Islanding System
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Transcript of Islanding System
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 1/22
Islanding System in RSP An Overview
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 2/22
Islanding Deliberate act of Isolation of a running Unit/s
with compatible loads to save the Unit/s from
tripping when Grid is having unstable
condition.
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 3/22
RSP Power System..
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 4/22
Islanding Scheme…
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 5/22
Islanding with One unit..
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 6/22
Sensing Islanding Condition …
• At MSDS-II:
– Single Unit Islanding &
– Double Unit Islanding
• Relay 1A & 1B connected to HSL Feeder-1
• Relay 2A & 2B connected to HSL Feeder-2 – MiCOM P341 (Areva Make) numerical relays
• At CPP-II
– Single Unit followed by Double Unit Islanding• FCX Relay connected to 132kV Islanding Bus CVT
– Sensing Under frequency during islanded condition
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 7/22
Islanding Conditions …
• Directional O/C ( E/F) combined with Under
Voltage
– Over Current
• Directional Forward ( towards line)
• IEC E Inv, 300A ( Each Feeder), TMS-0.125 – 150A, 0.125 for One Generator / One Feeder condition
– Under Voltage
• Definite Time
• 52.66 kV ( 70%) Phase- Neutral
• Time Delay- 0 s
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 8/22
Islanding Conditions …
• Reverse Power combined with U/F
– Reverse Power
• Directional Forward ( towards line)
• 28.8MW ( Each Feeder) for 5 Sec
– Under Frequency
• 48 Hz for 1.0 Sec
• Pure Under Frequency
– 47.6 Hz for 300 ms
• Rate of change of Frequency – 1.5 Hz /sec ( +/-)
– Time Delay 200 ms
– Inhibit band – 49.5 – 50.5 Hz
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 9/22
Islanding Conditions …
• Under Voltage (pure)
– 60 kV ( 80%) ( Phase to Neutral)
– Definite Time ; Time delay 1.5 sec
• Over Voltage – 91.2 kV ( 120%) ( Phase to Neutral)
– Definite Time ; Time delay 2.0 sec
• Voltage Vector shift
– 10 Degree
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 10/22
Sequence Logic …
1A 1B
2A 2B
OR d1 b1
d2/d3
d4
CPP-1 CPP-2DU
SU
TRIP HSL FDR-1 & 2
HSL FDR-1 OFF
HSL FDR-2 OFF
AND d5
MSDS-2
RM-2
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 11/22
Sequence Logic …
OR
d9
d6
RM-1
MSDS-3SU
DU
TRIP
SEC-2 B/C
CPP-1
MSDS-2
d8
CPP-2 U/F
SU
SU
DU
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 12/22
Sequence Logic …
OR
C21 TRIP MD2 LINE
CPP-2
MSDS-2
C22
CPP-1
FCX
DUAND
U1
U2
DU
DU
AND
AND
RH29
AND
G1 G2
AND
AND
OR
U1
U2
U1
U2
U2
U1
SU
SUAND
SUU2U1
TRIP B/C
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 13/22
Synchronisation…
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 14/22
Evolution …
CPP-1-GEN
CPP-1-GRID
RM-2
MSDS-3
MSDS-3
CPP-2 MSDS-2
MSDS-2
I nception
1980
1987
1997
1989-90 RM-1 Gen
RM-1 Grid
33 KV GRID
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 15/22
Evolution of Islanding Scheme …
• Since inception
– Isolation from grid at CPP-I and RM-1 through voltage
dependent U/F relays.
• Independent Relays at CPP-1 and RM-1
• 1987
– CPP-2 units commissioned
– No Islanding scheme was available for CPP-2 units.
• 1989
– Single Unit Islanding scheme commissioned• U/F, -dF/dt & U/V isolation provided
– Scheme suggested by Consultant (TCE)
– Although Double Unit Islanding scheme was provided by consultant, it
was not taken into service.
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 16/22
Evolution of Islanding Scheme …
• 1999
– Islanding on U/V kept defected.
• To prevent isolation followed by tripping of Islanded unit
during U/V caused by internal faults.
• 2000 – DOC Islanding put into service
• Current feedback to grid combined with Under Voltage
initiated isolation
• Isolation of HSL Fdr- 1&2 at MSDS-II
• IEC SI curve for DOC
– DU and SU islanding also included in the scheme.
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 17/22
Evolution of Islanding Scheme …
• 2002
– Numerical Islanding relay installed at MSDS-2
– DOC / DEF combined with U/V used for double
unit isolation.
• 2005
– DOC /DEF combined with U/V implemented for
Single Unit Islanding also.
• 2006 – Islanding scheme as in service now implemented.
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 18/22
Features of Present Scheme…
• Sensing of all islanding conditions shifted to MSDS-2
( Common Coupling point)• dF/dt rise, Over voltage , Over Frequency, Under
Voltage and Vector Shift introduced.
• IEC EI characteristics for DOC/ DEF
– For in-sensitivity to remote end faults
• Directional O/C & E/F relays introduced in grid sideof HSL fdr.
– To prevent tripping in case of grid fault.
• Dynamic relay setting for single Unit/ single Feeder configuration.
• Dedicated Islanding Panel commissioned in MSDS-2
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 19/22
Constraints….
• Post islanding stability of CPP-2 units is not
satisfactory.
– No of failure of Units after successful isolation is very high
– Problems attributed to Governing & Excitation system
• System is not designed from islanding perspective
– No dedicated load connected to generator bus
– All grid faults are terminal faults to CPP-2 generators.
– Transmission & Distribution configuration is inadequate in
isolated condition
– Multi-point isolation.
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 20/22
Constraints…. • Constraints of Islanding Load
– Fluctuating Loads have to be shed during islanded condition
– Manual estimation islanding loads.
– Post islanding load management feature not available
– Failure of islanding due to load-starvation
• Failure of islanding due to non-system faults
– Complicated Sequence logic
– Multiple islanding locations connected by control cabling
– CPP-2 unit status and Grid Power status not available in
islanding scheme
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 21/22
Constraints…
• Difficult synchronization process
– Synchronization facility not available in Common Coupling
point ( MSD-2)
– Multiple operations required for synchronization.
– Multiple asynchronous points• CPP-1 & CPP-2 not running synchronism after
islanding
– Limit on islanding loads even in presence of generation
capability
• Information for Disturbance / Failure analysis not
available
7/30/2019 Islanding System
http://slidepdf.com/reader/full/islanding-system 22/22
Actions…
• Dedicated control cables between islanding locations
– Status of Grid side CB of HSL feeders and CPP-2 unit CBshall be available
– No. of interposing relays shall be reduced- Islanding
commands shall be transmitted radially.
• Cable Laying job under progress- completion expected by Mar’07
• Redundant Islanding relays
– Ensure 100% sensing of islanding conditions
• Commissioned in Jun’06
• Third HSL Feeder to MSDS-3
– HSM/LHF can run during islanding(if power is available)
– Synchronization shall be easier.
• Job under progress- expected by APR’07