ON-LINE ECONOMIC POWER DISPATCH USING NATURE INSPIRED ALGORITHMS

Abstract

Economic load dispatch (ELD) is one of the fundamental issues in power system operation. It has objective of dividing the power demand among the online generators in economic way while satisfying various constraints. A major challenge for all power utilities is to not only satisfy the consumer power demand while maintaining its quality, but to do so at minimal cost. Thus, the main aim of electric utility has been identified as to provide the smooth electrical energy to the consumers. While doing so, it should be ensured that the electrical power is generated with minimum cost. The economic load dispatch plays an important role in the operation of power system, and several models by using different techniques have been used to solve these problems. Several traditional approaches, like lambda-iteration and gradient method are utilized to find out the optimal solution of non-linear problem. More recently, the soft computing techniques have received more attention and were used in a number of successful and practical applications. Nowadays, many powerful optimization algorithms are available which are categorized as nature inspired algorithms. Nature inspired algorithms are those whose concepts are inspired by natural phenomenon. The main motivation behind nature-inspired algorithms is the success of nature in solving its own myriad problems. Indeed, many researchers have found these nature-inspired methods appealing in solving practical problems where a high degree of intricacy is involved and a bagful of constraints need to be dealt with on a regular basis. For solving ELD problems, nature inspired algorithms have shown promising results than the other numerical approaches. The purpose of this work can be divided into three parts. i) Formulation of economic dispatch problems considering various constraints of the system, ii) description of nature inspired algorithms and procedure for solving ELD problems, and iii) application of the nature inspired algorithms to solve ELD problems. The ELD problems are formulated in two broad ways. The types of problems consider only economic operation for supplying a particular load demand which is considered as single objective economic dispatch problems. The second types of problems formulation consider economic operation along with emission minimization etc., which is considered as multi-objective economic dispatch problems. The nature inspired algorithms considered are, the particle swarm optimization (PSO), the differential evolution, and a newly proposed algorithm named Nawab's sensitivity evaluation optimization (NSEO). The procedures for solving ELD problems are explained in effective ways so that it will be easy to understand the concepts of solving ELD problems. New procedure and new coding scheme are adopted to solve power systems economic power dispatch (EPD) problems for the PSO and the DE. Also, the proposed new algorithm is applied to solve EPD problems. Here, three different standard cases of economic dispatch (ED) problems are considered which are IEEE 3-unit, 13-unit, and 40-unit power systems. In all the cases considered here, the fuel cost function takes account of valve-point effects. In this dissertation, all the method is applied individually to solve the three problems of economic dispatch. For comparison of the results a combined simulation results are given for each of the problems considered. Also, to compare the results obtained by the proposed new algorithm NSEO, the results available by some best research papers are tabulated and compared which clearly shows the superiority of the proposed method. All the program are written for MATLAB environment and simulated on an Intel Core 2 Duo processor with 3* 1024 MB RAM.