Power System Protection by Digital Methods

摘要

The report reviews, analyzes, and evaluates approaches to electric power system protection based on old technologies and also on new techniques arising from modern digital technology. The protection requirements of modern power systems are onerous, particularly with respect to the faster fault clearing times required to improve transient stability. The integral role which instrumentation plays in power system protection is discussed. Constructional features, performance characteristics, and applications of five different transformers are described. Signal sampling techniques and the use of data acquisition and computerized protection schemes to convert analog to digital functions for generating strings of numbers presenting analog inputs observed at prespecified intervals are explored. Digital techniques to filter out undesired quantities to ensure a high degree of accuracy in various calculated results are discussed. Details of signal processing techniques are reviewed together with the philosophy, principles, and practices of protective relaying currently used. The present state of digital protection and various algorithms which can be implemented by modern digital technology are described.