IEC 60700-3:2022

Overview

IEC 60700-3:2022 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies essential ratings and characteristics of thyristor valves used in high voltage direct current (HVDC) power transmission. This standard focuses on thyristor valves implemented in line commutated converters (LCC) with three-phase bridge connections, facilitating AC/DC and DC/AC conversion. The document applies to air insulated, liquid cooled, and indoor thyristor valve configurations.

The standard defines limiting values and service conditions critical for the design, operation, and testing of thyristor valves in HVDC systems. It covers environmental and system conditions, voltage and current ratings, insulation levels, firing angles, and temperature characteristics, ensuring reliable and efficient performance in demanding HVDC applications.

Key Topics

• Service Conditions:

  • Environmental factors such as site altitude, air temperature, humidity, cleanness, and seismic conditions in valve halls.
  • System conditions including AC system voltage, frequency, DC voltage and current, overload, and short circuit requirements.
  • Design parameters for six-pulse bridge configurations and insulation coordination.

• Essential Ratings (Limiting Values):

  • Rated and maximum steady state AC voltages across the valve.
  • Valve repetitive and non-repetitive peak off-state and reverse voltages.
  • Switching impulse and lightning impulse withstand voltages.
  • Rated and maximum currents, including RMS and average valve current and fault current scenarios.
  • Delay and extinction angle ratings defining limits for safe valve firing delay and commutation.

• Characteristics:

  • Losses characteristics specifying maximum load and no-load losses and heat emission to the valve hall.
  • Protection characteristics for lightning and steep front impulse protective firing voltages and forward recovery protection.
  • Temperature characteristics outlining maximum cooling medium and thyristor junction temperatures, plus storage conditions.
  • Reliability aspects including expected annual failure rates at the thyristor level.
  • Other performance characteristics such as valve on-state voltage and maximum commutation overshoot factors.

Applications

IEC 60700-3:2022 is essential for manufacturers, designers, and system integrators involved in HVDC transmission projects. The standard supports:

• High Voltage DC Power Transmission: Guidance in specifying thyristor valves for robust and efficient AC/DC or DC/AC conversion in HVDC lines, enabling long-distance, high-capacity power transfer with reduced losses.
• Converter Valve Design: Defining ratings that assist in the design and testing phases to ensure components operate within safe limits under varying electrical and environmental stresses.
• System Reliability and Safety: Establishing characteristics critical for protective measures and thermal management to maximize valve lifespan and reduce failure risks.
• Standardized Component Testing: Providing uniform criteria for validating thyristor valve performance across different manufacturers and geographic regions, facilitating international project collaboration and interoperability.

Related Standards

• IEC 60700 Series: Includes parts defining general requirements, testing methods, and other technical specifics for thyristor valves in HVDC systems.
• IEC 60060: High-voltage test techniques serving as a reference for insulation testing related to valve withstand voltages.
• IEC 61869: Instrument transformers used in power system measurements, often coordinated with HVDC converter standards.
• IEC 61992: Covers HVDC transmission overhead electrical lines, complementing equipment standards like IEC 60700-3.

Adherence to IEC 60700-3:2022 ensures compliance with globally recognized best practices and enhances the technical integrity of HVDC thyristor valves, fostering innovation and operational excellence in power transmission infrastructure.