SPP Transmission Constraint Mitigation in High Wind Areas

Mitigation of SPP Transmission Constraints in Areas with Relatively

Higher Wind Velocities

MAINTAINED BY

Southwest Power Pool

PUBLISHED: Draft – July 2006

Copyright © 2006 by Southwest Power Pool, Inc. All rights reserved.

Application of Higher Wind Overhead Conductor Capacities

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TABLE OF CONTENTS

INTRODUCTION .......................................................................................................................................................2

DISCUSSION...............................................................................................................................................................5

Traditional Conductor Rating Calculations.......................................................................................................5 Natural Convection vs. Forced Convection........................................................................................................5 Higher Wind Conductor Capacity Calculations ................................................................................................6 Risk Reduction Factors.......................................................................................................................................7 Wind Shielding Factor (WSF) ............................................................................................................................8 Parallel Winds Factor (PWF) .............................................................................................................................8 Wind Correlation Factor (WCF) ........................................................................................................................9 Conductor Map Location ....................................................................................................................................9 Risk Assessment ................................................................................................................................................10

METHODOLOGY ....................................................................................................................................................12

Application Approach .......................................................................................................................................12 Real Time Monitoring Equipment....................................................................................................................13 Application A: OATT – Long Term Firm Service...........................................................................................14 Application B: OATT – Monthly Short Term Transmission Service: ............................................................15

APPENDIX A – CLASS 4 (GOOD) WIND AREAS WITHIN THE SPP REGION ...........................................17

APPENDIX B - DRAKE 795 ACSR 27/2 CONDUCTOR CAPACITIES VARIED BY WIND VELOCITY,

345 KV ........................................................................................................................................................................23


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INTRODUCTION Several generation interconnection study requests are tendered in the SPP queue requesting the

integration of wind plants into the SPP network. When applying for new transmission service

many of these units encounter generation outlet difficulties because the transmission network in

most “high wind areas” is not developed to accommodate regional power transfer.

Certain areas within the Southwest Power Pool (SPP) footprint are fortunate to possess

consistently higher velocities of wind, as seen in Graph 1 (also refer to Appendix A for further

detail). These higher wind speeds may be realized as increased capacity to overhead conductors

within these areas.

GRAPH 1

(Data from National Renewable Energy Laboratory)

Exactly coinciding with these areas of increased wind are existing, planned and potential wind

plants. FERC Order 661 recognizes the unique nature of wind energy technologies “in an


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attempt to remedy undue discrimination” in the interconnection of large wind plants. Many

FERC jurisdictionally-bounded entities have enacted renewable portfolio standards mandating

significantly more wind energy development in the near future.

SPP believes it is essential that it develop standards and procedures upon which to aid its

members and customers in this regard. A process allowing for implementation of Real Time

Monitor equipment as mitigation to identified network constraints can make excess capacity

available to the open market (i.e., long term or monthly firm transmission service). In addition,

Real Time Monitoring Equipment will reduce the number of curtailments of active service

schedules on the basis of the ability to track increased capacity due to higher wind.

GRAPH 2

As seen in Graph 2, the geography of SPP most suitable to wind energy development is the

Texas Panhandle, New Mexico, west Oklahoma and west Kansas. As is typical of many wind

siting studies, this happens to be the least densely populated areas of the SPP region. The

transmission system in these areas was generally designed to serve the limited load in the region

and not designed to carry generation capacity on a cross-regional basis. A key challenge to the

integration of wind energy resources into the SPP transmission network is acquiring adequate


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transmission service over a transmission network designed to serve limited load and addressing

identified network constraints to the load market outside of the prime wind generation

geography. This same limitation likewise affects integration of other types of generation and, in

general, the market’s ability to use the system. Often, these network constraints are overhead

conductor emergency capacity limitations based on thermal loading limits derived from the

physical properties of the metal conductor.

Historically, emergency ratings for overhead conductors have been conservatively calculated

using cross-sectional wind velocity values of 2 ft/s. (This paper purposefully refers to conductor

‘capacity’ rather than ‘rating’ to distinguish between the rating as defined by SPP, and increased

ampacity due to increased wind velocity.) Current wind energy generating technologies require

approximately 10 ft/s wind to begin generating electricity, at least three times greater than the

commonly used values in typical overhead conductor rating formulas. With necessary wind

velocities for a unit to produce even 10% of name-plate capacity the correlating increase in

conductor capacity for the same wind velocity could be as much as a 80% increase in conductor

capacity. For typical 795 ACSR operated at 345 kV this is approximately an 875 MVA increase

in conductor capacity near a wind plant. Balanced with some Risk Reduction Factors, SPP

proposes to correlate higher wind velocities with the increased transmission capacity caused by

thermal cooling of transmission lines.

This approach is a mechanism for maximizing the use of the transmission system by eliminating

constraints to requests for monthly and long term firm transmission service under the SPP Open

Access Transmission Tariff. aid the integration of wind generation by instituting a process to

mitigate transmission constraints without costly physical upgrades with Risk Identification

Factors with Real Time Monitoring equipment.


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DISCUSSION Traditional Conductor Rating Calculations

SPP Criteria 12.2

In accordance with SPP Criteria 12, this methodology applies to conductors 69

kV and above and abides by other general principles of section 12.2, specifically

12.2.2. Therefore, the SPP overhead conductor rating methodology is based on

IEEE Standard 738-1993.

SPP Criteria section 12.2.2. Overhead Conductor, subdivides calculations into the

following categories:

1. Conductor Physical Properties

2. Conduct Geography

3. Radiation Properties

a. Solar Absorbtivity

b. Infrared Emissivity

4. Weather Conditions

5. Max Conductor Temperature

IEEE Standard 738-1993

Standard 738-1996 details temperature related ampacity calculations for overhead

conductors and provides the detailed basis for SPP Criteria 12.2. This standard

outlines the necessary data and formulas for determining total conductor

ampacity.

Natural Convection vs. Forced Convection

Aside from physical conductor size and solar radiation, the rate at which a conductor is

able to convect heat, Qc is the primary determination of maximum conductor ampacity.

Forced and Natural Convection calculations, found among the thermal convection rate

formulas, are used to determine the rate at which the bare overhead conductor most

quickly emits heat (ref: IEEE Std. 738-1993, sec 2.4). The natural convection, formula 2.4.4,

is the rate at which a material in a vacuum convects heat, i.e. 0 ft/s wind. The forced


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convection, formula 2.4.3, is the rate at which a material exposed to a given wind

velocity at a specified angle, Kangle, convects heat. The IEEE standard assumes 2 ft/s as

the maximum wind velocity and determines the greater convection rate of the two. For

Drake conductor, 795 kcmil 26/7 ACSR, the convection rate is greater in a vacuum.

(problem statement 2.6.1.1)

Problem statement 2.6.1.1 in the IEEE standard demonstrates where 795 ACSR 26/7

Drake conductor at 40 degrees C (104 deg F) and sea level has a higher Natural

Convection rate than would occur compared to the Forced Convection rate assuming heat

dissipation at a 2 ft/sec wind velocity. The results demonstrate the conservative

application of wind in the conductor rating calculations.

Comparison of Natural vs. Forced Convection is necessary on the assumption that only

low wind velocities are considered in the determination of conductor ampacities.

Industry practices, for conservative reasons, have implemented conductor ratings based

on low wind velocities in consideration of typical peak loading conditions.

Higher Wind Conductor Capacity Calculations

Conductor capacity based on increased wind velocity is calculated by application of a

range of wind velocities, Vw, applied in the forced convection (Qc) portion of the

capacity calculation. This is one of four components used to determine the total heating

of overhead conductors. The four components are: solar heat gain (Qs), radiated heat

loss (Qr), forced convection heat loss due to wind (Qc) and conductor heating due to the

current (I) and resistance (R) relationship, I2*R(Tc).

Velocity of wind in the forced convection formula, Qc = [1.01+0.371(DpfVw/UF)0.52],

has a significant impact on the final calculated ampacity of a conductor.


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0 200 400 600 800

1000 1200 1400 1600 1800 2000 2200 2400 2600

Conductor Capacity Increase

2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0 40.0 42.0 Wind Velocity (ft/sec)

GRAPH 3

Capacity Increase, MVA - 795 ACSR, 345 kV

Graph 3, below, shows ratings for a 795 ACSR (drake) conductor operated at 345 kV

(refer to Appendix B for further detail). Conductor capacities are recalculated for

increasing wind velocities through 42 ft/s. The standard rating for this conductor at 2 ft/s

is 1077 MVA. This is shown as the base graph in blue.

Risk Reduction Factors

Risk of violating line clearance and safety code or sacrificing conductor life are primary

concerns when increasing line capacities. With increased wind speed assumptions in

capacity calculations, the casual observer may be concerned that weather patterns are not

homogenous and, therefore, critical overhead conductors may not benefit from the same

wind patterns driving wind turbines. To reduce this associated risk, some conservative

assumptions are implemented into the proposed variable capacity application. These risk


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reduction mechanisms explained in the following discussion include: Parallel Wind

Factor, Wind Shielding Factor and Wind Correlation Factor.

Wind Shielding Factor (WSF)

A 10% reduction is applied to account for the possible shielding of wind due to trees or

geographical anomalies.

Parallel Winds Factor (PWF)

This factor reduces effective convection values by 60% to account for the possibility of

winds only parallel to the conductor, rather than perpendicular. This rate is taken from

IEEE std. 738-1993 section 3.2 as the reduction in effectiveness of convective heat loss

due to parallel wind.

Combining the Parallel Winds and Wind Shielding Factors reduce any calculated wind

based conductor capacity increase by 70% resulting in a more conservative Conductor

Capacity Increase profile. See Graph 4 (compare with Graph 3).

GRAPH 4

Reduced by 60% Parallel Winds and 10% Shielding Factors Rating Increase, MVA – 795 ACSR, 345 kV

0

500

1000

1500

2000

2500

2.0 6.0 10.0 14.0 18.0 22.0 26.0 30.0 34.0 38.0 42.0

Wind Velocity (ft/sec)

Conductor Capacity Increase


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Wind Correlation Factor (WCF)

Wind velocities at a nearby reference tower (or wind plant) can often be correlated to the

wind velocities at the transmission limiting overhead conductor. Wind correlations are

influenced by diurnal winds, microclimates and homogeneity of weather patterns. Given

specific geographical locations, this correlation can provide a basis for establishing the

variable velocity of wind for an identified transmission network constraint.

Similar to wind correlation studies performed when identifying potential wind sites, wind

Correlation Factors can be derived using data from environmental monitoring wind

stations, where available. For example, the Oklahoma Mesonet.org website lists one

hundred fifty-eight monitoring stations across the state with historical data posted for

these stations. This proposal requires a two year minimum of historical weather data to

establish a Wind Correlation Factor and applies to those wind power areas classified as

Fair (class 3) or better (refer to Conductor Map Location section; Appendix A). Data can

be compared with the initial data prepared for developed wind locations (accessible

online at: http://www.mesonet.org/).

Correlation Factors assign a percent value associating wind velocity at one location with

wind velocity at another. For example, if wind at location ‘A’ is considered 1 and wind

at location ‘B’ is correlated to ‘A’ by .5, there is a .5 relation or 50% correlation of

location ‘B’ to ‘A’. Or, if the wind velocity at location ‘A’ is measured 20 ft/s then the

Correlation Factor of .5 assumes wind is 10 ft/s at location ‘B’. Correlation Factors are

an average based on historical weather data.

If no data is available, a default 10% correlation will be assumed.

Conductor Map Location

1. To be qualified, the entire line (including both terminal ends) of identified

overhead conductor constraints must fall within a wind power area classified

as Good, or better.


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2. Qualified conductors shall be determined by SPP Staff.

3. The maps utilized for the location assessment are included in Appendix A.

Risk Assessment

Graph 5 shows two overhead conductor capacities comparing traditional conductor rating

calculations with the previously outlined approach of implementing risk reduction

factors. The blue line represents an approximate conductor capacity increase with the

application of parallel winds and risk reduction factors, while the other more aggressively

increasing red line represents an approximate conductor capacity increase as affected by

traditional cross sectional winds in calculations.

GRAPH 5

Area of Risk


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In this graph, increased risk associated with higher conductor capacities is represented as

a shaded area. The reduced amount of risk from application of the associated risk

reduction principles is shown as the cross section area under the blue line resulting in a

45% increase. This is taking into account the 60% decrease in convection for parallel

wind and the 10% decrease for potential conductor shielding.

Next, the application of Wind Correlation data results in further reduction in risk by tying

in a realistic expectation of wind levels. As examples show, the 50% correlation and

20% correlation factors reduce the potential conductor capacity increase to 22% and 9%

respectively. It must be kept in mind that a conductor has to meet the requirements of

Conductor Map Location to be eligible. Also, if no data is available, then a 10%

correlation will be assumed.

Finally, any remaining risk associated with the final calculated conductor capacity

increase is further mitigated with the requirement to install Real Time Monitoring

Equipment to all facility components subject to sag and clearance standards. The ability

to monitor conductor facilities for which this process is applied acts as a final safety net.


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METHODOLOGY Application of Higher Wind Overhead Conductor Capacities determination can be

triggered whenever overhead line conductors (i.e., not associated terminal equipment)

located near areas of relatively higher wind velocities are identified as constraints to

transmission service. However, the Higher Wind Overhead Conductor Capacities

approach is not a guarantee of transmission service and does not apply to identified

transmission constraints outside of the SPP region. Also, facilities associated with

system voltage or angular stability concerns shall not be considered.

To determine if an identified conductor constraint can be mitigated the only information

required beyond existing information is historical weather data, to derive the Wind

Correlation Factor. If weather data is not available, the constraint may still be eligible for

mitigation if it meets the requirements of Conductor Map Location. Wind studies

conducted for purposes of wind generation siting/micrositing may be utilized if the

results apply to the geographic area containing the facility and if the results coincide with

the peak loading time frame of the facility.

Application Approach

1. An SPP tariff study identifies an overhead conductor constraint to

transmission service.

2. SPP staff will calculate the base conductor capacity increase of the monitored

overhead conductor using 40 ft/s wind velocity (simulates wind velocity for

typical wind turbine operating at 100% capability).

3. The calculated capacity will be reduced by applying the known 60% and 10%

Risk Reduction Factors.

4. The WCF will be determined via two-year historical weather station records

or generation wind siting studies. If no data exists to substantiate a WCF, then

the WCF will be assumed to be 0.1 as long as the constraint meets the

requirements of Conductor Map Location.

5. SPP staff will apply the Risk Reduction Factors:


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A. Reduce by 60%;

B. Reduce by 10%; and

C. Multiply by Wind Correlation Factor.

6. The constraint can be considered mitigated if the remainder of the constrained

overhead conductor capacity increase is greater than zero:

A. After the reduction of the contingency loading level, and

B. Less the studied service request impact.

7. Service granted based on application of Higher Wind Overhead Conductor

Capacities will be curtailed based on SPP surveillance of Real Time

Monitoring Equipment output and analysis of results.

8. A constraint may only be mitigated once via Real Time Monitoring

Equipment, and mitigation applies only to the party or parties paying for said

equipment.

9. Service granted based on application of Higher Wind Overhead Conductor

Capacities will be included, as usual, in other Tariff and Planning studies.

Real Time Monitoring Equipment

Tension based transmission line monitoring systems provide real time data for

transmission lines upon which transmission operators can make real-time decisions.

These systems provide ready information by which transmission operators can monitor

how closely a conductor is to maximum clearances and loadings.

Installation of real-time monitoring equipment will improve the security aspect of the

transmission system. Real-time monitor systems installed on conductors identified as

constraints to transmission service will aid system operators in identifying system loading

risks.

Transmission Service Agreements approved through mitigation of identified overhead

conductor constraints via this procedure are not valid without an agreement to install

Real-Time Rating equipment on specified circuits. For practicality, Real-Time Rating


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equipment installation costs will be estimated based on the current cost per

kilometer/mile from approved vendors.

Real-time monitoring systems are required as part of the Higher Wind Overhead

Conductor Capacity provision and must be funded by the Transmission Customer. At the

time of this publication, costs are approximately $2,000 per conductor km to equip. An

approved list of vendors supplying Real-Time Monitoring Equipment will be maintained

by SPP staff. All real-time monitoring equipment must be selected from the approved list

of vendors and agreed upon by the Transmission Owner(s) of the identified conductors.

Application A: OATT – Long Term Firm Service

Requests for transmission service found to be limited by identified overhead conductor

constraints can seek application of the Higher Wind Overhead Conductor Capacity

procedure as a constraint mitigation alternative to facility upgrades. The Transmission

Customer commits to install Real-Time Monitoring Equipment per that section.

Example:

POR = Control Area ‘A’

POD = Control Area ‘B’

Amount = 200 MW

Duration = 12 Months

The service request is evaluated via the SPP Aggregate Study process and a constrained

overhead conductor is identified having a 12.5% Transmission Distribution Factor (TDF)

response. The 795 ACSR conductor is operated at 345 kV and is simulated at 105%

loading with Rate B = 1077 MVA. There is no wind correlation data available, but the

line falls within a Good wind power area. So a Correlation Factor of 0.1 will be applied.

In this example, the line is overloaded by 2.3% or 25 MVA over the emergency rating.

SPP staff will determine the conductor capacity increase based on 40 ft/s wind and then

apply the Risk Reduction Factors. This facility at 40 ft/s wind velocity will have a


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capacity of 1389 MVA. Application of the Risk Reduction Factors reduces this amount

by 60% for Parallel Winds, 10% for Wind Shielding and a 0.1 Wind Correlation ratio.

The resulting increase follows:

“High Wind Area” Overhead Conductor Capacity = 1077 + [1389 – (1389 x 0.6) – (1389

x 0.1)] x 0.1 = 1077 + 42 = 1119 MVA (1119 / 1077 = 3.9% capacity increase)

This constraint is mitigated since 42 MVA covers the calculated 25 MW service request

impact.

Application B: OATT – Monthly Short Term Transmission Service:

i.e. Flowgate Mitigation

This methodology can be applied toward mitigation of the constraining monitored

element of a traditional contingency based Flowgate.

Example:

POR = SPS, Source = Plant ‘A’

POD = ENTR

Amount = 100 MW

Duration = 1 Month (June)

Flowgates JUDGRNSPMUL, SPSSPPTIES and ELKXFRTUCOKU are identified as

possible constraints to flow in this direction. The Available Transfer Capability (ATC)

data associated with these flowgates for the SPS – ENTR transfer direction is as follows:

80 MW limit, JUDGRNSPEMUL, 3.4% TDF

287 MW limit, ELKXFRTUCOKU, 34.6% TDF

620 MW limit, SPSSPPTIES, 100% TDF

In this ATC analysis, the flowgate limits the service request to 80 MW of the requested

100 MW. This is a typical OTDF flowgate limited by the Judson Large to Greensburg


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115 kV circuit with an 80 MVA emergency rating for the outage of the Spearville to

Mullergren 230 kV circuit. The TDF for this circuit is 3.4%.

The other two flowgates are not candidates for this application. The ELKXFRTUCOKU

flowgate consists of a transformer limitation not subject to capacity adjustments from

wind. The SPSSPPTIES is a PTDF flowgate representing the SPS stability interface limit

and is also not subject to modifications by this approach. However, in this analysis, the

transmission customer may see a benefit because the only limit to this service request is

the Judson Large overhead conductor facility. With a 3.4% TDF, the 80 MW limit

indicates a very small margin of additional capacity required to accommodate the request.

(20 MW * 0.034 = 0.68 MW)

For this example we will say a 15% wind correlation factor was identified. Working

through the numbers in this example, SPP staff will determine the conductor capacity

increase again based on 40 ft/s wind and then apply the Risk Reduction Factors. This

facility at 40 ft/s wind velocity will have a capacity of approximately 101 MVA.

Application of the Risk Reduction Factors reduces this number by 60% for Parallel

Winds, 10% for Wind Shielding and applies a 0.15 Wind Correlation ratio. The resulting

increase follows:

“High Wind Area” Overhead Conductor Capacity = 80 + [101 – (101 x 0.6) – (101 x

0.1)] x 0.15 = 80 + 5 = 85 MVA (85 / 80 = 6.3% capacity increase)

The constraint will be mitigated and the full 100 MW service requested can be granted

since the additional 5 MVA is adequate to cover the calculated 0.68 MVA overload.


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APPENDIX A – Class 3 + Wind Areas within the SPP Region

Average Annual Wind Power by State

The wind resource is expressed in terms of wind power classes, ranging from class 1 (the lowest)

to class 7 (the highest). Each class represents a range of mean wind power density or

approximate mean wind speed at specified heights above the ground. Areas designated class 3 or

greater are suitable for most wind energy applications, whereas class 2 areas are marginal and

class 1 areas are generally not suitable (accessible online at: http://rredc.nrel.gov).

Power Class Legend:

Class Potential 1 Poor 2 Marginal 3 Fair 4 Good 5 Excellent 6 Outstanding 7 Superb


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Arkansas


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Missouri


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Kansas

Oklahoma


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West Texas


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New Mexico

Higher Wind Overhead Conductor Capacities

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APPENDIX B - DRAKE 795 ACSR 27/2 Conductor Capacities Varied by Wind Velocity, 345 kV

Conductor Capacity Calculations

Typical conductor capacity calculations assume a cross-sectional wind to the axis of the conductor. This is reflected as Kangle = 0 in the wind

direction multiplier. Application of a conservative assumption of only parallel wind, absence of any cross sectional wind benefit, provides the

most conservative wind-related convection numbers in the following calculations.

WEATHER INPUTWind Velocity (ft/s)= 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0 40.0

Angle (deg) between wind and conductor= 90.0Direction of Line (E-W =1 , N-S =0)= 1.0

Atmosphere (Clear =1: Indus =2)= 1.0Cond elevation (feet) above sea level= 1150.0

Cond. Latitude (degrees)= 38.5Local Sun Time (10, 11, 12, 13, 14)= 12.0

Ambient air temperature (Ta in celcius)= 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8 37.8Ambient air temperature (Ta in F)= 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

CONDUCTOR INPUTCond. O.D. (in.) = 1.2

Cond. Temperature (C):Tlo= 25.0Thi= 50.0

Cond. ac Resistance (R(Tc)) (ohm/mi):R(Tlo)= 0.0R(Thi)= 0.0

Emissivity (epsilon) = 0.7Solar absorptivity (alpha) = 0.9

Max. allowable cond. Temp (in C) = 100.0

Calc: THERMAL RATING IN AMPERES 1803.0 2122.3 2379.5 2583.0 2754.0 2902.9 3035.5 3155.6 3265.7 3367.6 3462.8 3552.1 3636.4 3716.3 3792.3 3864.9 3934.5 4001.2 4065.4 4127.3TR(Amps)= 1802.9 2122.3 2379.5 2583.0 2754.0 2902.9 3035.5 3155.6 3265.7 3367.6 3462.8 3552.1 3636.4 3716.3 3792.3 3864.9 3934.5 4001.2 4065.4 4127.3

Calc: THERMAL RATING IN MVAkV= 345.0

MVA= 1077.4 1268.2 1421.9 1543.5 1645.7 1734.6 1813.9 1885.6 1951.4 2012.4 2069.2 2122.6 2172.9 2220.7 2266.1 2309.5 2351.1 2390.9 2429.3 2466.3Normalized to MAX Ambient 1.0 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.8 1.9 1.9 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.3 2.3

Delta Increase in MVA 0.0 190.8 344.5 466.1 568.3 657.2 736.5 808.2 874.0 935.0 991.8 1045.2 1095.5 1143.3 1188.7 1232.1 1273.7 1313.5 1351.9 1388.9Incremental Increase 0.0 15.6 13.6 11.2 9.5 8.4 7.6 6.9 6.3 5.9 5.5 5.2 4.9 4.7 4.4 4.3 4.1 3.9 3.8 3.6

% Increase in Conductor Capacity 0.0 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.8 0.9 0.9 1.0 1.0 1.1 1.1 1.1 1.2 1.2 1.3 1.3

Base Conductor MVA @ 375kV Rating 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 1077 107760% Parallel Winds Factor and 10% Shielded Wind 0.0 57.2 103.3 139.8 170.5 197.2 220.9 242.5 262.2 280.5 297.5 313.6 328.7 343.0 356.6 369.6 382.1 394.1 405.6 416.7Adjusted % Increase in Conductor Capacity 0.000 0.053 0.096 0.130 0.158 0.183 0.205 0.225 0.243 0.260 0.276 0.291 0.305 0.318 0.331 0.343 0.355 0.366 0.377 0.387

SPP Transmission Constraint Mitigation in High Wind Areas

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