Maine Public Service Transmission System Reliability

Transcription

1 Maine Public Service Transmission System Reliability Presentation at the Northern Maine Planning Advisory Group 5/15/13

2 Today s Presentation will cover: Part I Assumptions & Methodology Assumptions used in transmission planning assessments Recent transmission reliability assessments of the MPS transmission system Differences between Planning vs. Operations Part II Results of Studies Planning: Identify reliability issues on MPS current transmission system under both radial and interconnected configurations with New Brunswick Operations: Identify Critical Load Level of MPS Transmission System when reliability issues appear 5/15/2013 MPS Reliability Studies Presentation 2

3 RLC Transmission System Reliability Investigations for MPS include: MPS Transmission System Reliability Planning Investigation Review transmission reliability needs Radial vs. Interconnected (covered later in more detail) Evaluated previously identified reliability solutions MPS Operational Study Assess the impact of the potential de-activation of last remaining thermal generator in operation Determination of critical load level for short-term reliability measures Joint effort with Northern Maine Independent System Administrator (NMISA) 5/15/2013 MPS Reliability Studies Presentation 3

4 MPS Transmission Planning Standards MPS participated in MPUC Docket No : Investigation into Maine Electric Utilities Transmission Planning Standards and Criteria Order determined MPS transmission planning practices were reasonable with minor exceptions MPUC created Safe Harbors that may be used in establishing need in certificate of public convenience and necessity (CPCN) proceedings Utilities may offer different assumptions along with cost/benefit analysis to justify any additional need MPS Safe Harbor assumptions are generally applied in current studies 5/15/2013 MPS Reliability Studies Presentation 4

5 MPS Safe Harbor Planning Assumptions Planning Standard Safe Harbor MPS Reliability Study Local Criteria Single contingency, single element Agree Regional Criteria Generation Hydro Single contingency, single and multiple element Peak hour of the four peak days during each year of a five year period Agree Agree - Tinker = 12MW Generation Thermal Single generator out Agree - Fort Fairfield Off Generation Wind Ten percent of nameplate Mars Hill = 0MW (based on historical data) Scheduled Maintenance Not modeled Agree (none conducted) Facility Ratings PP-7 with 28 C ambient temperature Agree Loss of Load 25 MW consequential load loss for single contingency Agree Load Levels 90/10 Peak Load forecast Agree Interface Transfers Stated transfer limits Agree 5/15/2013 MPS Reliability Studies Presentation 5

6 2012 MPS Reliability Study Most Recent Transmission Reliability Assessment Conducted by RLC Engineering Planning study of conditions in five years Study Driver Potential de-activation of last remaining major thermal generating plant (Fort Fairfield) in operation Radial configuration exposes weakness in ratings of existing facilities Reliability Concern MPS system now predominantly operated in radial mode with NBP with weak performance which is magnified by reduced generation Performance Issues 69 kv Line or transformer overloads and voltage violations reported for first contingency (Loss of 3855 or Flo s Inn 138/69kV transformer) 5/15/2013 MPS Reliability Studies Presentation 6

7 MPS Generation Dispatch Overview 2012 MPS Reliability Study Dispatch MPS Load Sum/Win (MW) Fort Fairfield Status Tinker Hydro (MW) Beechwood Hydro Status Other Hydro NB-NE Transfers D /128 Off 12 Typical 94MW Low -550 MW D /128 Off 12 Low 50MW Low MW D /131 Off 12 Typical 94 MW Low -550 MW D /131 Off 12 Low 50MW Low -550 MW 5/15/2013 MPS Reliability Studies Presentation 7

8 MPS Contingencies Studied Single element contingencies 2012 MPS Reliability Study 12 MPS 69 kv lines 2 Transformers (138/69 kv) 2 Generators (Tinker #1-4 and Tinker #5) 4 Capacitor Banks Multiple element contingencies For observation purposes only 5/15/2013 MPS Reliability Studies Presentation 8

9 MPS 90/10 Peak Load Assumptions 2012 MPS Reliability Study Traditional near term investigation of current situation Summer 2012 Peak load = 111 MW (August 2012, 109 MW) Winter 2012/13 Peak load = 128 MW (January 2013, 123 MW) Two transmission configurations Radial and Interconnected Traditional long term investigation of future 2017 conditions 3 MW system load increase over five years 0.5 MW per year growth Two transmission configurations No consideration for major spot load additions MPS Transmission System load includes Perth-Andover Summer 6 MW Winter 7 MW 5/15/2013 MPS Reliability Studies Presentation 9

10 MPS Transmission System Configuration Radial and Interconnected Interconnected configuration represents the normal system design with all lines in-service MPS Transmission System served via four tie points with NBP Two 69 kv lines from Iroquois Tinker 138/69 kv transformer (fed from 138 kv line 1144) Flo s Inn 138/69 kv transformer (fed from 138 kv line 3855) Radial configuration represents a system which has open lines which split the MPS system into two MPS Northern portion served from HQ through Iroquois MPS Southern portion served from NBP through Tinker and Flo s Inn 138/69 kv transformers 5/15/2013 MPS Reliability Studies Presentation 10

11 MPS Transmission System Configurations MPS Interconnected Operation Interconnected transmission system operated with all MPS lines normally closed Iroquois Tie Points Two 69 kv lines from Iroquois Tinker 138/69 kv transformer Feed from 138 kv line 1144 Flo s Inn 138/69 kv transformer Feed from 138 kv line 3855 Tinker Tie Point 5/15/2013 MPS Reliability Studies Presentation 11 Flo s Inn Tie Point

12 MPS Transmission System Configurations MPS Radial Operation To isolate load onto HQ, Edmundston is opened and 3113 is closed Radial out of Hydro Quebec (HQ) Northern Supply Points Northern portion served from HQ through Iroquois Summer Peak 2012 = 19 MW Winter Peak 2012/13 = 23 MW Southern portion served from NBP through the Tinker and Flo s Inn 138/69 kv transformers. Summer Peak 2012 = 93 MW Winter Peak 2012/13 = 107 MW Open lines on NBP System Line 1140 Line 22 (normally open) Open lines on MPS System 6905 line at Limestone S/S 6908 line at Caribou S/S Southern Supply Points 5/15/2013 MPS Reliability Studies Presentation 12

13 Reliability Assessments Comparison of Operational vs. Planning Assumptions Generation Operations: Available resources dispatched to meet reliability Planning: Assume most significant generator offline Contingencies Local systems are treated same Load Operations: Short-term forecast based on expected weather conditions Planning: Long-term forecast based on 90/10 conditions System Conditions Operations: Status dependent on equipment and facilities Planning: System normal all lines in-service 5/15/2013 MPS Reliability Studies Presentation 13

14 2013 MPS Operational Study Determination for Short-term Reliability Measures Conducted by RLC Engineering Operational study of conditions for 2013 Summer and 2013/14 Winter Study Driver Request to de-activate the last remaining thermal generating plant (Fort Fairfield) in operation Determine critical load level for short-term reliability measures Reliability Concern Single contingency coverage to meet reliability standards Performance Issues 69 kv Line or transformer overloads and voltage violations reported for first contingency (Loss of 3855 or Flo s Inn 138/69kV transformer) 5/15/2013 MPS Reliability Studies Presentation 14

15 2013 MPS Operational Study Assumptions MPS/NMISA requested a steady state analysis of critical conditions and contingencies to determine limiting voltage and thermal performance of the MPS system Without Fort Fairfield thermal generator (requested de-activation) Two 2013 MPS load levels were analyzed: Summer peak load level of 111 MW Winter peak load level of 128 MW NBP generation conditions (Beechwood Hydro) were modeled at typical output (50 MW) and low (30 MW) output levels. On MPS system, hydro and wind generating conditions were assumed as low. Only N-1 contingencies were analyzed. 5/15/2013 MPS Reliability Studies Presentation 15

16 Questions?? 5/15/2013 MPS Reliability Studies Presentation 16

17 2012 MPS System Reliability Study Results Planning study of MPS transmission system based on Safe Harbor Assumptions 5/15/2013 MPS Reliability Studies Presentation 17

18 Voltage 2012 MPS System Reliability Reliability Planning Criteria Acceptable: voltages greater than 90% before voltage regulation Acceptable: voltages greater than 95% after voltage regulation Thermal Pre-contingency Acceptable: Loadings below 100% Normal Rating Post-contingency Acceptable: Loadings below 100% Long Time Emergency (LTE) Rating 5/15/2013 MPS Reliability Studies Presentation 18

19 2012 MPS System Reliability 2012 Peak Load Interconnected Configuration Critical Contingency Loss of 3855 or Flo s 138/69 Transformer Voltage Summer - No voltage violations of reliability criteria with post contingency adjustments of distribution transformer load-tap-changers (LTC s), and switched capacitor banks Winter Voltages less than 95% reported within MPS with post contingency adjustments of distribution transformer load-tap-changers (LTC s), and switched capacitor banks Thermal Summer Line 6901 overloaded for both dispatches, highest loading was 108% (LTE of 48 MVA) with Beechwood at 94 MW Winter Tinker 138/69 kv transformer overloaded for both dispatches, highest loading was 108% (LTE of 72 MVA) with Beechwood at 94 MW 5/15/2013 MPS Reliability Studies Presentation 19

20 2012 MPS System Reliability Study 2017 Results similar only worse with higher system load Critical Contingency loss of Section 3855 or Flo s Inn 138/69 kv trans. Voltage Summer Interconnected no voltage violations of reliability criteria Winter Interconnected - Voltage violations of reliability criteria before voltage regulation adjustments (< 90%) and after adjustments (<95%) Thermal Summer Interconnected 6901 overloaded as high as 110% Winter Interconnected Tinker Transformer overloaded as high as 109% 5/15/2013 MPS Reliability Studies Presentation 20

21 MPS System Configuration Interconnected Tinker Transformer Loading Contingency: L/O 3855 or Flo s Inn 138/69 kv Transformer Percent Loading (LTE) D D D D4 Summer Winter 5/15/2013 MPS Reliability Studies Presentation 21

22 MPS System Configuration Interconnected Line 6901 Loading Contingency: L/O 3855 or Flo s Inn 138/69 kv Trans Winter Loadings less than 95% LTE rating Percent Loading (LTE) D D D D4 Summer Winter 5/15/2013 MPS Reliability Studies Presentation 22

23 2012 MPS System Reliability 2012 Peak Load Radial Configuration Critical Contingency Loss of 3855 or Flo s 138/69 Trans. Voltage Summer - Voltage violations of reliability criteria (< 90%) before voltage regulation adjustments of distribution transformer loadtap-changers (LTC s), and switched capacitor banks Winter Voltage collapse reported within MPS Thermal Summer - Tinker 138/69 kv transformer overloaded for both dispatches, highest loading was 122% (LTE rating of 72 MVA) with Beechwood at either 94 MW or 50 MW Summer Line 6901 overloaded for both dispatches, highest loading was 121% (LTE rating of 48 MVA) with Beechwood at 50 MW Winter - Tinker 138/69 kv transformer overloaded for both dispatches, highest loading was 141% (LTE rating of 72 MVA) with Beechwood at either 94 MW or 50 MW Winter Line 6901 overloaded to 101% (LTE rating of 69 MVA) with Beechwood at 50 MW 5/15/2013 MPS Reliability Studies Presentation 23

24 2012 MPS System Reliability Study 2017 Results similar only worse with higher system load Critical Contingency loss of Section 3855 or Flo s Inn 138/69 kv trans. Voltage Summer Radial - Voltage violations of reliability criteria (< 90%) before voltage regulation adjustments Winter Radial - Voltage collapse reported within MPS Thermal Summer Radial 6901 overloaded as high as 124% and Tinker Transformer overloaded as high as 121% Winter Radial - Tinker Transformer overloaded as high as 146% (voltage collapsing on contingency) 5/15/2013 MPS Reliability Studies Presentation 24

25 MPS System Configuration Radial Tinker Transformer Loading Contingency: L/O 3855 or Flo s Inn 138/69 kv Trans Percent Loading (LTE) D D D D4 Summer Winter 5/15/2013 MPS Reliability Studies Presentation 25

26 MPS System Configuration Radial Line 6901 Loading Contingency: L/O 3855 or Flo s Inn 138/69 kv Trans Percent Loading (LTE) D D D D4 Summer Winter 5/15/2013 MPS Reliability Studies Presentation 26

27 2012 Operational Study Results Determination of critical load level for short-term reliability measures 5/15/2013 MPS Reliability Studies Presentation 27

28 MPS Operational Study Summer Results Summer MPS Modeled Interconnected No MPS voltage violations Loss of 3855 Line or Flo s Inn 138/69 kv transformer Line 6901 overloads as high as 111% of its 48 MVA LTE rating for MPS Critical Load Level of 100 MW MPS Line 6901 at 100% loading for loss of Flo s Inn 138/69 kv transformer Summer MPS Modeled Radial No MPS voltage violations Loss of 3855 Line or Flo s Inn 138/69 kv transformer Tinker 138/69 kv transformer overloads as high as 122% of its 72 MVA LTE rating Line 6901 overloads as high as 131% of its 48 MVA LTE rating MPS Critical Load Level of 90 MW MPS 6901 line at 98% loading for loss of Flo s Inn 138/69 kv transformer. MPS Critical Load includes estimate for Perth-Andover 5/15/2013 MPS Reliability Studies Presentation 28

29 MPS Operational Study Winter Results Winter MPS Modeled Interconnected For loss of 3855 or Flo s Inn 138/69 kv transformer Low voltage violations were reported within the MPS system. Tinker 138/69 kv transformer overloads as high as 106% of its 72 MVA LTE rating MPS Critical Load Level of 119 MW. Tinker 138/69 kv transformer at 100% loading for loss of Flo s Inn 138/69 kv transformer. Winter MPS Modeled Radial For loss of 3855 or Flo s Inn 138/69 kv transformer MPS voltage collapse Tinker 138/69 kv transformer overloads which contribute to voltage collapse MPS Critical Load Level of 96 MW Tinker 138/69 kv transformer at 100% loading for loss of Flo s Inn 138/69 kv transformer. MPS Critical Load includes estimate for Perth-Andover 5/15/2013 MPS Reliability Studies Presentation 29

30 Short-term Reliability Operational Requirements Load includes MPS and Perth-Andover MPS System Load (MW) Summer - Int. Summer - Rad. Winter - Int. Winter - Rad. Critical Load Level Short-term Reliability Requirement 5/15/2013 MPS Reliability Studies Presentation 30

31 Questions?? 5/15/2013 MPS Reliability Studies Presentation 31