ML18026A305
| ML18026A305 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 08/14/1980 |
| From: | Lehman R PENNSYLVANIA POWER & LIGHT CO. |
| To: | |
| References | |
| NUDOCS 8008260792 | |
| Download: ML18026A305 (46) | |
Text
i;-
UNITED STATES OF AMERICA
$ pal ~ C UQe'ea aQ NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOA . +<-1C4MV;.""-~~v In the Matter of )
4j
)
PENNSYLVANIA POWER 5 LIGHT COMPANY ) Docket Nos. 50-
) 0-" 8 and )
g )g-gd
)
ALLEGHENY ELECTRIC COOPERATIVE INC.
)
(Susquehanna Steam Electric Station, )
Units 1 and 2) )
AFFIDAVIT OF ROBERT F. LEHMAN IN SUPPORT OF
SUMMARY
DISPOSITION OF OZONE CONTENTION County of Lehigh )
SS Commonwealth of Pennsylvania )
Robert F. Lehman, being duly sworn according to law,
'eposes and says as follows:
- 1. I am Senior Project Engineer, Bulk Power Engineering Development, System Power and Engineering Department, Pennsylvania Power 5 Light Company,- and give this affidavit in support of Applicants'otion for Partial Summary Disposition of Contention 17 (Ozone). I have personal knowledge of the matters set forth herein and believe them to be true and correct. A summary. of my professional qualifications and experience is attached as Exhibit "A" hereto.
- 2. Contention 17 in this proceeding alleges in part that the 500 kV transmission lines to be utilized for transmitting the electric power produced by the Susquehanna facility will "generate dangerous levels of ozone". This Contention is erroneous. While transmission lines can produce ozone by corona discharge at the
,8008 260 79 2 ~go 9 o(
surface of the lines, theoretical calculations and field measure-ments (further described below) show that the levels of ozone generation at the surface of high-voltage, transmission line con-ductors are low and that ground level concentrations of ozone are negligible.
- 3. Extensive field measurements have been conducted by electric utilities and research institutions to determine the levels of ozone generation near high-voltage transmission lines. I'1,2,3,4]-*/
One of those series of field measurements was conducted by Nesting-house Corporation at an experimental 765 kV line .in Apple Grove, Nest Virginia.
~ . ill The experimental line utilized by Westinghouse had a corona activity 2 to 4 times greater than an operating 765 kV line and had, therefore, a higher ozone production rate than'an operatic" line. Also, the experimental line utilized by. Westinghouse would have a higher ozone generation rate than a 500 kV line such's those to be utilized at Susquehanna.
- 4. Ozone concentration measurements were made at heights of 2 feet and 30 feet above ground at a distance of approximately 95 feet from the experimental line utilized by Westinghouse. During fair weather conditions (~.e., no precipitation or fog) ozone con-centrations were so low that they fell below the detection limit of the ozone measuring instrumentation (1 ppb) and could'ot be detected at either height. During foul weather conditions, small amounts of ozone (20 ppb) could be measured at the 30-foot height, and none at ground level.
<</ References cited are listed at the end of my,affidavit.
2
- 5. Other programs for ozone field measurement near high voltage transmission lines have been undertaken by American Electric Power Service Corporation ("AEP") and Battelle Memorial Institute in
[31 1970-71 , and by the Illinois Institute of Technology in 1971-72.
Again, the lines on which measurements were taken should generate comparable or greater amounts of ozone than the Susquehanna 500 kV lines. These measurement programs also concluded that ground level concentrations of ozone near high voltage transmission lines are negligible. Laboratory studies conducted by AEP and Ohio State Uni-versity in 1976 under conditions comparable to those found in operating high-voltage transmission lines concluded that no detectable amounts of. ozone 'could be measured at ground level, even during foul weather>
although some ozone generation was measured in foul weather near the surface of the conductors.
- 6. In addition to the field measurement programs, analytical methods validated by measured data have been developed for calculating the ozone concentration in the vicinity of a high-voltage transmission line. ' I have used these methods to compute the ozone concentration at the center of the right-of-way of the Susquehanna 500 kV transmission lines. *6/ My calculations assumed a very favorable set of conditions for ozone generation,
~.e., (a) maximum design operating voltage (550 kV); (b) stable low-speed wind (2.5 mph) blowing exactly parallel to the line; (c) heavy rain rate of 1 inch per hour; (d) maximum corona loss; (e) no ozone decay due to chemical reaction or due to the effect of rain and humidity; and (f) no upwards migration of ozone as it is generated.
"*/ The analytical methods utilized in my calculations are described in Exhibit "B" hereto.
3
- 7. Under such conditions, which I believe are highly improbable [5 ' 6 ' 7 8 ' 9] and will exist (if at all) for a period of one hour or less each year in the area traversed by the Susque-
[101 the maximum calculated ozone concentration hanna 500 kV lines,'
near a Susquehanna 500 kV transmission line during a one-hour period
- /
will be 19 parts of ozone per billion (ppb).
- 8. Variation in any of the above assumptions to incorporate more realistic conditions will reduce the estimated maximum ozone concentration significantly. For instance, assuming a rain rate of 0.05 inches per hour would reduce the maximum ozone concentration by 44: to 11 ppb. Assuming fair weather conditions reduces the maximum ozone concentration by at least 98: to .4 ppb or less. In the area traversed by the Susquehanna transmission lines, the average frequency of rain rates in excess of 1 inch per hour is about one hour per year; the average frequency of rain 'rates in excess of'.05 inches per hour is 290 hours0.00336 days <br />0.0806 hours <br />4.794974e-4 weeks <br />1.10345e-4 months <br /> per year. [10]. Similarly, assuming the wand to blow at a slight (10 degrees) angle to the line would reduce the maximum ozone levels by 70:, from 19 to 6 ppb. Assuming unstable wind would reduce the maximum ozone levels by 974, from 19 to .6 ppb.
Stable wind conditions occur in the geographic area of interest only 30-40'. of the time.'- [101 Utilizing the 30-minute half-life for ozone .
applicable during high humidity periods reduces the maximum level by 63~, from 19 to 7 ppb. Assuming the nominal 500 kV voltage would reduce the maximum level by 65;, from 19 to 6.6 ppb. Each of these reductions would operate independently of the others.
~*~/ Tables summarizing the results of my analysis are attached as Exhibit "C" hereto.
4
i~ '
- 9. Based on the above described experimental data and my own calculations utilizing an extremely conservative set of assumptions, it is my opinion that the levels of ozone emitted by the Susquehanna 500 kV transmission line will be very low and are unlikely to ever reach more than a small fraction of the Federal air quality standard for ozone of 120 ppb.
f/~/'~u / 7 o ert F. Le man Sworn to and subscribed
~
this p':+
~ ~
before me
/ day of t,'. ';.;, 1980, r'8' j
~ / 1 lic Public igi/N P. MILLB. iR.. Notary Po. s Alentown, t.ehign County.
C 0 mmissionExpirosQay24.
l
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References
- 1. Dietrich, Chartier and Nowak, "Ozone Concentration Measurements on the C-line at the Apple Grove 750 kV Project and Theoretical Estimates of Ozone Concentrations Near 765 kV Lines of Normal Design". IEEE Transactions on Power Apparatus and Systems, pp 1392-1401 (July/Aug. 1978) .
- 2. Frydman, Levy and Miller, "Oxidant Measurements in .the Vicinity of Energized 765 kV Lines", IEEE Transactions on Power Apparatus and Systems, pp. 1141-1148 (May/June 1973) .
- 3. Fern and Brabets, "Field Investigation of Ozone Adjacent to High Voltage Transmission Lines", IEEE Transactions on Power Apparatus and Systems. pp. 1269-1280 (Sept./Oct. 1974)-
- 4. Sebo, Heibel, Frydman and Shih, "Examination of Ozone Emanating from EHV Transmission Line Corona Discharges" IEEE Transactions on Power Apparatus and Systems, pp. 693-703 (March/Apr. 1976).
- 5. Roach, Chartier and. Dietrich, "Experimental Oxidant Production Rates for EHV Transmission Lines and Theoretical Estimates of Ozone Concentrations Near Operating Lines", IEEE Transactions on Power Apparatus and Systems, pp. 647-657 (March/Apr. 1974) .
- 6. "Transmission Line Reference Book, 345 kV and Above," Palo Alto, CA, Electric Power Research Institute (1975).
- 7. Scherer Jr., Hare and Shih, "Gaseous Effluents Due to EHV Transmission Line Corona", IEEE Transactions on Power Apparatus and Systems, pp. 1043-49 (May/June 1973).
- 8. "Electrical Effects of 345 kV and Above Transmission Lines",
Course Director, Dr. K.R. Shah, P.E., Jackson, Michigan, Professional Development Services (1977).
- 9. Frydman and. Shih, "Effects of the Environment on Oxidants Production in AC Corona", IEEE Transactions on Power Corona,"
IEEE Transactions on Power Apparatus and Systems, pp. 436-443 (1974) .
- 10. "Susquehanna Steam Electric Station, Units 1 6 2 Environmental Report Operating Stage", Pennsylvania Power and Light Co. (May 1978).
ll. 40 CFR 550.9 (a)(1979).
ROBERT F. LEHMAN SENIOR PROJECT ENGINEER BULK POWER ENGXNEERZNG DEVELOPMENT PENNSYLVANIA POWER & LIGHT COMPANY Education Formal Lehigh University, B.S.E.E. (1956)
Continuin Education Power Technology Incorporated: Course in Power, System Planning, Design and Operation (1965).
IEEE: EHV Transmission Line Corona Effects (1972).
XEEE: Location, Correction and Prevention of Radio Interference and TV Interference (1976).
Professional Development Services: Electrical Effects of 345 kV and Above Transmission Lines (1977).
ANSI/ZEEE: Seminar on ANSI C-2, 1977 Edition of the NESC (1977) .
Project UHV-GE-EPRZ: Field Effects of UHV Lines (1978) .
Professional Development Services: Power System Grounding (1978).
Professional Development Services: Biological Effects of Transmission Lines (1978) .
Re istration Professional Engineer, Commonwealth of Pennsylvania (PE-015181-E), (1969) .
Membershi s Institute of Electrical and Electronics Engineers (IEEE)
(Senior Member)
International Conference on Large Electric Systems (CZGRE)
ZEEE Thermal Rating Task Group ANSI Standards Committee C-29 ANSI Subcommittee 4 of Standards Committee C-2
Publications-External to P,PGL Lehman, Shankle, "Transmission Line Electrostatic Induction Effects", Proceedings of the American Power Conference, 1975.
J. C. Cronin, R. G. Col claser, R.F. Lehman, "Transient Lighting Overvoltage Protection Requirements for a 500 kV Gas Insulated Substation," ZEEE Power Apparatus and Systems, Jan/Feb 1978.
Internal P,PGL Publications Transmission System, Insulation Coordination, Analysis of Present Transmission Line Insulation Levels (Dec. 1975);
500 kV Conductor Study (Apr. 1976);
500 kV Gas-?nsulated-Substation, Insulation Study (Oct. 1976);
Siegfried-Wescosville 53 230 kV Line, Electric Field Gradient Reduction at Lehigh Service Center (Jun. 1977);
Conductor Temperature Response (Jan. 1978);
EHV Station Iightning Shielding Masts (Feb. 1978);
Electrical Environmental Effects of 500 kV Transmission Lines (Oct. 1978) .
Work E erience Pennsylvan'a Power a Light Co. (1959-present)
Engineering Development. Assigned to manage and conduct technical research and development projects, engineering studies, and investigations, 'and to establish engineering standards and specifications, for PP&L's high voltage bulk power transmission system.
Representative projects include:
a) preparation of computer programs to calculate substation ground grids, to select economical conductors, to calculate radio interference and audible noise, electrostatic and electromagnetic induction on parallel wires, electr'ic field gradients and line impedances;
b) selection of 500 kV conductors; c) calculation of electrostatic and electromagnetic field effects; d) instruction of transmissi'on line design personnel in EHV line electrical design fundamentals; e) insulation coordination studies, 500 kV gas insulated substation and 500 kV transmission lines; f) substation ground grid design; g) transmission line structure grounding;
- h) unbalanced transmission line calculations; and i) preparation-of Electrical Engineering Basics Manual used for technician training..
1959-1972: Engineer, Project Engineer and Senior Project Engineer, Transmission Line Design Section.
Assigned a variety of operations-oriented tasks.
Representative projects include:
a) preparation of design manuals for 500 kV and 138 kV lines; b) preparation of computer programs for line design, covering areas such as sag cal-culations, broken wire, blown out conductor, conductor and wind loadings, right of way widths and line centerline separations, conductor thermal ratings, and wood pole structure horizontal spans; c) cost estimating for 500 kV and 230 kV steel tower lines, and steel structure horizontal, vertical and longitudinal load calculations.
Other Work Ex erience 1956-1959: During military service, assigned to the Engineer Research and Development Laboratories at Fort Belvoir, Virginia.
CALCULATION OF CONDUCTOR SURFACE GRADIENTS FOR CORONA, AUDIBLE NOISE AND RADIO lNTERFERENCE CALCULATIONS The conductor surface gradients can be calculated as a function of the line voltage, the geometry, the radii, and effective height above ground of the conductors and overhead ground wires.
The first, step in determining the conductor surface gradient consists of calculating the linear charge on each conductor.
The linear charge is related to Maxwell's potential coefficients and the line voltages by [1]:
- /
where:
fQ] = linear charge densities, coulomb/meter
[V] = conductor line-to-ground voltages in volts
[P] = inverse of Maxwell's potential coefficients, farad/meter ii = ln 1 2h - Diagonal terms of the [P] matrix P.. 27te r P.. =
ij ln Li~
2Re
- Off diagonal terms of the [P] matriz ij where:
h = effective conductor height
= height at tower - 2/3 sag at midspan r ."- conductor radius
"/ References cited are listed at the end of the analysis.
L..
Lj
direct distance from conductor i to image coaductor j 1.. = direct distaace i to conductor 3 1J e
from conductor dielectric constaat for air =
36m x 10
-9 farads/meter The electric field at the surface of the conductor then:
E- 27ter kV/cm For bundled-conductors the above value would represent aa average for the individual conductor. Values around the periphery for each conductor are:
d Ee = Eavera e [1 + g (N-1) cos 8] kV/cm The maximum surface gradient for the individual coaductor is fouad by setting e = 0.
= E d E
e average (1 + D (N-1)] kV/cm max where:
d = subcoaductor diameter D = bundle diameter N = number of subconductor per phase The maxima for all of the conductors in a bundle are then averaged to give the maximum surface gradient of the phase. A sample computation of the maximum conductor surface gradient per ohase for one of the Susquehanna 500 kV lines will be given next:.
SAMPLE CALCULATION OF THE CONDUCTOR SURFACE GRADIEVZ FOR CORONA RELAWM CALCULATIONS For the conductor configuration shown in Figure 1, which corresponds to Section 4-4 of the Susquehanna 500 kV lines, the conductor surface gradient is calculated as follows:
- 1. Calculation of the Maxwell coefficient matrix (P] (using effective conductor hei hts)
The main diagonal terms are calculated using the relationship:
ii l Rn-P.. = ate 2H r
For instance:
Pll =
P22
=
P33 P44
=
P55
=
P66 1
'12 2n 8.85 x 10 ln 2 x 50.67 = 1.8 x 1 821 2z12 10 (7.19
= 1.8 x 10 10 2 x 92.73 = 10 P77
=
P88 ln 0.572 0 57 1.8 x 10 (8.9595) 2x12
24.
65'5.0'onductor(wf.th sag) 115.
0'4.50'ata:
?ower Concuctor 2 L.821" Diameter conductors per phase (18" spac~)
SAG 59.0 feet (100~ C oare no vind, 1330 ft. span)
EFFECTIVE MIGFZ . 90 2/3 (59) -" 50.67 feet MZHZM2f MX~a 90 59 = 31, feet Overhead Ground Wire 19 No . 9 Alumoweld (0.572" Dismete )
SAG 33.4 e t PrZCTXVE ~Z~ M~
5 2/3 (33.4) = 92.73 feet
~~KM MZGr~~ 115 33.4 = 81.6 feet Ope ating Vo1 zge 550 sV Phase Current 3470 amps Configuration, of a single circuit 500kV transmission structure utilized in sample calculations for the Susquehanna 500kV Lines Section 4-4.
The off diagonal terms are calculated using the relationship:
P..
ij = 1 2Re Rn L..
i 1..
i]
For instance:
= = = = 1.8 x 10 10 ln P23 P45 P56 12'12
'12 2+ 2
= 1.8 z ' 1.8 z 10 10 ln (1.1324)
Completing the calculation for the remaining conductor combinations results in the following P matrix which is symmetrical about the main diagonal.
T. 1971 1.1324 7.1971 0.5748 1.1324 7.1971 4.2131 1.1724 0.5899 7.1971 (P] = 1.8 x 10 1.0944 4.2131 1.1?24 1.1324 7..1971 0.5602 1.0944 4.2131 0.5748 1.1324 ?.1971 1.1985 1.1003 0.-7661 1.2057 1.0865 0.7530 8.9595 0.7530 1.0865 1.2057 0.7661 1.1003 1.1985 1.3591 8.9595
Inverting the P matrix results in:
0.2141
-0.0076 0.2158
-0.0021 -0.0074 0.2147
-0.120? -0.0088 "0.0024 0.2147
[P] = 5 56 z 10
-0;0064 -0.1193 -0.0088 -0.0073 0.2158 "0.0019 -0.0064 -0.120? -0.0021 -0.0075 0.2141
-0.0097 -0.0076 -0.0041 -0.0097 -0.0071 -0.0039 0.1187
-0.0039 -0.0071 -0.0097 -0.0041 -0.0076 "0.0097 "0.0135 0.1187 Calculation of the Volta e Matrix V]
The operating voltage is 550 kV. Assume the voltage vectors are as shown:
V1 & V4 V = V4 = 550 (-sin 30 + j cos 30)
= -158.77 + j 275.0 V
2
= V 5 =~ (-sin 550 30 - j cos 30)
V3 & V6
= -158.77 - j 275.0
.V & V V 3 V6 ~550 317 54 V7 V8 = 0 (ove head ground wires )
"158. 77 + j275.0
-158.77 - j275.0 317.54 - j0 (v) = -158.77 + j275.0
-158.77 - j275.0 31?.54 - jO 0 + jO 0 + jQ
- 3. Calculation of the Linear Char e Densit iiatrix [Q]
Using the values of [P] and (V] computed above (Q] = t1'] 'V]
-<3.9080 + j29.5294
-17.1148 - j31.0254 33.1172 + j3.22574 fQ] = 5.56 x 10 -13.7667 + j30.2967 coulombs/meter
-18.3102 - j30.3352 32.5234 + j2.71974 2.86294 - jl.31725
-2.57129 - j 1. 82050
- 4. Calculation of the liaximum Surface electric Field The average electric field at the surface of the conductor is determined by".
For each of the conductors r = 1.821 2
2.54 = 2.3127 cm For the overhead ground vires r = 0.572 2
2.64 = 0.7264 cm
-6.0138 + j12.7684
-7.4004 - j13.4152 14.3197 + j1.3948
~'~v] = "5.9527 + j13.1001 kV/cm "7.9172 - j13.1168 14.0630 + j1.1760 3.9413 - j1.8134 "3.5398 + j2.5062
The maximum electric field for the individual conductors is determined by:
[Ee] = [EAV] (1 + Dd (N 1))
d = subconductor diameter D = bundle diameter The factor N = Number of conductor per bundle (1 +
d D
(i%-1)) = 1 '2-1)
+ 1.821 18
= 1.1012.
mul tip lying:
-6.6224 + j14.0606
-8.1493 - j14.7728 15.7689 + jl 5360
~
-6.5551 + j14.4258
[Ee] = -8.,7184 - j14.4442 kV/cm 15.4862 + j1.2950 3.9413 - j1.8134
-3.5398 + j2.9062 Finally the phase surface gradients are the averages of the maximum electric field surface gradient for each pair of conductors.
Phase I (condrs 1 6 4) = [(-6.6224 + jl4.0606) + (-6.5551 + j14.4258)]/2
= -6.5888 + j14.2432 = 15.69/114.8 kV/cm Phase II (condrs 2 6 5) = $ -8.1493 - j14.7728) + (-8.7184 - j 14.4442)]/2
= -8.4339 - 14.6085 = 16.87/-120.0 kV/cm j
Phase III (condrs 3 6 6) = [(15.7689 + j1.5360) + (15.4862 + jl.2950)]/2 j
= 15.6276 + 1.4155 = 15.69 /5.18 kV/cm Th'e conductor surface gradients for the overhead ground wires are:'omdr 7 = 3.9413 - j1.8134 = 4.34 /-24.7 kV/cm Comdr.8 = -3.5398 + j2.5062 = 4.34 /144.7 kV/cm
The same method can be utilized to compute phase surface gradients for other transmission line configurations. A computer program was developed to perform these calculations. The output from a sample run which duplicates the above calculation is shown in Figure 2.
RL:DEB 17-E
CONDUCTOR SURFACE GRAD IEN7 LI NE VOLTAGE ZS 550 ~ 00 KV MIN LMUM CONDUCTOR HEIGHT ES 31 ~ 00 FEET CALCULATI CiN I S BASED ON AN EFFECT IVE HEI GHT OF 50 ~ 67' EE SUSQUEHANNA- 550 KV TRrV4&LLSSLONe SECT..4-4i&L2E-A VERAGE WAX IMUN PHASE T'GNDUCTOR NUiMBER SURFACE GR AQ ZEN T.
KVRMS/CM SURF ACE GRADIENT KVRMSt'CM
........ SURFACE GRAD IENT
.KVRMSi'CM 14~1 M2 1 15 '4 L 6~8.
3 1 4+39 15 ~ 85 4 14e39 1 5085 5 15 +32 16087 6 i14 4.1L .15 ~54 7'
1 4 4 ~33 4e33 4 '3 4+33 15069 2...5 L6 <<.87 3 6 15i69 FXGURE 2 Output- of sample computer computation" of ohase surface-gradients-for Section-4<<4---"-
of the Susquehanna 500kV Lines.
CALCULATION OF CORONA LOSS The corona discharge or corona loss levels from a transmission line vary widely depending on weather conditions. Therefore, the transmission line corona loss can only be estimated statistically by accumulating observations over periods of time and generating a cumulative frequency distribution curve for the corona loss on the line.
Another way to estimate the corona loss from a transmission line is to utilize measured corona losses for short test sections and combine these with a statistical weather model for the area in which the line lies.
Such a statistical weather model for the Central-Eastern Pennsylvania region was constructed by Project UHV for weather data at Harrisburg, PA. (1]. From the Project UHV results, the following table was constructed giving the corona loss distributions applicable to any transmission line that would operate in that geographic area.
Corona $ of Short T.oss Section 'Value Yearly Average 2.5 15$ Probability It 6.0 10$ 10.0 II 15.0 2g I1 22.0 ifaximum Loss 74.0 As can be seen from the table the maximum corona loss in a transmission line will never reach the theoretical 100$ "heavy-rain loss" level because. weather along a line is rarely constant.
The maximum corona loss under heavy rain condition (0.5 to l. inch/hour) was measured for test lines by Project UHV and a family of curves was generated giving the efzective corona loss under heavy rain conditions C
versus the lines maximum surface gradient for various conductor sizes.
That family of curves, reproduced from Figure 7.3.2 of reference [1] is shown in Figure 3.
En order to estimate the effective cozona loss for the Susquehanna transmission lines, the maximum surface gradient of the conductors determined earlier was entered into Figure 7.3.2 at the appropriate conductor size curve and the value of the corresponding effective corona loss was read off the graph's ordinate.
The effective corona loss of a conductor is the loss of an ideal bundle working at the same surface gradient but infinitely far from the ground.
As the proximity of the ground inc eases, the loss increases bv a factor K. Once the loss for each phase is determined, the total loss for the 3 phase line is:
P = K .
KCL . (CL.
jl + CL
)22
+ CL.3) j3 w/meter where:
CL 1
CL 2
and CL> are the effective corona 1 osses for each phase, ak determined from figure 7.3.2.
KC is a subconductor correction factor determined from figure 7.5.3 of reference [1]. (This figure also is reproduced in Figure 3.)
K is a correction factor to account. foz the proximity of ground. The value of K for a two-conductor bundle at 550 kV is 1.38.[1J
2.4 Ia i .t
>g 4~ca I
(L823.ia)i I84a I.4 ia I I
cs 4 s sscn oc 4 tv/cs cxs ca col sc lY/ca a I is
~ lo r
r r e
IOO gr I r s C I
c esca
~ Iles cc/ca ~ I }
cn 0.S
/ I I n I ~ nx tasccs C
/I ln I I I 0 nswna Cl I I 0 00t 0OZ 0OS at aa 0S ca tO 0000 asac aatf cis/I 8 20 ta 8 Ill/ I 000t CIPS Crt 00t acne 005 .
acts-is/i 01 0S 0S ll I I I/ I I / I / Fig. 7.3 4 Variatian of Corona Loss with Rain Rate. The Values are Q IO f . I FR& TEST DATA in per-Unit at the Loss at a Rain Rate af O.t in/h.
EXTRAR)LATED OESIQII
/ C I (
CURVES I
5~ceo/
- 4LM2 in) ~ i ~ i 2,33 cot
! I i i I I I I I I I I I~ ia~ I I I I i 3 3 cot I I m) in 4.63cm 2H ca Bl9I8ia), l c I IO 15 c9 25 MAX. SINFA/CE GRAOIDT. kV{RMS) /cat 2 Fig.7.3.2 Effective Carana Loss tar 8-Conouctor Bunales with Subconductars at Ollterent Ciameters.
8 'I i I I I i I Cl I ~
I I I > I I I I I I I O6 I I I I I I I 02 233cn I
O.i 2 3 4- 5 6 7 8 9 IO Ii '2 )3 l4 )5 )6
)IUMSER OF SUSCONOUCTORS F)g. 7.3.3 Correction Factar to Apply to the Loss Curves ot Figure 7.3.2 to Obtain the Loss!or Cifferent Numbers at Subconduc:ors.
-FIGURE 3 CORONA LOSS FIGURES FROM RErERWM 1 13
The maximum heavy rain loss P occurs for only a short length of time and on a short length of line, since rainstorms of intensity above 0.5 inches per hour are generally very localized. The influence of rain intensity on corona loss was investigated for different configurations. (1)
It appears that the losses are proportional to the logarithm of the rain rate as indicated in Figure 7.3.4 of Reference [1] (also reproduced in Figure 3) which was drawn from test results.
As the rain ceases, the loss will gradually decrease as the conductors dry off. The time constant of the decay is a complex function of gradient, wind and natural humidity.
During fair weather, the corona loss is neglig ble being of the order of 1/50 to 1/1000 of the foul-weather. loss. Tests at Project UHV have shown that the major fau-weather losses were insulator leakage losses.
14
SAMPLE CALCULATION OF CORONA LOSS Foz the configuration shown in Figure 1 (applicable to Section 4-4 of the Susquehanna. 500 kV lines) calculate the maximum yearly corona loss.
The phase conductor surface gradients were computed earlier as:
For the Outside Phases 15.69 kV/cm For the Center Phase 16.87 kV/cm From Figure 7.3.2 of Reference fl] the effective corona loss in heavy rain is (using the 1 823-in. conductor size curve in the Figure):
For the Outside Phases 110 w/meter For the Center Phase 175 w/meter
= K + CL)2 + CL$3)
P . KCL . (CL~1 K = 1.38 KCL
= 0.325, from Figure 7.3.3 of Reference [1) r P = 1.38 x 0.325 x (110 + 175 + 110)
= 177.16 I/M (285.2 kV/mile) this is the value fox the 100$ "heavy rain" loss.
15
74.0 The maximum corona loss for the line in Figure 1 is = 285 2 z 100
'211 1 kV/mile (i.e., 74/, of the 100$ "heavy rain loss" )
CALCULATION OF TRANSMISSION LINE OZONE CONCENTRATIONS In 1973, Westinghouse Electric Corporation published a technique for calculating the ozone concentrations near operating transmission lines. [21 The method is based on wind-tunnel measurements of ozone production rates for single and bundle transmission line conductors in. dry and wet.
corona. The ozone production rates are obtained as a function of the maximum conductor surface gradient.
Under this <echnique, the transmission line can be considered as an array of continuous line sources of ozone. Due to ambient wind and atmospheric mixing conditions, these effluents are dispersed away from the conductor. Based on solutions for scattering of air pollutants in a turbuleht atmosphere [3] , equations were derived by Westinghouse for calculating ozone concentrations downwind of three-phase transmission lines.
Expressions for'otal concentrations were derived for the dispersion of effluents in winds directed either normal to or parallel to the trans-mission line.
17
For the Mind Normal To The Line
~
The downward concentration in the X-direction, is estimated fzom 3 S.
(Z - H) (Z + S)
C (X,Z) = Z
.=1 2v 2c Z Z
where:
f41 C is the ozone concentration in 10 minutes in pg/m (to convert to ppb multiply by 0.51)
X is the distance in meters from the line centerline to where the observation, is made Z is the height in meters above the earth to where the observation is made S. is the source strength of the i th conductor in pg/sec/m H is the average height in meters of the line above ground p is the wind speed in meters/second (must be > = to 1 i'r 0.45 m/s)
O'Z is the spreading coefficient in the Z direction 18
The source strength S.
L is calculated in the following manner:
G 2
=
i S.
V x CL x 78.271 pg/sec/m where:
G is the maximum conductor surface gradient of the bundle in'Vrms /cm (previously computed)
V is the rms line-to-ground, voltage in kV CL is the corona loss of the conductor in kM/mile (previously'omputed) 78.271 converts the source strength in lb/hr/mi to pg/sec/m The spreading coefficients in the Y and Z directions are dependent on the vertical temperature distribution (the lapse rate) of the area.
If the lapse rate is positive, a temperature inversion exists and wind conditions are said to be stable, i.e., turbulent mixing in the atmosphere is weak and the spreading coefficient can be approximated by:
Stable Mind a< = 0.06 (X - X.) 0.71 where:
19
X.
L is the X coordinate of the i th line source or point source.
cf 5GZ y 'l For a negative or zero lapse rate, wind conditions are said to be unstable and turbulent mizing is good. In this case, the spreading coefficients can be approximated by:
Unstable Wind a = 0.0315 [(23/'4) + 4.75 (100/H) ' (X - X.)
y / z For The Wind Parallel To The Line In the case of a wind parallel to the transmission 1'ne, concentrations are estimated for a line of finite length X 0
. The line is arbitrarily located parallel to the X-azis so that for both normal and parallel wind conditions, the downstream direction is along the X-azis. The line is assumed to consist. of N equally spaced point sources of ozone. The strength of each point source on a given, bundle is S.L X0 /I, 20
where S.
I.
is the known line source strength of the i-th bundle. Summing the contributions from the N sources on each bundle and their corresponding image sources to account for ground reflections, the following expression for the total concentration at, a point (X,Y,Z) was derived):
S.X c (z,v,z) =
3 z
N Z
1 ~(- i) i=1 2npN k=1 0 GZ 2G 7 7 exp (z - H) (Z + K) 2vZ 2G Z
where:
L. =
i 0 for the center phase
+L or -L for the two outside phases L being the separation between phases Since the value of N is large, the solution of this equation equires a com-
'I puter.
The previous equations result in concentrations for a 10 minute per od. To convert the results to longer time'eriods [5).
's = '~ (V's) p where: 0. 17 < P < 0. 2 C,'K is estimated at t>. The equation is valid for ts up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The calculations that follow are for the configuration shown in Figure 1 assuming a maximum design operating voltage of 550 kV and no ozone 4
decay. As will be see> for a wind normal to the line, the maximum ozone concentration is 0.41 ppb. For a wind parallel to the line, the maximum is 11.2 ppb..
22
SAMPLE CALCULATION OF THE OZONE CONCENTRATION NEAR A SUS JUEHAiKA 500 kV LLK For the configuration. in Figure 1 (applicable to Section 4-4 of the Susquehanna 500 kV Lines), calculate the transmission line ozone concentrations for:
- 1. A wind normal to the line (2.5 MPH) e stable wind
~ unstable wind
- 2. A, wind parallel to the line (2.5 MPH)
~ stable wind' unstable wind The line is assumed to be 5 miles long and the line operating voltage V is 550 kV.
Calculation of the source strength S.: 1 Maximum conductor surface gradient G in kV Kms
/cm as computed earlier:
For the Outside phases 15. 69 For the Center Phase 16.87 23
The maximum corona loss (CL) during heavy rain in kW/mile using data computed earlier is:
For the Outside Phases = 110 z 1.38 x .325 x .74 = 36.51 w/m (58.77 kW/mile)
For the Center Phase = 175 x 1.38 z .325 z .74 = 58.08 w/m (93.50 kW/mile)
Therefore the source strength S.1 is:
S.
L for the Outside Phases 2
S. = (15.69/(550/~3)) x 58.77 x 78.271 =- 11.23 pg/sec/m i for the S; Center Phases S. = (16.87/(550/W3)) z 93.50 x 78.271 = 20.66 pg/sec/m
- 1. Wind Viormal To The Line Spreading coefficients in the Z direction assuming calculation of the ozone concentration at the right of way edge (100 feet from centerline 30.48 m)
Average Line Height 50.67 feet (15.44 m)
Phase Spacing 34.5 feet (10.52 m) 24
Stable Wiad
- X.) '.71 cr Z
= 0.06 (X i
= 0.06 (30.48 - (-10.52)) 0.84 ZPl cFZ~2
='.06 (30.48 - (0)) ' 0.68 Zg3= 0.06(30.48-10.52))'=0.50 Unstable Wind eZ = 0 0315 (23/P) + 4 75 (100/H) 'X - X-)
p = 25~i (1.12 m/s) 0.0513 (23/1.12) + 4.75 (100/15 .44) 'X - X.)
0.89 (X X )8.86 ZPl1 0 89 (30 48 ( 10 52) ) 21 70 ZP2 10 52) )
0.86 1 1 68 QZIZI 0 89 (30 48 ZIZI3 25
Downwind Concentration Normal to Line-Stable Wind For gl 11.23 (0 - 15.44) (o + 15.44)
C(100,0)1 ezp + ezp 2 2 1.12. z 0.84 x ~2n 2 x 0.84 2 z 0.84 4.76 4.31 z lo + 4.31 x 10 4.10 x. 10 pg/m For tj2 20.66 (0 - 15.44) (0 + 15.44)
C(100,0) 2 exp + exp 2 2 1.12 x. 0.68 x ~Zest 2 z 0.68 2 z 0.68 10.82 0 + 0 0 pg/m For g3 11.23 (o - ls.44) (o + ls.44)
C(100,0) + ezp 3 2 2 1.12 x 0.5 x~2K 2 x 0 50 2 z 0 50 8.00 0 + 0 Vg/m Total For 91 + 92 +'3 0 Vg/m 3
26
Downwind Concentration Normal To Line - Unstable Wind For IIIl 11.23 (o - ls.44) (0 + 15.44) c(loo,o)1 ezp 2 1.12 x 21.? z~2lt 2 x 21.70 2 x 21.70 2 0.1843 0.7764 + 0.7764 3
0.2862 pg/m For g2 20.66 (o - ls.44) (o + ls.44)
C(100) 0) 2 + exp 1.12 x 16.81 xl2n 2 x 16.81 2 x 16.81 0.4378 '.6559 + 0.6559 0.5743 pg/m For 93 11.23 (o - lS.44) (o + ls.44) c(loo,o) ezp 2
+ ezp 1.12, x 11.6 x~2n 2 x 11.68 2 x 11.68 0.3448 0.4174 + 0.4174 3
0.2879 pg/m
'0 3
C Total For pl + p2 + P3 = > >484 Vg/m (0 59 Ppb)
~
In 1 Hour C
1 hr
= C10 10 '0 min 10 0 2 59 0 2
= 0.41 ppb 27
- 2. Wind arallel to the line - results of the calculations are shown on the attached computer rintout.
As can be seen from the printout, reproduced as Figure 4, the maximum ozone concentration of 11.92 ppb occurs during stable wind condit'ions at a distance of 5.25 miles from the beginning of the line section.
Similar compute" calculations were performed utilizing an ozone half life of 30 minutes. Those calculations were based on the following relationship for ozone decay [6].
C (XYZ) = Z i=1 S.X 2npN iV Z
k-"1 Z
exp (X V
7 Xk) 2o 2
J1 exp (z - H) + exp (Z + H) 2
~
2oZ 2G Z
where:
X is the location in meters where the concentration is being measured Xk is the location in meters of the kth point source 28
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- 1. Transmission Line Reference Book, 345 kV and Above, Palo Alto, CA, Electric Power Research Institute, 1975
- 2. J. F. Roach, V. L. Chartier, F. M. Dietrich, "Experimental Oxidant Production Rates. For EHV Transmission Lines and Theoretical Estimates of Ozone Concentrations Near Operating Lines," IEEE Trans. (Power Apparatus and Systems), pp 647-65T, March/April, 1974.
- 3. D. Bruce Turner, "Workbook of Atmospheric Dispersion. Estimates,"
- 4. Stephen A. Sebo, etal, "Examination of Ozone. Emanating From EHV Transmission Line Corona Discharges," IEEE Trans. (Power Apparatus and Systems), pp 693-703, March/April, 1976.
- 5. Electrical Effects of 345 kV and Above Transmission Lines, Course.
- 6. J. F. Roach, Z. M. Dietrich, V. L. Chartier, H. J. Nowak, "Ozone Concentration deasurements on the C-Line at the Apple Grove 750 kV Project and Theoretical Estimates of Ozone Concentrations Near 765 kV Lines of Normal Design," EEEE (Power Apparatus and Systems), pp 1392-1401, July/August, 1978.
- Based on actual 1.8 mLLe line section
- Based on actual 1.0 mile line section
- + Based on actual 0.4 mile line section TABLE 1 MECEMUM ESTTKQZD OZONE CONCENTRATIONS FOR SUSQUEtDLHNA 500 KV THANS~aiXSSEON LZHES (Conditions assumed: 500 kV operating voltage; 1.0 inch per hour rainfall; steady wind. of 2.5 mph parallel to line; no ozone decay)
- Based. on actual 1.8 mile line section
- Based on actual 1.0 mi3.e line section
- Based on actual 0.4 mile line section TABLE 3 i~ZAN ESTZfATED OZONE CONC~MTRATIONS FOR SUSQUEKUKA 500 KV TRANSMISSION LZ%ES ASSUMZIG 30 MINUTE OZONE HALF LIFE