Stability Analysis of a Modulated AC/DC System Using the Eigenvalue Sensitivity Approach

This paper develops an optimal control strategy for improved dynamic performance of integrated ac/dc systems, based on power modulation techniques. The basic feature of the method is the minimization of the adverse reactive power interactions between the controls and voltage sensitive loads, which tend to reduce the effectiveness of the modulation process. A method for stability analysis, based on linearization techniques and eigenvalue sensitivities, is developed and applied to a typical ac/dc system with non-linearly voltage dependent load. The dynamic performance of the system, both with dc power modulation and power system stabilizer, is evaluated for various operating conditions, different load characteristics and different excitation systems. Finally, a dynamic simulation program is developed and used to obtain the exact transient response of the ac/dc system in the time domain. The simulation results presented in the paper verify the responses predicted from the linear eigenvalue sensitivity analysis.