Overview
IEC TS 63042-101:2019 - UHV AC transmission systems, Part 101: Voltage regulation and insulation design is an IEC Technical Specification that defines requirements and practical guidance for reactive power compensation, voltage regulation and control, and insulation design and coordination in ultra-high-voltage (UHV) AC transmission systems. Prepared by IEC TC 122, the document addresses challenges introduced when overlaying UHV (long-distance, high‑charging Mvar) circuits on existing 420 kV / 550 kV networks and aims to ensure safe, reliable and economical operation of UHV AC transmission.
Key Topics and Requirements
- Reactive power compensation design: Principles for locating and sizing reactive devices (shunt capacitors/reactors, controllable shunt reactors, dynamic reactive compensation) to manage line charging and control steady-state and transient voltage profiles.
- Voltage regulation and transformer tap control: Guidance on transformer tap‑changer selection, tap ranges and operational tap-position selection to maintain system voltages within acceptable limits.
- Generator reactive power coordination: Coordination between generators and system reactive devices to support voltage control and stability.
- Insulation design and coordination procedure: Methodology for specifying insulation levels for lines and substations, including procedures to assess overvoltages and optimize insulation.
- Overvoltage categories and mitigation: Analysis and mitigation measures for Temporary Overvoltage (TOV), switching/slow-front overvoltages, lightning/fast-front overvoltages, and Very Fast Front Overvoltages (VFFO).
- Overvoltage suppression measures: Use of surge arresters, resistor-fitted circuit-breakers, controlled switching, fast insertion of shunt reactors, and damping techniques in GIS/AIS to reduce required insulation levels.
- Annexes: Informative material such as multi-stage controllable shunt reactor (MCSR) examples and procedures for selecting transformer tap positions.
Applications
- Planning and design of UHV AC transmission projects where voltage stability, reactive power management and insulation coordination are critical.
- Specification and procurement of substation equipment (transformers, CSRs, surge arresters, switchgear).
- Operational guidance for system operators and control engineers on tap control, reactive device scheduling and contingency voltage management.
- Risk assessment and mitigation strategies for overvoltage phenomena during energization, switching and lightning events.
Who Should Use This Standard
- Transmission planners and system designers
- Utilities and grid operators
- Substation and line equipment manufacturers
- Protection, control and power system stability engineers
- Consultants involved in UHV project studies and insulation coordination
Related Standards
- IEC 60071-1 (insulation co‑ordination) - normative reference for overvoltage and insulation principles.
- Other parts of the IEC 63042 series covering UHV AC system topics.
Keywords: IEC TS 63042-101:2019, UHV AC transmission, voltage regulation, reactive power compensation, insulation coordination, overvoltage, controllable shunt reactor, transformer tap‑changer, surge arrester.