P.R. Barnes

On the direct calculation of a transient plane wave reflected from a finitely conducting half space

An approach to the computation of the electromagnetic field reflected from a lossy half-space directly in the time domain is discussed. This approach requires first evaluating the impulse response of the half-space and then convolving it with the specified incident field waveform. To obtain the impulsive reflected field, either for vertical or horizontal polarization, approximations to the Fresnel reflection coefficients are made, thereby permitting an analytical expression in the time domain. Several different numerical examples using this technique are presented to illustrate the use of the method and the error contained in the solution. >

A Modified Unit Commitment and Generation Control for Utilities with Large Wind Generation Penetrations

A modified unit commitment is proposed in this paper that would be updated on three different cycles (daily, quarter-hourly and every minute). The 24 hour updated unit commitment would include the effects of load and slow trend wind power change that could be predicted 24 hours ahead. The quarter- hourly updated unit commitment would handle the fast trend and cyclic change in wind power that could be predicted one hour ahead and would commit peaking, regulation, and quick pickup and possibly economic units to handle these wind power changes.

A multiconductor model for determining the response of power transmission and distribution lines to a high altitude electromagnetic pulse (HEMP)

A nuclear detonation at an altitude above 40 km above the earths surface would produce an intense transient electromagnetic field, known as a high altitude electromagnetic pulse (HEMP). These electromagnetic fields radiated from the blast vary with the detonation location and weapon characteristics. At detonation altitudes ranging from 100 km to 500 km, large portions of electrical power system interconnections would be illuminated by this intense transient field. The intensity of this HEMP field would be on the order of tens of KV per meter. Most of the energy of the HEMP environment lies within the radio-frequency (RF) portion of the electromagnetic spectrum, and ranges from several kilohertz to more than 100 MHz. This intense transient electromagnetic field will almost simultaneously induce fast electrical surges in transmission and distribution (T&D) systems and in elements of the control and communication systems throughout large portions of the nations electric grid. Earlier investigations have indicated that the HEMP-induced surges may well exceed the basic insulation level (BIL) on power distribution lines. This could result in flashovers and/or insulation damage. Insulation damage can occur in the form of a puncture or degradation of the insulation strength. On power transmission lines which are designed with a higher BIL, the possibility of line flashover is smaller, but it must be recognized that these lines may run for many miles and consequently, can deliver a large amount of EMP energy into a substation or other facility.

The effects of steep-front, short-duration impulses on power distribution components

A line-type pulser has been developed to test the effects of steep-front, short-duration (SFSD) pulses on distribution components. The risetime is 50-100 ns and the pulse duration is on the order of 300 ns. Terminators often shattered or punctured rather than flashing over. The insulator flashover voltage is approximately 1.5 times CFO for standard lightning impulses. Arresters exhibit an inductive character, with the SFSD peak voltage at 10 kA approximately 4-5 times the 8-pulse*20- mu s 10 kA discharge voltage. Polyethylene insulated cable has a characteristic degradation in which failure voltage decreases with number of SFSD pulses. >

Electromagnetic Pulse and the Electric Power Network

This paper defines the nuclear electromagnetic pulse (EMP)-electric power system interaction problem. A description of high altitude EMP (HEMP) characteristics, source region EMP (SREMP) characteristics, and magnetohydrodynamics EMP (MHD-EMP) characteristics are presented. The results of initial calculations of EMP induced surges on electric power transmission and distribution lines are presented and compared with lightning induced surges. Potential EMP impacts on electric power systems are discussed, and an overview of the Department of Energy (DOE) EMP research program is presented.

Economic consequences of geomagnetic storms (a summary)

The effects of the March 13, 1989, geomagnetic storm, which revealed significant vulnerabilities of electric power systems to this natural widespread phenomenon, are described. This vulnerability appears to be increasing during the 1990s. The economic consequences to the nation of this vulnerability are significant, on the order of several billion dollars for each major outage. It is suggested that the US government can play an important role in reducing the vulnerability of electric power systems to solar storms by installing an early warning satellite and cooperating with industry in a comprehensive research program. The Department of Energy can fill gaps in the research and provide for continuity of research during periods of reduced solar activity when industrial research tends to wane.<<ETX>>

Determination analysis of energy conservation standards for distribution transformers

This report contains information for US DOE to use in making a determination on proposing energy conservation standards for distribution transformers as required by the Energy Policy Act of 1992. Potential for saving energy with more efficient liquid-immersed and dry-type distribution transformers could be significant because these transformers account for an estimated 140 billion kWh of the annual energy lost in the delivery of electricity. Objective was to determine whether energy conservation standards for distribution transformers would have the potential for significant energy savings, be technically feasible, and be economically justified from a national perspective. It was found that energy conservation for distribution transformers would be technically and economically feasible. Based on the energy conservation options analyzed, 3.6-13.7 quads of energy could be saved from 2000 to 2030.

The response of MOV and SiC arresters to steep-front longer duration current pulses

An 80 m section of 138 kV transmission cable was used to produce pulses with voltages of several hundred kilovolts, currents greater than 20000 A, and voltage risetimes equal to approximately 50 ns. This line pulser was used to test the response of metal-oxide varistor (MOV) and gapped SiC surge arresters to steep-front, high-current, 1.4 mu s-duration pulses. The typical arrester voltage during a pulse consists of a very strong initial overshoot voltage spike, followed by a nearly constant residual voltage which lasts to the end of the pulse. The overshoot voltage is believed to be related to the inductance of the arrester/divider circuit; this voltage increases linearly with peak current and is about the same for the MOV and SiC arresters. The residual voltage indicates the protection offered by the arrester due to its voltage clamping action and is larger for the SiC arrester. Replacing the arrester by a similarly sized aluminum tube allows the inductive portion of the response to be removed, and the true arrester response is then seen to be quite fast. >

A Method for Determining How to Operate and Control Wind Turbine Arrays in Utility Systems

This paper addresses the simply stated but important question: If a utility has decided to install a number of arrays of wind turbine (WT) generators, how should they be operated and controlled on the load frequency control time-scale- seconds to minutes?

The optimization of solar heating systems

Abstract The optimization of a solar system with a limited number of discrete collection areas available has been discussed. This optimization is based on an exponential relationship between the auxiliary energy required and collector area. In most cases, the optimum area is that area formed by an array of collector panels which is closest to but greater than A op . In many cases, an even larger collection area can be used without a severe economic penalty since the cost curve changes slowly as collector area is increased. Larger collector areas are also preferable from the standpoint of reducing our dependence on non-renewable fuels.