VGB-Standard Electrical Generating Unit Protection

VGB-S-025-00-2012-11-EN First edition 2012

Editor: VGB PowerTech e.V.

Publisher: VGB PowerTech Service GmbH Verlag technisch-wissenschaftlicher Schriften Klinkestraße 27-31, 45136 Essen Tel. +49 201 8128-200 Fax +49 201 8128-329 E-Mail: [email protected] ISBN 978-3-86875-410-0

All rights reserved, VGB PowerTech www.vgb.org

VGB-S-025-00-2012-11-EN

Important notice – VGB copyright material VGB-Standards, hereafter referred to as “work”, including all articles and images, are protected by international copyright. VGB PowerTech is responsible to carry out the exploitation of the copyrights. The term “work“ covers this PDF-file and its content. The copyright covers the work in its entirety and its constituent parts, such as: text, tables, diagrams, photographs and illustrations. Any use and/or reproduction of this material without the prior written consent of VGB PowerTech e.V., is forbidden and will constitute an infringement of copyright law, liable to prosecution. Any unauthorised reproduction such as: photocopies, reprints, translations, its transfer: onto micro-film, entry into electronic data bases, to the Internet, or to a Web Site, saving onto CD-ROM or other digital media, any and all forms of digital storage and or reproduction will constitute an infringement of copyright. Disclaimer VGB-Standards are based on the collective experience and recommendations of PowerTech e.V. and its panel of experts and represent the best knowledge at the time of publication. No claim regarding its completeness is made as a matter of principle because of the numerous factors which must be taken into account and of course due to the dynamic process of continuous development. VGB-Standards can be used to reach and agree upon detailed specifications between the purveyor and the purchaser. Application of VGB-Standards is carried out at the user's own risk. VGB PowerTech e.V and contributors to VGB-Standards make no claim regarding its absolute accuracy and therefore accept no legal liability in the event of any claim relating to or resulting from its application. Treatment of proposing amendments Amendments can be sent to the e-mail address [email protected]. The subject line should contain the exact specification of the relevant document in order to clearly assign the e-mail content to the appropriate VGB-Standard.

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Foreword The present VGB-Standard “Electric Generating Unit Protection“ was newly compiled by the VGB project group of the same name. It continues the “Guidelines for electric generating unit protection” issued by the VDEW in 1985, and integrates new possibilities and requirements with the application of multi-functional digital protection devices. Due to the adaptation to new norms and guidelines a new edition became necessary. The VGB-work group “Electrical machines and plants” appointed the project group “generating unit protection”, compiled of experts of European power station operators. After the completion of a preliminary draft, this was discussed with manufacturers of protection devices and then jointly revised. The present VGB-Standard was compiled according to best professional know-how, whereas it does not claim to be complete. In essence this is a recommendation, and cannot replace expert knowledge of the user.

Essen, January 2012 VGB PowerTech e.V.

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The following decisively contributed to the development of the VGB Standard: Authors Marcel Bakkers Peter Demuth Dr. Udo Drechsler Ralf Drews Jörg Emmerich Thorsten Fricke Alexa Hausmann, Dr. Hans-Joachim Herrmann Jörg Kaiser Reiner Lohe Michael Mühl Alexander Muth Bernhard Nöcker Jan Pedersen Matthias Pairits Sören Sturm Dieter Willems

Essent Energie B.V., Geertruidenberg, (NL) ANDRITZ HYDRO GmbH, Wien, (A) Vattenfall Europe PowerConsult GmbH, Vetschau ABB AG, Mannheim EnBW Kraftwerke AG, Stuttgart swb Erzeugung GmbH & Co. KG, Bremen RWE Technology GmbH, Essen Siemens AG, Nürnberg VGB PowerTech e.V., Essen Schneider Electric Energy GmbH, Mülheim STEAG Energy Services GmbH, Essen Vattenfall Europe PowerConsult GmbH, Vetschau E.ON New Build & Technology GmbH, Gelsenkirchen Dong Energy, Fredericia, (DK) ANDRITZ HYDRO GmbH, Wien, (A) swb Netze GmbH & Co. KG, Bremen RWE Rhein-Ruhr Netzservice GmbH, Pulheim

VGB thanks all corporations and employees who contributed to the development of this VGB Standard. The VGB offices are always grateful for any suggestions.

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Content 1 1.1 1.2

Scope of application..................................................................................... 9 Introduction ..................................................................................................... 9 Field of application .......................................................................................... 9

2 2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 2.1.13 2.1.14 2.1.15 2.1.16 2.1.17 2.1.18 2.1.19 2.2 2.2.1 2.2.2 2.2.3 2.2.4

Description of the Protection Functions .................................................. 11 Protection of the Generator .......................................................................... 11 Time Overcurrent protection ......................................................................... 11 Impedance Protection ................................................................................... 11 Unbalanced load protection .......................................................................... 12 Overvoltage protection.................................................................................. 13 Undervoltage protection ................................................................................ 13 Under-frequency protection .......................................................................... 13 Power station de-coupling protection ............................................................ 14 Over-frequency protection ............................................................................ 14 Pole slip protection (Out-of-step protection) ................................................. 14 Differential protection .................................................................................... 15 Earth fault differential protection ................................................................... 16 Winding short-circuit protection for existing plant.......................................... 16 Stator earth fault protection .......................................................................... 16 Rotor earth fault protection ........................................................................... 18 Under-excitation protection ........................................................................... 19 Rotor over-load protection ............................................................................ 19 Reverse power protection ............................................................................. 19 Circuit-breaker failure protection ................................................................... 20 Special aspects in the case of reversing rotation with generators ................ 20 Protection of the generator transformer ........................................................ 21 Differential protection .................................................................................... 21 Distance protection ....................................................................................... 21 Earth fault protection on HV-side of the generator transformer .................... 22 Start-up earth fault protection (earth fault protection on the LV-side of the generator unit transformer) .................................................... 22 Over-excitation protection (U/f) ..................................................................... 22 Buchholz protection ...................................................................................... 22 Tank Ground Protection ................................................................................ 23 Other protection and monitoring installations of the generator transformer .. 23 Protection of the auxiliary transformer .......................................................... 23 Differential protection .................................................................................... 23 Overcurrent time protection on the HV side (generator side)........................ 23 Buchholz protection ...................................................................................... 23 Overcurrent time protection on the LV side (auxiliary supply side) ............... 24 Protection of external network transformers ................................................. 24 Auxiliary supply protection ............................................................................ 24

2.2.5 2.2.6 2.2.7 2.2.8 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.4 2.5

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Functional schematic of the protection .................................................... 25

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Construction and configuration of the protection ................................... 28 Scope of protection and allocation ................................................................ 28 Measures against under and over-function ................................................... 29 Measures in the event of a failure of the generator CB................................. 30 Auxiliary DC supply....................................................................................... 30 Tripping circuits............................................................................................. 36 Protection cubicles........................................................................................ 37 Physical location ........................................................................................... 38 Auxiliary and switching relays ....................................................................... 38 Terminal rails ................................................................................................ 38 Cables .......................................................................................................... 42

5 5.1 5.2 5.3 5.4 5.5 5.6 5.6.1 5.6.2 5.6.3 5.6.4 5.6.5 5.6.6 5.7 5.8 5.9 5.10 5.11 5.12

Other equipment and functions................................................................. 43 Current transformers..................................................................................... 43 Voltage transformers .................................................................................... 44 Monitoring the transformer circuits................................................................ 44 Capacitors on the undervoltage side of the generating transformer ............. 44 Overvoltage arrestors ................................................................................... 44 Relays and switch gear................................................................................. 45 Generator circuit-breaker .............................................................................. 45 Network CB................................................................................................... 46 De-excitation devices.................................................................................... 46 Automatic auxiliary supply switch-over ......................................................... 46 Auxiliary supply circuit-breaker ..................................................................... 46 Quick action valve......................................................................................... 46 Coupling of external signals .......................................................................... 47 Information Exchange, trip communication, .................................................. 48 Alarming devices .......................................................................................... 48 Deluge sprinkler systems .............................................................................. 49 Monitoring of the generator circuits............................................................... 49 Monitoring of the excitation systems ............................................................. 49

6 6.1 6.2 6.2.1 6.2.2 6.2.2.1 6.2.2.2 6.2.3 6.2.3.1 6.2.3.2 6.3

Testing the protection ................................................................................ 50 General ......................................................................................................... 50 Organisation of the testing ............................................................................ 50 Tests in the manufacturing plant (factory acceptance tests) ......................... 50 Initial Commissioning .................................................................................... 50 Pre-testing .................................................................................................... 50 Commissioning tests..................................................................................... 51 Re-testing ..................................................................................................... 55 Primary tests ................................................................................................. 55 Secondary tests ............................................................................................ 55 Devices for the tests ..................................................................................... 56

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6.3.1 6.3.2

Portable test and measuring devices ............................................................ 56 Stationary test equipment ............................................................................. 56

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Literature ..................................................................................................... 57

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Abbreviations .............................................................................................. 60

Annexure

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