PD IEC TR 62001 — High-Voltage Direct Current (HVDC) Systems: Guidance to the Specification and Design Evaluation of AC Filters Series

📐 PD IEC TR 62001 is a series of Published Documents issued by the British Standards Institution (BSI) that fully corresponds to IEC/TR 62001. It provides systematic guidance for the specification and design evaluation of AC filters on the AC side of high-voltage direct current (HVDC) converter stations. The series comprises four parts covering Overview, Performance, Modelling and Equipment, replacing the earlier single-volume PD IEC/TR 62001:2009. For engineers involved in HVDC system planning, converter station design, filter selection and power quality assessment, this series is an essential reference for understanding how AC filters satisfy system performance requirements.

1. Series Overview 📌

The PD IEC/TR 62001 series was prepared by working groups within IEC Technical Committee TC 22 (Power electronics); UK participation was entrusted to Technical Committee PEL/22 (Power electronics). The parts are published as Technical Reports providing guidance rather than mandatory requirements. Their central aim is to help the purchaser (owner / system operator) define the performance that AC filters must satisfy during procurement and design, and to help suppliers accurately evaluate and respond to those requirements.

The parts were published during 2016 and together supersede the 2009 edition of PD IEC/TR 62001. Compared with earlier editions, the new version expands and refines telephone-interference limit determination, harmonic-interaction modelling and filter-equipment specification, reflecting the stricter power-quality and EMC demands of larger-capacity, higher-voltage DC projects.

2. Structure and Technical Highlights 🧩

The series consists of four parts with clear but interconnected roles. The table below summarises each part by number, topic and core content.

3. Key Technical Requirements 🔥

3.1 Permissible voltage distortion limits

The first step in AC filter design is to determine the permissible harmonic voltage distortion levels of the system. Part 1 gives definitions, discussion and recommendations of voltage-distortion performance criteria, methods for determining limits, and emphasises accounting for pre-existing harmonic levels and future growth margins. In practice, owners specify single-order harmonic voltage distortion, total harmonic distortion (THD) and telephone harmonic form factor (THFF) as performance guarantees.

3.2 Telephone interference limits

Part 2 focuses on current-based interference criteria. Where converter stations run parallel and close to telephone lines, harmonic currents induce noise in telephone circuits. The report presents methods for determining whether telephone interference limits are necessary, interference mechanisms, noise performance coordination levels, the influence of power transmission lines, and step-by-step determination of current interference (IT) limits for a specific project. It also shows the cost implications for filter design and gives telephone-infrastructure mitigation options.

3.3 Harmonic interaction and modelling

Part 3 addresses harmonic interaction that may occur between multiple converters and multiple AC systems. The report summarises practical problems encountered, gives indicators of where interaction is significant, analyses interaction phenomena (e.g. AC-side third harmonic, direct current on the AC side, characteristic harmonics) and their impact on filter design, and systematically introduces time-domain and frequency-domain AC-DC-AC interaction models. Sound modelling is key to avoiding excessive deviation between design and actual operation.

3.4 Filter equipment specification

Part 4 addresses the filter components themselves. AC filters typically comprise tuned or damped branches with filter reactors, filter capacitors, damping resistors, surge arresters, disconnectors, circuit breakers and current transformers. The part provides guidance on technical conditions, losses, noise, temperature rise, insulation coordination and testing to ensure reliable operation under normal, fault and switching conditions.

4. Engineering Practice 🛠️

• 🔍 Design inputs: establish the AC system equivalent impedance, background harmonics, converter topology and rating, and converter transformer parameters as filter design inputs.
• 📊 Limit setting: set single-order distortion, THD and THFF limits per IEC/TR 62001-1 and grid codes, with a future growth margin.
• 📐 Scheme comparison: compare typical filter branch structures (C-type, double-tuned, damped high-pass) balancing filtering performance, reactive compensation, losses, cost and footprint.
• 🔬 Simulation verification: use the time/frequency-domain models from Part 3 to verify performance under different operating modes (rated, minimum load, monopole fault, etc.).
• 📋 Equipment procurement: specify filter equipment per Part 4, organise type and routine tests to ensure the equipment meets system requirements.

5. FAQ ❓