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TB 139 1999 SC 14 WG 14.30 Guide to the specification and design evaluation of AC filters for HVDC systems.

The principal purpose of the document is to give guidance to those responsible for : preparing the a.c. filtering aspects of Technical Specifications for HVDC projects ; evaluating the proposed designs, and monitoring the subsequent project. The main objective is to enable informed judgements to be made and future Technical Specifications to be written, such that the resulting a.c. filters are effective yet economical and are non under or over designed.

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TABLE OF CONTENTS

1. INTRODUCTION AND OBJECTIVES

      1.1 General

      1.2 Definitions

      1.3 Introduction

      1.4 Past experience

      1.5 Objectives

      1.6 Approach

2. GENERAL ASPECTS OF SPECIFICATIONS

      2.1 General

      2.2 Boundaries of responsibility

      2.3 Scope of studies

      2.4 Scope of supply

      2.5 Technical data to be supplied by Contractor

      2.6 Alternative proposals by Bidders

3. PERMISSIBLE DISTORTION LIMITS

      3.1 General

      3.2 Voltage distortion

      3.3 Distortion limits pertaining to the HV and EHV network equipment

      3.4 Telephone interference

      3.5 Special criteria

4. HARMONIC GENERATION

      4.1 General

      4.2 Converter harmonic generation

      4.3 Calculation methodology

      4.4 Sensitivity of harmonic generation to various factors

      4.5 Externally generated harmonics

5. HARMONIC INTERACTION ACROSS CONVERTERS

      5.1 Introduction

      5.2 Interaction phenomena

      5.3 Interaction modelling

      5.4 Impact on a.c. filter design

      5.5 Study methods

      5.6 Possible countermeasures

      5.7 Recommendations for the Technical Specification

6. FILTER ARRANGEMENTS

      6.1 Overview

      6.2 Advantages and disadvantages of typical filters

      6.3 Classification of filter types

      6.4 Tuned filters

      6.5 Damped filters

      6.6 Choice of filters

7. FILTER PERFORMANCE CALCULATION

      7.1 Calculation procedure

      7.2 Detuning and tolerances

      7.3 Network impedance for performance calculations

      7.4 Outages of filter banks / sub-banks

      7.5 Considerations of probability

      7.6 Flexibility regarding compliance

8. FILTER SWITCHING AND REACTIVE POWER MANAGEMENT

      8.1 Introduction

      8.2 Reactive power interchange with a.c. network

      8.3 HVDC converter reactive power capability

      8.4 Bank / sub-bank definitions and sizing

      8.5 Hysteresis in switching points

      8.6 Converter Q-V control near switching points

      8.7 Operation at increased converter control angles

      8.8 Filter switching sequence and harmonic performance

      8.9 Demarcation of responsibilities

9. STEADY STATE RATING

      9.1 Introduction

      9.2 Calculation method

      9.3 A.C. network conditions

      9.4 De-tuning effects

      9.5 Network impedance for rating calculations

      9.6 Outages

10. TRANSIENT STRESSES AND RATING

      10.1 General

      10.2 Switching impulse studies

      10.3 Fast fronted waveform studies

      10.4 Insulation co-ordination

11. LOSSES

      11.1 Background

      11.2 A.C. filter component losses

      11.3 Filter reactor losses

      11.4 Criteria for loss evaluation

12. DESIGN ISSUES AND SPECIAL APPLICATIONS

      12.1 Introduction

      12.2 Performance aspects

      12.3 Rating aspects

      12.4 Filters for special purposes

      12.5 Impact of new HVDC station in vicinity of an existing station

      12.6 Redundancy issues and spares

13. PROTECTION

      13.1 Introduction

      13.2 General

      13.3 Bank and sub-bank overall protection

      13.4 Protection of individual filter components

      13.5 Personnel protection

14. SEISMIC REQUIREMENTS

      14.1 General

      14.2 Load specification

      14.3 Method of qualification

      14.4 Examples of improvements in the mechanical design

15. AUDIBLE NOISE

      15.1 General

      15.2 Sound active components of a.c. filters

      15.3 Sound requirements

      15.4 Noise reduction

16. CUSTOMER SPECIFIED PARAMETERS AND REQUIREMENTS

      16.1 Introduction

      16.2 A.C. system parameters

      16.3 Harmonic distortion requirements

      16.4 Environmental conditions

      16.5 Electrical environment

      16.6 Requirements for filter arrangements and components

      16.7 Protection of filters

      16.8 Loss evaluation

      16.9 Field measurements and verifications

      16.10 General requirements

17. EQUIPMENT DESIGN AND TEST REQUIREMENTS

      17.1 General

      17.2 Capacitors

      17.3 Reactors

      17.4 Resistors

      17.5 Arresters

      17.6 Instrument transformers

      17.7 Filter switching equipment

18. FIELD MEASUREMENTS AND VERIFICATION.

      18.1 Introduction

      18.2 Equipment and subsystem tests

      18.3 System tests

      18.4 In-service measurements

      18.5 Measurements of pre-existing harmonic levels for design purposes

19. FUTURE DEVELOPMENTS

      19.1 Introduction

      19.2 New filter technology

      19.3 New converter technology

      19.4 Changing external environment

20. REFERENCES