FOREWORD
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 modeling
   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