Download PANDA EMF ASSESSMENT PLAN

ELECTROMAGNETIC FIELD ASSESSMENT PLAN
FOR THE
PROPOSED 230 kV TRANSMISSION LINE
PANDA BRANDYWINE GENERATING STATION
TO
BURCHES HILL SUBSTATION
IN
PRINCE GEORGES COUNTY
MARYLAND
FOR
POTOMAC ELECTRIC POWER COMPANY
Prepared For
PANDA ENERGY CORPORATION
By
GILBERT/COMMONWEALTH, INC.
MAY 1995
TABLE OF CONTENTS
Section
Title
Page
1.0
EXECUTIVE SUMMARY
1
2.0
INTRODUCTION
2
2.1
Proposed Routing
2
2.2
2.3
EMF Assessment Approach
Information Presented
2
3
3.0
ANALYSIS SITES
3
3.1
Site Selection Criteria
3.2
Analysis Site 1
3
3.3
Analysis Site 2
3
3.4
Analysis Site 3
4
3.5
Analysis Site 4
4
3.6
Analysis Site 5
4
3.7
Analysis Site 6
4
i
3
TABLE OF CONTENTS (CONT'D)
Section
4.0
Title
Page
CALCULATIONS
5
4.1
FIELDS Computer Program
5
4.2
RESICALC Computer Program
5
4.3
Electrical Shock
4.4
Input Data
4.5
Output Data
9
MEASUREMENTS
11
5.0
6
7
5.1
Measurement Procedures
11
5.2
Electric Field Measurement Equipment
11
5.3
Magnetic Field Measurement Equipment
12
6.0
DATA ANALYSIS
6.1
12
Calculated EMF- Existing Versus Proposed
ii
12
ATTACHMENTS:
A
LOCATION MAP OF EMF ANALYSIS SITES
B
SITE DOCUMENTATION PACKAGES
EXISTING EMF CALCULATIONS
C
SITE DOCUMENTATION PACKAGES
POST-ENERGIZATION EMF CALCULATIONS
D
INFORMATION PROVIDED BY PEPCO
E
EMF MEASUREMENT EQUIPMENT
iii
1.0
EXECUTIVE SUMMARY
This assessment plan presents the results of computer generated calculations of the predicted
electric and magnetic field(EMF) changes along the route of the proposed 230kV transmission
line from the PANDA Brandywine generating plant to the PEPCO substation at Burches Hill.
Calculations of the anticipated EMF strengths were performed for the following cases:
a. Pre-construction sites where existing transmission lines will parallel or cross-over
the proposed PANDA line.
b. Post-Energiziation sites along the entire proposed PANDA transmission line route
including parallel and cross-over sections.
Predicted results from analysis of the calculations are as follows:
a. Field strength values increased at the edges of the existing right-of-way at most
sites.
b. Maximum electric field values decreased in 3 of the 4 existing sites.
c. Maximum magnetic field values decreased in 2 of the 4 existing sites.
d. The new line as designed provides the minimum impact on the EMF field strength
values of all the available phase layout combinations.
EMF measurements at selected sites will be made before and after energization of the new
230kV line and compared with the calculated values. The plan will be revised to include that data
when it becomes available.
1
2.0
INTRODUCTION
2.1
PROPOSED ROUTING
Panda Energy Corporation is planning to construct a 230kV transmission line from their new
Brandywine cogeneration facility to the PEPCO substation at Burches Hill.
The 230kV line will leave the PANDA site and run parallel to the CONRAIL tracks before
crossing under a PEPCO 500kV line which runs from Burches Hill to Chalk Point.
A 69kV SMECO line also parallels the 230kV line during a PANDA route deviation span in the
vicinity of the 500kV line crossover.
The PANDA line then turns and runs parallel to two energized PEPCO 230kV lines and one
deenergized PEPCO 230kV line which all run between Talbert and Burches Hill substations.
Before entering the Burches Hill substation the PANDA line passes under PEPCO 500kV line
#5070 (Burches Hill-Possum Point) and #5071 (Burches Hill-Chalk Point).
2.2
EMF ASSESSMENT APPROACH
Computer calculations were performed to forecast the expected field strengths at the existing
cross-over sites prior to construction.
Calculations were also performed to predict the anticipated effect on the EMF values along the
entire transmission line route as a result of the PANDA 230kV line addition.
Electric and magnetic field measurements will be taken along the line and at the cross-over sites
along the existing right of way to establish pre-construction conditions.
Electric and magnetic field measurements will be taken at various sites along the entire
completed transmission line route to record the effect on the EMF values as a result of the
PANDA 230kV line addition.
2
2.3
INFORMATION PRESENTED
The following information is presented in this assessment plan:
a. Pre-construction calculated EMF values.
b. Post-energization calculated EMF values.
c. Comparison of calculated EMF values before and after the addition of the proposed
PANDA 230kV line.
3.0
ANALYSIS SITES
3.1
SITE SELECTION CRITERIA
Six sites along the route of the new PANDA 230kV line were selected for analysis in this
assessment plan. The sites were chosen to analyze representative geometries, and to include
cases where the new line runs along or crosses existing transmission lines.
A map indicating the location of each site is included in Attachment A. All sites are located in
the State of Maryland, Prince Georges County.
3.2
ANALYSIS SITE 1
4665 feet North of Cedarville Road (See Figure SLM, Attachment A). Steel pole and vertical line
configuration. There are no other transmission lines in the vicinity and the proposed PANDA line
runs parallel to the CONRAIL tracks. This location shows the basic EMF attributable to only the
new line. This is the only site where there are two conductors per phase.
3.3
ANALYSIS SITE 2
3724 feet North of Brandywine Road (See Figure SLM, Attachment A). Steel pole and vertical
line configuration. Site chosen is where the PANDA 230kV line deviation runs parallel to an
existing PEPCO 500kV line (flat line configuration) #5071 (Burchess Hill-Chalk Point) and an
existing SMECO 69kV line(vertical line configuration).
3
3.4
ANALYSIS SITE 3
9600 feet North of Brandywine Road (See Figure SLM, Attachment A). Steel pole and vertical
line configuration. There are no other transmission lines in the vicinity and the proposed PANDA
line runs parallel to the CONRAIL tracks. This location shows the basic EMF attributable to only
the new line.
3.5
ANALYSIS SITE 4
9376 feet West of Conrail tracks (See Figure SLM, Attachment A). Vertical line configuration
occupying the vacant position on the south side of PEPCO's steel south tower line, between
Burches Hill and Talbert substations. The PANDA line will parallel PEPCO 230kV vertical lines
#23081, #23082 and #23080 (deenergized).
3.6
ANALYSIS SITE 5
11040 feet West of CONRAIL tracks (See Figure SLM, Attachment A). Steel tower, flat line
configuration. The PANDA line will run parallel to PEPCO's 230kV flat configured lines
#23081, #23082 and #23080 (deenergized) each on their own steel towers. PEPCO 500kV lines
#5070 (Burches Hill-Possum Point) and #5071 (Burches Hill-Chalk Point) cross over all the
230kV lines in this area.
The cross-section was taken on the centerline of the PEPCO 500kV line #5071 where the
maximum existing calculated magnetic field strength was found. Although the left edge of the
cross-section is on the left edge of the existing 230kV right-of-way, the right edge is within the
boundaries of the intersection of the 230kV and 500kV right-of-ways.
3.7
ANALYSIS SITE 6
12396 feet West of CONRAIL tracks (See Figure SLM, Attachment A). Vertical line
configuration occupying the vacant position on the south side of PEPCO's steel south tower line,
between Burches Hill and Talbert substations. The PANDA line will parallel PEPCO 230kV
vertical lines #23081, #23082 and #23080 (deenergized). Phase positions are different from those
of Analysis Site 4, otherwise the configuration is the same.
4
4.0
CALCULATIONS
4.1
FIELDS COMPUTER PROGRAM
The computer program used to calculate the electric field values and all magnetic field values,
except at site 5, was the FIELDS 1.0 program developed by Southern California Edison.
The FIELDS program was designed to calculate and plot the 2-D magnetic and electric fields
produced by transmission and distribution lines. The program will compute fields for any
combination of up to 25 parallel conductors and 10 ground wires with voltage, current, and phase
angle independently specified.
Although the 230kV and 500kV conductors are not parallel at site 5, the FIELDS program was
utilized to calculate the electric fields in this area. The effect of the 500kV lines was modeled by
assuming a parallel 500kV line configuration above each of the 230kV lines.
FIELDS utilizes the basic algorithims for the calculation of electric and magnetic fields as listed
in EPRI's "Transmission Line Reference Book". The model calculations have been validated
against Electric Power Consultants Incorporated's program EBFANRI, and Bonneville Power
Administration's program, CORONA among others.
FIELDS operates on IBM or compatible personal computers with DOS 3.0 or above, and with a
minimum of 640 K of memory. Hewlett Packard laser printers and Epson dot matrix printers are
supported with CGA, EGA, or VGA graphics.
4.2
RESICALC COMPUTER PROGRAM
The RESICALC 2.0 program developed by Enertech Consultants was utilized for magnetic field
strength calculations at site 5 because the 230kV and 500kV lines are not parallel to each other in
this area.
RESICALC allows 3-D modeling of magnetic fields emitted by overhead transmission and
distribution lines. You can display the results components (x,y,z) and resultant magnetic fields in
either a 3-D surface map or a contour map of the area. It can also calculate the magnetic field
within and produce a 2-D graph of the magnetic field along a defined area, profile or at a point.
RESICALC operates on IBM or compatible personal computers with DOS 3.3 or higher,
minimum 386 CPU, Windows 3.1 or higher, 4 Mb RAM, 4 Mb minimum free hard disk space,
VGA or higher graphics, Microsoft compatible mouse and math coprocessor. Dot matrix and
laser printers are supported output mediums.
4.3
ELECTRICAL SHOCK
5
The National Electrical Safety Code (ANSI C2-1993), Section 232.C.1.C requires that
transmission lines of this voltage shall be designed to limit the current due to electrostatic effects
to 5.0 milliamperes, rms, if the largest anticipated truck, vehicle or equipment under the line
were short circuited to ground.
The PANDA 230kV transmission line crosses two highways where large vehicles may be
encountered:
-- U.S. Highway 301 between measuring sites 3 and 4
-- Brandywine Road (SR 381) on the CONRAIL line in Brandywine
The crossing of US 301 contains four circuits ( 1 PANDA, 3 PEPCO ) on the right-of-way at this
location. The circuits configuration and loading at this location are similar to that shown for
measurement site 4.
The crossing of Brandywine Road is the single PANDA circuit; similar in configuration and
loading to measurement site 1.
Each of these locations has been modeled utilizing a lowest conductor height of 60 feet for the
US 301 crossing and 52 feet for the Brandywine Road crossing. The model indicates the
maximum electric field at US 301 is 953 v/m and 1643 v/m at Brandywine Road.
Calculations for short circuit current are based on Section 8.5 of "Transmission Line Reference
Book 345 kV and Above" (RED BOOK); published by Electric Power Research Institute.
The vehicle assumed is a large school bus (12 m long x 3 m high) parked on the road at the point
of highest electric field. The conductors on the respective lines are assumed at their maximum
sag.
The predicted short circuit at the US 301 crossing is .38 mA and at the Brandywine Road is .66
mA; in each case significantly less than the code requirement of 5 mA.
4.4
INPUT DATA
The following input data was required to perform the calculations:
a. Voltage:
Nominal phase to phase voltages used for the transmission lines were
69kV, 230kV and 500kV as applicable.
b. Phase Angles:
6
"A" Phase-0 degrees, "B" Phase-240 degrees, "C" Phase 120 degrees.
c. Phase Currents:
1. PANDA 230kV line- 680 amperes
2. PEPCO 230kV and 500kV lines
Before
PANDA
230kV Feeder #23081 = 502 amperes
230kV Feeder #23082 = 502 amperes
500kV Feeder #5070 = -624 amperes
500kV Feeder #5071 = 878 amperes
3. SMECO 69kV line- 60 amperes
7
After
PANDA
377 amperes
377 amperes
-739 amperes
866 amperes
d. Conductor Data:
Number of phases and ground conductors, sub-conductors per bundle, conductor
diameter and bundle diameter.
1. PANDA -- 1 or 2, 1590 KCM, 45/7 ACSR, 1 static wire
2. PEPCO --- 1, 1590 KCM, 45/7 ACSR, 1 static wire for 230kV
--- 3, 1590 KCM, 45/7 ACSR, 2 static wire for 500kV
Note: 1590 KCM = 1.502" dia., bundle dia. = 18"
e. Geometric Data:
1. Left and right coordinates of right of way.
2. Horizontal coordinates for all phase and ground conductors. Origin in
all cases is the center of the right of way.
3. Vertical coordinates for all phase and ground conductors. Origin in all cases
is the ground line. The actual vertical dimension used for each conductor is
the calculated low point above ground.
f. Data Sources:
The load information provided by PEPCO for their transmission lines is included
in Attachment D.
The load for the PANDA line is based on the plant design of 230 MW @ .85 pf.
8
4.5
OUTPUT DATA
The drawings and the calculation packages for the existing conditions and post energization
calculations are presented in Attachments B and C.
The information included in Attachment B for each existing site where calculations were
performed is as follows:
Site 2 - Dwg. F-2E
- FIELDS Calculation Package
Site 4 - Dwg. F-4E
- FIELDS Calculation Package
Site 5 - Dwgs. F-5A, F-5E, and F-5BE
- FIELDS Calculation Package
- RESICALC Calculation Package
Site 6 - Dwg. F-6E
- FIELDS Calculation Package
The information included in Attachment C for each post energization site where calculations
were performed is as follows:
Site 1 - Dwg. F-1P
- FIELDS Calculation Package
Site 2 - Dwg. F-2P
- FIELDS Calculation Package
Site 3 - Dwg. F-3P
- FIELDS Calculation Package
Site 4 - Dwg. F-4P
- FIELDS Calculation Packages for six (6) cases
9
Site 5 - Dwgs. F-5A, F-5P, and F-5BP
- FIELDS Calculation Packages for six (6) cases
- RESICALC Calculation Package for six (6) cases
Site 6 - Dwg. F-6P
- FIELDS Calculation Packages for six (6) cases
FIELDS calculation packages include the following documentation:
a. Site profile data input sheet
b. Electric field values sheet(s)
c. Electric field profile
d. Magnetic field value sheet(s) (Not included for Site 5)
e. Magnetic field profile (Not included for Site 5)
RESICALC calculation packages include the following documentation:
a. Site plan view
b. Profile descriptive statistics
c. Profile order statistics
d. Field survey information(Left right-of-way field value)
e. Field survey information(Right right-of-way field value)
f. Magnetic field profile
g. Magnetic field contour map
h. Magnetic field 3-D map
The magnetic field calculations performed by the RESICALC program compute the resultant,
maximum major axis and maximum minor axis. To provide the best correlation with the
FIELDS program we have utilized the maximum major axis value in our evaluation.
Six cases were calculated at sites 4,5, and 6 for post energization conditions. This was done to
show that the phase layout of the new line as designed provides the minimum impact on the EMF
field strength values of all the available combinations. The six cases had the following PANDA
phase layout from top to bottom, left to right in each site as applicable:
a. Case A - CBA
b. Case B - CAB
c. Case C - ABC
d. Case D - ACB
e. Case E - BCA
f. Case F - BAC
10
5.0
MEASUREMENTS
5.1
MEASUREMENT PROCEDURES
The electric and magnetic field strengths attributable to the existing lines will be measured at
analysis sites 2,4, 5 & 6 prior to construction of the new 230kV line.
Field strength measurements will also be taken at all six analysis sites after the line is constructed
and energized.
All measurements will be taken perpendicular to the route of the new PANDA 230kV line from
one edge of the right of way to the other.
Load current of each transmission line in the cross section of each analysis site will be recorded
for the existing and post-energization measurements.
Post-energization EMF measurements will be made at the lowest phase conductor sag point of
the new 230kV line at each cross-section. The height of the lowest conductor above ground will
be measured with an optical range-finder instrument.
All EMF measurements will be made with the sensors positioned approximately 3 feet above the
ground.
5.2
ELECTRIC FIELD MEASUREMENT EQUIPMENT
Electric field strength measurements will be made with an Electric Field Measurement Company
Model EFM160 single-axis electric field sensor and Model EFM139 multimeter. The sensor coil
can be positioned to record data in any direction. For x,y and z values, the resultant can be
calculated.
Information regarding the electric field strength measurement equipment is included in
Attachment E.
11
5.3
MAGNETIC FIELD MEASUREMENT EQUIPMENT
Magnetic field strength measurements will be made with a Dexsil Model MAGNUM 310 threeaxis digital magnetic survey meter. This meter measures magnetic field strengths in x,y and z
directions and also calculates the resultant.
Information regarding the magnetic field strength measurement equipment is included in
Attachment E.
6.0
DATA ANALYSIS
6.1
CALCULATED EMF - EXISTING VERSUS PROPOSED
A comparison of the calculated electric and magnetic field strengths along the proposed route of
the new 230kV PANDA line before and after energization is shown in Tables A and B.
The addition of the new 230kV line decreased the maximum electric field value within 3 of the 4
existing sites. Maximum magnetic field values decreased in 2 of the 4 existing sites. In sites
where the electric and magnetic field strengths increased, the percentage increase ranged from
5.3 to 18%.
Field strength values at the edges of the right-of-way increased at most sites. Maximum increase
of electric field value was a modest 0.636kV/m. Magnetic field strength increased by 30.026 mG
at one site edge. The increase at all other sites which had increased magnetic field values was
much less.
The existing site with the largest increase in both electric and magnetic field strength values was
Site 2 where the 230kV PANDA line is routed beneath the PEPCO 500kV line #5071.
At Sites 4,5 and 6 six cases were looked at to study the effect on the field strengths as a result of
changing the PANDA line conductor phasing. After the calculated data was tabulated, point
numbers were assigned to each field value. The lowest value at each site in each category was
given one point and the highest value was given six points. Evaluation points are shown in
parenthesis ( ) beside each field value in Tables A and B.
The individual evaluation points were added and at all three sites the PANDA line phasing as
designed came out with the lowest overall total points. This information is shown in Table C.
12
ATTACHMENT A
LOCATION MAP
OF EMF ANALYSIS SITES
ATTACHMENT B
SITE DOCUMENTATION PACKAGES
EXISTING EMF CALCULATIONS
ATTACHMENT C
SITE DOCUMENTATION PACKAGES
POST-ENERGIZATION EMF CALCULATIONS
ATTACHMENT D
INFORMATION PROVIDED
BY PEPCO
ATTACHMENT E
EMF MEASUREMENT EQUIPMENT