Optimization of dynamic systems: A trigonometric differential evolution approach

In many chemical engineering applications, one frequently encounters dynamic optimization problems. The solution of these types of problems is usually very difficult due to their highly nonlinear, multidimensional and multimodal nature. In fact, several deterministic techniques have been proposed to solve these problems but difficulties related to ease of implementation, global convergence, and good computational efficiency have been frequently found. Recently, evolutionary algorithms (EAs) are gaining popularity for solving complex problems encountered in many engineering disciplines. They are found to be robust and more likely to locate global optimum as compared to several deterministic (gradient based) optimization methods. This paper deals with the application and evaluation of one such algorithm called trigonometric differential evolution (TDE) algorithm for solving dynamic optimization problems encountered in chemical engineering. This is a modified version of differential evolution (DE) which provides enhanced convergence speed. Both DE and TDE algorithms have been applied to seven dynamic optimization problems (five optimal control problems and two kinetic parameter estimation problems) taken from recent literature. The obtained numerical simulation results indicate better performance of TDE as compared to that of DE particularly for problems involving large number of control stages.