South Dakota 890 Study

Transcription

1 South Dakota 890 Study September 16, 2011

2 South Dakota 890 Study Presentation of 890 Study results from 2011 Includes WAPA suggested system improvements and timelines Stakeholder Feedback Questions? 2

3 Western South Dakota 3

4 Western South Dakota System Improvements During 2011 Increased size of Rapid City Capacitor Banks Capacitors were increased from MVAR to MVAR April 2011 Installation ti of Rapid City Area UVLS Three stages of UVLS were installed at the Rapid City Substation in May 2011 to shed load if 115 kv voltage remains below 0.88 pu for 3 seconds Installation of Pierre Area UVLS Three stages of UVLS are installed at the Pierre Substation in May 2011 to shed load if 115 kv voltage remains below 0.88 pu for 3 seconds One stage of UVLS is installed at the Irv Simmons Substation in May 2011 to shed load if 115 kv voltage remains below 0.88 pu for 3 seconds Bus Replacement at Midland Substation Replaced limiting buswork and jumpers May 2011 Bus Replacement at Wall Substation Replaced limiting buswork and jumpers May 2011 Bus Replacement at Wicksville Substation Replaced limiting buswork and jumpers May 2011 Raised limiting structures on Philip Wicksville Wall New Underwood 115 kv line Line is at conductor thermal limit of 90 MVA June 2011 Special high temperature temporary jumper ratings developed for Fort Randall 95 MVA Continuous, 124 MVA 2 hour emergency Installation ti of Mission i Capacitors Two 8.5 MVAR capacitors installed at Mission September

5 Western South Dakota Near Term Issues (2011) Oahe Area Deficiencies Prior outage of 230/115 kv Auto-Transformer Prior outage of Unit 1 Prior outage of Oahe Ash Tap Prior outage of Oahe Irv Simmons 115 kv Bus fault Can cause low voltages in the Pierre Area Can overload Oahe Ash Tap or Oahe Irv Simmons lines Corps plans to populate existing Double Breaker/Double Bus 115 and 230 kv bays and install a second 230/115 kv transformer This fixes the 115 kv bus fault and the prior outage issues with the Auto-Transformer and Unit 1 5

6 Western South Dakota Near Term Issues (2011) Oahe Area Deficiencies (cont.) Work at Oahe Substation does not address voltage and thermal issues caused by the prior outage either Pierre Ash Tap or Pierre Irv Simmons An additional transmission line is required into the Pierre load pocket Proposed solution is to abandon Ash tap and tie Ash Street directly to Oahe providing a three separate sources to the Pierre load pocket 6

7 Western South Dakota Near Term Issues (2011) 7

8 Western South Dakota Near Term Issues (2011) Rapid City Area Deficiencies Loss of New Underwood KV1A 230/115 kv Transformer 115 kv Bus fault 230 kv Bus fault Prior outage of New Underwood Rushmore Prior outage of New Underwood Ellsworth or Ellsworth Rapid City Can cause low voltages in the Rapid City Area Rapid City area improvements are planned in four phases 8

9 Western South Dakota Near Term Issues (2011) Phase 1 (In Service before Summer 2012): Add additional UVLS Phase 2 (In Service before Summer 2013): Installation of a parallel 230/115 kv 200 MVA transformer (KV2A) at New Underwood Installation of series bus sectionalizing breakers at New Underwood 115 kv bus between 1462 and 1562 One bus section would contain KV1A and the Rushmore line Second bus section would contain the Ellsworth line and the Wicksville/Wall/Philip line Reconfiguration of New Underwood 230 kv bus Possibly series bus sectionalizing breakers between 582 and 682 Phase 3 (In Service before 2015): Installation of a 230/115 kv 200 MVA transformer at RCDC tie Construction of a 115 kv RCDC-Rapid City line Possibility of constructing 230 double circuit to be determined Potential Removal of UVLS Phase 4 (future): Close 230 kv loop at Rapid City DC tie Replace existing 230/115 kv 100 MVA transformer (KV1A) at New Underwood with a 200 MVA transformer 9

10 Western South Dakota Near Term Issues (2011) Rapid City Area voltage issues 10

11 Western South Dakota Mid Year Issues ( ) Uprate Oahe Philip Tap New Underwood 230 kv line Also identified in Keystone XL Study Currently limited to 240 MVA by CT settings New limit will be 320 MVA CT limit CT change should be completed before new Philip 200 MVA Transformer is installed Uprate Eagle Butte - Oahe 115 kv line CT tap change at Oahe (currently limits to 60 MVA) CT tap change at Eagle Butte (currently limits to 80 MVA) New limit will be 104 MVA jumpers 11

12 Western South Dakota Mid Year Issues ( ) Uprate New Underwood Rapid City 115 kv lines New Underwood Rushmore Rapid City New Underwood Ellsworth Ellsworth Rapid City Currently limited it by 80 MVA CT settings Increase rating to conductor rating Will require a LIDAR study 12

13 Western South Dakota Mid Year Issues ( ) A major rebuild of Fort Randall Substation is planned by the Corps beginning in 2012 Replace buswork and jumpers Install dedicated transformer breakers for both 230/115 kv transformers Targeted completion date of 2015 High temperature jumper ratings have been implemented for limiting iti substation ti conductors until rebuild is complete 95 MVA continuous 124 MVA 2-hour emergency 13

14 Western South Dakota Mid Year Issues ( ) A new Lower Brule substation is planned just outside of Big Bend on the Big Bend Fort Thompson line in 2013 A Lower Brule Witten 230 kv line is also planned A 200 MVA 230/115 kv transformer will be installed at Witten A SPS or Generator dropping scheme will be needed for loss of Lower Brule Fort Thompson UVLS is required at Keystone XL PS 21 near Gregory for the prior outage of the new 230 kv line 14

15 Western South Dakota Out Year Issues ( ) Replacement of Martin 115/34.5 kv transformer Required before 2021 Sizing to be determined at a later date Replacement of Newell 115/69 kv transformer Required before 2021 Sizing to be determined at a later date 15

16 Summary of New Facilities Continue with Oahe improvements (completion 2015) Continue with Fort Randall improvements (completion 2015) Construct Oahe Ash Tap 115 kv line (In service 2012) Uprate Oahe Philip Tap New Underwood 230 kv line (2012) Uprate Oahe Eagle Butte 115 kv line (2012) Study Nebraska Panhandle for system improvements in 2012 Install SPS/Generator Dropping for Lower Brule Witten 230 kv line (2013) 16

17 Action Items Install additional UVLS in the Rapid City Load Pocket (Early 2012) Determine ROW options in the Rapid City area for future 230 kv transmission (2011) Begin study based on available transmission routes Study Lower Brule SPS/Generator dropping (2012) Determine New Underwood 230 kv bus arrangement (double breaker/double bus or series bus sectionalizing breakers) 17

18 Questions? 18

19 Eastern South Dakota 19

20 Eastern South Dakota System Improvements During 2011 Installation of Eagle Area UVLS on 69 kv system NIPCO and MEC installed a load dropping scheme to shed load during critical contingencies i at Eagle substation. ti NIPCO and MEC are studying additional system improvements in the area to reinforce the 69 kv system Replacement of Sioux City 161/69 kv transformer KV3A 74 MVA transformer replaced with 100 MVA transformer Installation of a 20 MVAR reactor at Sully Buttes Required for the outage of Oahe Sully Buttes Increased Huron Redfield Groton 115 kv line rating Increased from 80 MVA to 120 MVA Increased Watertown Brookings #2 line rating Increased from 80 MVA to 120 MVA 20

21 Eastern South Dakota Near Term Issues (2011) Ordway Area issues Ordway substation serves load in the Aberdeen area Loss of Groton Ordway leaves Ordway load hanging radially from Jamestown Can be masked in off-the-shelf powerflow cases by waste heat generation at Ordway and a wind farm at Edgeley East River has added 12 MVAR capacitors on the 69 kv system Were not previously modeled Capacitors and transmission improvements recommended To Jamestown 21

22 Eastern South Dakota Near Term Issues (2011) Add a capacitor at Ordway Not sufficient to keep voltages at an acceptable level as load continues to grow Large capacitors would only be required under prior outage conditions May have to be automatically fast switched with loss of Groton Ordway line 10 MVAR is suggested in combination with transmission improvements Additional 10 MVAR may be required as loads continue to increase Construct Ordway Aberdeen 115 kv line Provides an additional source into the Ordway area Also helps to support the Aberdeen area for loss of Groton Aberdeen 115 kv line 22

23 Eastern South Dakota Near Term Issues (2011) Sioux Falls Area Issues Sioux Falls 230/115 kv transformers are near the end of their expected life span Breaker failure of the 230 kv bus sectionalizing breaker results in low voltages on the 115 kv system Loss of one transformer can overload the second transformer in the out year cases Circulating VAR/voltage set point issue between Western s Sioux Falls and with NSP s Split Rock Sioux Falls transformers are 220/115 kv transformers The 115 kv Sioux Falls Lawrence line is operated normally open 23

24 Eastern South Dakota Near Term Issues (2011) High flows between Western and NSP load up the 230/115 kv transformer at Split Rock and the 230/115 kv transformers at Sioux Falls The Sioux Falls Lawrence 115 kv line is operated normally open due to historical post contingent loading concerns Closing the Sioux Falls Lawrence 115 kv line reduces transformer loading while having a minor effect on net powerflow between Western and NSP Power flows on both the 230 and 115 paths reducing 230/115 kv transformer loading at both Sioux Falls and Split Rock Closing the Sioux Falls Lawrence line helps both Western and NSP under prior outage conditions When Sioux Falls Lawrence line is closed transformer sizing requirements are reduced 24

25 Action Items Size Sioux Falls transformers and determine replacement timeline 25

26 Eastern South Dakota Near Term Issues (2011) Sioux Falls Gavins Point Loop Issues Loss of either end of the loop results in low voltages when a large amount of load is served radially Closing the Sioux Falls Lawrence line helps voltages for loss of the Gavins Point end of the loop A capacitor is suggested for N-1 low voltage issues Transmission improvements are suggested to prevent load from being dropped under N conditions 26

27 Eastern South Dakota Near Term Issues (2011) Add 20 MVAR capacitor bank at Spirit Mound or Beresford substation Increases voltages during a single contingency Add Rasmussen EJ Manning 115 kv line Creates a third source into the load pocket to increase reliability under prior outages Requires the addition of a 230/115 kv transformer and a 115 kv yard at Rasmussen Rasmussen Vermillion line is also an option 27

28 Eastern South Dakota Near Term Issues (2011) Replacement of Creston transformers Currently scheduled for 2012 Operating guide has been created to prevent violations until improvements are completed Dedicated transformer breakers will be added when transformers are replaced Existing 56 MVA transformers will be replaced with 150 MVA transformers Dedicated transformer breakers will be installed A 69 kv bus tie breaker will be installed A 69 kv capacitor will be installed 28

29 Eastern South Dakota Near Term Issues (2011) Eagle Substation Issues Breaker failure can de- energize the entire substation and cause low voltages on the 69 kv system NIPCO and MEC have installed a load dropping scheme on the 69 kv system NIPCO and MEC are studying options for additional transmission for the 69 kv system No Bulk Electric System problems for these contingencies Large load pocket on networked 69kV system 29

30 Eastern South Dakota Mid Year Issues ( ) Replacement of Spencer transformers Currently scheduled for 2013 Dedicated transformer breakers will be added when transformers are replaced Capacitor will be added to the 161 kv bus Transformer sizing will be finalized in a supplemental study Large load pocket on networked 69kV system 30

31 Eastern South Dakota Out Year Issues ( ) Replacement of Granite Falls 115/69 kv transformer Required before 2020 Sizing to be determined at a later date 31

32 Summary of New Facilities Ordway 115 kv Capacitor (In service 2012) Beresford/Spirit Mound Capacitor (In service 2012) Continue with Creston improvements (In service 2012) Continue with Spencer improvements, finalize transformer sizing (In service 2013) Construct t Ordway Aberdeen Siebrecht 115 kv line (In service 2013) Add 230/115 kv transformer at Rasmussen and construct Rasmussen EJ Manning (or Vermillion) 115 kv line (In service 2013) Size Sioux Falls transformers and determine timeline for replacement 32

33 2011 South Dakota Additional Sensitivities Aurora New delivery point that relocates City of Aurora load from Brookings to Aurora Roberts County New delivery point on the Summit Forman 115 kv line Summit Transformer Verify sizing of replacement transformer Study combined with Roberts County request Fort Randal/Tyndall Voltage Support Additional voltage support required, especially during Corps bird runs Voltages drop to 0.98 pu system intact t 33

34 Questions? 34