ANATOMY OF POWER-SYSTEM BLACKOUTS - PREVENTIVE RELAYING STRATEGIES

Major blackouts of electric power systems in which many customers are left without power are rare events. However, the effects of blackouts, for instance, can be catastrophic. It has been observed that protecti ve system failures are a contributing factor in a large proportion of these blackouts. The most troublesome protection system failures are h idden failures, which remain dormant during normal system conditions, and are exposed during system disturbances. A study of hidden failures of the protective systems is undertaken to uncover their modes of fai lures, and to determine means of supervising their actions in times of highly stressed power system operations. The main contribution of thi s paper is to develop and document a method of quantitative analysis o f the significance of hidden failures of protection systems. A complet e protection system was designed for the New England 39-bus system and the hidden failure modes were used to develop regions of vulnerabilit y and a vulnerability index. Through this analysis, critical protectio n systems, whose hidden failures would have a major impact on cascadin g failures or blackouts of the power system, can be identified. These protection systems are candidates for increased monitoring and control , which would help alleviate the problems posed by hidden failures.