Constant voltage and frequency operation of a two windings single phase self-excited induction generator [articol]

Abstract

This paper presents the steady-state and dynamic analysis of a two windings single phase self-excited induction generator (TWSPSEIG) equipped with an excitation capacitor and a compensation capacitor for operation at constant rated load voltage and frequency irrespective the no load or different load conditions. The performance equations at steady-state conditions are obtained by applying loop impedance method via the exact equivalent circuit models of the TWSPSEIG based on the double revolving field theory. Rather than the conventional methods of analysis, to get two non-linear higher order equations keeping the magnetizing reactance and the frequency as unknowns, these equations are rearranged to get two second order equations keeping the values of the excitation capacitor and the compensation capacitor as unknowns for given values of generator parameters, prime mover speed, output frequency and load impedance. The two second order equations are solved using simple iterative method to calculate the optimum values of the two capacitors under the constrains that the load voltage and frequency are constant at rated values. The range of capacitors variations required for maintaining constant rated load voltage and frequency while supplying variable load at variable prime mover speed are calculated. The steady-state results are confirmed by developing a dynamic model of the TWSPSEIG incorporating its nonlinearity behavior and various no-load and load conditions. The dynamic behavior of the TWSPSEIG at different operating conditions proves the capabilities of the proposed configuration and calculations method to maintain both the load voltage and frequency constants.