Showing papers on "Voltage sag published in 1995"

Electrical Power Systems Quality

Abstract: CHAPTER 1: INTRODUCTION What is Power Quality? Power Quality -- Voltage Quality Why Are We Concerned About Power Quality? The Power Quality Evaluation Procedure Who Should Use This Book Overview of the Contents CHAPTER 2: TERMS AND DEFINITIONS Need for a Consistent Vocabulary General Classes of Power Quality Problems Transients Long-Duration Voltage Variations Short-Duration Voltage Variations Voltage Imbalance Waveform Distortion Voltage Fluctuation Power Frequency Variations Power Quality Terms Ambiguous Terms CBEMA and ITI Curves References CHAPTER 3: VOLTAGE SAGS AND INTERRUPTIONS Sources of Sags and Interruptions Estimating Voltage Sag Performance Fundamental Principles of Protection Solutions at the End-User Level Evaluating the Economics of Different Ride-Through Alternatives Motor-Starting Sags Utility System Fault-Clearing Issues References CHAPTER 4: TRANSIENT OVERVOLTAGES Sources of Transient Overvoltages Principles of Overvoltage Protection Devices for Overvoltage Protection Utility Capacitor-Switching Transients Utility System Lightning Protection Managing Ferroresonance Switching Transient Problems with Loads Computer Tools for Transients Analysis References CHAPTER 5: FUNDAMENTALS OF HARMONICS Harmonic Distortion Voltage versus Current Distortion Harmonics versus Transients Harmonic Indexes Harmonic Sources from Commercial Loads Harmonic Sources from Industrial Loads Locating Harmonic Sources System Response Characteristics Effects of Harmonic Distortion Interharmonics References Bibliography CHAPTER 6: APPLIED HARMONICS Harmonic Distortion Evaluations Principles for Controlling Harmonics Where to Control Harmonics Harmonic Studies Devices for Controlling Harmonic Distortion Harmonic Filter Design: A Case Study Case Studies Standards of Harmonics References Bibliography CHAPTER 7: LONG-DURATION VOLTAGE VARIATIONS Principles of Regulating the Voltage Devices for Voltage Regulation Utility Voltage Regulator Application Capacitors for Voltage Regulation End-User Capacitor Application Regulating Utility Voltage with Distributed Resources Flicker References Bibliography CHAPTER 8: POWER QUALITY BENCHMARKING Introduction Benchmarking Process RMS Voltage Variation Indices Harmonics Indices Power Quality Contracts Power Quality Insurance Power Quality State Estimation Including Power Quality in Distribution Planning References Bibliography CHAPTER 9: DISTRIBUTED GENERATION AND POWER QUALITY Resurgence of DG DG Technologies Interface to the Utility System Power Quality Issues Operating Conflicts DG on Distribution Networks Siting DGDistributed Generation Interconnection Standards Summary References Bibliography CHAPTER 10: WIRING AND GROUNDING Resources Definitions Reasons for Grounding Typical Wiring and Grounding Problems Solutions to Wiring and Grounding Problems Bibliography CHAPTER 11: POWER QUALITY MONITORING Monitoring Considerations Historical Perspective of Power Quality Measuring Instruments Power Quality Measurement Equipment Assessment of Power Quality Measurement Data Application of Intelligent Systems Power Quality Monitoring Standards References Index INDEX

A feasibility study for a fault current limiter to reduce voltage sags at sensible loads

Abstract: In relatively weak electrical networks, that is, those with sparse interconnection between them; a fault occurring in any part of the network causes voltage sags to appear in different nodes, more severely in those adjacent to the fault. This occurs at every voltage level in an electrical network. Particularly so in distribution systems, when radial feeders originate from a same substation. In this case, a fault in one of the feeders will produce a voltage sag at the substation bus, thus affecting adjacent feeders. If any of these feeders supplies sensitive loads, like adjustable speed drives, PLC`S, computer systems, etc.; problems may arise at the customer loads where these voltage sags are seen as interruptions. It is suggested that a way to reduce these voltage sags to acceptable values can be achieved by limiting the fault current in the distribution feeders. A fault current limiter is defined as a series device that presents a low impedance to steady state currents, but acts quickly to limit the instantaneous magnitude of a fault current to a predetermined value. Many new fault current limiters (FCL) have been proposed lately in the literature but for this feasibility study a FCL of the LC resonantmore » link type was chosen for its simplicity.« less

Energy storage and alternatives to improve train voltage on a mass transit system

Abstract: The wide separation of substations in the Bay Area Rapid Transit system`s transbay tunnel contributes to voltage sag when power demand is high. In the future, expansions to the system will exacerbate this problem by increasing traffic density. Typically, this situation is remedied through the installation of additional substations to increase the system`s power capacity. We have evaluated the efficacy of several alternatives to this approach - specifically, installation of an 8 megajoule energy storage system, modification of the existing substations, or reduction of the resistance of the running rails or the third rail. To support this analysis, we have developed a simple model of the traction power system in the tunnel. We have concluded that the storage system does not have sufficient capacity to deal with the expected voltage sags; in this application, the alternatives present more effective solutions. We have also investigated the potential impact of these system upgrades on expected future capital outlays by BART for traction power infrastructure additions. We have found that rail or substation upgrades may reduce the need for additional substations. These upgrades may also be effective on other parts of the BART system and on other traction power systems.

Power quality case studies-voltage sags: The impact on utility and industrial customers

Abstract: This paper describes the impact of voltage sags on the utility and the customer`s equipment. Several utility measures are presented to minimize the customer`s exposure to voltage sags. However, these measures cannot completely eliminate the impact of voltage sags on sensitive equipment. Additional measures taken on the customer side are presented. These measures were incorporated to minimize the impacts of voltage sags on the customer. In this case study, the lessons learned from the systems approach analysis can be applied to resolve a wide range of voltage sag problems.