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Where I
S1
, I
S2
, K
1
and K
2
are setting values:
I
S1
: The minimum threshold for differential current;
I
S2
: The slope changing point (when the bias current is larger than this value, security is much more important than
reliability for differential protection);
K
1
: The slope of character when the fault is slight;
K
2
: The slope of character when the fault is severe.
The differential protection characteristic is shown below:
Tripping
Zone
Restrain
Zone
I
diff
I
bias
K
1
K
2
I
S1
I
N1
I
S2
E00762
Figure 33: Current differential discriminative criterion
The value of the minimum setting threshold for differential current (I
S1
) is required to be set higher than the
maximum unbalanced current due to measurement and calculation errors. Normally, I
S1
is set to be 0.1~0.5 p.u. to
avoid unbalanced current.
When the fault is low, the bias current value will be smaller as well. In this case, reliability is more important than
security, so that the slope of the character is smaller (Normally, K
1
is set to be 0.3~0.5).
On the other hand, when the fault is severe, bias current will be higher and security will become more important
than reliability (in this case, the CTs could be unbalanced and saturated, which can result in much higher
unbalanced current in I
diff
), so the protection will follow the character of slope K
2
, which has a much steeper slope
(k
2
=1.0~1.5).
All the settings should be set following the best balance between the security and reliability.
When the phase-differential protection issues a trip command, it sends a per-phase ‘differential intertrip’ signal to
the remote terminals to instruct them to trip their circuit breakers. This is to ensure that all ends of the protected
line trip, even for marginal fault conditions.
For grading with other protection, the phase differential protection trip signal can be time delayed using either a
definite time, or an inverse time characteristic. By default, the delay characteristic is set to definite time with a zero
second delay, resulting in instantaneous tripping.
Since differential and bias current calculations are made on a per-phase basis, the values vary on a per-phase
basis. For optimum stability the highest value of the three-phase bias currents is used to restrain all three phases.
P54A/B/C/E
Chapter 6 - Current Differential Protection
P54xMED-TM-EN-1
101
Содержание P4A
Страница 2: ......
Страница 20: ...Contents P54A B C E xviii P54xMED TM EN 1 ...
Страница 27: ...CHAPTER 1 INTRODUCTION ...
Страница 28: ...Chapter 1 Introduction P54A B C E 2 P54xMED TM EN 1 ...
Страница 38: ...Chapter 1 Introduction P54A B C E 12 P54xMED TM EN 1 ...
Страница 39: ...CHAPTER 2 SAFETY INFORMATION ...
Страница 40: ...Chapter 2 Safety Information P54A B C E 14 P54xMED TM EN 1 ...
Страница 52: ...Chapter 2 Safety Information P54A B C E 26 P54xMED TM EN 1 ...
Страница 53: ...CHAPTER 3 HARDWARE DESIGN ...
Страница 54: ...Chapter 3 Hardware Design P54A B C E 28 P54xMED TM EN 1 ...
Страница 86: ...Chapter 3 Hardware Design P54A B C E 60 P54xMED TM EN 1 ...
Страница 87: ...CHAPTER 4 SOFTWARE DESIGN ...
Страница 88: ...Chapter 4 Software Design P54A B C E 62 P54xMED TM EN 1 ...
Страница 99: ...CHAPTER 5 CONFIGURATION ...
Страница 100: ...Chapter 5 Configuration P54A B C E 74 P54xMED TM EN 1 ...
Страница 120: ...Chapter 5 Configuration P54A B C E 94 P54xMED TM EN 1 ...
Страница 121: ...CHAPTER 6 CURRENT DIFFERENTIAL PROTECTION ...
Страница 122: ...Chapter 6 Current Differential Protection P54A B C E 96 P54xMED TM EN 1 ...
Страница 149: ...CHAPTER 7 AUTORECLOSE ...
Страница 150: ...Chapter 7 Autoreclose P54A B C E 124 P54xMED TM EN 1 ...
Страница 207: ...CHAPTER 8 CB FAIL PROTECTION ...
Страница 208: ...Chapter 8 CB Fail Protection P54A B C E 182 P54xMED TM EN 1 ...
Страница 219: ...CHAPTER 9 CURRENT PROTECTION FUNCTIONS ...
Страница 220: ...Chapter 9 Current Protection Functions P54A B C E 194 P54xMED TM EN 1 ...
Страница 244: ...Chapter 9 Current Protection Functions P54A B C E 218 P54xMED TM EN 1 ...
Страница 247: ...CHAPTER 10 VOLTAGE PROTECTION FUNCTIONS ...
Страница 248: ...Chapter 10 Voltage Protection Functions P54A B C E 222 P54xMED TM EN 1 ...
Страница 261: ...CHAPTER 11 FREQUENCY PROTECTION FUNCTIONS ...
Страница 262: ...Chapter 11 Frequency Protection Functions P54A B C E 236 P54xMED TM EN 1 ...
Страница 268: ...Chapter 11 Frequency Protection Functions P54A B C E 242 P54xMED TM EN 1 ...
Страница 269: ...CHAPTER 12 MONITORING AND CONTROL ...
Страница 270: ...Chapter 12 Monitoring and Control P54A B C E 244 P54xMED TM EN 1 ...
Страница 300: ...Chapter 12 Monitoring and Control P54A B C E 274 P54xMED TM EN 1 ...
Страница 301: ...CHAPTER 13 SUPERVISION ...
Страница 302: ...Chapter 13 Supervision P54A B C E 276 P54xMED TM EN 1 ...
Страница 312: ...Chapter 13 Supervision P54A B C E 286 P54xMED TM EN 1 ...
Страница 323: ...CHAPTER 14 DIGITAL I O AND PSL CONFIGURATION ...
Страница 324: ...Chapter 14 Digital I O and PSL Configuration P54A B C E 298 P54xMED TM EN 1 ...
Страница 336: ...Chapter 14 Digital I O and PSL Configuration P54A B C E 310 P54xMED TM EN 1 ...
Страница 337: ...CHAPTER 15 FIBRE TELEPROTECTION ...
Страница 338: ...Chapter 15 Fibre Teleprotection P54A B C E 312 P54xMED TM EN 1 ...
Страница 354: ...Chapter 15 Fibre Teleprotection P54A B C E 328 P54xMED TM EN 1 ...
Страница 355: ...CHAPTER 16 ELECTRICAL TELEPROTECTION ...
Страница 356: ...Chapter 16 Electrical Teleprotection P54A B C E 330 P54xMED TM EN 1 ...
Страница 366: ...Chapter 16 Electrical Teleprotection P54A B C E 340 P54xMED TM EN 1 ...
Страница 367: ...CHAPTER 17 COMMUNICATIONS ...
Страница 368: ...Chapter 17 Communications P54A B C E 342 P54xMED TM EN 1 ...
Страница 439: ...CHAPTER 18 CYBER SECURITY ...
Страница 440: ...Chapter 18 Cyber Security P54A B C E 414 P54xMED TM EN 1 ...
Страница 457: ...CHAPTER 19 INSTALLATION ...
Страница 458: ...Chapter 19 Installation P54A B C E 432 P54xMED TM EN 1 ...
Страница 469: ...5 2 CASE DIMENSIONS 60TE E01409 Figure 197 60TE case dimensions P54A B C E Chapter 19 Installation P54xMED TM EN 1 443 ...
Страница 471: ...CHAPTER 20 COMMISSIONING INSTRUCTIONS ...
Страница 472: ...Chapter 20 Commissioning Instructions P54A B C E 446 P54xMED TM EN 1 ...
Страница 513: ...CHAPTER 21 MAINTENANCE AND TROUBLESHOOTING ...
Страница 514: ...Chapter 21 Maintenance and Troubleshooting P54A B C E 488 P54xMED TM EN 1 ...
Страница 530: ...Chapter 21 Maintenance and Troubleshooting P54A B C E 504 P54xMED TM EN 1 ...
Страница 531: ...CHAPTER 22 TECHNICAL SPECIFICATIONS ...
Страница 532: ...Chapter 22 Technical Specifications P54A B C E 506 P54xMED TM EN 1 ...
Страница 558: ...Chapter 22 Technical Specifications P54A B C E 532 P54xMED TM EN 1 ...
Страница 559: ...APPENDIX A ORDERING OPTIONS ...
Страница 560: ...Appendix A Ordering Options P54A B C E P54xMED TM EN 1 ...
Страница 565: ...APPENDIX B SETTINGS AND SIGNALS ...
Страница 566: ...Appendix B Settings and Signals P54A B C E P54xMED TM EN 1 ...
Страница 790: ...Appendix B Settings and Signals P54A B C E B224 P54xMED TM EN 1 ...
Страница 835: ...APPENDIX C WIRING DIAGRAMS ...
Страница 836: ...Appendix C Wiring Diagrams P54A B C E P54xMED TM EN 1 ...
Страница 849: ......