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Title: Optimal Transmission Line Switching under Geomagnetic Disturbances

Abstract

This report is a seminar for the University of Michigan. It describes the energy infrastructure at LANL and a model of GIC physics that combines AC power flow physics.

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1321712
Report Number(s):
LA-UR-16-26759
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 24 POWER TRANSMISSION AND DISTRIBUTION

Citation Formats

Bent, Russell Whitford, Lu, Mowen, Backhaus, Scott N., Nagarajan, Harsha, and Yamangil, Emre. Optimal Transmission Line Switching under Geomagnetic Disturbances. United States: N. p., 2016. Web. doi:10.2172/1321712.
Bent, Russell Whitford, Lu, Mowen, Backhaus, Scott N., Nagarajan, Harsha, & Yamangil, Emre. Optimal Transmission Line Switching under Geomagnetic Disturbances. United States. doi:10.2172/1321712.
Bent, Russell Whitford, Lu, Mowen, Backhaus, Scott N., Nagarajan, Harsha, and Yamangil, Emre. Tue . "Optimal Transmission Line Switching under Geomagnetic Disturbances". United States. doi:10.2172/1321712. https://www.osti.gov/servlets/purl/1321712.
@article{osti_1321712,
title = {Optimal Transmission Line Switching under Geomagnetic Disturbances},
author = {Bent, Russell Whitford and Lu, Mowen and Backhaus, Scott N. and Nagarajan, Harsha and Yamangil, Emre},
abstractNote = {This report is a seminar for the University of Michigan. It describes the energy infrastructure at LANL and a model of GIC physics that combines AC power flow physics.},
doi = {10.2172/1321712},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Sep 06 00:00:00 EDT 2016},
month = {Tue Sep 06 00:00:00 EDT 2016}
}

Technical Report:

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  • Recently, there have been increasing concerns about how geomagnetic disturbances (GMDs) impact electrical power systems. Geomagnetically-induced currents (GICs) can saturate transformers, induce hot spot heating and increase reactive power losses. These effects can potentially cause catastrophic damage to transformers and severely impact the ability of a power system to deliver power. To address this problem, we develop a model of GIC impacts to power systems that includes 1) GIC thermal capacity of transformers as a function of normal Alternating Current (AC) and 2) reactive power losses as a function of GIC. We also use this model to derive an optimizationmore » problem that protects power systems from GIC impacts through line switching, generator dispatch, and load shedding. We then employ state-of-the-art convex relaxations of AC power flow equations to lower bound the objective. We demonstrate the approach on a modified RTS96 system and UIUC 150-bus system and show that line switching is an effective means to mitigate GIC impacts. We also provide a sensitivity analysis of decisions with respect to GMD direction.« less
  • A comparative study of the effects of solar storm geomagnetically induced current (SS-GIC) and nuclear detonation induced currents (MHD-EMP-GIC) on the power system is presented. The earth surface electric field of the MHD electromagnetic pulse is given to be on the order of 100 V/km, with a duration up to several minutes; and the electric field of the solar storms is given to be on the order of 10 V/km, and lasts from several minutes to one hour. Both phenomena cause flow of almost direct current in the windings of power transformers through the grounding system. For lone transmission lines,more » i.e. 300 miles or longer, this DC current offsets the 60 Hz AC and may saturate transformer cores, with secondary results such as high magnetization currents, increased harmonics, and concomitant effect on power system operation. The level of the transformer core saturation depends on the time constant of the saturation process, and on the duration and magnitude of the direct current through the transformer windings, but the degree of transformer saturation is comparable. Thus, the effects on system voltage could be expected to be about the same. Furthermore, although the solar storm electric field is much lower than MHD-EMP, the solar storm effects on the power system, from the thermal stress point of view, are greater due to their much longer duration. A technique for the computation of the induced and/or transferred voltages and currents to an electric power system form geomagnetic disturbances is presented. Models of transmission lines which explicitly represent grounding, earth potential, and frequency dependent phenomena, and power transformers which explicitly represent nonlinear magnetization characteristics, are utilized. A parametric analysis of saturation time constants is performed and the effects of MHD-EMP and SS-GIC are compared. 36 refs., 14 figs., 8 tabs.« less
  • An optimal single-shaker test procedure is developed for the seismic qualification of Class 1E multicomponent electrical equipment. The method comprises a single test that uses an uniaxial excitation having certain minimum intensity applied at the equipment support location in a predetermined optimal direction. Analytical expressions for the optimal test parameters are obtained by maximizing the risk of component failure during testing. The apriori evaluation of these parameters requires a frequency response test. The optimization problem is expressed as a matrix eigenvalue problem. The primary advantages of the proposed method over the currently employed four-rotation test simulating tri-axial input are reductionmore » of the test duration, minimization of the excitation intensity and elimination of unnecessary overtesting in the vertical direction. The test procedure may be fully automated.« less