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TB 388 2009 JWG B2/B4/C1.17 IMPACTS OF HVDC LINES ON THE ECONOMICS OF HVDC PROJECTS

The study considers the overall HVDC system economics, capital (lines and stations), losses, operation and maintenance. The most economically favorable voltages and conductor configurations are studied for several HVDC system alternatives. It is shown how the HVDC line and the converter stations selection impact each combination. Directives are presented on the 'best-solutions' for different sets of transmission parameters

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TABLE OF CONTENTS

 EXECUTIVE SUMMARY

ABSTRACT

1 Introduction

2 Objectives

3 Overview of Configurations Studied

      3.1 Overview

      3.2 Configuration

            3.2.1 Transmission Line Configurations

            3.2.2 Converter Configurations

            3.2.3 System Configurations

            3.3 Cases Studied

4 Transmission Line Considerations

      4.1 Overvoltages

            4.1.1 Types of Overvoltages

            4.1.2 Determination of Switching Surge Overvoltage (Fault Application)

                  4.1.2.1 Modeling

                  4.1.2.2 Fault Application Phenomena

                  4.1.2.3 Calculation Results

      4.2 Insulation Coordination

            4.2.1 Operating Voltage

                  4.2.1.1 Air Clearances

                  4.2.1.2 Number of Insulators

                  4.2.1.3 Insulator String Swing Angle

            4.2.2 Clearances for Switching Surge Withstand

                  4.2.2.1 Clearances for an Established Flashover Risk of Failure.

                  4.2.2.2 Switching Overvoltages with Conductor Displacement due to Wind

                  4.2.2.3 Composite Risk Calculation

      4.3 Pole Spacing Determination

            4.3.1 Case of I Strings

            4.3.2 Case of V strings

      4.4 Conductor Current Carrying Capability and Sags

            4.4.1 Current Capability

            4.4.2 Sag for Conductor Maximum Temperature

      4.5 Tower Height

      4.6 Lightning Performance

      4.7 Right-of-Way Requirements for Insulation

            4.7.1 Line with I Strings

            4.7.2 Line with V Strings

      4.8 Corona effects

            4.8.1 Concepts

                  4.8.1.1 Conductor Surface Gradient

                  4.8.1.2 Corona Loss

                  4.8.1.3 Radio Interference and Audible Noise .

            4.8.2 Calculation Results

                  4.8.2.1 Conductor and Shield Wires Surface Gradient

                  4.8.2.2 Corona Losses

                  4.8.2.3 Radio Interference and Audible Noise

      4.9 Ground-Level Electric Field and Ion Current

            4.9.1 Preliminary Design

            4.9.2 Further Considerations .

            4.9.3 Design Criteria

            4.9.4 Calculations for Existing Projects

      4.10 Mechanical Design

            4.10.1 Base Case

            4.10.2 Meteorological Conditions and Basic Stresses

                  4.10.2.1 Region I

                  4.10.2.2 Region II

            4.10.3 Sag and Tension Calculations

                  4.10.3.1 General Conditions

                  4.10.3.2 Conductor Configuration Alternatives and Wind Pressures

                  4.10.3.3 Tensions

                  4.10.3.4 Tower Families

            4.10.4 Loading Conditions

            4.10.5 Results of the Tower Weights

            4.10.6 Sensitivity Analysis

      4.11 Line Economics

            4.11.1 Line Costs Involved

            4.11.2 Transmission Line Costs

            4.11.3 Losses

            4.11.4 Operating and Maintenance Costs

            4.11.5 Interest During Construction

            4.11.6 Most Economical Conductor

5 Converter Station Cost Equation

      5.1 Cost Data

      5.2 Cost Equation

      5.3 Cost Support Information and Breakdown

      5.4 Converter Station Considerations.

            5.4.1 Introduction HVDC/FACTS

            5.4.2 Transport Limitation

            5.4.3 Station Losses

                  5.4.3.1 General

                  5.4.3.2 Converter Valves

                  5.4.3.3 Converter Transformers

                  5.4.3.4 Smoothing Reactor

                  5.4.3.5 AC filter Circuits and Capacitor Banks

                  5.4.3.6 DC Filter Circuits

                  5.4.3.7 Other Components of HVDC Stations

                  5.4.3.8 Environmental Conditions

                  5.4.3.9 Load Cases

                  5.4.3.10 Practical Loss value

            5.4.4 Standard Thyristor Bipoles

                  5.4.4.1 Layout and Single Line Diagram

                  5.4.4.2 Power Range

            5.4.5 Cost Basis

                  5.4.5.1 Primary Equipment

                  5.4.5.2 Secondary Equipment

            5.4.6 Individual Design or Equipment

            5.4.7 Power Tap (T off)

6 Electrodes, Electrode Lines and Metallic Return

      6.1 Introduction

      6.2 Ground Return

      6.3 Metallic Return124

      6.4 Electrode Line Cost

      6.5 Electrode Line and Metallic Return Design

      6.6 Electrode Design and Costs

7 System Economics

      7.1 Introduction

      7.2 Components of the System Costs

            7.2.1 Transmission Lines

            7.2.2 Joule Losses

            7.2.3 Corona Losses

            7.2.4 Line Operating Cost and Interest During Construction

            7.2.5 Most Economical Conductor

            7.2.6 Converter Station Cost

      7.3 Simplified Calculation

            7.3.1 Base Case Results

            7.3.2 Sensitivity to Cost of Losses

            7.3.3 Evaluation of the Impacts

            7.3.4 Simplified Evaluation of the Impacts

            7.3.5 Further Considerations

      7.4 Calculations Considering Cost Components Allocated in Different Years (General Approach)

            7.4.1 Study Case 1: Basic Case

            7.4.2 Study Case 2: As Basic Case; P taking 4 years to reach 3,000MW

            7.4.3 Study Case 3: Power 6,000 MW; 2 x 600 kV or 1 x 800 kV

            7.4.4 Study Case 4: Power 6,000 MW; ±800 kV; series or parallel arrangement

8 Conclusions and Summary

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