Life of the association

Journey of a CIGRE Green Book: "Flexible AC Transmission Systems"

The “Flexible AC Transmission Systems” commonly referred to as FACTS has been published in the CIGRE Green Book series in July 2020. This two-volume inspiring book is the major milestone of a 4-year effort to produce a comprehensive treatise about the available options for improved utilization of existing AC transmission lines as well as the opportunities to reduce the capital expenditures for new AC transmission lines.

By Bjarne Andersen and Stig Nilsson,
Editors of the “Flexible AC Transmission Systems”

The production of the “Flexible AC Transmission Systems” Green Book was initiated in the fall of 2016 by Study Committee B4 on DC Systems and Power Electronics.  

Integration of solar and wind power generating systems often located far from the load centers and also often located where the power transmission systems are weak has increased the loading of existing AC transmission lines in ways that were not considered when the lines were originally built. Considering that permits to build new overhead AC lines often are very time consuming and long AC cables are costly and often not practical, increasing the loadability of the existing AC transmission lines is often an attractive alternative. This may be feasible using power electronic systems to control the power flows across key transmission lines as well as for control of the AC voltages in the critical system nodes. This is part of the scope of Study Committee B4 on DC Systems and Power Electronics. 

The Green Book on Flexible AC Transmission Systems was produced to provide the electric power industry with a comprehensive treatise about the modern options available to the industry for control of the AC power systems as well as practical examples documenting the experience to date among users of the so called FACTS technologies. This is a part of CIGRE’s objectives to provide high quality, unbiased publications and other contributions to the electrical supply industry adding value by:

  • Providing information about the many different power electronic options available to the industry for power flow and voltage control,
  • Identifying the issues associated with increased loading of AC lines and cables,
  • Providing information about the power system planning process and needed studies to be performed when evaluating the FACTS options,
  • Providing information about proven solutions for incorporating FACTS technologies in the power systems, and
  • Providing information about the cost assessment, specification of controllers, life extension of the power electronic systems and the expected useful life of such systems.

A large group of CIGRE members from all over the world was engaged in the preparation of the 2-volume Green Book.  The assistance provided by the SC Chair of SC C2, and members of SC C2 is gratefully acknowledged.  The Green Book on Flexible AC Transmission Systems is comprised of two volumes.

This Green Book on FACTS covers a large range of topics in its 6 sections in two volumes as follows:

Volume #1:

Part I: Introduction to Flexible AC Transmission Systems (FACTS) Controllers: A Chronology

Part II: AC Systems

  • AC System Characteristics
  • AC Network Control Using Conventional Means
  • AC Network Control using FACTS Controllers (Flexible AC Transmission Systems)

Part III: Technical Description of FACTS Controllers

  • Power Electronic Topologies for FACTS Controllers
  • Technical Description of Static Var Compensators (SVC)
  • Technical Description of Static Compensators (STATCOM)
  • Technical Description of Thyristor Controlled Series Capacitors (TCSC)
  • Technical Description of Unified Power Flow Controller (UPFC) and its Potential Variations

Part IV: Application Examples of FACTS controllers

  • Controllers Using the Saturation of Iron for AC Network Control
  • Development of Magnetically Controlled Shunt Reactors in Russia
  • Application Examples of the SVC
  • Application Examples of the STATCOM
  • Application Examples of the Thyristor Controlled Series Capacitor
  • Application Examples of the UPFC and its Variants

Volume #2:

Part V: Facts Planning and Procurement

  • Economic Appraisal and Cost-Benefit Analysis
  • FACTS Planning Studies
  • Environmental Considerations for FACTS Projects
  • Procurement and Functional Specifications for FACTS Controllers

Part VI: Implementation of FACTS Controllers

  • FACTS Controller Integration and Design Studies
  • FACTS Equipment Design and Testing
  • Commissioning of FACTS Controllers

Part VII: FACTS operation and lifetime management.

  • Operation of FACTS Controllers
  • Lifetime Management of FACTS Controllers

As should be evident from the list of topics above, the 2-volume Flexible AC Transmission Systems Green Book covers topics from simple power system theory through the selection, design, operation and eventual decommissioning of power electronic systems built for power system power flow control. It includes information from users and suppliers of FACTS controllers, which should be helpful for anyone involved with how to solve AC power load limitations.   In each chapter, the current state of the art, available technologies or methods are discussed.  Each chapter also includes an extensive list of reference material for anyone who requires an in-depth understanding of FACTS technologies.

The texts provided by CIGRE experts supplemented by subject matter experts constitute valuable material to understand the trends and developments available for AC power system power flow control. Bjarne Andersen, former Chair of SC B4 and Stig Nilsson, former Secretary to SC B4 and past US representative to SC B4, have performed the main editorial work. The overall presentation of the book is introduced by the CIGRE President Rob Stephen with contributions by the TC Chair Marcio Szechtman and the Secretary General of CIGRE Philippe Adam.

The Green Book of  Flexible AC Transmission Systems provides information supporting the recently published  “Green Book on Electricity Supply Systems of the Future” and the two  demonstrates the width and breadth of collective knowledge acquired in CIGRE SCs and its Technical Brochures spanning several decades. The Green Books provides CIGRE’s unique and unbiased technical views of technology that can be applied to help transmission system owners and operators to meet todays and future power system loading challenges.  They show the value of global collaborative work of numerous experts from industry and academia mobilized within the CIGRE community. It clearly demonstrates that CIGRE is the foremost authority for end-to-end power system expertise.  

The Green Book is available for purchase on e-cigre and on our partner's website Springer 

  • Printed copy : place an order on e-cigre, for Members and non-members.
  • Electronic copy or package Printed+Electronic : Place an order on Springer. If you are a CIGRE Member, please contact us to benefit from a 40% discount on your purchase (please indicate your active member number and your National Committee in your message).

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