Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 1 of 149 Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 2 of 149 Newfoundland and Labrador Hydro - Lower Churchill Project DC1010 - Voltage and Conductor Optimization Final Report - April 2008 Table of Contents List of Tables List of Figures Executive Summary 1. Introduction ......................................................................................................................................... 1-1 1.1 Background and Purpose ............................................................................................................ 1-1 1.2 Interrelation with other Work Tasks.............................................................................................1-1 2. Approach to the Work ......................................................................................................................... 2-1 2.1 Overview.................................................................................................................................... 2-1 2.2 Selection of Optimal HVDC Operating Voltage .......................................................................... 2-2 2.3 Selection of Optimal Overhead Line Conductor(s) ...................................................................... 2-2 3. Details of the Work/Analysis ................................................................................................................ 3-1 3.1 Selection of Optimal HVdc Transmission Voltage ....................................................................... 3-1 3.1.1 List of HVDC Projects, World-Wide Operating at 400, 450 and 500 kV ............................ 3-1 3.1.2 Impacts of System Voltage on Overhead Line Tower Design ............................................. 3-2 3.1.2.1 Description of Corona and Other Field Effects ......................................................... 3-2 3.1.2.2 Insulation Clearances............................................................................................... 3-6 3.1.2.3 Tower Design Criteria.............................................................................................. 3-6 3.1.2.4 Calculation of Corona and Field Effects ................................................................... 3-8 3.1.2.5 Electrode Line Conductors....................................................................................... 3-9 3.1.2.6 Preliminary Tower Designs.................................................................................... 3-12 3.1.3 Selection of Optimal Conductors at Each Operating Voltage ........................................... 3-12 3.1.3.1 System Design Parameters ..................................................................................... 3-12 3.1.3.2 Main Evaluation Parameters and Criteria ............................................................... 3-12 3.1.3.3 Preliminary List of Conductors............................................................................... 3-13 3.1.3.4 Costs of Losses ...................................................................................................... 3-13 3.1.3.5 Results................................................................................................................... 3-13 3.1.4 Impact of Operating Voltage on Submarine Cable Designs.............................................. 3-14 3.1.4.1 Design Considerations........................................................................................... 3-14 3.1.4.2 Costs of Losses ...................................................................................................... 3-15 3.1.4.3 Conclusions........................................................................................................... 3-15 3.1.5 Impact of System Voltage on Converter Stations .............................................................. 3-16 3.1.5.1 Overview .............................................................................................................. 3-16 3.1.5.2 Converter Station Pole and Bipole Ratings ............................................................. 3-16 3.1.6 Conclusions on HVdc Operating Voltage ........................................................................ 3-17 3.2 Comparative Cost Estimates ......................................................................................................3-17 3.2.1 Overhead Transmission Lines.......................................................................................... 3-17 3.2.2 Submarine Cables ........................................................................................................... 3-19 3.2.3 HVdc Converter Station................................................................................................... 3-19 3.2.4 Total Comparative Costs for HVdc Transmission Systems ................................................ 3-19 3.2.5 Conclusions .................................................................................................................... 3-20 4. Discussion of Results............................................................................................................................ 4-1 4.1 Technologies............................................................................................................................... 4-1 4.2 HVdc Overhead Transmission Lines............................................................................................ 4-1 PRH325967 .10044, Rev. 0 , Page i Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 3 of 149 Newfoundland and Labrador Hydro - Lower Churchill Project DC1010 - Voltage and Conductor Optimization Final Report - April 2008 4.3 Comparative Cost Estimates ........................................................................................................ 4-2 4.4 Comments and Conclusions........................................................................................................4-3 Appendices Appendix A – Referenced Technical Documents Appendix B – List of HVdc Projects Appendix C – Cost Estimates for Overhead Transmission Line Towers Appendix D – Overview of Submarine Cable Designs Appendix E – Typical Sag / Tension Charts PRH325967 .10044, Rev. 0 , Page ii Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 4 of 149 Newfoundland and Labrador Hydro - Lower Churchill Project DC1010 - Voltage and Conductor Optimization Final Report - April 2008 List of Tables Number Title Table 3-1 HVdc Transmission Projects at Operating Voltages Between 400 and 500 kVdc Table 3-2 HVdc Overhead Line Transmission Projects Similar to the Lower Churchill Project Table 3-3 List of HVdc Submarine Cable Projects (in service, under construction or proposed) Table 3-4 Nominal Pole Currents for Full Load and Monopole Overload Pole Currents Table 3-5 Clearances for HVdc Overhead Line Transmission Projects Table 3-6 Nominal Design Parameters for the LCP HVdc Transmission Systems Table 3-7 Sample Calculations of Voltage Gradients and Field Strengths with Optimal LCP Conductors Table 3-8 Calculated Field Effects, L50 Fair and RI Levels for +/- 500 kVdc Table 3-9 Calculated Field Effects, L50 Fair and RI Levels for +/- 450 kVdc Table 3-10 Calculated Field Effects, L50 Fair and RI Levels for +/- 400 kVdc Table 3-11 LCP Conductor Configurations that Satisfy Corona and Mechanical Strength Requirements Table 3-12 Annual Costs of Losses (@ 55°C Conductor Temperature) for Different Overhead Line Conductor Configurations Table 3-13 Present Value of Annual Costs of Losses (@55°C Conductor Temperature) for Different Overhead Line Conductor Configurations Table 3-14 Preliminary Submarine Cable Parameters Table 3-15 Present Value of the Annual Costs of Losses for Submarine Cables Table 3-16 Comparative Costs for Construction of Overhead Lines with Different Conductor Configurations Table 3-17 Comparative Total Cost Estimates for Overhead Transmission Lines Table 3-18 Comparative Total Cost Estimates for Submarine Cables Table 3-19 Comparative Cost Estimates for HVdc Converter Station Construction PRH325967 .10044, Rev. 0 , Page iii Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 5 of 149 Newfoundland and Labrador Hydro - Lower Churchill Project DC1010 - Voltage and Conductor Optimization Final Report - April 2008 List of Figures Number Title Figure 1-1 Lower Churchill Project Transmission Systems Figure 3-1 Sketch of Preliminary ±500 kVdc Tower Configuration for Corona and Field Effect Analysis Figure 3-2 Sketch of Preliminary ±450 kVdc Tower Configuration for Corona and Field Effect Analysis Figure 3-3 Sketch of Preliminary ±400 kVdc Tower Configuration for Corona and Field Effect Analysis Figure 3-4 Typical HVdc Tower Configurations for Weight & Cost Estimates Figure 3-5 Comparative Cost Estimates for Overhead Transmission Lines as Functions of Conductor Size and Voltages Figure 3-6 Comparative Cost Estimates for ±500 kVdc Overhead Transmission Lines as Functions of Load Factors (0.6, 0.7 & 0.8) Figure 3-7 Comparative Cost Estimates for ±450 kVdc Overhead Transmission Lines as Functions of Load Factors (0.6, 0.7 & 0.8) Figure 3-8 Comparative Cost Estimates for ±400 kVdc Overhead Transmission Lines as Functions of Load Factors (0.6, 0.7 & 0.8) PRH325967 .10044, Rev. 0 , Page iv Muskrat Falls Project - CE-01 Rev. 1 (Public) Page 6 of 149 Newfoundland and Labrador Hydro - Lower Churchill Project DC1010 - Voltage and Conductor Optimization Final Report - April 2008 Executive Summary Introduction The objective of WTO DC1010 was to determine the optimum operating