Software Application and Algorithm Designed for Power Systems Equipment and Network Construction Optimization

Abstract

The main goal of this article is to conceive an algorithm for a software application designed to solve many power engineering optimization problems applying the critical path method (CPM). The classical solution for these problems is found via the schedule graph (the Gantt method), which presents a series of shortcomings: it does not highlight clearly the interdependencies between operations, it does not explain the temporal coincidences, it does not indicate the alternatives of declaring the various operations, it does not have a rigorous mathematical foundation, it does not allow any studies of optimization. All the shortcomings are cleared when using the representation of the program via a graph, where the values of the arcs are the durations of the component operations, and applying the critical path method (CPM), which mainly consists in determining a path of a maximum value between two peaks of that graph. Using CPM offers a great number of advantages: it offers a clear image of the evolution in time of the program, it allows the decreasing of the total duration of implementation for the program without condensing the component operation, it highlights the operations that directly determine the duration of implementation of the program, as well as those that allow the redistribution of the resources and the reduction of cost; it offers the alternative of rapid evaluation of the consequences of certain delays in realizing certain operations (without totally rebuilding the graph and the calculations); it can be easily implemented on a computer, having a solid mathematical base. Applying CPM and optimizing the program is achieved via the following steps: a) setting the list of the component operations, of their characteristics and representing the program via graphs; b) setting the graphs in order; c) determining the critical path (CP) and its value; d) calculating the time stocks related to the realization of the component operation (using the Ford and the Bellman-Kalaba algorithms); e) optimizing the program as from the length, the cost and the necessary resources points of view. For illustrating the algorithm and the computing program we propose an application from power engineering: a 400 kV electrical overhead line section construction. In the first part of the paper we present the application as a critical path problem. In the second part, we determine the critic path in a program graph and time reserves. In the third part, we present a representative numerical application. In the fourth part, it is described the computing program.