Mica Gas Insulated Switchgear (GIS) Replacement Project Workshop

Transcription

1 B-3 Mica Gas Insulated Switchgear (GIS) Replacement Project Workshop 26 August 2009

2 Agenda Mica GIS Replacement Project BCUC Order Mica Generating Station and GIS equipment Need for the Project Project Scope and Cost Architecture Evaluation and Decision Making Timing and Sequencing Project Risks Rate Impact Consultation Conclusions 2

3 Order Sought from BCUC 44.2 (3) (a) of the Utilities Commission Act (the UCA) BCUC acceptance that the expenditures to replace the aging GIS at Mica with new GIS equipment by 2013 are in the public interest Considerations: > the Government s energy objectives; > BC Hydro s most recent long term resource plan; > whether the expenditure schedule is consistent with section and of the UCA in respect of electricity self sufficiency and clean and renewable resources; and > the interests of present and future ratepayers. Project costs: > Expected cost: $180.6 M > Authorized cost: $200.2 M 3

4 Mica Generating Station Mica Generating Station is on the Columbia River 135 km upstream from Revelstoke. Mica Generating Station and GIS Equipment 4

5 Mica Generating Station Mica supplies 16% of energy & 17% of capacity for BCH. The expected cost of a forced or unplanned outage in any month could range from $0 to $20 million per month depending upon time of year and other conditions. Replacement energy and capacity may need to be purchased from the market. Underground powerhouse Mica Generating Station and GIS Equipment 5

6 Mica Gas Insulated Switchgear Lead Shafts 1-3 Mica 500 kv Switchgear conducts energy from the underground transformers to the transmission system at the surface. Energy is conducted via Lead Shafts. Lead Shafts are tunnels running between the powerhouse and surface. Mica Generating Station and GIS Equipment 6

7 Mica Gas Insulated Switchgear GIS allows high voltage conductors to be deployed in limited spaces such as those in an underground powerhouse Sulphur Hexaflouride (SF6) is the insulating gas that allows the equipment to be compact when compared to air insulated switchgear. Mica Generating Station and GIS Equipment 7

8 Mica Dam and Generating Station 3-D Animation Video Mica Generating Station and GIS Equipment 8

9 GIS Equipment: GIS Bus Gas Insulated Bus includes: 1. An inner conductor, 2. SF6 insulating gas 3. Outer housing Bus Cone Insulator Conductor Epoxy cones support conductor and insulate between conductor and housing. Cut Away of GIS Bus Mica Generating Station and GIS Equipment 9

10 GIS Equipment: GIS Bus 3 phases of GIS Bus in Lead Shafts Total of 1200 m of Bus in Mica Mica Generating Station and GIS Equipment 10

11 GIS: Disconnect Switches GIS Bus Disconnect switches are used to isolate sections of the 500kV system. Disconnect switches are manually operated. Mica Generating Station and GIS Equipment 11

12 GIS: Circuit Breakers A circuit breaker is an automaticallyoperated electrical switch designed to protect an electrical circuit from damage caused by overload. Mica Generating Station and GIS Equipment 12

13 GIS: Surge Arrestors Surge arrestors protect transformers and other equipment from over voltage spikes. Surge arrestor being repaired in 2008 Mica Generating Station and GIS Equipment 13

14 Need for the Project: Independent GIS Condition Assessments Key conclusions of independent assessments BC Hydro can expect prolonged, multi-unit outages with the current switchgear; > Disconnect switches and majority of bus in the transformer chamber require two unit outages for repair work to proceed. Surge arrestors and disconnect switches present the greatest risks; Failure of the GIS in one lead shaft restricts the output to 1,500 MW > During the repair period for such a failure, Mica is vulnerable to a full plant outage if a second GIS failure occurs There is a 99 % chance of GIS failure within ten years > Nine months after this prediction, a surge arrestor failed on Unit 3, which resulted in it being out of service for ten weeks. The Mica GIS is > 30 yrs old. It may be the last 500 kv GIS equipment of its type still in operation in North America. Need for the Project 14

15 Need for the Project: Condition Assessment Conclusions 5L71 5L72 Equipment is in GOOD Condition Equipment is in FAIR Condition Equipment is in POOR Condition Equipment is in UNSATISFACTORY Condition Circuit Breaker T1 T2 T3 T4 Disconnect Switch Transformer Generator Surge Arrester G1 G2 G3 G4 Reactor Transmission Line Note: Circuit breakers in the Switchgear Building were replaced in 2007 and 2008 due to their unsatisfactory conditions. 15

16 Project scope Replace the original 500KV Gas Insulated Switchgear at Mica Develop a system that provides benefits by improving upon the current 500KV switchgear. Project scope and cost 16

17 Project Benefits Develop a more robust architecture than the current architecture > Improved layout Disconnect switches > Remote operation Maintenance access Environmental benefits > Reduce SF6 leakage to <0.5% per year. Mica 5 & 6 > Enables BCH to maintain Contingency Resource Plan (CRP) dates for Mica 5 & 6. New Switchgear will be meet Safety by Design requirements. The Switchgear will be floor mounted. It will be accessible using a new overhead crane. Project scope and cost 17

18 Project Cost PROJECT COMPONENT Direct Construction Cost Project Management and Engineering Sub-total: Construction Cost before Contingency (Note 1) Contingency on Expected Cost Dismantling and Removal Inflation and Escalation (Note 2 ) Sub-total: Implementation Phase Cost (Direct) Capital Overhead (Note 3) Interest During Construction (Note 4) Sub-total: Implementation Phase Cost (Loaded) Identification and Definition Phase (loaded) Total Expected Cost Project Reserve (Note 5) Total Authorized Cost (note 6) AMOUNT ($ million) $ $ $ $ $ $200.2 Project scope and cost 18

19 Agenda Mica GIS Replacement Project BCUC Order Mica Generating Station and GIS equipment Need for the Project Project Scope and Cost Architecture Evaluation and Decision Making Timing and Sequencing Project Risks Rate Impact Consultation Conclusions 19

20 Project Requirements (summary) Maintain the reliability of the 500kV GIS Realize project benefits: > Robust architecture > Disconnect switches > Maintenance access > Environmental benefits Develop a system level design that can be implemented without significant impacts upon the operating generating station Low life cycle cost Architecture Evaluation and Decision Making 20

21 Architecture Evaluation Revolutionary Architectures that did not include GIS were: 1. moving the 500 kv transformers out of the Mica powerhouse to the surface; 2. using an insulating gas other than SF6. Conclusions: Not viable Evolutionary Architectures were developed: Evolutionary switchgear designs were developed for more detailed consideration. Architecture Evaluation and Decision Making 21

22 Structured Decision Making Process Engineering Analysis and Constraints Engineering Study Detailed Study, Estimating Final Structured Decision making and ranking Architecture Evaluation and Decision Making 22

23 Recommended Architecture 5L71 5L72 Style Legend Remain New Replace Not In Scope Circuit Breaker Disconnect Switch T1 T2 T3 T4 T5 T6 Transformer Generator Surge Arrester G1 G2 G3 G4 G5 G6 Not in the scope of this project Reactor Transmission Line New architecture substantially reduces consequences of future failures. Lead shaft 3 improves system reliability and has construction benefits. Architecture allow the realization of the additional project benefits. 23

24 Replacement Sequencing Alternative 1 Full implementation of Project by 2013 Schedule for GIS component Installation/Replacement Activity PV Project Cost Low Cost ($6 M) Probability (33%) PV Project and Outage Costs (in $millions) Moderate Cost ($12 M) Moderate Probability (25%) High Cost ($19 M) Outage probability increasing by 1% per year Low Probability (15%) Replace Existing GIS $61 Lead shaft 3 and interface $56 PV of project costs $117 $117 $117 $117 Range of Outage costs $5 $8 $8 GHG Credit Cost $1 $1 $1 Range of Adjusted PV of Project $123 $126 $126 Recommendation Alternative 2 a Do Nothing - Defer implementaion of Project by 5 years Alternative 2 b Do Nothing - Defer implementaion of Project by 10 years Alternative 3 Implement project piecemeal over time Replace Existing $54 Lead shaft 3 and interface $53 PV of project costs $107 $107 $107 $107 Range of Outage costs $13 $19 $18 GHG Credit Cost $2 $2 $2 Range of Adjusted PV of Project $122 $129 $128 Replace Existing $46 Lead shaft 3 and interface $53 PV of project costs $99 $99 $99 $99 Range of Outage costs $18 $28 $27 GHG Credit Cost $3 $3 $3 Range of Adjusted PV of Project $121 $130 $129 Replace Existing $65 Lead shaft 3 and interface $53 PV of project costs $119 $119 $119 $119 Range of Outage costs $11 $17 $19 GHG Credit Cost $2 $2 $2 Range of Adjusted PV of Project $132 $138 $140 Alternative 4 Same as Alternative Replace existing GIS in tranformer $42 1 but defer chamber and switchgear building replacement of lead Lead shaft 3 and interface $56 shafts 1 and 2 Lead shafts 1 and 2 $20 PV of project costs $118 $118 $118 $118 Range of Outage costs $7 $10 $9 GHG Credit Cost $2 $2 $2 Range of Adjusted PV of Project $127 $130 $130 24

25 Sensitivity Analysis of Mica 5 ISD Option/ Year Present Value Cost ($millions) ) Base Case - Do All Now 2) Defer Lead Shaft 1&2 $117 x x $124 x x MICA 5 ISD 3) Defer Lead Shaft 3 $127 x x x x MICA 5 ISD 4) Defer Lead Shaft 1 $119 x x 5) Defer Lead Shaft 1&2 ten years $118 x x 6) Defer Lead Shaft 3 ten years $114 x x x x MICA 5 ISD 7) Defer Lead Shaft 1 ten years LEGEND Lead Shaft 3 and switchgear building Lead Shaft 1 Lead Shaft 2 Base Components Planned Outage - 4 months Mica Unit 5 In-service date $116 x x x Option 1 is lowest cost risk regardless of Mica Unit 5 In Service Date Timing and sequencing 25

26 Construction Sequencing Animation Timing and sequencing 26

27 Mica Switchgear Project Schedule Design & Manufacture July 09 Dec 09 Jan 10 Jun 10 Jun 10 Dec 10 Jan 11 Jun 11 Jun 11 Dec 11 Jan 12 Jun 12 Jun 12 Dec 12 Jan 13 Jun 13 Stage 1 Lead Shaft 3 Lead Shaft 3 Stage 2 Stage 3 Switchgear Building Ring Extension Interface existing GIS to Lead Shaft 3 Ring Interface Stage 4 Mica Units 3 & 4 Unit 3 & 4 Stage 5 Switchgear Building Ring Bus Ring Stage 6 Mica Units 1 & 2 Units 1 & 2 Stage 7 Switchgear Building Ring Bus Ring Stage 8 Lead Shaft 2 LS 2 Stage 9 Lead Shaft 1 LS 1 Sequencing of the work minimizes disruption to the operating plant. Replacement of the GIS for Completion Completion 27 1 Units Mica 1 Switchgear 4 can be completed Project in the spring of 2011 and 2012 when outage costs are low.

28 Project Risks Cost risks mitigated by BC Hydro s decision to tender early and obtain firm pricing Schedule risks are mitigated by: > Including lead shaft 3 to reduce outage time and increase reliability during construction > Apply CHC Collective Agreement Safety risks during construction are mitigated by: > BC Hydro and Contractor Safety Management Plans > Site Specific Safe Work Procedures > Monitoring by BC Hydro during construction Environmental risks are mitigated by: > Environmental Management & Environmental Protection Plans > During construction BC Hydro will have an on-site Environmental Monitor. 28

29 Annual Incremental Rate Impacts 0.60% 0.50% 0.40% Expected Approved Per Cent 0.30% 0.20% 0.10% 0.00% Fiscal Year 29

30 Consultation BC Hydro has undertaken consultation with First Nations and with public stakeholders to identify issues specific to the Project. BC Hydro expects the Project will have minimal, if any adverse impacts. > Project will be implemented within Mica GS or on previously disturbed ground. > There will be no impact on the Kinbasket or Revelstoke reservoirs. BC Hydro believes that the consultation conducted for the Project is adequate. 30

31 Conclusions BC Hydro is seeking BCUC acceptance that expenditures to replace the aging GIS at Mica with new GIS equipment by 2013 are in the public interest. Project costs are: > Expected cost: $180.6 M > Authorized cost: $200.2 M The condition of the original Mica 500kV switchgear poses the risk of forced outages The project will: 1. replace the 500 kv GIS; and 2. improve upon the current GIS system. BC Hydro has planned work so that costs are understood BC Hydro has identified and is managing project risks. 31