A knowledge-based system for the structural design of high-voltage lines

The basic structure of the knowledge-based system consists of a database of tower configurations and associated parameters, a knowledge base of design rules and a program to fire the rules so as to produce one or several designs based on the specified design criteria. An examination of existing software on tower design was carried out but it was found that these programs were too detailed and too specific to be of use for the preliminary design of a number of alternatives. The input to this expert system consists of the voltage level and the physical environment. Selection of the conductor assembly is probably the most important aspect of transmission line design. For EHV lines the minimum conductor is determined from corona considerations, namely the audible noise (AN) and radio interference (RI) standards. Larger conductors can be evaluated based on the increased cost of the lines and the reduced cost of the losses for a given power transfer. The methodology itself consists, first of all, in obtaining the knowledge associated with the structural design of towers from recognized experts. The second step consists in formalizing this knowledge as a series of heuristic rules. It also includes the development of a hierarchy of objects to represent the design parameters. The third step involves integrating the rules and objects in the form of software and making sure this software is functional. The output of this knowledge-based system is the cost per kilometer of high-voltage transmission lines as a function of any combination of the specified design parameters. This output is vital to the planning of HV transmission systems.