Real-time reliability index of a steam power plant: A systems approach

Abstract

The present system of reporting reliability (also known as product performance) of a power generating plant on annualized basis has failed to serve the plant managers to take technocommercial decisions. Moreover, these indices show a wide variance depending upon the method of selection by the peer group for indexing purposes. For assessing reliability, a model has been developed for a steam power plant (SPP) in this paper using a systems approach of graph theory in conjunction with matrix method. A concept of real-time reliability index (RTRI) of the SPP has also been proposed, which overcomes the problems associated with the selection of a peer group for comparison. The value of RTRI indicates the probability of complete shut down or operation of the SPP at partial load. For finding the reliability of a SPP in real-time, its system structure graph (SSG), variable permanent system structure matrix and variable permanent function (VPF-s) have been converted into the corresponding reliability graph, matrix, and variable permanent function (VPF-r), respectively by associating reliability attribute to the nodes (S i) and the edges (c ij) of the SSG. When all the equipment, subsystems in different systems (S i) of a SPP are performing as per design specifications, the corresponding value of the VPF-r is termed as VPF-r design. Under real-time operation when, some of the equipment/subsystem of a particular system(s) may not be available or not performing at the designed level; the corresponding value of VPF-r is different from its design value and is termed as VPF-r real-time and the ratio of the real-time-value to the design value is the RTRI value. The proposed model is capable of taking real-time situations of various systems of the SPP simultaneously. A step-by-step procedure for calculation of RTRI has been suggested and also been illustrated by means of an example.