W912P522R0003 RTA DDR.pdf

US Army Corps of Engineers

Turbine-Generator Rehabilitation

Design Documentation Report

BCOES Review

Prepared By:

Hydroelectric Design Center U.S. Army Corps of Engineers

January 2022

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Old Hickory Powerhouse

Old Hickory Turbine-Generator Rehabilitation

100% DDR

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EXECUTIVE SUMMARY

The Old Hickory Turbine Generator Rehabilitation project will rehabilitate Units 1-3 and includes specific optional modifications to Unit 4. The work for this project includes three phases of work: studies and assessments, plans and specifications (“P&S”), and construction. The first phase included the execution of studies, tests, and assessments needed to determine the feasibility and scope of work. In this second phase, the contract (P&S) will be developed. The third is construction, including disassembly, rehabilitation, and reassembly.

Several studies and assessments have been undertaken to help inform designers and stakeholders of the capacity of an uprate and the scope of work required to achieve certain magnitudes of uprate. These assessments have included a generator uprate study (GPEA, 2001), Major Rehabilitation Evaluation Report/MRER (MWH, 2011), shaft study (HDC, 2017), and the electrical powertrain study (HDC, 2019).

Details identified in these studies were revisited and summarized, culminating in the Hydropower Rehabilitation Analysis Report/HRAR (HDC, 2020). The HRAR considered the equipment limits determined through previous studies and consolidated input from turbine manufacturers and historical hydrology data to compare replacement and uprate alternatives. The HRAR recommendation was to uprate the turbines and generators to 45 MVA (40.5 MW at a 0.9 power factor). The completion of the HRAR allowed for the project to proceed into the P&S phase. The ability of the turbine runners to produce up to 45 MW (45 MW will be unity power factor operation of the generator) will be limited to times when only one unit is operating. When two or more units are operating, the tailwater versus flow relationship reduces the available head that would allow the replacement turbines to reach this magnitude of output.

44.5 MW is the limit of the shafting as determined by the shaft study, but the fatigue evaluation has been revisited to confirm that 45 MW is acceptable for the shafting.

Old Hickory Unit 4 is undergoing a repair to the linkages of its original turbine runner along with a rewind and restack of its generator stator to the aforementioned 45 MVA rating. The construction phase of this Unit 4 effort is scheduled for completion in FY21. A variety of turbine and generator components are being inspected and/or refurbished through the course of the Unit 4 work, and thus offers lessons learned and insight into refined planning and scoping for the rehabilitation of Units 1-3. The design for Units 1-3 will include an effort to maintain consistency, where practical, with parts or modifications made to Unit 4.

The purpose of this Design Documentation Report (DDR) is to include a narrative of the design, a summary of calculations performed and miscellaneous supporting documentation, and a summary of the assumptions and risks addressed during the design process. The DDR is meant to serve as a concise historical stand-alone summary document that illustrates the design process.

Old Hickory Turbine-Generator Major Rehabilitation

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TABLE OF CONTENTS

1. Introduction

1.1. Project Purpose

1.2. Site-Specific Information

1.3. Project goals

1.4. Project Delivery Team (PDT)

2. Project Description

2.1. Project Scope

2.2. Project Schedule and Deliverables

2.3. Project Budget

2.4. Acquisition Process

2.5. Hazardous Materials

2.6. Reference Documents

2.7. Design Guidance And Standards

2.8. Design and Reference Drawings

2.9. Specifications Sections

2.10. Government Furnished Equipment

2.11. Risk Considerations

3. Scope of Work

3.1. General

3.2. Unit Disassembly, Reassembly, and Operational Testing

3.3. Electrical Work - Generator

3.3.1. Stator Winding

3.3.2. Stator Core

3.3.3. Rotor Poles

3.3.4. Generator Verification Tests

3.3.5. Cleaning Rotating Main and Pilot Exciters and Replacing Collector Rings

3.3.6. Other Items

3.3.7. Model Validation

3.4. Electrical Work – Electrical Powertrain and Controls, Monitoring, and Protective Devices

3.4.1. High Resistance Grounding (HRG)

3.4.2. Electrical Powertrain Analysis

3.4.3. Power Feeders

3.4.4. Raceways

3.4.5. Grounding and Bonding

3.4.6. Protection, Relaying, and Monitoring Equipment

3.4.7. SCADA and Data Acquisition (DAQ) Systems

3.4.8. Annunciation

3.4.9. Cyber Security

3.5. Turbine Work

3.5.1. Runner Replacement

3.5.2. Oil Head and Kaplan Pipes

3.5.3. Blade Servomotor and Operating Rod

3.5.4. Wicket Gates

3.5.5. Operating Ring and Wicket Gate Linkages

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3.5.6. Replacement Central Grease System (Farval)

3.5.7. Bearings

3.5.8. Shafts, Packing Box, and Shaft Sleeve

3.5.9. Shear Pins

3.5.10. Stay Ring and Stay Vanes

3.5.11. Vacuum Breaker

3.5.12. Discharge Ring

3.5.13. Winter-Kennedy Tap Treatment, Index Tetsting, and Prototype Cams

3.5.14. Head Covers

3.5.15. Wicket Gate Servomotors

3.5.16. Bottom Ring Facing Plates

3.5.17. Turbine Spiral Case and Draft Tube Access Doors

3.6. Ancillary Mechanical Components

3.6.1. Generator Air and Thrust Bearing Coolers

3.6.2. Fire Alarm, Fire Suppression, & Life Safety

3.6.3. Bridge Crane and Lifting Equipment

3.6.4. Cooling Water Piping

3.6.5. Turbine Oil Piping

3.6.6. Thrust Bearing High Pressure Lift System

3.6.7. Generator Braking and Jacking Equipment

3.6.8. Machine Condition Monitoring

3.6.9. Turbine Pit Equipment

3.6.10. Governor

3.6.11. Turbine Oil Replacement

3.6.12. Miscellaneous

3.7. STRUCTURAL

3.7.1. Stator Foundation Repair

3.7.2. Discharge Ring and Draft Tube Grouting

3.8. IDIQ CONTRACTS

A. Appendix A - Component Treatment Summary Tables B. Appendix B – HRG Calculations C. Appendix C – Drawing Index

TABLE OF FIGURES

Figure 1 - Phase 2 - Design & Acquisition Approval Schedule Figure 2 - Phase 3 - Award/Delivery/Installation Schedule Figure 3 - Projected construction schedule for major rehab, GSU transformer, and excitation system work.

Site work for the major rehab effort to begin with work on Unit 3 at end of FY 2024 Figure 4 - Simplified one line for station showing one unit. Refer to Table 6 below for details Figure 5 - Unit 4 non-segregated bus, showing bushings to unit (top) Figure 6 - Unit 4 surge arrestor Figure 7 - Unit 4 surge arrestor for C Phase Figure 8 - Unit 4 neutral CT Figure 9 - Generator guide bearing temperature relays (38 devices) to be replaced Figure 10 - Bearing protective temperature relay (38 device)

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Figure 11 - Level switch to be replaced Figure 12 - Unit 4 cooling water pump controls and starter; other units are similar. They were recently replaced and will not be modified for this contract Figure 13 - Unit 4 cooling water temperature and flow monitoring; other units are similar. They were recently replaced and will not be modified for this contract Figure 14 - Unit 4's new terminal enclosure. U1-3 will look similar but may have different features Figure 15 - Existing U1 generator terminal enclosure inside the air housing to be replaced Figure 16 - DAQ nameplate Figure 17 - Old Hickory Lake elevation exceedance plot Figure 18 - Old Hickory tailwater and gross head relationship. Note practically linear relationship Figure 19 - Old Hickory tailwater rating curve for flows less than 50,000 CFS Figure 20 - Old Hickory gross head histogram displaying peaks relative to the number of units in operation. Red stars mark the “peaks” in the data; moving right to left, these correspond to no units running, 1 unit running, 2 units running, 3 units running, and 4 units running Figure 21 - Old Hickory gross head exceedance Figure 22 - Governor sump sight glass Figure 23 - Unit turbine oil supply/return manifold Figure 24 - Manual generator jack pump Figure 25 - Generator brake and jack Figure 26 - Turbine guide bearing lubrication system Figure 27 - Turbine pit sump pump

LIST OF TABLES

Table 1: Participants and Roles Table 2: Major Features of Work Table 3: Deliverables Schedule Table 4 - Specification Sections Table 5: Risk Considerations Table 6: Summary of Electrical Powertrain Components Table 7 - Machining Scope for Stay Ring Upper Flange Table 8: Structural Scope Summary

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1. INTRODUCTION

This design documentation report (DDR) documents the scope and intent of the design for Old Hickory Turbine-Generator Major Rehabilitation. This DDR discusses the evolution of the design and the design development process, including key influences and drivers for decisions, and will act as a guide for a finalized plans and specification package. Justification for the design phase of this project can be found in the Old Hickory Hydropower Rehabilitation Analysis Report/HRAR (March 2020).

1.1. PROJECT PURPOSE

The purpose of the Old Hickory Turbine-Generator Rehabilitation is to provide an increase in power output, restore maximum efficiency, and extend the service life reliability of the units within the capabilities of equipment replacements and refurbishments to optimize economics. The major equipment at Old Hickory powerhouse has been in service since the original installation in 1957, and the turbines and generators have reached the end of their design life. The objective of this design effort is to create a 100% complete contract package that Nashville District can immediately advertise for award.

Economic benefits will be realized through increasing reliability, efficiency and capacity of the hydroelectric generating units by replacing existing turbine runners with increased capacity turbine runners that provide improved power generating efficiency, rewinding and restacking the generators, and replacing and refurbishing other powertrain equipment.

1.2. SITE-SPECIFIC INFORMATION

The Old Hickory powerhouse is located on the Cumberland River in Tennessee near the city of Nashville.

The original primary purposes of the Old Hickory project were hydropower, recreation, and navigation.

The project was constructed between the years of 1952 and 1957.

There are four vertical-axis, five-bladed Kaplan turbines installed at the powerhouse with diameters of 264 inches and synchronous speed of 75 RPM. The turbines were manufactured by the Baldwin-Lima- Hamilton Corporation (BLH). The generators were manufactured by the General Electric Company (GE).

Their original nameplate ratings are 31,250 kVA, 25,000 kW, 13.8 kV, and 0.8 pf, with a 115% overload rating of 35,937 kVA.

1.3. PROJECT GOALS

As determined through the Hydropower Rehabilitation Analysis Report (HRAR), the units will be uprated from a maximum of 35,937 kVA (28,750 kW at 0.8 and 1.0 pf) to 45,000 kVA (40,500 kW at 0.9 pf). This uprate will be achieved through replacement and refurbishment of turbine and generator components under this project, coinciding with coordinated efforts for replacement of the generator step up (GSU) transformers and exciters. The ability of the replacement turbine runners to produce power at 40.5 MW or greater (if generating above rated power factor) will be limited to those times when only one or two units are operating. As discussed in Section 3.5.1, the relationship between flow, tailwater elevation, and head will prevent the turbines from achieving outputs greater than approximately 37 MW once a third unit is operating. The replacement turbine runners will allow generator output up to 45 MW output when operating at unity power factor and when only one unit is running. To achieve this, the replacement runners will be rated at 61,600 hp with a rated net head of 54 feet.

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1.4. PROJECT DELIVERY TEAM (PDT)

Roles for the Project Delivery Team (PDT) are detailed in Table 1 below. Nashville District (LRN) personnel will support with project management duties, developing Division 1 specifications, and scheduling outages with the Project. The Hydroelectric Design Center (HDC) will provide technical plans and specifications and Old Hickory personnel will support by assisting in drawing and records acquisition, site visit coordination, and addressing questions as needed.

Table 1: Participants and Roles

Name Office Title/Role Phone Zachary Langel CELRN-PMM-D Project Manager 615-736-7851 Joseph Van Deusen CELRN-ECD-H Tech Lead 615-736-5623 Ryan Frye CELRN-OPS-H Civil Engineer 615-736-7187 Louis (Allan) Steele CELRN-ECD-H Electrical Engineer 615-736-7923

David Mistakovich CERN-OP-H Hydropower Section Supervisor

615-736-7974

Valerie McCormack CELRN-PMP Environmental Section Supervisor

615-736-7847

Omar Acevedo CELRN-ECE-T Civil Engineer (Cost) 615-736-7588

James (Jamie) Nabakowski CELRN-EC-C Construction Section Supervisor

615-736-7619

Alexander Bohlin CELRN-OPB Maintenance Engineer 615-736-7965 Alexander Fenili CELRN-ECE-S Land Surveyor 615-736-2047 Cody Flatt CELRN-PM-P Biologist 615-736-7954

Stephen Hutchens CELRN-ENT-S Contracting Section Supervisor

206-316-3965

Stephen Salaman CELRN-EC-D-CS Civil Engineer 615-736-7989 Nathan Sporin CELRN-OPS-E Senior Electronics Mechanic 615-824-1032 Terry Ward CELRN-ECC Construction Support Engineer 615-736-2601 Joseph Conatser CELRN-OPN-OP Maintenance Supervisor 615-824-5820 Jason (Jake) Kennedy CELRN-OP-H Sr. Electrician 615-824-5820 John (Greg) Forte CELRN-OPN-OP Sr. Mechanic 615-824-5820

Richard Rieger CELRN-OP-H-

ESS

Chief, Electronic Service Section

615-824-1032

Ellen Ballantine CENWP-HDC-C Regional Design Manager 503-808-4535

Jack McCollister CENWP-HDC-M Mechanical Engineer, HDC Design Lead

503-808-5263 (O) 503-805-9422 (C)

Alex Parks CENWP-HDC-M Mechanical Engineer 503-808-4202 Rudy Hernandez CENWP-HDC-E Electrical Engineer 503-808-4234 Matt Gable CENWP-HDC-E Electrical Engineer 503-808-4246 Hans Lillevold CENWP-HDC-E Electrical Engineer 503-808-4582 David Howden CENWP-HDC-E Electrical Engineer 503-808-4287 Mark Voss CENWP-HDC-M Structural Engineer 503-808-4294 Jason Bedard CENWP-HDC-M Mechanical Engineer 503-808-4321

Catherine Campbell CENWP-HDC-M Senior Mechanical Engineer, ATR Reviewer

(503) 808-4255

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Name Office Title/Role Phone

Scott Cotner CENWP-HDC-E Senior Electrical Engineer, ATR Reviewer

(503) 808-4272

Dan Ramirez CENWP-HDC-M Senior Mechanical Engineer, ATR Reviewer

(503) 808-4271

Bob Siegle CENWP-HDC-E Electrical Engineer, ATR Reviewer

(503) 808-4899

Pat Keller CENWP-HDC-E Electrical Engineer, DQC Reviewer

(503) 808-4821

Jackie Floyd CENWP-HDC-E Electrical Engineer, DQC Reviewer

(503) 808-5244

Scott Hinnen CENWP-HDC-M Mechanical Engineer, DQC Reviewer

(503) 808-4267

Dan Watson CENWP-HDC-M Mechahincal Engineer, DQC Reviewer

(503) 808-4212

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2. PROJECT DESCRIPTION

The following sections of this document address the work being performed on this project, including but not limited to its scope, schedule, and budget.

2.1. PROJECT SCOPE

Detailed descriptions of the project scope are included in Section 5 and a summarized list addressing this project and other parallel efforts is included in Appendix A.

Significant features of this scope of work are detailed in Table 2.

Table 2: Major Features of Work

Item Units 1-3 Unit 4 Disassembly and reassembly of turbine-generator, to include unit alignment Base Option

Realignment considerations to address powerhouse tilt issues, particularly prominent on Unit 3 Base Option

Thrust bearing work Base N/A Guide bearing work Base N/A New turbine runners Base Option

Wicket gate replacement Base Option

Rewind of generator stator Base N/A Replacement of generator core Base N/A Reinsulation of field poles Base N/A Replacement of collector rings Base N/A Installation of high pressure lift system Base N/A Installation of a machine condition monitoring system Base N/A High resistance grounding work Base N/A RTDs for bearing and stator temperatures Base N/A Level transducers for oil reservoirs Base N/A

Turbine oil piping flushing and turbine oil replacement Base Option (Oil Supply Only)

Items listed as N/A have been replaced or refurbished during the Unit 4 rehabilitation.

2.2. PROJECT SCHEDULE AND DELIVERABLES

The schedule of deliverables for development of plans and specifications is as shown below in Table 3.

Table 3: Deliverables Schedule Deliverable Description Date

30% Package 30% design discussion Preliminary specification list Preliminary drawings list

8 Jan 2021

60% Package 60% design discussion Preliminary specifications, drawing list, draft drawings Incorporation of 30% review comments

14 May 2021

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Deliverable Description Date

90% Package 90% design discussion 90% plans and specifications Incorporation of 60% review & ATR comments

6 Aug 2021

BCOES Package Incorporation of 90% review comments 5 Nov 2021

Final Package Final 100% plans and specification sections Incorporation of BCOE review comments 14 Jan 2022

Contract Award Project award 29 Jul 2022

Nashville District is under a requirement due to customer funding constaints to award the contract in FY22, and the schedule is thus compressed compared to other major rehabilitation P&S phases. Figure 1 on the following page shows the process expressed as a Gantt chart. Figure 2 is a Gantt chart of the construction phase; recent major rehabilitations of this complexity have taken two years per unit. Site mobilization does not occur until after the Contractor has completed the detailed hydraulic design and a significant portion of fabrication. Figure 3 shows the major rehabilitation projected schedule alongside the schedules for other major scopes of work.

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Figure 1 - Phase 2 - Design & Acquisition Approval Schedule

Figure 2 - Phase 3 - Award/Delivery/Installation Schedule

Fiscal Year Quarter

Acquisition Plan 30% Design & Review 60% Design & Review 90% Design & Review BCOES Design & Review Ready to Advertise Contract Review Advertise Government Review/Negotiations Award Turbine-Generator Rehabilitation

2021 2022 3rd 4th1st 2nd 3rd 4th 1st 2nd

Fiscal Year Award Model/Fabrication Unit 3 - Turbine & Generator Unit 2 - Turbine & Generator Unit 1 - Turbine & Generator Unit 4 - Turbine (Optional)

22 2023 20252024 20272026 2031 2032203020292028

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Figure 3 - Projected construction schedule for major rehab, GSU transformer, and excitation system work. Site work for the major rehab effort to begin with work on Unit 3 at end of FY 2024.

Fiscal Year Unit 4 - Turbine & Generator Major Rehabilitation Award Model/Fabrication Unit 3 - Turbine & Generator Unit 2 - Turbine & Generator Unit 1 - Turbine & Generator Unit 4 - Turbine (Optional) GSU Transformers Excitation System

2021 2022 2023 2024 2030 2031 20322025 2026 2027 2028 2029

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2.3. PROJECT BUDGET

The projected total cost for the recommended alternative (Alternative 2) in the HRAR is $124,700,000, which includes the construction cost, Government costs, and escalation. Note that this figure is less than what had been included in the HRAR for Alternative 2, as that estimate had included items from parallel scopes of work. Nashville District is working on the cost projection. The SSB reflects $649,620 allotted for HDC’s efforts in developing plans and specifications.

2.4. ACQUISITION PROCESS

The fixed price with economic price adjustment, hybrid supply with construction installation contract is the recommended contract type for turbine replacements and rehabilitations. Historical examples in the use of this contract type include Bonneville Lock and Dam First Powerhouse (USACE Portland District awarded a single contract in 1990 for 10 new turbine runners and generator rewinds), Chief Joseph Hydropower Project (USACE Seattle District awarded a firm fixed price contract for the supply and install of 16 turbine units at Chief Joseph Hydropower Project), and McNary Lock and Dam turbine runner replacement (USACE Walla Walla District awarded a firm fixed price contractor for the design, supply, and installation of 14 fish-friendly turbine runners and two generator stator winding replacements).

A best value trade-off source selection approach (FAR Part 15) will be best suited for a project this large and complex. The nature of the work, a protracted schedule, and economic uncertainties pose risks to potential contractors. This risk, in turn, is reflected in cost back to the Government. To mitigate risk and uncertainty, the PDT will engage with the contractors early and often, both formally and informally with the intent of providing as much technical information as possible.

2.5. HAZARDOUS MATERIALS

Environmental protection and compliance should be considered during all design work and repairs.

Appropriate precautions must be taken to prevent worker exposure to any hazardous material on site or brought on site and to prevent a release of a hazardous material or waste into the natural environment.

During site work, the proximity of the water requires additional attention to eliminate all spills and to prevent any waste or debris from entering the water. Precautions should be taken to identify any potentially hazardous material, and then handle and dispose of all confirmed hazardous material according to all applicable laws and regulations.

Lead-based paint (LBP) may be present in the work area and on the components to be modified or replaced. It is assumed that LBP is potentially present on all carbon steel surfaces, and requirements for testing, proper handling, and disposal will be addressed in Section 02 83 00. For the purposes of this project, LBP is defined to include any paint or coating that has detectable concentrations of one or more heavy metals. Heavy metals are metallic elements with high atomic weights such as mercury, chromium, cadmium, arsenic, and lead. They can damage living organisms at low concentrations. LBP abatement will be required for the blasting of the embedded water passage components at site and for existing components shipped offsite for refurbishment. Handling and disposal of LBP disturbed during disassembly and reassembly will also be required.

Most major turbine and generator suppliers will not handle asbestos. Therefore, any asbestos abatement will require a separate contract. See Section 5.7 on the plan to address asbestos.

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2.6. REFERENCE DOCUMENTS

The following studies and reports were utilized to inform the scope of this project:

Old Hickory Units 1-4 Shaft Study Report HDC, 2017

Electrical Powertrain Analysis (Appendix to HRAR) HDC, 2020

Old Hickory Hydropower Rehabilitation Analysis Report HDC, 2020

Generator Uprate Study GPEA, 2001

Generator Uprate Study Canada General Electric, 1989

Old Hickory Unit 4 Return to Kaplan and Rewind HDC, LRN, 2017

Old Hickory Major Rehabilitation Evaluation Report MWH 2011

2.7. DESIGN GUIDANCE AND STANDARDS

The following design guides and standards are being utilized in the preparation of plans and specifications. These are the broad scope standards related to rehabilitation. The various standards applicable to specific materials and procedures are not listed here, but are included in Part 1 of each relevant specification section.:

ASME BTH-1 (2017) Design of Below the Hook Devices

ASME PTC 18-2011 Hydraulic Turbine and Pump-Turbines

NFPA 70 (2017): National Electrical Code

NFPA 70E (2015): Standard for Electrical Safety in the Workplace

EM 385-1-1 (2014): Safety and Health Requirements Manual

ER 385-1-31 (2009) The Control of Hazardous Energy

EM 1110-2-3006 (1994): Hydroelectric Power Plants – Electrical Design

EM 1110-2-4205 (1995): Hydroelectric Power Plants – Mechanical Design

CEATI T122700-0381: CEATI International’s Hydroelectric Turbine-Generator Units Guide for Erection Tolerances and Shaft System Alignment

2.8. DESIGN AND REFERENCE DRAWINGS

The design and reference drawings to accompany the turbine-generator rehabilitation scope of work are listed in Appendix C.

The drawings numbers were created such that the removal and installations drawings use the same reference drawing for ease of identification. For example, drawing ED101 will show equipment removal at the same location where equipment installation is depicted in E-101.

ARCH E1 sheet size will be used. For those drawings that had been created for the Old Hickory Unit 4 return-to-Kaplan and rewind project, the drawings will need to be resized to ARCH E1. LRN provided the District’s CAD Standards Supplement and seed drawings to clarify formatting.

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2.9. SPECIFICATIONS SECTIONS

The specification sections included in the design package along with the responsible party are listed below in Table 4.

Table 4 - Specification Sections

SECTION TITLE PARTY

RESPONSIBLE

01 11 10.00 26 SUMMARY OF WORK HDC

01 22 00.00 26 MEASUREMENT AND PAYMENT HDC/LRN

01 30 00 GENERAL REQUIREMENTS & SITE OPERATIONS LRN

01 32 01 PROJECT SCHEDULE LRN

01 33 00 SUBMITTAL PROCEDURES LRN

01 35 26 GOVERNMENTAL SAFETY REQUIREMENTS LRN

01 35 50 SITE SECURITY AND AT/OPSEC PROCEDURES LRN

01 41 00 DRAFT BID SCHEDULE HDC/LRN

01 42 00 SOURCES FOR REFERENCE PUBLICATIONS LRN

01 45 00.00 QUALITY CONTROL LRN

01 45 00.15 RESIDENT MANAGEMENT SYSTEM CONTRACTOR

MODE (RMS CM) LRN

01 50 00 TEMPORARY CONSTRUCTION FACILITIES AND

CONTROLS LRN

01 57 19 TEMPORARY ENVIRONMENTAL CONTROLS LRN

01 78 00 CLOSEOUT SUBMITTALS LRN

01 78 23 OPERATIONS AND MAINTENANCE DATA LRN

01 91 00.00 26 UNIT COMMISSIONING HDC/LRN

01 95 00 FORMS AND ATTACHMENTS HDC/LRN

02 82 01 ASBESTOS COORDINATION LRN

02 83 00 LEAD ABATEMENT, REMOVAL, & DISPOSAL LRN

03 60 00.02 26 STATOR FOUNDATION REPAIR HDC

03 64 23.00 26

DISCHARGE RING AND DRAFT TUBE EPOXY

INJECTION AND GROUTING

HDC

05 05 23.20 26 WELDING HDC

05 05 33.20 26 NON-DESTRUCTIVE TESTING HDC

05 50 03.20 26 METALWORK, FABRICATION, MACHINE WORK AND

MISCELLANEOUS PROVISIONS HDC

09 97 02.23 PAINTING HDC

13 48 00.00 26 SEISMIC RESTRAINT FOR MECHANICAL AND

ELECTRICAL EQUIPMENT HDC

25 05 11.00 26 CYBER SECURITY HDC

26 05 00.00 26 BASIC ELECTRICAL MATERIALS AND METHODS FOR

MAJOR UNIT REHABILITATION HDC

26 05 13.00 26 MEDIUM-VOLTAGE CABLE HDC

26 05 19.00 26 INSULATED WIRE AND CABLE HDC

26 05 26.00 26 GROUNDING HDC

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SECTION TITLE PARTY

RESPONSIBLE

26 11 15.00 26 HIGH RESISTANCE GROUNDING SYSTEM HDC

40 05 13.00 PIPING AND EQUIPMENT HDC

41 67 13.12 26 FLUSHING AND CLEANING OF LUBRICATING OIL

SYSTEMS HDC

48 06 15.00 26 TURBINE OIL HDC

48 13 13.00 26 HYDRAULIC TURBINE MODEL TESTING HDC

48 13 13.01 26 HYDRAULIC TURBINE HDC

48 13 13.02 26 DISASSEMBLY AND REASSEMBLY OF HYDRAULIC

TURBINE GENERATOR UNIT HDC

48 13 13.03 26 GENERATOR THRUST BEARING HIGH PRESSURE

LIFT SYSTEM HDC

48 13 13.04 26 EXISTING TURBINE COMPONENT REFURBISHMENT

AND REPLACEMENT HDC

48 13 13.06 26 THRUST BEARING INSPECTION AND

REFURBISHMENT HDC

48 13 13.07 26 GUIDE BEARING INPSECTION AND

REFURBISHMENT HDC

48 13 13.09 26 DISCHARGE RING OVERLAY HDC

48 13 13.11 26 MISCELLANEOUS PARTS, MATERIALS, AND

SERVICES HDC

48 13 13.25 26 GENERATOR BRAKE SYSTEM REFURBISHMENT HDC

48 13 13.26 26 TURBINE GUIDE BEARING LUBRICATION SYSTEM

AND TURBINE SUMP PUMP REHABILITATION HDC

48 13 16.00 26 GENERATOR REWIND HDC

48 13 16.01 26 MACHINE CONDITION MONITORING OF HYDRAULIC

TURBINE GENERATOR UNIT HDC

48 13 16.03 26 GENERATOR THRUST BEARING HIGH PRESSURE

LIFT PUMP SYSTEM (ELECTRICAL) HDC

48 70 01.00 26 NERC COMPLIANCE FOR HYDROGENERATORS HDC

2.10. GOVERNMENT FURNISHED EQUIPMENT

Certain features of work will be accomplished by the Contractor using Government furnished equipment (GFE). This includes such items as the powerhouse bridge crane and below-the-hook lifting devices. The GFE list should be included in the Division 01 specifications, alongside the requirements of the expected management of the equipment.

Per email on 2/24/2021 that LRN does not intend to make the new turbine maintenance platform available as GFE.

2.11. RISK CONSIDERATIONS

There are a number of details that should be considered for their potential impact to schedule or contractual issues. These are listed below in Table 5.

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Table 5: Risk Considerations

TOPIC POSSIBLE RISKS RECOMMENDED HANDLING

Asbestos

The primary contractors typically involved hydropower rehabilitation jobs express resistance or refusal to bid on work including asbestos abatement

Handle asbestos abatement via IDIQ contract

Bulkheads, gates, stoplogs

During the onsite construction, the Contractor will have a unit unwatered for a significant amount of time. If an additional unit needs to be unwatered due to unexpected outage, or to complete certain scheduled maintenance items, it may become necessary to unwater an additional unit. Without sufficient components related to unwatering, it can become necessary to either incur a longer outage or interrupt the Contractor’s work to borrow these components. One set of tailwater gates currently requires refurbishment. The existing setup for the tailrace crane and gate slots hinders the ability to install more than one tailrace gate.

Ensure that sufficient equipment is available for use in order to fully dewater two units

Cranes and below-the-hook (BTH) lifting devices

Contractors have been known to refuse to work with below-the hook devices that have not been certified. Outstanding issues with cranes may result in non-functionality of the cranes at inopportune times. Either issue would cause delays to the Contractor’s site work, attributable to the Government.

Ensure cranes and BTH lifting devices are certified, which entails having the engineering analyses on record and maintiaining documentation that the device has been load tested and inspected

Other major site work

Interference between major contractors onsite at the same time can lead to delays and requests for equitable adjustment.

Ensure that GSU transformer and exicter replacement work, as currently anticipated in the schedule, is completed ahead of the major rehabilitation contractor’s mobilization

Powerhouse tilt

Risk is related to potential bidders’ understanding of the scope related to shifting the discharge ring and understanding of the potential for seasonal powerhouse movements related to unit alignment

The BCOES P&S package includes descriptions of both the long-term powerhouse movement that relates to the discharge ring and the seasonal movement that impacts unit alignment measurements. Two stationary alignment checks will be performed in addition to the typical pre-disassembly and post-reassembly alignment checks

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3. SCOPE OF WORK

3.1. GENERAL

The scope of work covers the rehabilitation of hydroelectric generating Units 1-3 at Old Hickory, with optional turbine runner replacement included for Unit 4. Units 1-3 (and optionally Unit 4 if it is determined to exercise replacement of its runner) will be disassembled down to the embedded components, which will remain in place. In general, the scope of work on turbine components will be driven by consideration of the component condition, opportune accessibility while the unit is disassembled, and the role of component refurbishment or replacement within the assembly with regard to alignment and function.

In general, the progression of work will begin with the design of turbine runners and other turbine components. Some design effort will occur in parallel for the generator stator windings and core, which will be informed by the design undertaken during the rewind of Unit 4. Design will be followed by fabrication of new components, and as fabrication of the first unit’s new components nears completion, site mobilization and site work will commence. The acceptance of prototype coils and stator core laminations, as well as the shop inspection of the runner assembly, will be completed before the first unit is taken out of service. Fabrication of new components for additional units should be timed for completion before site work on the subsequent unit begins.

Site work will revolve around the disassembly and reassembly process one unit at a time. With each unit, the rehabilitation effort will be refined and checked through pre-disassembly and post re-assembly operations tests on the units. After disassembly of a main unit, there is an extended period during which existing components identified for reuse will be shipped offsite and refurbished. The refurbishment process for individual components proceeds through cleaning, as-found inspections, shipment to a machine shop, machining, and then return shipment to the Project for reassembly. The major components of the turbine assembly will have detailed refurbishment requirements specified in the contract; smaller miscellaneous components may not require extensive work beyond cleaning. Such components will be subject to as-found inspections and cleaning under the disassembly and reassembly bid item.

Reassembly will occur with the combination of new and refurbished components. Pre-disassembly alignment checks, as well as measurements of embedded components while the unit is unstacked, will help to inform the decision making for placement of components upon reassembly. Field machining work will occur about a reference centerline determined from the measurements and the scope of component refurbishment, and then disassembled components will be reassembled with respect to that same reference centerline, to be confirmed by post-reassembly alignment checks.

A discussion follows for major components. All refurbishment and replacement work will be covered under a series of technical specifications sections, which are listed in 2.9. A broader overview of component treatment and scopes of work is included in Appendix A.

3.2. UNIT DISASSEMBLY, REASSEMBLY, AND OPERATIONAL TESTING

The units will be disassembled and reassembled following alignment tolerances recommended in CEATI T122700-0381 (CEATI is the Centre for Energy Advancement through Technological Innovation, a collective group of hydropower owner operators that serves to advance the industry through collaborative

Page | 19 knowledge sharing). The units will undergo baseline performance testing, both wet and dry, prior to being disassembled. The wet testing includes incremental speed testing (40%, 60%, 80%, and 100% rated speed), steady state testing at various generator loadings (25%, 50%, 75%, and 100%). During this testing, the Contractor will record the behavior of the unit (i.e. bearing temperatures, runout, generator output, vibration, and wicket gate opening). The dry testing includes wicket gate characteristic measurements. Similar testing will be conducted after the units are reassembled. The expectation for the rehabilitated unit is that the work should not introduce excessive increases in temperatures, runouts, or vibrations.

Pre-disassembly alignment checks will be performed by the Contractor and submitted to the Government.

Any alignment issues found during the pre-disassembly checks will shed light on the current conditions of the units. It is known that the Old Hickory Powerhouse experiences monolith tilt issues as introduced in the discussion of risks, above, to the extent that both Unit 3 and Unit 4 blade tips have contacted the discharge ring. Project staff report that Unit 2 was aligned to be plumb in 2019 within CEATI specified tolerances and centered in the turbine guide bearing; at that time, the blade tip clearance was measured to be particularly close at the 4:00 position.

Pre-disassembly alignment checks and further measurement and evaluation of the units while disassembled will help the Contractor and Government make informed decisions about how to refurbish components and reassemble the units. As discussed in the turbine component section, two possible approaches to address powerhouse tilt are:

1) Design the new runner blade tip diameter and the discharge ring profile for an increased blade tip gap

2) Center the rotating components in a position slightly off-center to land side and upstream from the center of the discharge ring

After the units are reassembled, their alignments will be checked and they will be put through commissioning testing, in a similar fashion to the pre-disassembly testing. Once the commissioning testing is complete, the units will start the 72-hour run as the final phase of determining acceptability.

Upon successful completion of the 72-hour run, the unit’s warranty period begins. The specifications include a commissioning-specific section (01 91 00.00 26), in which the phases and details of commissioning are detailed. The plan allows for two weeks for the Nashville District’s Electronics Service Section (ESS) to complete trip checks (electrical trip checks and wire-to-wire continuity checks). This duration can be shortened if the Government works in parallel with the Contractor.

3.3. ELECTRICAL WORK - GENERATOR

In general, the work scope/design for the Units 1-3 generator rehabilitation will be the same as for Unit 4.

It will include replacement of the generator stator winding, field winding insulation, stator core, and reinforcement of the stator frame. The PDT has concluded that stator winding removal will be tasked to an asbestos abatement contractor if the presence of asbestos is confirmed. Refer to the discussion of recommended parallel IDIQ contracts in Section 3.8. A spare coil from the original spares is planned for testing to determine the presence or absence of asbestos.

Generator Units 1- 4 were manufactured by the General Electric Company with the following nameplate ratings: 31,250 kVA, 25,000 kW, 13.8 kV, 0.8 power factor. The kVA rating included a 115% overload

Page | 20 capacity at 0.8 and 1.0 power factors as confirmed by the original commissioning tests. These generators are of the salient pole, air cooled (via air-water heat exchangers) design. The three-phase stator windings are connected in a wye configuration. Each phase consists of 4 parallel circuits with each circuit containing 42 five-turn coils; a total of 504 coils comprise the stator winding. Unit 4 generator (not the entire unit) has been rehabilitated and rated at 45,0000 kVA, 40,500 kW, 13.8 kV, 0.9 power factor.

The remaining generators will be rated to match Unit 4. Operation that takes full advantage of this capacity will be limited to times when only one unit is operating as discussed in Section 3.5.1.

An engineering study dated April 1989 for the uprate potential of the Old Hickory generators was performed by General Electric Canada Inc. It advised on the following possible rewind ratings: 45,000 kVA and 1.0 power factor, 42,000 kVA and 0.90 power factor, and 37,000 kVA and 0.80 power factor.

Each of these ratings is based on replacing the stator winding with a new class F stator winding and changing the coil span from 4 to 5.

A second engineering study for uprate potential dated July 2001 was prepared by General Power Engineering Associates, Inc (GPEA). It recommended a range of uprate potentials based on replacing various generator components. The GPEA study recommended a maximum uprate level of 43,670 kVA at 0.90 power factor based on a shaft stress limit of 39.9 MW. Where the shaft is concerned, HDC’s strain testing and fatigue analysis of the shafting in 2017 determined that a loading of 44.5 MW is acceptable for the existing geometry of the shaft; fatigue calculations at 45 MW were revisited to confirm that this is acceptable for this shafting. The results of HDC’s shaft study are in line with the General Electric Canada Inc study for a rating of 45,000 kVA at unity power factor. Adjusting the rating to 45,000 kVA and 0.9 power factor introduces additional heating in the field winding from the increased field current needed for the flow of reactive power. The following work is needed to achieve this recommended rating: Replace the stator winding, re-insulate the stator leads, re-insulate the field winding, replace the collector rings and brushes, and replace the neutral current transformers. The following paragraphs discuss the salient features of the specifications.

3.3.1. Stator Winding

A new Class F temperature rated winding will be provided. Multi-turn stator coils will again be used since Roebel bars are not feasible for use in the Old Hickory units for the present slot configuration. The General Electric Canada Inc study stated that excitation requirements increased unacceptably and manufacturing bars for this slot configuration would be prohibitably difficult. Prior to beginning full winding production, four prototype coils will be produced and subjected to accelerated life testing by a third party.

Production quality control coil tests will include strand continuity and strand insulation, turn and ground wall dielectric tests, power factor tip-up, dissipation factor test, and dimensional checks.

The stator winding will be rated 45,000 kVA with a temperature rise limited to 83 °C above a 40 °C ambient temperature. The 83°C temperature rise is based on the Unit 4 rehababilitation where this was allowed to achieve the 45,000 kVA rating. This rating is based on the uprate study performed by Canada General Electric and adjusted to 0.9 power factor. This rating is a change from the present rating and power factor of 31,250 kVA and 0.8 respectively. The new ratings are the maximum output of the generator; there will be no overload capability like the present 115% rating.

A thermal cycling test, as described was done on representative coils for Unit 4 and is again proposed for Units 1-3. Alternately, in lieu of performing this test, if the Contractor can show the Government that the

Page | 21 stator winding system proposed for Old Hickory Units 1-3 generators has previously successfully completed the thermal cycling test the Government may elect to waive this test since thermal cycling concerns are more pronounced on stator cores over 2 meters long and less severe on shorter cores such as at Old Hickory. Thermal cycling concerns suggest that the stator winding insulation of hydrogenators with longer stator cores that are subjected to start/stop cycles in the range of 3000 to 10000 may experience a loosening or breaking of the bond holding the insulation and the copper together.

As the generator is quickly loaded from no load to full load, the coil copper temperature rapidly increases, causing an axial expansion of the copper. At the same time, the groundwall insulation temperature increases, but at a slower rate. This creates a shear stress between the copper and the groundwall insulation. Many thermal cycles will tend to fatigue the bond between the copper and the insulation and eventually the copper may break away from the insulation.

This test attempts to simulate the thermal cycles a winding may experience in service. There are currently no industry standard pass/fail criteria for this test. For these specifications, two coils will be subjected to this test (plus one additional coil used for temperature control) which involves circulating sufficient current to raise the copper temperature from 40 °C to 135 °C then cooling back to 40 °C and repeating for 500 cycles. At the completion of the 500 cycles the two coils will be subjected to a voltage endurance test. The test coils will pass the thermal cycling test if they can withstand the voltage endurance test and meet post-thermal cycling test power factor tip up and dissipation factor test criteria for new coils as stated in the specifications. The cost of this test is in the range of $100,000. This test will also add a couple months to the coil delivery schedule. The test will be performed by an independent test facility to be approved by the Government.

3.3.2. Stator Core

Stator core replacement is typically included as an optional bid item to be exercised in case the stator core fails the stator core interlaminar insulation resistance (loop) test or stator core lamination tightness following disassembly. The Southeastern Power Administration (SEPA) has expressed a preference to replace stator cores as base scope for the sake of reliability during the design life of the generator.

Replacing the stator core also allows the contractor to optimize generator design to more readily meet the rehabilitated generator capability and allows for adjusting the centering of the stator core. In this case, the existing stator core will be replaced, and the stator frame will be reinforced like it was for Unit 4. A stator may need to be moved for unit alignment like it was moved for Unit 4. This move can be addressed by a contract modification or an optional bid item. The new stator core will include new core laminations, vent plate laminations, keybars, and clamping system. The new stator core will be stacked to be concentric with the turbine shaft centerline, be made round, plumb, and level in accordance with the CEATI guide for unit erection and alignment tolerances. Factory and field testing will be performed to ensure a quality stator core installation.

3.3.3. Rotor Poles

The Canada General Electric study states that the rotor pole collars are manufactured from ½” textolite and rapidly lose mechanical properties above 100°C. The calculated field winding temperature at the 45 MVA and 0.9 power factor is 115°C. Operating the generators at the new rated conditions will require replacing the collars with a higher temperature material. While the collars are being replaced the pole ground and turn insulation will also be replaced along with inter-pole connecting leads to preculude any possibility of loss in ductility from hydrogen embrittlement. The inter-pole connecting leads are built up of

Page | 22 multiple copper thin leafs and will be replaced in-kind. The field leads located between the slip rings and the first and last rotor poles will be re-insulated with Class F insulation. The Contractor will remove all field poles from the rotor rim, load them on a truck and ship them to his off site facility for rehabilitation. The poles will be inspected then re-insulated with Class F insulation and factory tested. Optional work to the rotor poles has been added based on the Unit 4 contract and includes replacing rotor pole rivets, welding the rotor pole dovetail, and correcting pole straightness. The Contractor will return ship the poles to the job site, install them on the rotor rim, and test them. The Unit 4 contractor analyzed the rotor pole T-key for static stresses and fatigue and determined that the rotor poles could safely operate for the next 50 years and no changes were made to T-key. An analysis of the rotor pole T-key is not planned for Units 1- 3 since all units are assume to have similar operating histories.

3.3.4. Generator Verification Tests

Following completion of the first rehabilitated generator, the contractor will perform testing of that generator to both confirm contract guarantees for losses and to determine generator parameters used in mathematical models. Testing for loss guarantees has generally been done by the retardation method outlined in IEEE standard 115 for Corps of Engineers rewind jobs. Testing by the heat transfer method will be allowed as an alternate. Assuming the new static exciters are installed by the time of these generator tests, two units will be needed to perform the tests by the retardation method. If the rotating exciters have not been changed out to static exciters, three generating units may be required for performance of some of these tests. This means an outage on the order of one week for two units in addition to the test unit. Including set up and tear down, these tests will take two weeks, possibly a bit longer. A heat run will be performed to verify the winding temperature rise. The ozone level in the generator air housing will be measured during the heat run. Determination tests will be performed to measure the saturation curves, obtain waveform oscillograms, and to determine various generator model parameters. Total testing time will be about three weeks.

3.3.5. Cleaning Rotating Main and Pilot Exciters and Replacing Collector Rings The existing rotating exciters are planned for replacement and are likely to be replaced before this turbine-generator rehabilitation project begins site construction work. However, if these rotating exciters are not replaced the main and pilot exciters will be inspected and cleaned after unit disassembly. The collector rings will be replaced to limit their temperature rise to 85 °C for the estaimted field current of 1300 Adc when the unit is operating at the new rated kVA and power factor.

3.3.6. Other Items

The other items listed below are stator winding components or auxiliary components that are replaced in the course of a stator rewind or to add new functionality.

3.3.6.1. Stator winding Resistance Temperature Detectors (RTDs). The existing twelve stator winding RTDs will be replaced with twenty-four new 100-ohm platinum 4- Wire RTDs and new extension wire.

3.3.6.2. Circuit Rings. New circuit rings will be provided. Added statement to bring the contractor designer’s attention to the oil pipes routed above the circuit rings.

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3.3.6.3. Surge Rings. New surge (bracing) rings will be provided.

3.3.6.4. Stator Main and Neutral Leads. The stator main and neutral leads located within the generator air housing will be replaced with new Class F insulated main and neutral leads.

3.3.6.5. Generator Neutral Current Transformers (CTs). The existing generator neutral

CTs will be replaced to accommodate the new generator rating.

3.3.6.6. Partial Discharge Analysis (PDA) System. A new PDA system will be installed adding new functionality to monitor the health of the stator winding. Six PDA couplers will be installed and connected to the stator winding and a new termination panel will be mounted to the outside of the generator air housing.

A new PDA analyzer has already been procured with the Unit 4 rewind and another one is not necessary. A sole source justification may be needed to match existing Unit 4 PDA system. A benchmark PDA test of the stator winding will be performed between six and twelve months of operating time. A PDA system training session will be provided at the time of the benchmark testing.

3.3.6.7. Spares. Spare parts will be provided and include two new rotor poles with universal field coils, 25 stator coils, 100 stator core laminations and 10 vent plates, and 4 stator RTDs.

3.3.6.8. Generator Nameplate. A new generator nameplate will be provided.

3.3.6.9. Bearing Temperature Devices. Bearing temperature devices which consist of temperature switches…