Capacitances Required For Self Excited Induction Generator Driven By Wind Energy For Constant Output Voltage

Abstract

In recent years, owing. to the increased emphasis on renewable energy resources, development of the self excited induction generator (SEIG) driven by wind energy has been of great significance. 'This is due to its reduced unit cost, brushless rotor construction, absence of separate DC source of excitation, ruggedness and ease of maintainance. Therefore, methods to analyse the performance of this generator are of considerable practical interest. The terminal capacitance in such machines must have a certain value so that self excitation may take place. This value increases as the machine is loaded. The value of terminal capacitance C depends on the machine parameters, its speed, load conditions and terminal voltage. The 'SEIG' has been simulated by several non-liner complex equations, an experimental relation is obtained between 'Xm' and airgap voltage 'Vg' from the reactance test for the used machine. A computer program is developed to obtain the magnetizing reactance 'Xm' and frequency 'F' for a given load, speed and assumed capacitance, using Newton-Raphson method to solve the highly non-linear complex equations. TI1e values of 'C' to sustain constant terminal voltage for different loads and different speeds were iteratively determined. These values of 'C' have been applied to an induction generator running in the laboratory at different loads. The ouput voltage was practically constant at the required value. The determination of tem1inal capacitance 'C' for different loads is repeated to give the same voltage Vt. Accordingly, the preformance curves of the machine were obtained at different values of speed and load conditions. Finally theoretical results are compared with experimental results which shows good agreement together.