共查询到20条相似文献，搜索用时 62 毫秒
1.
《Journal of Atmospheric and Solar》2007,69(12):1305-1311
Geomagnetically induced currents (GIC) flowing in ground-based technological networks, such as electric power transmission grids, are the ground end of the space weather chain originating from the Sun. GIC constitute a possible source of problems to the system. Matrix formulas enabling the calculation of GIC in a power grid have been presented before. In this paper, we summarise the formulas and also express them in an alternative form that includes the (geo)voltages driving GIC during a space weather event more explicitly. An issue usually ignored in GIC modelling is the effect of overhead shield wires protecting a power grid and generally earthed at the towers. By numerical examples, it is shown in this paper that such neglect causes an insignificant error in comparison with other inaccuracies involved in GIC modelling and is thus really acceptable in practice. 相似文献
2.
Geomagnetically induced currents (GIC) in technological systems, like electric power transmission grids, at the Earth's surface are caused by space weather processes, whose origin is in the Sun. In power systems, transformers may be saturated due to GIC leading to different problems extending from an increase of harmonics to a blackout of the system and damage of transformers. To design reasonable measures against impending problems, GIC magnitudes in the network should be estimated in different circumstances. This paper tackles basic features of GIC flow in a fictitious five-transformer/four-line power system, which is simple enough to make the equations easily manageable but complex enough to yield real and usable information. It is shown that the direction of the geoelectric field affects GIC at different sites but the dependence is not straightforward since GIC produced in one part of the system flows to others. Generally, transmission lines experience much larger GIC than transformers. Series capacitors in transmission lines prevent the flow of dc-like GIC but, without a careful analysis, their installation may result in larger GIC at some transformers of the system thus increasing the risk of problems. 相似文献
3.
Modelling of space weather effects on pipelines 总被引：1，自引：0，他引：1
Antti Pulkkinen Risto Pirjola David Boteler Ari Viljanen Igor Yegorov 《Journal of Applied Geophysics》2001,48(4)
The interaction between the solar wind and the Earth's magnetic field produces time varying currents in the ionosphere and magnetosphere. The currents cause variations of the geomagnetic field at the surface of the earth and induce an electric field which drives currents in oil and gas pipelines and other long conductors. Geomagnetically induced currents (GIC) interfere with electrical surveys of pipelines and possibly contribute to pipeline corrosion.In this paper, we introduce a general method which can be used to determine voltage and current profiles for buried pipelines, when the external geoelectric field and the geometry and electromagnetic properties of the pipeline are known. The method is based on the analogy between pipelines and transmission lines, which makes it possible to use the distributed source transmission line (DSTL) theory. The general equations derived for the current and voltage profiles are applied in special cases. A particular attention is paid to the Finnish natural gas pipeline network.This paper, related to a project about GIC in the Finnish pipeline, thus provides a tool for understanding space weather effects on pipelines. Combined with methods of calculating the geoelectric field during magnetic storms, the results are applicable to forecasting of geomagnetically induced currents and voltages on pipelines in the future. 相似文献
4.
地磁感应电流（GIC）可能对各种人工长距离导电体造成影响与危害.地磁扰动产生的感应电场的强度与地磁场强度、地下电阻率结构相关，在导电系统内生成的GIC的强度则同时与导电系统的内在结构有关.计算了加拿大Manitoba省三个典型地区在2000年7月15日的一个强烈磁暴期间产生的感应电场.通过对地磁活动性的统计分析，估计加拿大魁北克电网可能经受的最大GIC达每相78A（一年一次）和234A（每十年一次）. 相似文献
5.
The Earth’s lithosphere and mantle respond to Space Weather through time-varying, depth-dependent induced magnetic and electric fields. Understanding the properties of these electromagnetic fields is a key consideration in modelling the hazard to technological systems from Space Weather. In this paper we review current understanding of these fields, in terms of regional and global-scale geology and geophysics. We highlight progress towards integrated European-scale models of geomagnetic and geoelectric fields, specifically for the purposes of modelling geomagnetically induced currents in power grids and pipelines. 相似文献
6.
《Journal of Atmospheric and Solar》2002,64(16):1765-1778
It has been well known for more than 50 years that electric utilities in northern latitudes can have geomagnetically induced currents (GICs) flowing in their transmission lines and transformer ground points, and that these are caused by geomagnetic storms. Initially, these GICs were considered harmless and very little attention was paid to them. However, in the last 40 years it was realized that large GICs can flow in power systems and become problematic and even severe enough to cause a complete system shutdown. Utilities susceptible to GIC do not expect to rely on luck that the geomagnetic storm will not affect them, or if it does, the loading conditions at the time will allow enough margin to ride through it. This is precisely why many utilities today are studying the cause, effect, and mitigation of GICs and why utilities respect GICs. This paper presents a detailed discussion on how electric utilities are affected by GICs and what can be accomplished to mitigate the harmful effects. 相似文献
7.
大地电性结构的横向变化会对磁暴时的感应地电流和地面电磁场产生影响.本文假设扰动地磁场变化的源为地面以上一定高度的面电流,以某一典型层状大地电导率结构为基础,构造含有电导率横向突变的地电模型.针对感应电流的方向与横向分界面平行的情形,采用伽辽金有限元法对电导率横向突变处的感应地电场进行了分析,揭示了电导率横向差异产生的趋肤效应和邻近效应的机理,针对与电性结构分界面平行的输电线路,从评估地磁感应电流的角度讨论了影响的严重程度和范围. 相似文献
8.
9.
We consider geomagnetically induced currents (GICs) in power systems from the viewpoint of a geophysicist. Special attention is paid to the Finnish high-voltage power system, in which exact theoretical model calculations together with recordings have been performed for several years. We present several examples of theoretically computed GICs using different geophysical models for estimating the geoelectric field driving GICs. Statistical prediction of GICs is outlined referring to studies made in Finland. We show that a combination of GIC recordings at few sites with theoretical modelling of ionospheric currents and the earth's conductivity, and data of geomagnetic activity makes it possible to derive GIC statistics of the entire power system. Finally, we discuss requirements for a long-range prediction of GICs, which will obviously be a widely-studied topic in future. 相似文献
10.
因太阳活动而引起的地磁扰动,会在地球表面感生出地电场,从而在地表附近的导体系统中产生地磁感应电流(GICs).太阳表面的异常活动而引起的磁暴会导致强烈的GICs,严重威胁电信设备、电网、油气管道和铁路运输网络等基础设施系统的安全运行,已经成为最严重的空间天气灾害之一.因此,对GICs进行深入研究以建立对其做出迅速预测的能力,在科学和应用方面都有重要意义.本文综述了GICs的研究进展,从引入空间天气的概念开始,将GICs作为从太阳活动到太阳风再到地球扰动的空间天气链的最终环节;重点阐述了GICs的计算中所涉及的三个步骤:地球表面地磁场重建、感应地电场的计算,以及地面导体系统中GICs计算;对每一步骤中主要方法的相关原理和应用做了简要介绍与评估;最后总结了当前GICs的研究现状,并对未来GICs的研究方向与挑战进行了展望. 相似文献
11.
The time varying conditions in the near-Earth space environment that may affect space-borne or ground-based technological
systems and may endanger human health or life are referred to as space weather. Space weather effects arise from the dynamic
and highly variable conditions in the geospace environment starting from explosive events on the Sun (solar flares), Coronal
Mass Ejections near the Sun in the interplanetary medium, and various energetic effects in the magnetosphere–ionosphere–atmosphere
system. As the utilization of space has become part of our everyday lives, and as our lives have become increasingly dependent
on technological systems vulnerable to the space weather influences, the understanding and prediction of hazards posed by
these active solar events have grown in importance. In this paper, we review the processes of the Sun–Earth interactions,
the dynamic conditions within the magnetosphere, and the predictability of space weather effects on radio waves, satellites
and ground-based technological systems today. 相似文献
12.
Louise Pellerin 《Surveys in Geophysics》2002,23(2-3):101-132
Electrical and electromagnetic methods are powerful tools in environmentaland geotechnical investigations. Techniques developed for deeper applications, such as mining,geothermal and crustal studies, are scaled for shallow targets by moving to higher frequencies,earlier decay times and/or smaller array configurations. Another extremely important factor is dense stationspacing, to reduce spatial aliasing, and high quality data to resolve small features. Hence, new instrumentsare concerned with making continuous or dense measurements with high precision, and interpretationalmethods fast enough to handle large datasets quickly. Continuously measuring electrical and time-domainelectromagnetic systems have been developed for geological mapping in hydrological investigations withone-dimensional inversion routines that are rapid and robust. At a smaller scale an electrical systemis used for archaeology studies with excellent results. Working to and above the upper limits ofthe quasi-static approximation, a very early time electromagnetic system is proving successful at mapping subsurfaceinfrastructure in areas of conductive, clay cover, where ground penetrating radar is ineffective.Induced polarization (IP) and resistivity systems that employ multiplexing techniques, while not continuouslymeasuring, allow for relatively rapid production rates and dense sampling for applications ranging fromlandfill and contaminant characterization studies, to verifying the integrity of engineeredsubsurface structures and monitoring infiltration in the vadose zone. 相似文献
13.
2001年以来,随着我国阳\|淮系统等多条500 kV长距离线路的相继建成投运,江苏上河、广东岭澳等地变压器多次发现不明原因的强烈振动和噪声增大事件.本文通过对2004年11月以来、十几次磁暴地磁数据与变压器中性点实测电流数据的比较,证明了干扰事件是磁暴在电网产生的地磁感应电流（GIC）所为;其中,2004年11月7日和10日磁暴在岭澳核电站引发的GIC最大值为47A和55.8A,大于直流输电单极运行时变压器中性点的直流电流水平,因此磁暴对岭澳核电站的瞬时影响比直流输电的影响大;监测数据表明广东电网的GIC水平高于阳淮输电系统的水平,初步分析认为与电网结构和海岸效应等因素有关.目前,举世瞩目的1000 kV特高压工程已开工建设,特高压线路的单位电阻最多是500 kV的二分之一,并且线路更长、规划规模大、且变压器采用单相变压器组结构,磁暴影响问题迫切需要研究. 相似文献
14.
15.
Complex image method for calculating electric and magnetic fields produced by an auroral electrojet of finite length 总被引：3，自引：0，他引：3
The electromagnetic field due to ionospheric currents has to be known when evaluating space weather effects at the earths surface. Forecasting methods of these effects, which include geomagnetically induced currents in technological systems, are being developed. Such applications are time-critical, so the calculation techniques of the electromagnetic field have to be fast but still accurate. The contribution of secondary sources induced within the earth leads to complicated integral formulas for the field at the earths surface with a time-consuming computation. An approximate method of calculation based on replacing the earth contribution by an image source having mathematically a complex location results in closed-form expressions and in a much faster computation. In this paper we extend the complex image method (CIM) to the case of a more realistic electrojet system consisting of a horizontal line current filament with vertical currents at its ends above a layered earth. To be able to utilize previous CIM results, we prove that the current system can be replaced by a purely horizontal current distribution which is equivalent regarding the total (= primary + induced) magnetic field and the total horizontal electric field at the earths surface. The latter result is new. Numerical calculations demonstrate that CIM is very accurate and several magnitudes faster than the exact conventional approach. 相似文献
16.
A project implemented to study the effects of space weather on the Finnish natural gas pipeline was started in August 1998. The aims of the project were (1) to derive a model for calculating geomagnetically induced currents (GIC) and pipe-to-soil (P/S) voltages in the Finnish natural gas pipeline, (2) to perform measurements of GIC and P/S voltages in the pipeline and (3) to derive statistical predictions for the occurrences of GIC and P/S voltages at different locations in the pipeline network.GIC and P/S voltage were recorded at a compressor station. The GIC measurement was made with two magnetometers, one right above the pipe, and another at the Nurmijärvi Geophysical Observatory about 30 km southwest. The largest GIC since November 1998 has been 30 A. The P/S voltage recording was stopped in May 1999, but GIC is still measured.GIC statistics were derived based on the recordings of the geomagnetic field at Nurmijärvi. The geoelectric field was calculated by using the plane wave model. This field was input to the general pipeline model resulting in the distribution of currents and P/S voltages at selected points in the pipeline. As could be expected, the largest P/S voltage variations occur at the ends of the pipeline network, while the largest GIC flow in the middle parts. 相似文献
17.
YanMei Cui SiQing Liu A. ErCha QiuZhen Zhong BingXian Luo XianZhi Ao 《中国科学:地球科学(英文版)》2016,59(6):1292-1298
In space weather forecasting, forecast verification is necessary so that the forecast quality can be assessed. This paper provides an example of how to choose and devise verification methods and techniques according to different space weather forecast products. Solar proton events (SPEs) are hazardous space weather events, and forecasting them is one of the major tasks of the Space Environment Prediction Center (SEPC) at the National Space Science Center of the Chinese Academy of Sciences. Through analyzing SPE occurrence characteristics, SPE forecast properties, and verification requirements at SEPC, verification methods for SPE probability forecasts are identified, and verification results obtained. Overall, SPE probability forecasts at SEPC exhibit good accuracy, reliability, and discrimination. Compared with climatology and persistence forecasts, the SPE forecasts are more accurate. However, the forecasts for SPE onset days are substantially underestimated and need to be considerably improved. 相似文献
18.
《Journal of Atmospheric and Solar》2005,67(12):1074-1084
Ionospheric space weather effects can degrade the performance of global navigation satellite systems (GNSS), i.e. their accuracy, reliability and availability. However, well established ground based and innovative space based GNSS measurements offer the unique chance for a permanent monitoring of the electron density structure of the global ionosphere–plasmasphere system. In this paper we review various types of perturbations in the ionospheric plasma density and distribution. In order to analyze these space weather effects we use 30 s sampled measurements provided by the global GPS ground tracking network of the IGS. Furthermore, to get a more comprehensive view on the perturbations analyzed also are simultaneously obtained GPS measurements onboard the LEO satellite CHAMP (challenging minisatellite payload). Whereas the ground based measurements show strong horizontal redistribution of plasma during ionospheric storms, the space-borne measurements indicate a severe vertical redistribution of the ionospheric plasma during the selected events. The role of the various dynamical forces such as meridional winds and electric fields is also discussed. 相似文献
19.
J. B. Wardman T. M. Wilson P. S. Bodger J. W. Cole C. Stewart 《Bulletin of Volcanology》2012,74(10):2221-2241
Modern society is highly dependent on a reliable electricity supply. During explosive volcanic eruptions, tephra contamination of power networks (systems) can compromise the reliability of supply. Outages can have significant cascading impacts for other critical infrastructure sectors and for society as a whole. This paper summarises known impacts to power systems following tephra falls since 1980. The main impacts are (1) supply outages from insulator flashover caused by tephra contamination, (2) disruption of generation facilities, (3) controlled outages during tephra cleaning, (4) abrasion and corrosion of exposed equipment and (5) line (conductor) breakage due to tephra loading. Of these impacts, insulator flashover is the most common disruption. The review highlights multiple instances of electric power systems exhibiting tolerance to tephra falls, suggesting that failure thresholds exist and should be identified to avoid future unplanned interruptions. To address this need, we have produced a fragility function that quantifies the likelihood of insulator flashover at different thicknesses of tephra. Finally, based on our review of case studies, potential mitigation strategies are summarised. Specifically, avoiding tephra-induced insulator flashover by cleaning key facilities such as generation sites and transmission and distribution substations is of critical importance in maintaining the integrity of an electric power system. 相似文献
20.
开展天地一体化地震观测是目前推动地震短临科学研究取得突破的重要途径之一。以卫星观测为主要手段的空间对地观测技术是实现对我国及临区进行地震电磁效应高精度、大范围和大动态连续观测的有效途径,并且为地震短临预报开创空基监测的新思路。地面传输系统是连接地震电磁卫星各应用系统之间的重要桥梁和纽带。它的科学设计是地震电磁卫星项目建设的基础。本文拟从国内外发展现状、系统建设指导思想、系统组成、链路功能描述、系统运行性能指标等方面对我国即将建设的地震电磁卫星地面传输系统进行简要分析介绍,从而为地震电磁卫星地面传输系统初步设计的完成提供一个基本框架。 相似文献