covering note for ppi anual fy 09 report fy-09 final .pdfnon operation of siemens make 7sv6001 lbbu...
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Protection Performance
Analysis Report FY 09
Electrical Testing and Automation Division (ET&A)
PPA FY - 09 Annual Report Page 1 of 8
Electrical Testing and Automation Division (ET&A)
Protection Performance Analysis Report for the year FY 09
1. Protection Performance Index
The Security Index for the year FY09 is 96.95% as against 98.34% for FY08. This is below the targeted level of 98.90%. The Dependability and the Reliability Indices are 99.73% and 96.69% respectively, which are also below last year’s achievements. The Security index is lower than last year on account of mal-operation of relays due to wrong relay setting adoptions, three terminal line operation and defective LBBU & Buchholz relays. Nc = No. of correct tripping =1111 Nf = No. of failure to Operate (Missing operation) = 03 Nu = No of Unwanted Operations (Incorrect tripping) = 35
Security Index (PPI) = Nc / (Nc + Nu)
Dependability Index = Nc / (Nc + Nf)
Reliability Index = Nc / (Nc + Nf + Nu)
2. Analysis of Relay Mal-operation (Faulty relays)
The details of instances of relay mal-operations are given in Table 1. Relay make
Relay Type No Date Station Description of relay mal-
operation Learning /
Actions
ABB LBBU-RAICA 1 21.09.08 Dharavi
Defective Module in 220 kV BD-7 line LBBU relay caused operation of bus Fault of zone-1
Defective RXIB24 relay of LBBU was replaced
ABB LBBU-RAICA 1 01.02.09 Carnac
Suspected Mal-operation of LBBU relays of 110 kV Bkr on bus section-2, caused 110 KV GIS bus-2 shutdown
LBBU relays were made inoperative for observation. Replacement is planned.
ABB Dead M/C -
RAGUA 1 13.01.09 Trombay-A
Unit-4 tripped on Dead Machine Protection for fault on 110 kV Tr-Chem-3 line
Mal-Operation of timer in RAGUA Dead M/C relay. Defective unit was replaced
Security Index (PPI)
98.3498.86
98.1296.95
90
95
100
FY 06 FY 07 FY 08 FY 09
Years
PP
I (%
)
�
Dependability Index
99.7999.64 99.82 99.73
90
95
100
FY 06 FY 07 FY 08 FY 09Years
(%)
� Reliability Index (PPI)
97.78 98.1498.69
96.69
90
95
100
FY 06 FY 07 FY 08 FY 09Years
(%)
�
Faulty Relays
14
17
129
0
5
10
15
20
FY 06 FY 07 FY 08 FY 09
YearsN
o. o
f Trip
ping
�
PPA FY - 09 Annual Report Page 2 of 8
Electrical Testing and Automation Division (ET&A)
Siemens 7SV600 1 25.04.08 Khopoli Non Operation of SIEMENS make 7SV6001 LBBU relay which was found defective.
Defective relay was replaced.
AREVA SGNH 163 1 17.07.08 Bhira
25 MW Gen. Unit-5 tripped, without relay action, Failure of power supply module in Differential relay (Static High Impedance Differential relay) observed
Fault relay was replaced by spare relay
Buchholz 3
05.07.08 10.10.08 16.10.08
Malad Bhivpuri Dharavi
10 MVA 22 kV/11 kV DT-1 tripped due to Mal-operation of Buchholz relay for AB phase Fault at BMC end 1 MVA Trf tripped by Buchholz protection. Trf IR & mag. Balance were OK. Buchholz relay was replaced 75 MVA DT -3 tripped on Buchholz protection
Old Buchholz relay was replaced by better designed Buchholz relay
OSR 1 05.08.08 Borivli
10 MVA 22/11 kV Distribution trf-2 tripped by OSR of OLTC. Reason could not be established. Suspected mal-operation of OSR relay,
Transformer tested ok and was cleared for service
Total 9 Table 1: Details of Relay Mal-operation
3. Other Causes of Protection Defects:
The number of defects due to sneak circuits (tracking across terminals etc.) are same as in FY 08. In first case, 110 kV bkr of ICT-5 tripped by breaker trip relay operation due to DC Ground (220 V DC bus-2 DC ground had appeared at the time of occurrence). In the second case, Unit-9 at Khopoli tripped because of Auxiliary contact problem of Breaker causing governor to initiate Emergency shutdown of unit. Thirdly 110 kV bkr of Salsette-Dharavi line tripped because of, sulphation on Breaker control switch which was replaced.
Trippings Due to Sneak Ckts
34
1
3
0
2
4
6
FY 06 FY 07 FY 08 FY 09
Years
No.
of T
rippi
ng
�
PPA FY - 09 Annual Report Page 3 of 8
Electrical Testing and Automation Division (ET&A)
4. Analysis of Total Number of Trippings
Total number of tripping in the system had gone down by 20.86 % to 1146 as compared to FY 08. The decrease in tripping is on account of better surveillance of cable route, improved transmission line maintenance practices and “Jan-Jagruti Abhiyan” initiative taken up by T&D division. Also, replacement of electromechanical relays by numerical relays contributed in reduction of wrong trippings.
110 kV Line Trippings FY 09
Transient AccidentInclement Bird/AnimalKite String Relay Set t ing problemConductor Part ing Relay M al-Operat ionInsulator Equipment FailureConductor Theft
220 kV Line Trippings FY 09
Transient Kite St ring Conductor Part ing Inclement
Replacement of Static / Electro-mechanical distance relays by Numerical relays was achieved on almost all 110 kV lines except few locations. Difficulty in setting distance relays for three terminal lines resulted in increase of tripping of 110 kV lines. The number of trippings in Tata System had decreased by 12.45 % from 771 in FY 08 to 675 in FY 09. The number of tripping in the months of May, August & October FY09 were considerably higher than the corresponding numbers in FY 08.
Tata System Trippings
0
40
80
120
Apr
-08
May
-08
Jun-
08
Jul-0
8
Aug
-08
Sep
-08
Oct
-08
Nov
-08
Dec
-08
Jan-
09
Feb
-09
Mar
-09
No
of tr
ippi
ngs
FY 08 FY 09
110 kV Line Trippings
1158491
132
0
50
100
150
FY 06 FY 07 FY 08 FY 09Years
No.
of T
rippi
ng
� 220 kV Line Trippings
25
46
26
15
0
10
20
30
40
50
FY 06 FY 07 FY 08 FY 09Years
No.
of T
rippi
ng
�
Total Trippings1706
16741448
1146
1000
1400
1800
FY 06 FY 07 FY 08 FY 09Years
No.
of T
rippi
ng
�
PPA FY - 09 Annual Report Page 4 of 8
Electrical Testing and Automation Division (ET&A)
5. Overhead Line faults
Overhead Line faults (snapping of conductors, jumpers, tower collapsing and Conductor theft) had come down compared to last year. The number of line faults in FY 09 is 7 compared to 22 in FY 08. Three occasion of Copper Conductor thefts were reported on 110 kV Bhira-Khopoli line-1/2. Further there was four occasion of conductor parting .
6. Failure / Defects of Switchgear / Switchyard Equipment
There was only one cases of breaker failure in the system. At Khopoli for 110 KV Unit-9 breakers, failure of operating rod linkage mechanism of A & B phase poles was observed.
Bushing / Insulator failures show decreasing trend. There were five instances of 22 kV bushing failure at a) Kalyan (75 MVA trf-3 LV), b) Dharavi (Direct fdr-23), c) Trombay (BPCL-2), d) Parel (Fdr-77), e) Salsette (Consumer-HDFC s/s). Other three instances are oil leakage in 433 V bushing at station transformer at Mahalaxmi R/S, 110 kV support insulator shattering at Trombay and flashover of string insulator on 110 kV Parel-Mkd line. Number of CT/PT/CVT failures had increased in FY 09 as compare to FY 08. All failures of 22 KV CT’s, One CT failed at Dharavi due to opening of CT secondary and other three CT’s failed at Trombay G/S.
Line Faults
17
9
22
7
0
10
20
30
FY 06 FY 07 FY 08 FY 09Years
No.
of F
ailu
res
�
Bushing / Insulator failures
12
88
4
0
5
10
15
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
� CT / PT / CVT failures
34
2
8
0
5
10
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
�
Breaker Defects
5
89
1
0
4
8
12
FY 06 FY 07 FY 08 FY 09
Years
No.
of f
ailu
res
�
PPA FY - 09 Annual Report Page 5 of 8
Electrical Testing and Automation Division (ET&A)
There were three case of Lighting Arrester (LA) failures viz. two numbers 110 kV LA failure at Mankhurd (30 MVA trf-2) & Trombay B (ICT-5), and third case was 5 kV LA failure at Bhivpuri G/S. The 110 kV LA failure were attributed to moisture ingress into LA. Capacitor bank unit failures have decreased in FY 09 compared to FY 08.
One consumer transformer at Tata Interactive sub-station was found defective and was replaced.
At Trombay Unit-7B Generator was having stator winding failure, due to Partial discharge and the same was attended.
7. Cable faults
The numbers of cable faults were 78 in FY 09 as compared to 130 in FY 08.
8. Equipment Failure Analysis
Equipment Failure FY 09
78
9 8 8 4 3 2 2 10
50
100
150
Cable Fault
Capacitor bank
Line fault
Bushing/Insulator
CT/PT/CVT
LA Failure
Breaker failure
Transformer faults
Generator faults
No
of fa
ults
LA failures
4
3
1
3
0
3
6
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
� Capacitor Bank failures
15
11
14
9
0
10
20
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
�
Cable Faults
63
106130
78
0
50
100
150
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
�
PPA FY - 09 Annual Report Page 6 of 8
Electrical Testing and Automation Division (ET&A)
It can be seen that cable faults, Line faults (conductor parting & theft / snapping), faults on capacitor bank units, bushing/Insulator and breaker failure constitute the majority of equipment failure. Division-wise drill down of the four major classes of equipment failure (on the basis of number of failures) is given below.
Capacitor Bank Faults FY 09
0
2
4
6
Kalyan Kolshet Vikhroli Parel Dharavi Malad
Station w ise Bird / Animal Faults FY 09
0
2
4
6
8
10
Trombay Borivli Dharavi Khopoli Kalyan
Salsette Chembur Kolshet Saki
Line Faults FY 09
0
2
4
6
110 kV BK-1 110 kV TD-1 110 kV BM -2 Dharavi 110 kV LCM
9. Faults due to Birds / Animals
Station wise Bird / Animal Faults FY 09
0
2
4
6
8
10
No
of
Trip
ping
s
Trombay Borivli Dharavi
Khopoli Kalyan Salsette
Che mbur Kolshet Saki
Month w ise Bird / Animal Faults FY 09
0
5
10
15
No
of T
rippi
ngs
Apr-08 M ay-08 Jun-08 Jul-08 Aug-08 Sep-08Oct-08 Nov-08 Dec-08 Jan-09 Feb-09 M ar-09
The chart alongside shows the number of faults due to Birds / Animals. It can be seen that the number has decreased from 52 in FY08 to 28 in FY09. The charts below shows the Division-wise and month-wise break-up of bird/animal faults during FY 08. It is observed that the Bird faults occur maximum in the month of April and May (Nesting season).
Bird / Animal Electrocution
49
75
52
28
0
20
40
60
80
FY 06 FY 07 FY 08 FY 09Years
No.
of f
ailu
res
�
PPA FY - 09 Annual Report Page 7 of 8
Electrical Testing and Automation Division (ET&A)
10. Trippings Due to Human Error
Nine incidences of tripping due to human error were reported as given in table -2 Sr. No Type Station Tripping Reason Action
1 Trombay A
220 kV bkr ICT-4, ICT-5 and 110 kV ST Bus Section bkr tripped, 110 kV LA of ICT-4 failed
Wrong relay settings adopted on 220 kV bkr of ICT-5 OC relay caused tripping. Blocking arrangement of Inst settings was disturbed on OC relay of 110 kV ST BS bkr
ICT - 5 was taken in service after adopting correct relay settings & Inst setting was blocked for ST BS bkr.
2 Lodhivli /
Chembur / Mankhurd
110 kV Chembur-Lodhivli -Mankhurd line tripped. 110 kV Parel - Mankhurd line tripped
Transient fault on Mankhurd-Lodhivli line section. In absence of carrier acceleration scheme adopted relay setting of Zone-2 timing was 0.35 sec, against advised 0.20 sec. The Parel end relay has operated in zone-2 and same caused Mankhurd shut down.
The Zone-2 setting was set to 0.20 sec at all three stations.
3
Relay
Setting Adoption
Trombay / Dharavi
110kV Trombay - Dharavi line no.2 tripped, 110 kV PM-2 and DM lines tripped at Mahalaxmi end.
Two people came in arcing of TD-2 line Near Naik nagar Sion. The 110 kV PM-2 and DM line tripped due to wrong relay settings adopted on Dir Over current relays at Mahalaxmi R/S
Adopted correct relay settings
4 Switching error Saki
22 kV Bus Section-3 got shut down without relay target
22 kV BS bkr 2-3 was open inadvertently before closing Trf-3 LT bkr-3A during normalization of 22 kV bus after schedule outage of Trf-1
Operational error
5 Testing error Trombay B ST # 7 tripped on
differential Protection
Inadvertently injected current in differential circuit during commissioning of new FDR in Unit -07
Trf taken into service immediately, after consulting
6 Trombay A
110 kV TP-4 line tripped at Trombay end without relay action
DC grounding problem appeared in 110 kV DT-5 bkr while replacing pressure switch. SCADA shows Low pressure Alarm for TP-4 bkr. Nothing abnormal found during inspection.
Bkr taken into service
Others
Table 2 : Analysis of Tripping due to Human Error in FY09
Trippings Due to Testing Error
1
32
1
01
2
3
4
FY 06 FY 07 FY 08 FY 09
Years
No.
of T
rippi
ng
� Trippings Due to Switching Error
1
5
2
6
0
4
8
FY 06 FY 07 FY 08 FY 09
Years
No.
of T
rippi
ng
�
PPA FY - 09 Annual Report Page 8 of 8
Electrical Testing and Automation Division (ET&A)
11. Major Recommendations for Protection system improvements
1. Knowledge sharing with O&M Engineers on Protection schemes & its Settings is suggested to reduce human errors in relay settings adoption and correct tarter reporting during faults
2. Commissioning of Line differential relays on three terminal lines is proposed to overcome the relay setting difficulties and to achieve fast clearance of faults.
3. Replacement of LBBU relays (RAICA) by Numerical Relays at all stations is recommended as these relays are failing due to ageing.
4. Replacement of old Over Load Trimming scheme (OLTS) on transmission lines and Transformers is recommended to reduce faulty operations.
5. Protection up-gradation by replacing ageing electromechanical and static relays by numerical relays to be taken up on priority.
6. Relay Networking for faster analysis and corrective action to be done. 7. Time synchronisation of FDR’s, Numerical Relays, On line monitoring devices and
SCADA system to be done for proper fault analysis and quick restoration. 8. Online condition monitoring devices for breaker, Transformer, cables etc. to be
explored to identify faults in incipient stage. 9. DCRM (Dynamic Contact Resistance Measurement) test, testing with travel
transducers to be taken up to identify breaker mechanism problem. These measures more useful for PASS type hybrid breakers as conventional testing is not possible to do for these.
10. Criss crossing of transmission line to be avoided to minimize simultaneous tripping of lines.
Enclosed: Monthly Protection Performance and Protection Analysis – Weekly Reports for FY 09
AVJ / SKP / TMK / MVK