SEL-700G Protection, Control and Automation Leo Gaghan ...
Transcript of SEL-700G Protection, Control and Automation Leo Gaghan ...
S E L - 7 0 0 G P r o t e c t i o n , C o n t r o l a n d A u t o m a t i o n
L e o G a g h a n , C a s c o S y s t e m s
J a n u a r y 2 4 , 2 0 1 9
Table of Contents
Device Overview………………………………………………………….… 3Sample System………………………………………………………………. 4Logic Diagram………………………………………………………………… 5Example Protection Elements………………………………………… 9
Loss-of-Field (40)………………………………………………….…… 9Voltage-Controlled Overcurrent (51C)……………….…….. 12Ground Over Voltage (59G)…………………………….……..… 14100% Stator Protection (64G)………………………….….…… 16
Event Reporting………………………………………………….….……. 19References…………………………………………………………….….…. 24
Device Overview
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Example Protection Elements
Loss of Field (40)
The source of excitation for a generator may be completely or partially
removed through such incidents as accidental tripping of a field breaker, field
open circuit, field short circuit (flash over of the slip rings), voltage regulation
system failure, or the loss of supply to the excitation system. Partial or total
loss-of-field on a synchronous generator is detrimental to both the generator
and the power system which it is connected.
Sample System
Loss of Field (40)
The SEL-700G uses a pair of offset mho circles to detect loss-of-field.
Loss of Field (40)
Mho circles plotted against generator capability curve.
Voltage-Controlled Overcurrent (51C)
The differential relay generally provides primary fault protection for the
generator. Backup fault protection is also recommended to protect the
generator from the effects of faults that are not cleared because of failures
within the normal protection scheme. The backup relaying can be applied to
provide protection in the event of a failure at the generation station, on the
transmission system, or both.
Sample System
Voltage-Controlled Overcurrent (51C)
Ground Overvoltage (59G)
When a SLG fault occurs on an ungrounded system the effected phase
potential to ground goes to zero but the potential from that phase to the other
two phases does not change. The result is the un effected phases potential to
ground being increased by a square root of three and having a phase angle
difference of 60 degrees between each other. This phase arrangement creates
a zero-sequence voltage.
Sample System
Ground Overvoltage (59G)
100% Stator Protection (64G)
The SEL-700G provides a two-zone function designed to detect stator winding
ground faults on high-impedance grounded generators. The Zone 1 element
uses a fundamental-frequency neutral overvoltage element that is sensitive to
faults in the middle and upper portions of the winding. The Zone 2 element
uses a third-harmonic neutral undervoltage scheme to detect ground faults on
the lower portions of the winding
Sample System
100% Stator Protection (64G)
100% Stator Protection (64G)
No Load Full Load
Event Reporting
Event reporting can be triggered from any predefined logic or protection
element. Reports can be as long as 180 cycles (3 seconds) and can record
defined pre and post event lengths
Event reporting give's three phase oscillography as well as word bit status
during the duration of the event.
Can be remotely accessed with proper network configuration
Very helpful tool for troubleshooting
Event Reporting (Differential Trip)
Event Reporting (Lightning Arrestor Fail)
Event Reporting (Sync Capture)
Sync Report
References- Protective Relaying: Principles and Applications, 4th Edition by
Blackburn and Domin
- Protective Relaying for Power Generation Systems by Donald
Reimert
- IEEE Tutorial on Synchronous Generators: Cat. Number 95 TP 102
- IEEE Guide for AC Generator Protection, Standard C37.102-2006
- IEEE 1547 Standard for Interconnecting Distributed Resources with
Electric Power Systems
- SEL-700G Instruction Manual, Date Code 20180629
- Paul Shea and Todd Ward
THANK YOU !