IEC 62751-2-2023 PDF

Full title and description

IEC 62751-2:2014/AMD2:2023 — Power losses in voltage sourced converter (VSC) valves for high-voltage direct current (HVDC) systems — Part 2: Modular multilevel converters. This publication is Amendment 2 (2023) to the Part 2 (2014) document, providing updated procedures and formulae specific to modular multilevel converter (MMC) valve loss calculations.

Abstract

This amendment updates and supplements IEC 62751-2:2014 with additional guidance and calculation methods for determining power losses in VSC valve assemblies when the converter topology is a modular multilevel converter (MMC). It clarifies loss components, refines modeling of submodules and valve arrangements, and provides worked examples and parameter definitions to support consistent loss estimation for HVDC design, ratings and thermal management.

General information

• Status: Published (Amendment 2 to IEC 62751-2:2014, active amendment).
• Publication date: 28 August 2023 (IEC issuance date for Amendment 2).
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 29.200; 29.240.99 (rectifiers, converters, equipment for power transmission/distribution).
• Edition / version: Edition 1.0 (IEC 62751-2:2014) with Amendment 2 (2023) — commonly designated IEC 62751-2:2014/AMD2:2023.
• Number of pages: Amendment document: 17 pages (bilingual English/French amendment PDF).

Scope

This Amendment 2 specifically addresses the calculation of power losses in the valves of HVDC systems that use modular multilevel converters (MMC). It supplements the general loss-calculation principles given in IEC 62751-1 (Part 1) and the original Part 2 text by detailing the MMC valve topology, submodule behavior, switching and conduction loss models applicable to MMC valves and the recommended procedures to derive total valve losses for converter substations. The amendments are intended for designers, manufacturers and system engineers who need consistent, reproducible loss estimates for thermal design, component selection and performance studies.

Key topics and requirements

• Definition and classification of MMC valve configurations and submodule types relevant to loss calculations.
• Procedures to calculate conduction losses for semiconductor devices used in MMC submodules, including diode and IGBT/IGBT-like device treatment.
• Methods for estimating switching-related losses in MMC topologies and how switching duty and modulation affect losses.
• DC voltage-dependent losses, losses in DC-link / submodule capacitors and auxiliary components relevant to valve loss budgets.
• Recommended measurement/monitoring points, ambient and operating condition assumptions for loss normalization.
• Examples and worked calculations to illustrate application of formulas to common MMC arrangements and to produce total valve loss per converter station.

Typical use and users

Used by HVDC converter designers, power-electronics manufacturers (MMC vendors and submodule suppliers), utility transmission planners, testing and certification laboratories, and consultants performing thermal, efficiency and lifecycle analyses for HVDC converter stations. The standard is also referenced by researchers and universities working on converter loss models and system-level studies.

Related standards

IEC 62751 series — Part 1: General requirements (IEC 62751-1:2014 and its amendments) provides the overarching principles for valve loss calculation and is essential companion reading. Other related documents include IEC 62747 (terminology for VSC/HVDC converters) and relevant IEC/EN standards on power-electronic converter safety, EMC and thermal testing that inform practical application of the loss data.

Keywords

HVDC, VSC, MMC, modular multilevel converter, valve losses, power losses, conduction losses, switching losses, submodule, converter station, IEC 62751, loss calculation.

FAQ

Q: What is this standard?

A: IEC 62751-2:2014/AMD2:2023 is Amendment 2 (2023) to Part 2 of the IEC 62751 series, which provides methods for calculating power losses in VSC converter valves when the converter topology is a modular multilevel converter (MMC).

Q: What does it cover?

A: It covers specific procedures, models and examples for determining conduction, switching, DC-voltage-dependent and related losses in MMC valve assemblies and how to combine those to obtain total valve losses for HVDC converter substations. It supplements the general rules given in Part 1 of IEC 62751.

Q: Who typically uses it?

A: Manufacturers of MMC converters and submodules, HVDC system designers, utilities, testing/validation laboratories, consultants and academics performing loss, thermal and efficiency studies for HVDC projects.

Q: Is it current or superseded?

A: This publication is an amendment (Amendment 2) published on 28 August 2023 to the 2014 edition of IEC 62751-2. As an amendment to the 2014 Part 2 document it remains the current issued amendment; users should consult the IEC webstore or national adoption bodies for any later consolidations or further amendments.

Q: Is it part of a series?

A: Yes — it is Part 2 of the IEC 62751 series. Part 1 (IEC 62751-1:2014 with its amendments) contains the general requirements; Part 2 focuses on MMC-specific details and provides procedures that implement the Part 1 principles for that topology.

Q: What are the key keywords?

A: HVDC, VSC, MMC, power losses, valve losses, submodule, conduction losses, switching losses, DC-link capacitor losses, IEC 62751.