Chapter 8 - Impact of Poor Power Quality on Reliability, Relaying, and Security

Abstract

This chapter addresses the impact of poor power quality on reliability, relaying, and security. It introduces reliability indices and discusses the degradation of reliability and security due to poor power quality including the effects of harmonics and interharmonics on the operation of overcurrent and under-frequency relays, electromagnetic field (EMF) generation, corona in transmission lines, distributed generation, cogeneration, and frequency/voltage control. Various tools for detecting poor power quality and for improving reliability or security are available. To be able to detect power quality problems one must rely on voltage and current sensors such as low-inductive voltage dividers for voltage pickup, and low-inductive shunts and Hall sensors for current pickup. Components representing the interface between sensors and measuring instruments are potential and current transformers as well as optocouplers. Voltmeters, amperemeters, oscillographs, spectrum analyzers, and network analyzers are indispensable. Special power quality tools and selection guides have been developed for detecting power quality for single- and three-phase systems, such as power quality clamp meters, power quality analyzers, voltage event recorder systems, three-phase power loggers, series three-phase power quality loggers, three-phase power quality recorders, AC. It also provides information on the techniques for improving and controlling the reliability of power systems including load shedding and load management, energy-storage methods and matching the operation of intermittently operating renewable power plants with energy storage facilities.