RELIABILITY EVALUATION OF SUBTRANSMISSION CONFIGURATIONS IN ELECTRIC POWER SYSTEMS

Abstract

An electric power system as a whole is an enormous entity. It is very difficult to evaluate the reliability of a complete power system on this basis. It has been, therefore, divided into the three functional zones of generation, transmission and distribution. The distribution functional zone can be further subdivided into subtransmission and radial parts. This thesis pertains to the analysis of an electric subtransmission system. An analysis of a subtransmission system involves the identification of the individual component failure modes based on which load point failure events and restoration modes are assessed. Component permanent, maintenance and temporary failure modes are considered in the reliability predictions. In addition active failures and adverse weather effects have also been considered. A digital computer program `SUBTREL' which takes into consideration most of the factors affecting the adequacy of a subtransmission system and which is highly user friendly is presented in this thesis. The RBTS subtransmission system, which is sufficiently large that practical factors can be realistically modelled and assessed yet sufficiently small that the effect of sensitivity studies can be easily identified, is utilized as the test system for studies described in this thesis. The radial part of the RBTS distribution system is described briefly and analysis of the radial distribution segment is done by making use of the computer program 'DISREL'. Some sensitivity studies are also performed on the RBTS distribution system by making use of the above mentioned computer programs. Finally a comparison of the subtransmission system and the radial distribution system, with regard to their reliability indices, is made.