Suboptimal Control of Power System Dynamics Using a Gradient Method

Since the development of large - scale interconnected power systems , many new power system dynamic problems have emerged. One of the most important problems is low frequency intersystem oscillations. Although many techniques have been developed to improve dynamic stability of power systems, by damping of low frequency oscillating modes , the new solutions can be devised to improve the computational process and with the aim of still more economical results. In the present work , a new solution for suboptimal control of power system dynamics based on the nonlinear gradient approach has been developed. The choice for control feed back variable is based on a primary sensitivity analysis which only selects the most effective feedback variables to bring the system dominant modes to predefined locations. The method has the advantages of being more efficient computationally and it would allow for a closer solution to optimal solution than other methods of suboptimal control. The method applied to a three machine system and the results are compared with optimal control and another suboptimal control results which shows the advantage of new method.