The effects of geomagnetic disturbances on electrical systems at the earth's surface

Abstract Geomagnetic disturbances have affected electrical systems on the ground for over 150 years. The first effects were noted on the early telegraph in the 1840s and in this century magnetic storms have caused power system blackouts and phone system outages. Affected systems include all those that use electrical conductors: whether for transmission of power or signals or where the conducting properties are incidental to their use such as with pipelines and railway tracks. In power systems geomagnetically induced currents cause partial saturation of power transformers producing transformer heating and distortion of the ac waveform leading to misoperation of relays and other equipment. On pipelines, induced currents may contribute to corrosion but also present a problem with the electrical surveys of the pipe performed to monitor the corrosion prevention systems. Severity of these effects depends on disturbance size, proximity to the auroral zone, and the conductivity structure of the Earth. Also significant are system parameters such as the use of higher resistance coatings on pipelines and the linking of power systems into larger networks. In this paper we have attempted to catalogue all the published reports of geomagnetic effects on electrical systems and show their occurrence in the context of the solar cycle and geomagnetic activity variations for the years 1844 to 1996.

The Effects of Geomagnetic Disturbances on Electrical Systems at the Earth's Surface - An Update

Why utilities respect geomagnetically induced currents

The general characteristics and system level concepts for space-based magnetometers are presented to illustrate the instruments, principles, and tools involved in making accurate magnetic field measurements in space. Special consideration is given to the most important practical problems that need to be solved to ensure the accuracy of the measurements and their overall impact on system design and mission costs. Several types of instruments used to measure magnetic fields aboard spacecraft and their capabilities and limitations are described according to whether they measure scalar or vector fields. The very large dynamic range associated with magnetic fields of natural origin generally dictates the use of optimized designs for each particular space mission although some wide-range, multimission magnetometers have been developed and used. Earth-field magnetic mapping missions are the most demanding in terms of absolute accuracy and resolution, approaching <1 part in 100 000 in magnitude and a few arcsec i...

Space-based magnetometers

A close association has been identified between the theoretical calculation of geomagnetically induced currents (GICs) in a large network, practical measurements of GICs, the results of dissolved gas analysis (DGA) records, and damage in recently failed transformers in Southern Africa. Together these indicate that GICs may contribute significantly to transformer failures on large transmission systems in mid-latitude regions, where GICs are generally thought not to be significant.

Transformer failures in regions incorrectly considered to have low GIC-risk

In the northern hemisphere, the aurora borealis is visual evidence of simultaneous fluctuations in the earth's magnetic field (geomagnetic field) These geomagnetic disturbances (GMD's), or geomagnetic storms, can affect a number of man-made systems, including electric power systems The GMD's are caused by the electromagnetic interaction of the solar wind plasma of protons and electrons with the geomagnetic field These dynamic impulses in the solar wind are due to solar flares, coronal holes, and disappearing filaments, and reach the earth from one to six days after being emitted by a solar event Instances of geomagnetic storms affecting telegraph systems were noted in England in 1846, and power system disturbances linked to GMD's were first reported in the United States in 1940 This Working Group report is a summary of the state of knowledge and research activity to the present time, and covers the GMD/Geomagnetically-induced currents (GIC) phenomena, transformer effects, the impact on generators, protective relay effects, and communication system effects It also summarizes modeling and predicting GIC, measuring and monitoring GIC, mitigation methods, system operating guidelines during GMD's, and alerting and forecasting procedures and needs for the power industry

W. E. Feero

Papers

Geomagnetic disturbance effects on power systems

Geomagnetic disturbance effects on power systems. Discussion