HVDC power transmission environmental issues review

Abstract

Thii report has been reproduced directly from the best available copy. Available to the public from the National Technical Information Servii, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22 16 1.This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nof any of their employees, makes any warranty, express or implied, or assumes any legal l i b i l i i or responsibili for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disdosed, or represents that its use would not infringe privately owned rights.Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER IntroductionEnvironmental issues are addressed in the permitting process of every transmission line project, whether it be a new line or an upgrade of an existing line. In recent years, the most controversial issue associated with alternating current lines is the potential effects of electromagnetic fields on human health. However, environmental effects on animals, plant life and other electrical and communication systems also must be assessed in every case. Although different from ac lines, high voltage direct current (HVDC) lines also produce environmental effects that warrant review and assessment in every project. This report strives to define the various environmental effects associated with HVDC lines, discusses the current knowledge of their potential effects on biological and non-biological systems, and compares these effects associated with ac lines where appropriate. The Environment Near an Electric Power LineThe electrical environment of a high voltage transmission line can be characterized by three electrical parameters: 1) the electric field, 2) the air ion and charged aerosol concentration, and 3) the magnetic field. The electric field arises from both the electric charge on the conductors and for an HVDC transmission l i e , charges on air ions and aerosols surrounding the conductor.In addition, corona may also produce low levels of ozone, audible noise, electric field and radio interference. A magnetic field is produced by current flowing through the conductors. Summary of Key FindingsIons. Neither the animal nor human studies provide any reliable evidence for the proposition that air ions produce any harmful effects. In fact, there is considerable uncertainty as to whether there are any biological responses to air ions. At the levels produced by HVDC transmission lines, the possibility of risk to human health appears remote, if not vanishingly small. There are no published guidelines for maximum ex...

Application of Interval Methods to Uncertainty Analysis of HVDC Transmission Lines Fields

“…The peak value of E using method A is 13.4722 kV/m ;while using method B the interval value is [12.8169,14.1265] kV/m which shows the validity of the interval approach. The slight asymmetry of the field profiles, commonly observed in many outdoor studies [1,3,10,11], may be partly explained by the uncertainty in the value of S as observed here at the zero crossing. The E profiles with uncertainty in H only are shown in Fig.5.…”

“…This may partly explain the discrepancies which usually observed in outdoor field measurements when compared with calculations [1,3,10,11]. The above analysis demonstrates the accuracy of interval techniques in producing accurate bounds for the output result.…”

“…The reasons for the variations in H are numerous including environmental conditions, loading conditions, deviations during the design and erection stages, or simply errors in measurements [3,10,11]. Similarly, the lateral location X may be inaccurately determined; though with a lesser error than H. The results for E when H alone or X alone or both are treated as interval numbers are shown in Figure 3 a,b,c.…”

“…As a result, there are many uncertainties associated with utility decisions in this regard. HVDC electric fields are currently a source of environmental and public health concerns [2][3][4]. These fields depend mainly on the line clearances and their values and distributions; thus, should be treated as uncertain as it is no longer valid to assume that the input parameters are known with certainty.…”

“…HVDC transmission lines ionized fields have been a source for environmental and biological public concerns[2][3][4]10,11]. Calculation of HVDC fields, even without space charges, is important to determine the ionized field quantities.…”