Power system planning — a reliability perspective

One of the basic objectives of power system planners is to determine the necessary generating capacity to satisfy the system demand in the presence of scheduled and unscheduled outages and unforeseen variations in the system load. A second important objective is the development of a suitable transmission network to transport the generated electrical energy to the bulk load centers. This aspect is dealt with in conjunction with the available and planned generation facilities. Lastly, adequate distribution facilities must be constructed in order to deliver the available energy from the bulk load centers to the actual customer premises. The reliability at which these three subsystems (namely, generation, transmission, and distribution) will function is of utmost importance. The power system engineer, therefore, must consider the reliability aspect right from the beginning, i.e. from the planning stage. This paper presents the basic concepts of power system reliability assessment and reviews the relability indices and methodologies from a planning viewpoint and also from an economic cost-benefit perspective. Some realistic data which can be used as a guide in the absence of any collected system data are also presented.