1

WG for Revision of C57.142IEEE Guide to Describe the Occurrence and Mitigation of

Switching Transients Induced by Transformers, Switching

Device, and System Interaction

Jim McBride - Chairman

Xose Lopez-Fernandez – Vice-Chairman

Tom Melle - Secretary

IEEE Transformers Committee Fall 2020

Virtual Meeting

Tuesday, October 20th , 2020

Participants have a duty to inform the IEEE

• Participants shall inform the IEEE (or cause the IEEE to be informed) of the identity of each holder of any potential Essential Patent Claims of which they are personally aware if the claims are owned or controlled by the participant or the entity the participant is from, employed by, or otherwise represents

• Participants should inform the IEEE (or cause the IEEE to be informed) of the identity of any other holders of potential Essential Patent Claims

Early identification of holders of potential Essential Patent Claims is encouraged

Slide #1

Ways to inform IEEE

• Cause an LOA to be submitted to the IEEE-SA (patcom@ieee.org); or

• Provide the chair of this group with the identity of the holder(s) of any and all such claims as soon as possible; or

• Speak up now and respond to this Call for Potentially Essential Patents

If anyone in this meeting is personally aware of the holder of any patent claims that are potentially essential to implementation of the proposed standard(s) under consideration by this group and that are not already the subject of an Accepted Letter of Assurance, please respond at this time by providing relevant information to the WG Chair

Slide #2

Other guidelines for IEEE WG meetings

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Slide #3

Patent-related information

The patent policy and the procedures used to execute that policy are documented in the:

• IEEE-SA Standards Board Bylaws(http://standards.ieee.org/develop/policies/bylaws/sect6-7.html#6)

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If you have questions, contact the IEEE-SA Standards Board Patent Committee Administrator at patcom@ieee.org

Slide #4

6

IEEE Copyright Policy

Hamid Abdelkamel Xose Lopez-Fernandez Subhas Sarkar

Israel Barrientos Colby Lovins Cihangir Sen

Enrique Betancourt Mark Lowther Masoud Sharifi

William Boettger Nigel Macdonald Michael Sharp

Jeffrey Britton Arnaud Matig Hemchandra Shertukde

Jagdish Burde James McBride Thomas Sizemore

David Caverly Ross McTaggart Steven Snyder

Jorge Cruz Cienfuegos Vinay Mehrotra Sanjib Som

J. Arturo Del Rio Thomas Melle Mike Spurlock

Yamille del Valle Juliano Montanha Craig Stiegemeier

Huan Dinh Aniruddha Narawane Shankar Subramany

Eduardo Garcia Dhiru Patel Babanna Suresh

Monty Goulkhah Harry Pepe Vijay Tendulkar

John Hall Klaus Pointner Kiran Vedante

Kyle Heiden Bertrand Poulin Rogerio Verdolin

Sergio Hernandez Cano Ulf Radbrandt Dharam Vir

Thomas Hirsch Ashley Reagan Sukhdev Walia

Philip Hopkinson Leslie Recksiedler David Walker

Mohammad Iman Afshin Rezaei-Zare Baitun Yang

John John Pierre Riffon Joshua Yun

Akash Joshi Rodrigo Ronchi Waldemar Ziomek

Deepak Kumaria Marnie Roussell

Moonhee Lee Manish Saraf

Weijun Li Amitabh Sarkar

77

C57.142 WG - Current Members(69) Quorum (35)

8

Investigation of the Interaction between

Substation Transients and Transformers in

HV and EHV Applications IEEE Task Force within Performance Characteristic – IEEE PES Transformers Committee

Contributing Authors: J. McBride (Chair), Member, IEEE, T. Melle (Secretary), Member, IEEE, X. M. Lopez-Fernandez, Senior Member, IEEE, L. Coffeen, Member, IEEE, R. Degeneff, Fellow Member, IEEE, P. Hopkinson, Fellow Member, IEEE, B. Poulin, Member, IEEE, P. Riffon, Member, IEEE, A. Rocha, M. Spurlock, Member, IEEE, L. Wagenaar, Member, IEEE

TF Paper – Early Access

TF – Paper Status

ACCEPTED

Xose Lopez-Fernandez (Thanks)

9

Fall 2020 Agenda

Approval of Agenda – Fall 2020

10

Approval of Meeting Minutes - Columbus, OH

Fall 2019 Minutes

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WG for Revision of C57.142IEEE Guide to Describe the Occurrence and Mitigation of Switching Transients

Induced by Transformers, Switching Device, and System Interaction

- IEEE Transformers Committee document

- Co-Sponsored by IEEE Switchgear Committee

Jim McBride - Chairman

Xose Lopez-Fernandez – Vice-Chairman

Tom Melle - Secretary

“Liaison Task Force”Dave Caverly – Chairman

Jim McBride – Vice Chairman

Carl Schuetz - Secretary

Update from Switchgear Liaison Task Force

Fall 2020 Meeting (which was held on Oct. 6, 2020)

Unrestricted Oct. 20, 2020

12

Switchgear Liaison Task Force: Meeting History

Meeting Transformers Switchgear LTF

2018 Fall Jacksonville, FL: October 16 Kansas City, MO: Oct 14-18Swgr agreement to establish LTF

2019 Spring Anaheim, CA: March 26Burlington, VT: May 1Inaugural LTF Meeting

2019 FallColumbus, OH: Oct 29

San Diego, CA: Oct 9

2020 Spring Charlotte, NC: March 2 cancelled Virtual : May 3-7, 2020

(LTF did not meet)

2020 Fall

Virtual : Oct. 21, 2020

Virtual : Oct. 6, 2020

2021 Spring

April 25-29, 2021

April 18-23 2021

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• Fall 2019 Switchgear Meeting -San Diego:

technical comments were received from some

switchgear experts (Draft 6). These were

partially reviewed in San Diego.

Liaison Task Force Status Update:(since Fall 2019, Columbus)

• Fall 2019 Transformers Meeting – Columbus: some discussion of comments on Draft 6

from Switchgear meeting in San Diego

• No Spring meetings in Trx or Switchgear. New Draft 8 addressing many of the earlier

comments was circulated in advance of Fall Swgr meeting 2 weeks ago.

• Fall 2020 Switchgear Meeting –Virtual: Oct. 6: Further discussions during the meeting

(Draft 8) and subsequent to the meeting leading ultimately to Draft 8B (which has now

been circulated). Key elements to be discussed today.

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• Observation re “the essence” of the comments and Key Discussion Points from

Switchgear:

▪ Original 2010 version of C57.142 focused mainly on:

- internal resonance cases on MV transformers

- excited by sinusoidal excitation from switching, faults etc at

frequencies at or near internal resonance

▪ Our new document up until draft 6 focused on the same – but with inclusion of HV

and EHV

▪ Comments from Switchgear (E. Dullni) proposes additional material on multiple

reignition mechanism of exciting the internal resonance >> Steep Voltage steps or

breakdowns contain a wide range of frequencies and as such will excite the

transformer internal resonance. If oscillations of successive steep voltages line up with

each other this can result in amplification and severe internal resonant voltages.

Liaison Task Force Status Update:(since Fall 2019, Columbus)

15

• General Comment:

• in informal discussions, several folks within Switchgear have

commented that they view these “cross-committee”, “cross

fertilization” activities very positively …

Liaison Task Force (LTF) Status Update:

16

Questions?

17

Draft 8B

Comments

Edgar Dullni #1

Comments

Carl Schuetz

Comments

Dave Caverly

Comments

Edgar Dullni #2

18

Dr. Edgar Dullni

19

Explanation of amplification of internal resonance (2)

October 19, 2020 IEEE switchgear meeting fall 2019

Slide 19

-0.0112 -0.011 -0.0108 -0.0106-60

-40

-20

0

20

40

60

Time [s]

Voltage [

kV

]

-0.0112 -0.011 -0.0108 -0.0106-60

-40

-20

0

20

40

60

Time [s]

Voltage [

kV

]

20/0.69 kV

900 kVA

Transformer

with taps at 1/2

winding

12 12.2 12.4 12.6 12.8 13

-20

-10

0

10

20

Time [ms]

Voltage [

kV

] H2

H3

Tap12

H1

20 kV/ div

0.2 ms/div

10 kV/ div

0.2 ms/div

Voltage

breakdowns

at H2

Oscillation

at Tap12

Taken from CIGRE paper A3-302 (2014) by E. Dullni, J. Meppelink and L. Liljestrand entitled "Vacuum

circuit breaker, switching interactions with transformers and mitigation means"

Dr. Edgar Dullni – Add to Sections 5 and 6

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Poll Question #1

Changes to Clause 6.4

21

Each reignition creates a steep voltage impulse at the terminals of the

transformer which excites a voltage oscillation inside the winding at the

natural frequency of the transformer (see this excitation after application of

a full wave voltage in Fig. 9b). This excited oscillation already implies

some amplification of the internal winding voltage at the center tap the

impact of which should be covered by lightning impulse testing. If a

subsequent re-ignition occurs in phase with this oscillation before it has

damped out, further amplification by a factor of up to two takes place. Since

the repetition rate of such reignitions varies significantly, it is not expected

they produce a steady train of equally spaced pulses. Therefore, not only

amplification will happen but also extinction or damping. Still, there is a

high probability to temporarily generate high over voltage inside the

windings.

6.4 Interruption with repetitive reignition

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Time Domain Frequency Domain

Pulse Response Resonant Frequency

1,300 Hz

Transient and Frequency Response of 345kV Potential Transformer

(200kV/120V)

23

H and X Terminal Energization Transients Zoomed

H Input – 160kV 1µS X 2,400 µS

X Response - 20-35kV @ 41kHz Phase to Ground

Distribution Transformer 230 kV / 20kV 60MVA TX

Energization Transients (Zoomed)

24

H-X Magnitude Ratio at 41kHz ≈ 2.5:1

Nominal 60 Hz Ratio ≈ 11:1

Distribution Transformer 230 kV / 20kV 60MVA TX

High Voltage to Low Voltage Frequency Transfer

25

Disconnect Switch Energization of 230 kV / 20kV 60MVA TX

Consider the frequency content of the entire transient.

If the reignitions create an in phase voltage amplification that could be

damaging, the frequency content will be high near natural resonant

frequency of the transformer.

26

27

Poll Question #2

Delete to Clause 6.6

- Is clause 6.6. necessary after the addition of 6.5 and modification of other clauses? I would rather delete it.

28

6.6 Transformer internal voltage response

For the majority of the time, multiple reignitions will pose no problem to the transformer in service. This is because

the TRV produced and the subsequent reignition transients will be neither of a great enough magnitude nor at one of

the natural frequencies of the transformer winding. However, the reason for concern is simply that all complex

electrical equipment possesses impedance versus frequency characteristics which are not linear. In other words, a

voltage of 50% in the center of a winding at 60 Hz is to be anticipated, but at higher frequencies the observed voltage

may be much lower, or (unfortunately), much greater than normal turns ratio voltage. If a transformer (or motor, or

reactor, etc.) were excited by a periodic voltage at one of its natural frequencies, one would expect to see internal

voltages develop within the winding structure much greater than those seen during normal operation (or even factory

tests). As such, these periodic voltages, if near resonance, can produce voltages within the winding structure that

could result in failure of a perfectly sound transformer insulation structure designed to withstand production induced

and impulse voltage tests.

Frequencies above 0.25 MHz have a time to peak (similar to front time) less than one microsecond. When analyzing

the response of a winding at these high frequencies the standard methods used to compute the impulse response of a

winding (full and chopped wave) and the corresponding windings natural frequencies may not produce a correct

result. The model may not have a frequency response high enough to produce accurate results when analyzing the

voltage distribution at these high frequencies. To obtain reliable analytic solutions the model must possess a

frequency response capability in excess of the exciting wave form.

The saving characteristic in most instances is the sharpness or narrowness of the resonance. Unfortunately, with a

statistical switching devices’ dynamic voltage withstand characteristic, the same switching device and transformer

can produce a broad range of frequencies which increases the probability of producing a voltage applied to the

transformer terminals at a frequency close or equal to one of the natural frequencies of the transformer and thus

producing internal over-voltages. Additionally, it is quite possible for the transient voltage to last for many cycles (of

the high frequency), thereby providing time for the voltage to build within the winding. Given these conditions, it is a

very real possibility that a voltage of periodic shape and of modest magnitude could produce dangerously high

internal over voltages.

29

Poll Question #3

Changes to Clause 7.2

30

Replace Last Paragraph of Clause 7.2

New Verbiage

Edgar Dullni

Nonlinear resistors or metal oxide varistors connected across portions of a

transformer’s winding structure are also a method for dealing with high

internal voltages caused by external oscillatory excitation at one of the

transformers natural frequencies. This can effectively address the concerns at

one frequency and one location within the winding, but should not be

considered as a complete solution for all natural frequencies.

7.2 Other mitigation methods

Last Paragraph

31

Poll Question #4

Changes to Example A1

- I have also reviewed the examples. In particular, A1 gives me a lot of headache, since it focusses so much on the internal resonances. In this context it is very speculative I think. The analysis should rather refer to the clauses in the main text than describing the phenomenon with own words. I think example A1 needs a major revision.

Draft 8B

32

Poll Question #5

Changes to Example A5

- Example 5 is also not consistent and should be revised. I think with disconnector switching, which is described in this example, only the steepness of the breakdowns and the high number of breakdowns is decisive. Transformer resonances do not play a role.

Draft 8B

33

Request / Comment from

Switchgear Committee TF Meeting October 6, 2020

There are very fast re-ignition transients that

occur with reactor switching and sometimes with

transformer switching. It is understood that these

very fast transients are not always covered by

standard factory acceptance tests. The

switchgear committee requestor would like to see

some guidance from the transformer and reactor

manufacturers on some realistic limits for these

high frequency transients. These transients can

also damage the switching devices.

34

Membership of TF on Mitigation MethodsPhil Hopkinson – TF Chair

Pierre Riffon – TF Vice-Chair

Akash Joshi – TF Secretary

Don Ayers Changir Sen

Dave Caverly Hamid Sharifnic

Monty Goulkhah Steve Shull

John Hall Thomas Sizemore

Chuck Johnson Mike Spurlock

Jim McBride Rogerio Verdolin

Bertrand Poulin Shekhar Vora

Amitabh Sarkar Loren Wagenaar

Pugal Selvaraj Waldemar Ziomek

35

Switching Mitigation Concepts

Phil Hopkinson

36

Next Meeting

(April 27, 2021 - Toronto, CA)

Adjournment