STEADY STATE ANALYSIS OF GRID CONNECTED INDUCTION GENERATOR USING AC VOLTAGE CONTROLLER

Abstract

Traditional wind turbines are equipped with induction generators. Induction generators are preferred because they are inexpensive, rugged, and require very little maintenance. Unfortunately, induction generators require reactive power from the grid to operate. In grid connected induction generator, the voltage and frequency are fixed thus the power factor is fixed by its slip and its equivalent circuit parameters are not affected by the load. The quadrature component of the output current is nearly constant for any fixed terminal voltage and frequency and leads the voltage. It is necessary, therefore, to operate such generators in parallel with synchronous machines. These synchronous machines do not only supply the quadrature lagging current demanded by the load but also supply sufficient quadrature lagging current to neutralize the quadrature leading component of the current delivered by the induction generator. Induction generator when driven by wind turbine is liable to run near its synchronous speed when the wind speed is low. This results in operation at 'bad power factor and low efficiency. To overcome this drawback of the generator at such loads, it is recommended to lower its terminal voltage. Thus an ac voltage controller used as an interface between the network and generator which are useful in this concern. Symmetrical angle control was used to control the voltage of induction generator. In this report, the steady state performance of grid connected induction generator using ac voltage controller is analyzed for different conduction angle for different rotor speed and the graph is plotted for different parameter with the variation of the conduction angle. For feasible operation of the machine the voltage of the machine can be control for higher values of conduction angle.