Design of a Distributed Data Acquisition and Control System for a Thermoelectric Power Plant

Abstract

This paper describes the design and implementation of a Distribued Data Acquisition Control System for a Thermoelectric Power Plant already in operation and controlled by conventional means.The system design is based on a two-level Hierarchical structure. The first level is defined by several distributed microprocessor-based remote stations that will perform most of the control tasks on a local basis. For a second level or Master station, a minicomputer is used to carry out coordination operations as well as to drive display terminals and other peripherals.Besides the availability and costs, the selection of the most adequate Data Acquisition and Process Control equipment is based on considerations such as: the number of variables per local station, the volume of information to be transmitted, the type of communication to be used, speed of transmission, noise minimization, wiring costs and the maximum utilization of the intrumentation already installed and in operation.The existence of conventional control system in operation, suggests the implementation of our Distributed system in two stages. It is imperative that the plant not be shut-down at any moment. Therefore, the first stage would consist of the implementation of the Data Acquisition and Display system.The complementary stage will be the transition from the conventional control to a microprocessor-based distributed scheme. In this way, not only will a higher reliability be possible, but the operator/process communication will be enhanced and will provide flexibility for future expansion.