IEEE DRAFT C37.116 : D9 2006

1 Overview
  1.1 Scope
  1.2 Purpose
2 Normative references
3 Preliminary considerations
  3.1 Major equipment considerations
      3.1.1 Capacitor unit
      3.1.2 Capacitor fusing and unit arrangement
      3.1.3 Overvoltage protective devices
      3.1.4 Discharge current-limiting reactor
      3.1.5 Bypass switch and bypass gap
      3.1.6 Thyristor-protected series capacitors (TPSC)
  3.2 System conditions
      3.2.1 System representation
      3.2.2 Fault current
      3.2.3 Line
      3.2.4 Low-frequency transients
      3.2.5 Subharmonic resonance or subsynchronous resonance (SSR)
      3.2.6 System unbalance
      3.2.7 Required speed for reinsertion
  3.3 Duty cycle
  3.4 Multiple segment series capacitors
  3.5 Single-phase trip/reclose considerations
      3.5.1 System requirements
      3.5.2 Bank requirements
      3.5.3 Line protection requirements
  3.6 Impact on line protection
  3.7 Line protection and series capacitor protection/control
      interaction
      3.7.1 Capacitor deenergize/energize logic
      3.7.2 Line protection initiated triggering of bypass gap
4 Protective functions
  4.1 Protection and control philosophy
      4.1.1 Introduction
      4.1.2 Protection and control functions
      4.1.3 Capacitor bank physical configuration
      4.1.4 Reduction
  4.2 MOV protection
      4.2.1 MOV energy calculations
      4.2.2 MOV protection functions
  4.3 Capacitor protection
      4.3.1 Capacitor unit failure protection
      4.3.2 Capacitor unbalance protection
      4.3.3 Capacitor overload protection
  4.4 Bypass gap protection
      4.4.1 Introduction
      4.4.2 Gap only scheme
      4.4.3 MOV scheme with forced triggered bypass gap
      4.4.4 Applied bypass gap protection
  4.5 Platform fault protection
      4.5.1 Flashover to platform protection
      4.5.2 Platform-to-ground protection
  4.6 Bypass switch protection
  4.7 Discharge current-limiting reactor protection
5 Platform power and signal transmission
  5.1 Current transformer supply
  5.2 Coupling capacitor voltage transformer supply
  5.3 Optically-powered supply
  5.4 Battery supply
  5.5 Power supplies specific to bypass gap firing circuits
  5.6 Platform information transmission methods
6 Control and monitoring functions
  6.1 Control actions
      6.1.1 Lockout bypass
      6.1.2 Permanent bypass
      6.1.3 Temporary bypass
      6.1.4 Automatic control
      6.1.5 Bank interlocks
  6.2 Monitoring
      6.2.1 Human machine interface (HMI)
      6.2.2 Digital fault recorders (DFRs) and sequential
            event recording systems (SERs)
7 Additional protection considerations
  7.1 Environmental
  7.2 Insulation
  7.3 Electromagnetic interference
  7.4 Bypass gap firing circuits
8 Testing
  8.1 Pre-energization tests
  8.2 Energization sequence tests and operation tests
      8.2.1 Voltage test
      8.2.2 Energization test with load current (through a
            shunt reactor)
      8.2.3 Normal sequence for capacitor bank energization
  8.3 Protection functions with bank energized verification test
      8.3.1 Low MOV current injection test
      8.3.2 Capacitor unbalance
  8.4 Immunity test
  8.5 Fault tests
      8.5.1 Benefits of staged fault testing
      8.5.2 Disadvantages of staged fault testing
ANNEXES
Annex A (informative) Glossary
Annex B (informative) Low frequency transients
Annex C (informative) Typical economic evaluation for a
        redundant protection and control unit
Annex D (informative) Example utility calculations for MOV
        protection functions
Annex E (informative) Calculation of unbalance currents for
        an H-configured externally-fused series capacitor bank
Annex F (informative) Calculation of unbalance currents for
        an H-configured internally-fused series capacitor bank
Annex G (informative) Calculation of unbalance currents for
        a fuseless series capacitor bank
Annex H (informative) Summary of suggested
        alarms/indications/control action
Annex I (informative) Actual staged fault test results
Annex J (informative) Bibliography

Specifies the application of protective relays on transmission line series capacitors. The guide will provide alternative approaches to the design, testing, and maintenance of protective relays based on the latest knowledge and the application experience of the industry. The guide will also cover issues related to the reliability of the protection system.