Combined heat and power system is a well-organized approach for generating power and thermal energy from a single source. This book presents economic dispatch of cogeneration units in modern power system for practical designing applications. The purpose of economic dispatching of various generating units is scheduling the power and heat units so that the cost is minimum. But the complexity of this system lies in the satisfaction of all the constraints regarding both heat and power genearting units i.e. equality constraints, inequality constraints and the feasible operating region for heat and power. For this purpose, a heuristic searching technique is used in this book for obtaining a satisfactory global solution.