| Abstract |
Thyristor converters are used in a wide variety of power system applications. they generate harmonics on both ac and dc sides. DC harmonic distortion drastically increases when the three-phase ac voltage system supplying the converter is unbalanced. An assymetrical firing angle technique for dc harmonic distortion minimization of thyristor converters under unbalanced voltage supply has been recently presented. However, the minimization technique requires the computation of some nonlinear transcendental equations, which are difficult to solve on-line by a microprocessor-based controller. In this paper an interpolation method known as dual kringing is used to obtain approximated compensation firing angles for the first order dc non-characteristic harmonics cancellation. Dual kringing interpolation procedures a set of analytical expressions, which approximate solutions to the transcendental equations. These equations can then be solved on-line in real time by a relatively low performance microprocessor. To verify the feasibility of the proposed method, a twelve-pulse ac/dc converter was assembled with a microcontrolled-based system. Simulations and experiemtnal results, which show the effectiveness of the proposed method, are presented. |
