ABSTRACT
Initiatives for improving the performance of the protective systems that are applied on electric supply systems are a continuous process and an ongoing challenge. An important part of this process includes
• Analyzing the performance of protective systems during actual disturbances • Maintaining an effective performance measurement system • Taking action to remedy problems that are identied
This process can go a long way to improve power system reliability. A reliable supply of electricity is vital to the well-being of individuals, businesses, and industrial complexes. Such supply is often considered as an expectation by the public. When electric supply is lost for extended periods of time, the health and welfare of the public is threatened and practices of the related electric utility are often scrutinized. It is highly important for utilities to minimize outages, extended or momentary, in order to be viewed favorably by the public and government agencies and, most importantly, to continually carry out a critical service to society. As an example, during a heat wave in the summer of 2012, severe winds and thunderstorms in the Baltimore/Washington areas caused numerous outages to electric supply mainly due to tree contacts. Restoration of service was difcult and slow because of the very large number of failures. Many people were out of service for a number of days in sweltering heat. Several deaths were attributed to the heat combined with the loss of electric supply. The electric utilities involved were highly scrutinized by regulatory and political entities. Penalties were being considered due to the alleged lack of preparation and inadequate operating practices. The state of Maryland formed a committee to identify and initiate action that would serve to limit the occurrence and scope of extended power outages in the future. The results of these outages emphasize the need to factor the costs associated with power outages into the cost/benet analysis when projects to build or modify power system facilities are being considered. While this incident did not directly relate to the performance of protective systems, it does illustrate the important function protection performs in limiting the scope of outages and the potential impacts that can result when protective systems operate incorrectly. Protective relay performance issues during wide-area disturbances are discussed later in this chapter.
