Line excited and self excited induction generator
Line excited and self-excited induction generator:
The squirrel cage induction generators are basically used in two different configurations for wind power generation purpose.
· Self excited induction generators
· Line excited induction generators
SELF EXCITED INDUCTION GENERATORS
Fig: Self excited induction generator scheme
Self-excited induction generators are basically used for stand scheme a capacitor bank is connected to the system to supply the required reactive power to the induction generator. The self-excited induction generator scheme is shown in the Figure 1
LINE EXCITED INDUCTION GENERATORS
Fig: Line excited induction generator scheme
Line excited cage induction generators are most commonly used for wind power applications. These generators are robust, cheaper than its counter parts and need less maintenance. Cage induction generators have drawback that, due to the coupling effect between active and reactive power the transient response becomes sluggish and the control becomes difficult and complex. Because of this there arises stability problem when the system is connected with the grid. A lot of research has been done in recent past to improve the transient characteristics of induction machines. When induction machines are operated using vector control techniques, fast dynamic response and accurate torque control are obtained. Squirrel cage generators with shunt passive or active VAR (volt ampere reactive) generators generate constant frequency power through a diode rectifier and line commutated thyristor inverter.