– Roesel generator
• POWER CONDITIONER
– Diode rectifier
– Inverter
– Solid-state switching system
• ELECTRICAL LOAD
– Battery
– Water heater
– Space (air) heater
– Heat pump
– Water pump
– Fan
– Lights
– Appliances
– Electrolysis cells
– Fertilizer cells
If our generator produces ac, then a rectifier may be required to deliver the dc needed by
some loads or storage systems. Necessary switching may be accomplished by electromechanical
switches or by solid state switches, either silicon controlled rectifiers (SCRs) or triacs. These
switches may be used to match the load to the optimum turbine output.
The electrical load and storage components may have items which operate either on ac or
dc, such as heating elements, on ac only, such as induction motors, lights, and most appliances,
or dc only, such as electrolysis cells and batteries. Some of the devices are very long lived and
inexpensive, such as heating elements, and others are shorter lived and more expensive, such
as batteries and electrolysis cells. Some items can be operated in almost any size. Others,
such as electrolysis cells and fertilizer cells, are only feasible in rather large sizes.
Economics must be carefully considered in any asynchronous system. First, a given task
must be performed at an acceptable price. Second, as many combinations as possible should
be examined to make sure the least expensive combination has been selected. And third, the
alternatives should be examined. That is, a wind turbine delivers either rotational mechanical
power or electrical power to a load, both of which are high forms of energy, and inherently
expensive. If it is desired to heat domestic hot water to 40 o C, a flat plate solar collector would
normally be the preferred choice since only low grade heat is required. If the wind turbine
Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001