IEC TR 61869-102:2014

IEC TR 61869-102 ®
Edition 1.0 2014-01
TECHNICAL
REPORT
colour
inside
Instrument transformers –
Part 102: Ferroresonance oscillations in substations with inductive voltage
transformers
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IEC TR 61869-102 ®
Edition 1.0 2014-01
TECHNICAL
REPORT
colour
inside
Instrument transformers –
Part 102: Ferroresonance oscillations in substations with inductive voltage

transformers
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
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ICS 17.220.20 ISBN 978-2-8322-1308-7

– 2 – TR 61869-102 © IEC:2014(E)
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Introduction to ferroresonance oscillations . 8
3.1 Definition of ferroresonance . 8
3.2 Excitation of steady state and non-steady state ferroresonance
oscillations . 10
4 Single phase and three phase oscillations . 12
4.1 Single phase ferroresonance oscillations . 12
4.2 The simplified circuit for the single phase ferroresonance oscillations . 13
4.3 Capacitive voltage transformers . 15
4.4 Three-phase ferroresonance oscillations . 15
4.4.1 General . 15
4.4.2 Configuration . 15
4.4.3 Ferroresonance generation . 16
4.4.4 Resulting waveform of ferroresonance oscillation . 16
4.4.5 Typical oscillogram of three phase ferroresonance . 19
5 Examples of ferroresonance configurations . 20
5.1 Single-phase ferroresonance power line field in a 245 kV outdoor
substation . 20
5.2 Single phase ferroresonance oscillations due to line coupling . 22
5.3 Three-phase ferroresonance oscillations . 25
6 Inductive voltage transformer (key parts) . 26
7 The circuit of the single-phase ferroresonance configuration . 28
7.1 Schematic diagram . 28
7.2 Magnetisation characteristic . 29
7.3 Circuit losses . 30
8 Necessary information for ferroresonance investigation . 31
8.1 General . 31
8.2 Single phase ferroresonance. 31
8.3 Three phase ferroresonance . 32
9 Computer simulation of ferroresonance oscillations . 33
9.1 General . 33
9.2 Electrical circuit and circuit elements . 33
9.3 Circuit losses . 33
9.4 Examples of simulation results for single phase ferroresonance
oscillations . 33
9.4.1 General . 33
9.4.2 Case 1: Transient, decreasing ferroresonance oscillation . 34
9.4.3 Case 2: Steady-state ferroresonance oscillation at network
frequency . 34
9.4.4 Case 3: Steady-state subharmonic ferroresonance oscillation. 35
9.4.5 Case 4: Steady-state chaotic ferroresonance oscillation . 36
9.5 Simulation of three phase ferroresonance . 37

TR 61869-102 © IEC:2014(E) – 3 –
10 Experimental investigations, test methods and practical measurements. 38
10.1 General . 38
10.2 Single-phase ferroresonance oscillations . 38
10.3 Three-phase ferroresonance oscillations . 41
11 Avoidance and suppression of ferroresonance oscillations . 42
11.1 Flow diagram . 42
11.2 Existing substations . 44
11.3 New projects . 44
11.4 Avoidance of ferroresonance oscillations . 44
11.4.1 General . 44
11.4.2 Single phase ferroresonance oscillations . 44
11.4.3 Three phase ferroresonance oscillations . 45
11.5 Damping of ferroresonance oscillation . 45
11.5.1 General . 45
11.5.2 Single-phase ferroresonance oscillations . 45
11.5.3 Three-phase-ferroresonance oscillations . 47
Annex A (informative) Oscillations in non-linear circuits . 49
A.1 Overview . 49
A.2 The simplification of non-linear electrical circuits with the theorem of
Thévenin . 51
A.3 The differential equation for ferroresonance oscillations . 51
A.4 Oscillation frequencies in ferroresonance systems . 53
Bibliography . 54

Figure 1 – Example of a typical magnetisation characteristic of a ferromagnetic core . 9
Figure 2 – Schematic diagram of the simplest ferroresonance circuit . 9
Figure 3 – Examples of measured single-phase ferroresonance oscillation with
16 / Hz oscillation . 11
Figure 4 – Schematic diagram of a de-energised outgoing feeder bay with voltage
transformers as an example in which single-phase ferroresonance oscillations can
occur . 12
Figure 5 – Diagram of a network situation that tends toward single-phase
ferroresonance oscillations, in which they can be excited and maintained over the
capacitive coupling of parallel overhead power line systems . 13
Figure 6 – Electrical circuits for theoretical analysis of a single-phase ferroresonance
oscillation . 14
Figure 7 – Insulated network as an example of a schematic diagram of a situation in
which a three-phase ferroresonance oscillation can occur . 15
Figure 8 – Phasor diagram to explain the oscillation of the earth potential . 16
Figure 9 – Laboratory test set used by Bergmann . 17
Figure 10 – Domains in the capacitance C and line voltage U where different harmonic
and sub-harmonic ferroresonance oscillations are obtained for a given resistance R of
6,7 Ω in Bergmann’s test set . 18
Figure 11 – Domains in the capacitance C and line voltage U where second sub-
harmonic ferroresonance oscillations are obtained for a variation of the resistance R in
Bergmann’s test set . 18
Figure 12 – Domains in the capacitance C and line voltage U where different modes of
second sub-harmonic ferroresonance oscillations are obtained for a given resistance R
of 6,7 Ω in Bergmann’s test set . 19
Figure 13 – Fault recorder display of a three-phase ferroresonance oscillation . 20

– 4 – TR 61869-102 © IEC:2014(E)
Figure 14 – Switching fields in the 245 kV substation in which single-phase
ferroresonances occur . 21
Figure 15 – Examples of oscillations of single-phase ferroresonance when switching off
the circuit breaker in Figure 14 . 22
Figure 16 – Single-phase schematic of the network situation on the 60 kV voltage level
in the area of substations 1, 2, and 3 . 23
Figure 17 – Tower schematic of the common stretch of overhead lines between
substations 1 and 2 . 24
Figure 18 – Ferroresonance oscillations recorded in line no. 5 at Substation 2 . 24
Figure 19 – Single-line diagram of th
...