Adequacy equivalent development of composite generation and transmission systems

This paper presents a technique for the development of adequacy equivalents for composite generation and transmission systems using a d.c. load flow approach. Adequacy equivalent concepts can be very useful in large composite power system adequacy evaluation where extremely long computation times are usually required. The computation time burden can be effectively alleviated by using a reduced equivalent model to represent the unchanging portion of a composite system. These reduced models, designated as reliability or adequacy equivalents, retain the essential elements in their desired form but eliminate much of the system detail. Network flow methods are usually used to develop adequacy equivalents for composite systems. The d.c. load flow technique, however, is a more widely accepted procedure for composite system analyses as it can provide more accurate solutions than a network flow method. The concepts associated with developing adequacy equivalents using a d.c. load flow method are illustrated using simple power networks. Results and analyses of system studies based on two test systems are presented in the paper.