Jul 7, 2004 - 1 SCOPE. This document gives additional information on how to implement a digital communication interface
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IMPLEMENTATION GUIDELINE FOR DIGITAL INTERFACE TO INSTRUMENT TRANSFORMERS USING IEC 61850-9-2 1
SCOPE
This document gives additional information on how to implement a digital communication interface to non conventional instrument transformers according to IEC 61850-9-2 and IEC 60044-7/8. The purpose of the document is to define a subset of IEC 61850-9-2 that shall support a fast market introduction of this standard. The subset facilitates first implementations, especially in existing products. It further clarifies uncertainties with respect to the interpretation of the standards and/or to precisely define what options to choose in case the standards permit a choice of options. The paper defines all the generally binding issues and is intended to be used together with Protocol Implementation Documents (PID’s) that are established for all equipment supporting this digital interface. The PID’s of the individual equipment then define what functions a unit supports and how it reacts to error conditions. The purpose of the definitions stated below is to ensure that equipment designed accordingly is interoperable within the limits defined in the PID documents of the connected units.
2
SUMMARY
The subset of IEC 61850-9-2 defined in this document only supports the service SendMSVMessage. As a consequence, the communication is unidirectional from the merging unit to the bay level devices and does not need to support the MMS stack. Therefore, implementation in existing bay level devices is straightforward. The document further defines a logical device merging unit and a encoding="UTF-8"?> Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 18 / 31 < ln> 0.001 0 0.01 0 20 24.1 Î o.k., since 2 < 231 • The max binary value becomes 217.1 x 27.0 = 224.1 Note: Voltage measurement: • Distance- and accurate reverse power- functions are not applied for voltages below 6 kV. • For voltage measurement on objects with rated voltages below 3 kV, class 0.5 for metering is sufficient. Current measurement: • For current measurement on objects with rated current below 100 A, class 0.5 for metering is sufficient. • Highest current values have to be expected for faults near terminals of large generators. In such cases the maximum short-circuit current is limited by the block transformer to below 10 times the rated generator current.
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 23 / 31
21 22 25 26 28 29 211 212 213 214 215 216 217
218
219
220
221
222
Max. current expected 25 Irated
Max. current expected 65 I
223
rated
224
225
226
227
228
Value for generator and transformer protection applications. (Accuracy limit factor = 50)
229
230
Value for busbar and line protection applications. (Accuracy limit factor = 130)
Doubling, to take into account a full DC-offset of the short-circuit current.
1'000 kA (r.m.s.)
210
100 kA (r.m.s.)
Move this line - together with the arrows applicable to the rated current of the object. The two arrows shall remain within the +/- 31 Bit scale. (Application similar to the good old „slide-ruler“)
10 kA (r.m.s.)
27
Class 0.2S/2 Class 0.2S Class 0.5S
Class 0.1 Class 0.2 Class 0.5 Class 1
1 kA (r.m.s.)
141 A (peak) 100 A (r.m.s.)
Rated object current 100 A (r.m.s.) in this example
24
10 A (r.m.s.)
Phase currents and 3 I0 23
1 A (r.m.s.)
Requirement for distance, DEF et al protection functions
100 m A (r.m.s.)
1 mA = LSB
20
10 m A (r.m.s.)
Peak value (sinusoidal waveform) r.m.s. value
1 m A (r.m.s.)
231
2'147 kA (peak)
Figure 6 – Nomogram for current
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2
Modification Index: R2-1 Last date of storage: 2004-07-07
Page 24 / 31
21
22
25
26
28
29
211
212
213
214
215 216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
10'000 kV (r.m.s.)
231
21'475 kV (peak)
The maximum rated voltage factor is chosen to be 2.5 to cover most applications (instead of only 1.9 according to IEC 60044-7).
Maximum voltage = 2.5 Urated
Move this line - together with the arrows applicable to the rated voltage of the object. The two arrows shall remain within the +/- 31 Bit scale. (Application similar to the good old „slide-ruler“)
1'000 kV (r.m.s.)
210
Class 0.1 Class 0.2 Class 0.5 Class 1 Class 3P Class 6P
100 kV (r.m.s.)
14.1 kV (peak) 10 kV (r.m.s.) Rated object voltage 10 kV (r.m.s.) in this example
27
1 kV (r.m.s.)
24
100 V (r.m.s.)
Requirement for distance, DEF et al protection functions
10 V (r.m.s.)
Phase to ground voltages and 3 U0
23
1 V (r.m.s.)
10 mV = LSB
20
100 mV (r.m.s.)
Peak value (sinusoidal waveform) r.m.s. value 10 m V (r.m.s.)
Figure 7 - Nomogram for voltage
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2
Modification Index: R2-1 Last date of storage: 2004-07-07
Page 25 / 31
APPENDIX E: REFERENCE ARROW ORIENTATION SYSTEM Legend U I N E
Voltage Current Neutral Earth (IEC notation) = Ground (ANSI notation)
Indices A B C N E P 1 2 0
(subscript) Phase A Phase B Phase C Neutral Earth = Ground Parallel overhead line, if applicable Positive sequence Negative sequence Zero sequence
The positive sense of arrows (phasors) follows the „load vector system“ i.e., the voltage-drop across a resistor is in phase with the current. DBB OHB IE
Double Bus Bar arrangement 1½ (One and a Half) Breaker arrangement Earth (ground) return current
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 26 / 31 Parallel Line (ov erhead line)
3 I 0p Feeder under consideration
IA A
UAB
UAN
IB B
UBC
UBN
UCA
IC C
UCN
N
3 I0
UAE UB E UCE
Z = 0 …. inf inite
U0
IE = 3 I 0 3 U 0 = U AE +U BE+U CE
3 I 0 = I A+I B+I C
E
3 I 0p is mainly used f or mutual zero-sequence compensation in distance to f ault locators
Figure 8 - Generic three phase system including voltages and currents
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 27 / 31 Bus 1 Bus 2
QA1
P1
IA, IB, IC , (3I0)
BZ1 P2 IN
HV Tertiary
IA, IB, IC , (3I0) P2
P1 P2
P1
IN
P1 P2
LV
IA, IB, IC , (3I0)
P2
P2
IE
P1
P1
Figure 9 - Currents in DBB (double bus bar) arrangement
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 28 / 31 Bus 1 Difference of tw o currents
QA11
P1
IA11- IA31 IB11- IB31 IC11- IC31 (3I011- 3I031)
BZ11
IA11. IB11, IC11, (3I011)
P2 Feeder 1
QA31
P1 BZ31
IA31. IB31, IC31, (3I031)
Sum of tw o currents
P2 Feeder 2
IA21+ IA31 IB21+ IB31 IC21+ IC31 (3I021+ 3I031)
P2 BZ21
IA21. IB21, IC21, (3I021)
P1 QA21 IN
HV
Bus 2
Tertiary
IA, IB, IC , (3I0) P2
P1 P2
P1
IN
P1 P2
IA, IB, IC , (3I0)
LV P2
P2 IE
P1
P1
Figure 10 - Currents in OHB (one and a half breaker) arrangement
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 29 / 31
Figure 11 shows the connections between conventional equipment and CT’s. The neutral of the CT’s is formed on object-side. The primary current and the current in the protection relay are “in phase”. The arrow orientation is in line with the system used for NCIT’s (as defined in IEC 600448, clause 11.1.3). The drawing shall help to co-ordinate mixed mode configurations (mixed-mode uses digital data streams from NCIT’s and inputs from conventional CT’s and VT’s). Furthermore the diagram shall illustrate that IN, as it is used with conventional CT’s, results in IN = - 3 I0.
N IA
B
IB
C
IC Protection A B C N
IA
3 I0 = IA + IB + IC
IB IC IN = -3 I0
IE = 3 I0 = IA + IB + IC
Figure 11 – Reference arrow orientation system, conventional CTs with CT star-point (neutral) on object side
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 30 / 31
Figure 12 shows an alternative connection for conventional equipment as used by several vendors i.e., the neutral of the CT’s is formed on bus-side. In this case the arrow orientation for the secondary equipment is inverted (The primary current and the current in the protection unit are “in counter phase”. This must be considered for directional- and differential- functions. To ease adaptation to the two conventions, the IEC61850-9 inputs should preferably be selectable: direct or inverted.
N IA
B
IB
C
IC Protection A B C N
IA
3 I0 = IA + IB + IC
IB IC IN = -3 I0
IE = 3 I0 = IA + IB + IC
Figure 12 - Reference arrow orientation system, conventional CTs with CT star-point (neutral) on bus-side
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
Page 31 / 31
CHANGE INFORMATION Date
Change Index
Document State
Author
Remarks
04-03-01
2.0a
Released
Ch. Brunner
04-07-07
2.1
Released
Ch. Brunner
Version released at UCA usersgroup meeting Modifications in Figure 4 (Length of ConfRev) and 5 (Quality fields)
Implementation Guideline for Digital Interface to Instrument Transformers using IEC 61850-9-2 Modification Index: R2-1 Last date of storage: 2004-07-07
