GE L30

GE Multilin L30 Line Current Differential System vii
TABLE OF CONTENTS
7.1.5 RELAY MAINTENANCE .................................................................................... 7-3
7.1.6 PHASOR MEASUREMENT UNIT ONE-SHOT.................................................. 7-4
7.1.7 SECURITY ......................................................................................................... 7-5
7.1.8 TARGETS MENU............................................................................................... 7-6
7.1.9 TARGET MESSAGES ....................................................................................... 7-6
7.1.10 RELAY SELF-TESTS......................................................................................... 7-6
8. THEORY OF OPERATION 8.1 OVERVIEW
8.1.1 L30 DESIGN ...................................................................................................... 8-1
8.1.2 L30 ARCHITECTURE ........................................................................................ 8-1
8.1.3 REMOVAL OF DECAYING OFFSET................................................................. 8-2
8.1.4 PHASELET COMPUTATION............................................................................. 8-2
8.1.5 DISTURBANCE DETECTION............................................................................ 8-3
8.1.6 FAULT DETECTION .......................................................................................... 8-3
8.1.7 GROUND DIFFERENTIAL ELEMENT............................................................... 8-4
8.1.8 CLOCK SYNCHRONIZATION ........................................................................... 8-5
8.1.9 FREQUENCY TRACKING AND PHASE LOCKING.......................................... 8-6
8.1.10 FREQUENCY DETECTION............................................................................... 8-7
8.1.11 PHASE DETECTION ......................................................................................... 8-7
8.1.12 PHASE LOCKING FILTER .............................................................................. 8-10
8.1.13 MATCHING PHASELETS................................................................................ 8-11
8.1.14 START-UP ....................................................................................................... 8-11
8.1.15 HARDWARE AND COMMUNICATION REQUIREMENTS ............................. 8-11
8.1.16 ONLINE ESTIMATE OF MEASUREMENT ERRORS ..................................... 8-12
8.1.17 CT SATURATION DETECTION ...................................................................... 8-13
8.1.18 CHARGING CURRENT COMPENSATION ..................................................... 8-13
8.1.19 DIFFERENTIAL ELEMENT CHARACTERISTICS........................................... 8-14
8.1.20 RELAY SYNCHRONIZATION.......................................................................... 8-15
8.2 OPERATING CONDITION CHARACTERISTICS
8.2.1 DESCRIPTION................................................................................................. 8-16
8.2.2 TRIP DECISION EXAMPLE............................................................................. 8-18
8.2.3 TRIP DECISION TEST .................................................................................... 8-18
8.3 FAULT LOCATOR
8.3.1 DESCRIPTION................................................................................................. 8-20
9. APPLICATION OF
SETTINGS
9.1 CT REQUIREMENTS
9.1.1 INTRODUCTION................................................................................................ 9-1
9.1.2 CT SATURATION ANALYSIS TOOL................................................................. 9-2
9.2 CURRENT DIFFERENTIAL (87L) SETTINGS
9.2.1 INTRODUCTION................................................................................................ 9-4
9.2.2 CURRENT DIFFERENTIAL PICKUP................................................................. 9-4
9.2.3 CURRENT DIFF RESTRAINT 1 ........................................................................ 9-4
9.2.4 CURRENT DIFF RESTRAINT 2 ........................................................................ 9-4
9.2.5 CURRENT DIFF BREAK POINT ....................................................................... 9-4
9.2.6 CT TAP .............................................................................................................. 9-5
9.3 CHANNEL ASYMMETRY COMPENSATION USING GPS
9.3.1 DESCRIPTION................................................................................................... 9-7
9.3.2 COMPENSATION METHOD 1 .......................................................................... 9-7
9.3.3 COMPENSATION METHOD 2 .......................................................................... 9-8
9.3.4 COMPENSATION METHOD 3 .......................................................................... 9-8
9.4 INSTANTANEOUS ELEMENTS
9.4.1 INSTANTANEOUS ELEMENT ERROR DURING L30 SYNCHRONIZATION. 9-10
10. COMMISSIONING 10.1 TESTING
10.1.1 CHANNEL TESTING ....................................................................................... 10-1
10.1.2 CLOCK SYNCHRONIZATION TESTS ............................................................ 10-2
10.1.3 CURRENT DIFFERENTIAL ............................................................................. 10-3