This part of IEC 61869 provides technical information for understanding the undesirable phenomenon of ferroresonance oscillations in medium voltage and high voltage networks in connection with inductive voltage transformers. Ferroresonance can cause considerable damage to voltage transformers and other equipment. Ferroresonance oscillations may also occur with other non-linear inductive components.<\/p>\n
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| 4<\/td>\n | CONTENTS <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | 1 Scope 2 Normative references 3 Introduction to ferroresonance oscillations 3.1 Definition of ferroresonance <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | Figures Figure 1 \u2013 Example of a typical magnetisation characteristic of a ferromagnetic core Figure 2 \u2013 Schematic diagram of the simplest ferroresonance circuit <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 3.2 Excitation of steady state and non-steady state ferroresonance oscillations Tables Table 1 \u2013 Types of excitation and possible developments of ferroresonance oscillations <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Figure 3 \u2013 Examples of measured single-phase ferroresonance oscillationwith 162\/3\u00a0Hz oscillation <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 4 Single phase and three phase oscillations 4.1 Single phase ferroresonance oscillations Figure 4 \u2013 Schematic diagram of a de-energised outgoing feeder bay with voltage transformers as an example in which single-phase ferroresonance oscillations can occur <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 4.2 The simplified circuit for the single phase ferroresonance oscillations Figure 5 \u2013 Diagram of a network situation that tends toward single-phase ferroresonance oscillations, in which they can be excited and maintained overthe capacitive coupling of parallel overhead power line systems <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | Figure 6 \u2013 Electrical circuits for theoretical analysis of a single-phase ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 4.3 Capacitive voltage transformers 4.4 Three-phase ferroresonance oscillations 4.4.1 General 4.4.2 Configuration Figure 7 \u2013 Insulated network as an example of a schematic diagram of a situation in which a three-phase ferroresonance oscillation can occur <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 4.4.3 Ferroresonance generation 4.4.4 Resulting waveform of ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Figure 9 \u2013 Laboratory test set used by Bergmann <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure 10 \u2013 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 \u03a9 in Bergmann\u2019s test set Figure 11 \u2013 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\u2019s test set <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 4.4.5 Typical oscillogram of three phase ferroresonance Figure 12 \u2013 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 \u03a9 in Bergmann\u2019s test set <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | 5 Examples of ferroresonance configurations 5.1 Single-phase ferroresonance power line field in a 245 kV outdoor substation Figure 13 \u2013 Fault recorder display of a three-phase ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | Figure 14 \u2013 Switching fields in the 245 kV substation in which single-phase ferroresonances occur <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 5.2 Single phase ferroresonance oscillations due to line coupling <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Figure 17 \u2013 Tower schematic of the common stretch of overhead lines between substations 1 and 2 Figure 18 \u2013 Ferroresonance oscillations recorded in line no. 5 at Substation 2 <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | 5.3 Three-phase ferroresonance oscillations <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | 6 Inductive voltage transformer (key parts) Figure 20 \u2013 Oscillograms of the three-phase voltages at inductive voltage transformer T04 (Figure 19) <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Figure 21 \u2013 Schematic circuit of voltage transformer and the simplification for ferroresonace studies <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | 7 The circuit of the single-phase ferroresonance configuration 7.1 Schematic diagram <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | 7.2 Magnetisation characteristic Figure 22 \u2013 Circuit for the analysis of single-phase ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | 7.3 Circuit losses Figure 23 \u2013 Example of a hysteresis curve of a voltage transformer core measured at 50 Hz <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | 8 Necessary information for ferroresonance investigation 8.1 General 8.2 Single phase ferroresonance Table 2 \u2013 Parameters <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | 8.3 Three phase ferroresonance Figure 24 \u2013 Schematic diagram for three phase ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | 9 Computer simulation of ferroresonance oscillations 9.1 General 9.2 Electrical circuit and circuit elements 9.3 Circuit losses 9.4 Examples of simulation results for single phase ferroresonance oscillations 9.4.1 General <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | 9.4.2 Case 1: Transient, decreasing ferroresonance oscillation 9.4.3 Case 2: Steady-state ferroresonance oscillation at network frequency Figure 25 \u2013 Transient decreasing ferroresonance oscillation with the fifthsubharmonic 50\/5\u00a0Hz (10\u00a0Hz) <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | 9.4.4 Case 3: Steady-state subharmonic ferroresonance oscillation Figure 26 \u2013 Steady state ferroresonance oscillation with network frequency <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | 9.4.5 Case 4: Steady-state chaotic ferroresonance oscillation Figure 27 \u2013 Steady state ferroresonance oscillation with 10\u00a0Hz <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | 9.5 Simulation of three phase ferroresonance Figure 28 \u2013 Steady state chaotic ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | 10 Experimental investigations, test methods and practical measurements 10.1 General 10.2 Single-phase ferroresonance oscillations <\/td>\n<\/tr>\n | ||||||
| 41<\/td>\n | Figure 29 \u2013 Example of the connection of a measuring resistor for capturing the current signal through the voltage transformer\u2019s primary winding at terminal N (see connection diagram in Figure 30) <\/td>\n<\/tr>\n | ||||||
| 42<\/td>\n | Figure 30 \u2013 Current measurement through voltage transformer\u2019s primary winding and the voltage at the secondary winding <\/td>\n<\/tr>\n | ||||||
| 43<\/td>\n | 10.3 Three-phase ferroresonance oscillations Figure 31 \u2013 Measurement of a single-phase ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 44<\/td>\n | 11 Avoidance and suppression of ferroresonance oscillations 11.1 Flow diagram Figure 32 \u2013 Measurement of three-phase ferroresonance oscillations with an oscilloscope <\/td>\n<\/tr>\n | ||||||
| 45<\/td>\n | Figure 33 \u2013 Flow diagram for analysis and avoidance of ferroresonance oscillations <\/td>\n<\/tr>\n | ||||||
| 46<\/td>\n | 11.2 Existing substations 11.3 New projects 11.4 Avoidance of ferroresonance oscillations 11.4.1 General 11.4.2 Single phase ferroresonance oscillations <\/td>\n<\/tr>\n | ||||||
| 47<\/td>\n | 11.4.3 Three phase ferroresonance oscillations 11.5 Damping of ferroresonance oscillation 11.5.1 General 11.5.2 Single-phase ferroresonance oscillations Figure 34 \u2013 Electrical circuit with damping device (red circles) connected to the secondary winding of the voltage transformer <\/td>\n<\/tr>\n | ||||||
| 48<\/td>\n | Figure 35 \u2013 Example of successful damping of single-phase ferroresonance oscillations of 162\/3 Hz <\/td>\n<\/tr>\n | ||||||
| 49<\/td>\n | 11.5.3 Three-phase-ferroresonance oscillations Figure 36 \u2013 Damping of the ferroresonance oscillation in the open delta connection of the voltage transformers in the feeder bay <\/td>\n<\/tr>\n | ||||||
| 50<\/td>\n | Figure 37 \u2013 Damping of ferroresonance oscillations with voltage transformer in the star point of the power transformer <\/td>\n<\/tr>\n | ||||||
| 51<\/td>\n | Annex A (informative) Oscillations in non-linear circuits Figure A.1 \u2013 A simplified electrical circuit for the analysis of ferroresonance oscillation <\/td>\n<\/tr>\n | ||||||
| 54<\/td>\n | Figure A.2 \u2013 Diagram for the derivation of non-linear differential equation of second order <\/td>\n<\/tr>\n | ||||||
| 55<\/td>\n | Figure A.3 \u2013 A non-linear oscillation system <\/td>\n<\/tr>\n | ||||||
| 56<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Instrument transformers – Ferroresonance oscillations in substations with inductive voltage transformers<\/b><\/p>\n |