A REPORT TO THE BOARD OF COMMISSIONERS OF PUBLIC UTILITIES. Electrical. Mechanical. Civil. Protection & Control. System Planning

Transcription

1 A REPORT TO THE BOARD OF COMMISSIONERS OF PUBLIC UTILITIES Electrical vo1e.5s 0j 44, AMY., CK NI r. SIGNATURE Mechanical Civil Protection & Control t^ /DATE 1 o Transmission & Distribution AND Telecontrol System Planning REPLACE CIRCUIT BREAKER B1L21, STRUCTURES AND DISCONNECTS Hawke's Bay Terminal Station April 2010 newfoundland lahrador h dro nalcor energy company

2 Replace Circuit Breaker B1L21, Structures and Disconnects Hawke's Bay Terminal Station Table of Contents 1 INTRODUCTION 1 2 PROJECT DESCRIPTION 2 3 EXISTING SYSTEM Age of Equipment or System : Major Work and/or Upgrades Anticipated Useful life Maintenance History : Outage Statistics Industry Experience Maintenance or Support Arrangements Vendor Recommendations Availability of Replacement Parts Safety Performance Environmental Performance Operating Regime 7 4 JUSTIFICATION Net Present Value Levelized Cost of Energy Cost Benefit Analysis Legislative or Regulatory Requirements Historical Information Forecast Customer Growth Energy Efficiency Benefits Losses during Construction Status Quo Alternatives 10 5 CONCLUSION Budget Estimate Project Schedule 11 Newfoundland and Labrador Hydro

3 1 INTRODUCTION The Great Northern Peninsula (GNP) is connected to the Island Interconnected System through a 138 kv transmission line TL-239 and a 69 kv transmission line TL-226. Both lines originate at the Deer Lake Terminal Station. Transmission line systems, in general, get renamed when they terminate at a terminal station before continuing on to another terminal station. The 69 kv transmission system serving the GNP is composed of four individual transmission lines, TL-226, TL-227, TL-262 and TL-221. The Hawke's Bay Terminal Station is supplied by transmission line TL-221 which originates at the Peters Barren Terminal Station. TL-221 is approximately 53 kilometers in length. The 69 kv oil filled circuit breaker, B1L21 is the main protection device at the termination of TL-221 in the Hawke's Bay Terminal Station. Figure 1 is a picture of the 69 kv oil filled circuit breaker. Figure 1: 69 kv Oil Filled Circuit Breaker at the Hawke's Bay Terminal Station Newfoundland and Labrador Hydro Page 1

4 2 PROJECT DESCRIPTION This project is required to replace the 69 kv oil filled circuit breaker B1L21 and its auxiliary equipment at the Hawke's Bay Terminal Station. The existing 69 kv oil filled circuit breaker will be replaced with a new sulfur hexachloride (SF6) gas insulated breaker. The auxiliary equipment to be replaced includes: three isolating disconnect switches; a high speed ground switch; and the wood pole structure on which the disconnect switches are mounted. There are also two capacitive voltage transformers mounted on the wood pole structure. They are used for protection and control of the transmission system and will be remounted on the new wood pole structure. There is sufficient space in the station to construct the new wood pole structure and install the circuit breaker and disconnect switches without immediately dismantling the existing equipment. This will minimize power outages to customers. Upon completion of this work, the termination of transmission line TL-221 will be relocated to the new wood pole structure and connected to the new circuit breaker. During the relocation of the line termination, diesel generation will be required to provide service to customers. Newfoundland and Labrador Hydro Page 2

5 3 EXISTING SYSTEM The Hawke's Bay Terminal Station was built in 1970 to provide electrical power to approximately 1,300 customers in the communities of Hawke's Bay, Port Saunders, Port aux Choix, Eddie's Cove West and River of Ponds. The terminal station has a 69/ kv 5/6 MVA transformer and a 69/ kv 2.5/3.3 MVA transformer. The transformers step the voltage down to 12.5kV for distribution to customers. The terminal station also consists of various other equipment including circuit breakers, disconnect switches, current transformer and potential transformers. The existing 69 kv circuit breaker has had several minor leaks in recent years and the circuit breaker's isolating disconnect switches have been experiencing jamming problems. The wood pole support structure where these isolating disconnect switches are mounted has also deteriorated and as a result has become unstable and warped which is a contributing factor to the jamming of the switches. At the Hawke's Bay Terminal Station there are also two 3 MW diesel generating units used for voltage support on the transmission system and for emergency power when there is a transmission system outage. Figure 2 shows part of the Interconnected Island System including Hawke ' s Bay. COOK'S HR. L'ANSE AUX L' ANSE-AU-LOUP. / MEADOWS ST. L' ANSE-AU-CLAIR LUNAIRE EDDIES ST. COVE E. rya1 ^' ANTHONY BEAR COVE \,1gb n GOOSE COVE ST. ANTHONY MAIN AIRPORT PLUM PT. BROOK CROQUE,`v HAWKES BAY RIVER OF PONDS BELLBURNS DANIELS HR. Figure 2: GNP Portion of the Island Interconnected System Newfoundland and Labrador Hydro Page 3

6 3.1 Age of Equipment or System The circuit breaker, disconnect switches, ground switch and wood pole support structure were installed in 1970 as part of the original station construction. 3.2 Major Work and/or Upgrades There have been no major upgrades to the circuit breakers, structures and disconnects. 3.3 Anticipated Useful life The anticipated useful life of the circuit breaker, disconnect switches and wood pole structure is 30 years. 3.4 Maintenance History The five-year maintenance history for the circuit breaker, disconnect switches and ground switch is shown in Tables 1 and 2. The corrective maintenance includes PCB testing and repair, replacement and upgrades of equipment accessories. The preventive maintenance includes regular preventive maintenance checks, oil sampling and dissolved gas analysis testing. Table 1: Five-Year Maintenance History For Circuit Breaker B1L21 Preventive Maintenance Corrective Maintenance Total Maintenance Year ($000) ($000) ($000) Newfoundland and Labrador Hydro Page 4

7 Table 2: Five-Year Maintenance History For Disconnects B1L21-1, B1L21-2, B1L21-BP and Ground Switch L21G Preventive Maintenance Corrective Maintenance Total Maintenance Year ($000) ($000) ($000) Outage Statistics Terminal equipment outages statistics are provided in two tables. Table 3 lists the performance of Hydro's 66 kv circuit breakers versus the CEA latest five years (2003 to 2007). Table 4 details the performance of the Hawke's Bay Delivery Point. Table 3: Hydro's 66 kv Circuit Breaker Performance Versus CEA latest five years Number of Outages Frequency (per a) Unavailability 66 kv Breakers ( ) CEA 66 kv Breakers ( ) Frequency (per a) is the number of failures per year. Unavailability is the percent of time per year the unit is available. Table 4: Performance of the Hawke's Bay Delivery Point Five Year Averages ( ) Forced Outages Only Delivery Point Affected T-SAIFI T-SAIDI Hawke's Bay Northern Region Hydro System CEA ( ) Newfoundland and Labrador Hydro Page 5

8 3.6 Industry Experience Hydro's communication with other major Canadian utilities concerning utility operating and maintenance issues confirm that Hydro's experiences with oil filled breakers of this vintage is similar to that of the other Canadian utilities. 3.7 Maintenance or Support Arrangements Operation and maintenance work is performed by Hydro Operations personnel. 3.8 Vendor Recommendations The manufacturer, Canadian General Electric recommends replacing the equipment when it reaches the end of its useful service life of 30 years. 3.9 Availability of Replacement Parts Replacement parts for the oil filled breaker and disconnects are no longer available from the manufacturer Safety Performance The disconnect switches have been experiencing jamming problems which make them unable to operate. An inoperable disconnect switch creates a safety hazard for personnel because malfunctioning parts can break off and fall onto the workers below. A worker may suffer an injury as a result of broken pieces from disconnect switches failing from above. Due to age and deterioration beyond repair the wood pole support structure is unstable and at risk of falling down which would cause equipment damage and expose workers to live conductors. Newfoundland and Labrador Hydro Page 6

9 Figure 3: Wood Pole Structure at the Hawke ' s Bay Terminal Station 3.11 Environmental Performance There are no environmental issues related to normal operation of oil filled circuit breakers and disconnect switches but leaks from the oil filled breaker is an environmental concern. Oil from a leaking circuit breaker seeps into the earth and therefore must be cleaned up Operating Regime The equipment is in full time continuous operation. Newfoundland and Labrador Hydro Page 7

10 4 JUSTIFICATION This project is justified on the requirement to replace failing or deteriorated equipment in order for Hydro to provide safe, least-cost and reliable electrical service. The 69 kv oil filled circuit breaker B1L21 in the Hawke's Bay Terminal Station has experienced several minor leaks in recent years and is beyond its useful service life. As the circuit breaker ages, it is at increased risk for more oil leaks, outages or even complete failure which negatively impacts the reliability of electrical service. Replacement of the circuit breaker will reduce the risk of failures and ensure reliable system operation. The three breaker isolating disconnect switches are inoperable due to jamming problems and are beyond their useful service life. Reliable and secure operation of the disconnect switches is essential to a safe work environment and for reliable and secure system operation. An inoperable disconnect switch does not allow isolation of the circuit breaker making it difficult, if not impossible, for maintenance work. A safety hazard also exists because malfunctioning parts can break off and fall onto the workers below. The disconnect switches must be replaced in order to maintain a safe and reliable operating condition. The wood pole support structure has deteriorated beyond repair and is at risk of failure. Failure of the wood pole structure could result in injury to workers, damage of equipment and interruption of service to the customers. Replacement of the wood pole support structure is required in order to eliminate safety hazards and the risk of interruption to system operation. 4.1 Net Present Value A net present value calculation was not performed as there is no viable alternative to replacing the circuit breaker, disconnect switches and structure. 4.2 Levelized Cost of Energy This project does not affect the levelized cost of energy as it does not involve any new source of generation. Newfoundland and Labrador Hydro Page 8

11 4.3 Cost Benefit Analysis A cost benefit analysis is not applicable to this project as there are no quantifiable benefits. 4.4 Legislative or Regulatory Requirements There are no legislative or regulatory requirements for this project. 4.5 Historical Information Similar projects for the replacement of switches and circuit breakers at Hydro's terminal stations are shown in Table 6. These projects did not require diesel generation to minimize customer outages. Newfoundland and Labrador Hydro Page 9

12 Replace Circuit Breaker 61L21, Structures and Disconnects at Hawke's Bay Terminal Station Table 6: Historical Information Year Capital Budget Actual Expenditures Units Cost per unit Comments ($000) ($000) ($000) 2010F N/A Replacement of disconnect switches at English Harbour West, Conne River and Corner Brook Frequency Converter Replacement of 69 kv circuit breaker at Howley Replacement of disconnect switches at Cow Head and Daniel's Harbour 4.6 Forecast Customer Growth Forecast customer load growth has no effect on this project. 4.7 Energy Efficiency Benefits There are no energy efficiency benefits associated with this project. 4.8 Losses during Construction There will be no production or revenue losses resulting from this project. 4.9 Status Quo The status quo is not an option. The breaker, disconnect switches and support structure must be replaced since continuous operation with the existing equipment presents unacceptable safety and reliability issues Alternatives There are no viable alternatives to this project. Newfoundland and Labrador Hydro Page 10

13 5 CONCLUSION This project is necessary to address the safety and reliability issues related to the deteriorated condition of the circuit breaker, disconnect switches and the supporting wood pole structures. 5.1 Budget Estimate The budget estimate for this project is shown in Table 7. Table 7: Budget Estimate Project Cost:($ x1,000) Beyond Total Material Supply Labour Consultant Contract Work Other Direct Costs O/H, AFUDC & Escln Contingency TOTAL Project Schedule The anticipated project schedule is shown in Table 8. Activity Table 8: Project Schedule Milestone Project Initiation, Design & Equipment Ordering June 2011 Project Safety Plan June 2011 Field Construction/Installations October 2011 Operations Installations October 2011 Commissioning November 2011 Project In Service November 2011 Project Completion and Close Out December 2011 Newfoundland and Labrador Hydro Page 11