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Abormality Report_TG Tripped

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ankit shukla

TG-1 tripped due to underfrequency and the gas turbine (GT) tripped due to reverse power flow after fans tripped, overloading the system. This caused the maximum demand to exceed the contract limit. The turbine first tripped on underfrequency protection and then the generator circuit breaker tripped on undervoltage. The GT then tripped on reverse power protection after fans tripped, isolating the only remaining generation source and overloading the GT.

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ABNORMALITY REPORT -2023 Page 1 of 7 CPSU/Elect./M-103/10/2023 Date: 23.06.2023 Sub: Abnormality report for TG-1 tripped on Under frequency and GT unloaded to FSNL (Reverse power relay operated) on 15.06.2023. Date& Time of Event: On 15/06/23 at 17:04:08 hrs. Effect on Plant: Maximum demand reached to 47.092 MVA (Contract demand 30.0 MVA). Description of events:  Before event, TG-1 was running @ at 11.0 MW (APR mode), GT was running @ 25.0 MW (PS mode), import was @15.0 MW. Total plant load was @ 51.0MW. TG-2 and Boiler-4 were under shutdown. Boiler-1,2 & 3 were running.  MRS 11 KV Bus-B Incomer feeder circuit breaker tripped on "HV CB Open" contact sensed by REC 670 relay falsely.  Hence, at 17:04:13:342 hrs. TG-1 isolated from grid (CCB open contact) came as per scheme and APR to AFR change over took place successfully. However, continuous hunting was observed in frequency and load; hence TG manual lift control command given to 50% by process group.  TG-1 Turbine tripped on under frequency stage-2 at 17:06:15:615 hrs.  At 17:06:26:51 TG1 generator circuit breaker & field circuit breaker tripped on Under voltage stage 2.  MRS Bus-B became dead hence CPP 11 KV INC-1 tipped on u/v at 17:06:28:494 and Auto change over took place in CPP 11 KV swgr successfully..  No any change over took place in downstream of swgrs of CPP and CPSU.  At 17:06:27.055, TK Fan-1 & 3 tripped on overload. Process tried to increase load on GT to maintain import but GT load was continuously on decreasing trend and at 17:10:32:064 GT tripped on reverse power stage-1 (FSNL) due to TKE fan 1 & 3 tripped on O/L as per logic. Active power at time of tripping registered : 2.05MW, Reactive power : 1.56 MVAR.
ABNORMALITY REPORT -2023 Page 2 of 7  At 17:18:34:052 GT synchronized after clearance from process.  At 18:15:54:563 TG#1 synchronized after clearance from process. TG-1 & GT GPR Relay events: Time Duration Event Setting 17:04:13:342 00:00:00.000 TG-1 isolated from Grid_ON. 17:05:52:607 00:01:39.265 81-1 Picked up_ ON 17:05:53:753 00:01:40.411 81-1 Picked up_ Off 17:06:02:766 00:01:49.424 81-1 Picked up_ ON 48 HZ & 1 Sec. 17:06:04:828 00:01:51.486 81-2 Picked up_ ON 17:06:14:826 00:02:01.484 81-2 Trip_ ON 47.5 HZ &10Sec 17:06:15:615 00:02:02.273 86T Trip_ ON 17:06:21:791 00:02:08.449 27-1 Under voltage V < picked up_ ON 87.3 % V 17:06:22:046 00:02:08.704 24-1 v/f> warning stage_ ON V/F -1.10 & 10 sec. 17:06:22:691 00:02:09.349 27-1 Under voltage V < trip_ ON 17:06:23:052 00:02:09.710 27-2 Under voltage V << Picked up_ ON 17:06:24.000 BFP-1 Tripped on process from DCS 17:06:26:051 00:02:12.709 27-2 Under voltage V << Trip_ ON 83.6 % & 3.09 sec. 17:06:26:051 00:02:12.709 27-2 Under voltage V << Trip_ ON 83.6 % & 3.09 sec. 17:06:26:078 00:02:12.736 86 U1U2 optd_ ON 17:06:26:145 00:02:12.803 TG1_FLCB&EXCON_ OFF 17:06:26:190 00:02:12.848 TG1_52G1 Close_ OFF 17:06:27:055 00:02:13.713 TK fan-3 trip on over load GT DCS Event
ABNORMALITY REPORT -2023 Page 3 of 7 17:06:27:055 00:02:13.658 TK fan-1 trip on over load GT DCS Event 17:06:28:494 00:02:15.152 11kV IC-1 Tripped on 27-1& BC Closed 53% @1000ms 17:10:22:066 00:06:08.724 GT_Reverse power picked_up_ON 17:10:32:064 00:06:18.722 GT_Reverse power trip_ON -1.5% @ 10 secs 17:10:32:065 00:06:18.723 GT_86 G1 trip relay_optd_ON 17:10:32:068 00:06:18.726 GT_86 G2 trip relay_optd_ON 17:10:32:151 00:06:18.809 GT_52G1 Open_ON 17:12:02:000 00:07:48.658 TK fan#2 started and clearance given for Sync. GT DCS Event 17:14:16:962 00:10:03.620 TG-1 isolated from Grid_OFF. 17:18:34:052 00:14:20.710 GT_52G1 Close_ON GT Syncronised 17:40:14:231 00:36:00.889 11kV IC-1 MCO & BC OFF 18:15:54:563 01:11:41.221 TG-1 _52G1 Close_ON TG-1 Syncronised Analysis:  TG#1 came on AFR as per CCB open contact received from MRS as per scheme. Hunting in frequency was observed and subsequently Turbine tripped on 86T relay actuated from 81-2 (47.5 HZ &10Sec). Further Generator CB & Field CB tripped on 27-2 (83.6 % & 3 sec.)  Since MRS Bus –B was isolated from MT-02 and TG#1was the only generation source available, after tripping of TG1 MRS Bus B got dead and 11kV I/C-1 of CPP that is from MRS Bus B got tripped on under voltage (27- 1, 53% @1000ms). A/C/O taken place successfully as per scheme.  During frequency hunting, running TK Fan-1 & Fan-3 tripped on overload. Both motors were on MRS Bus –B on which TG#1 was connected. Hence, motors were tripped during frequency hunting. Due to unavailability of TK-
ABNORMALITY REPORT -2023 Page 4 of 7 1/ 2 & 3 GT unload command given after 15 sec by MARK-VI as per logic. Auto start command of standby TK-2 was after 60secs from running fan trip, as per logic in MARK VI.  Refer Annexures for Trend view. Remedial action:  System worked as per scheme. QEHSEn (ISO 14001, 45001, 9001 & 50001) related impact:  Nil Sr. EE(AAS) Through: SM(PLP)------->SM(BGS) ------->CM(KKB) ------->AGM(RPT) BFP-1 tripped from DCS on process at 17:06:16.591 as per event list from REM620.
45 46 47 48 49 50 51 52 53 54 55 0 10 20 30 40 50 60 17:02:01 17:02:11 17:02:21 17:02:31 17:02:41 17:02:51 17:03:01 17:03:11 17:03:21 17:03:31 17:03:41 17:03:51 17:04:01 17:04:11 17:04:21 17:04:31 17:04:41 17:04:51 17:05:01 17:05:11 17:05:21 17:05:31 17:05:41 17:05:51 17:06:01 17:06:11 17:06:21 17:06:31 17:06:41 17:06:51 17:07:01 17:07:11 17:07:21 17:07:31 17:07:41 17:07:51 17:08:01 17:08:11 17:08:21 17:08:31 17:08:41 17:08:51 17:09:01 17:09:11 17:09:21 17:09:31 17:09:41 17:09:51 17:10:01 17:10:11 17:10:21 17:10:31 17:10:41 17:10:51 17:11:01 17:11:11 17:11:21 17:11:31 17:11:41 17:11:51 17:12:01 17:12:11 17:12:21 17:12:31 17:12:41 17:12:51 17:13:01 17:13:11 17:13:21 17:13:31 17:13:41 17:13:51 17:14:01 17:14:11 17:14:21 17:14:31 17:14:41 17:14:51 17:15:01 17:15:11 17:15:21 17:15:31 17:15:41 17:15:51 17:16:01 17:16:11 17:16:21 17:16:31 15/05/2023: TG1 Turbine tripped on 81-2 (47.5@10s) followed by GCB tripped on 27-2 (83.6%@3.09s) GT trunloaded to FSNL by TK1 & TK3 tripping on overload. Import Power GT Load TG#1 Load Total Load TG#1 Frequency GT Unloaded To FSNL CCB OPEN To TG#1, TG1 changed to AFR 86T ON_due to 81-2 Turbine Tripped TG-1 GCB Tripped on 27-2 ACO in CPP 11kv & MRS-B o/g feeders Annexure-A Note: Refer secondary axis for TG#1 frequency trend

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Abormality Report_TG Tripped

  • 1. ABNORMALITY REPORT -2023 Page 1 of 7 CPSU/Elect./M-103/10/2023 Date: 23.06.2023 Sub: Abnormality report for TG-1 tripped on Under frequency and GT unloaded to FSNL (Reverse power relay operated) on 15.06.2023. Date& Time of Event: On 15/06/23 at 17:04:08 hrs. Effect on Plant: Maximum demand reached to 47.092 MVA (Contract demand 30.0 MVA). Description of events:  Before event, TG-1 was running @ at 11.0 MW (APR mode), GT was running @ 25.0 MW (PS mode), import was @15.0 MW. Total plant load was @ 51.0MW. TG-2 and Boiler-4 were under shutdown. Boiler-1,2 & 3 were running.  MRS 11 KV Bus-B Incomer feeder circuit breaker tripped on "HV CB Open" contact sensed by REC 670 relay falsely.  Hence, at 17:04:13:342 hrs. TG-1 isolated from grid (CCB open contact) came as per scheme and APR to AFR change over took place successfully. However, continuous hunting was observed in frequency and load; hence TG manual lift control command given to 50% by process group.  TG-1 Turbine tripped on under frequency stage-2 at 17:06:15:615 hrs.  At 17:06:26:51 TG1 generator circuit breaker & field circuit breaker tripped on Under voltage stage 2.  MRS Bus-B became dead hence CPP 11 KV INC-1 tipped on u/v at 17:06:28:494 and Auto change over took place in CPP 11 KV swgr successfully..  No any change over took place in downstream of swgrs of CPP and CPSU.  At 17:06:27.055, TK Fan-1 & 3 tripped on overload. Process tried to increase load on GT to maintain import but GT load was continuously on decreasing trend and at 17:10:32:064 GT tripped on reverse power stage-1 (FSNL) due to TKE fan 1 & 3 tripped on O/L as per logic. Active power at time of tripping registered : 2.05MW, Reactive power : 1.56 MVAR.
  • 2. ABNORMALITY REPORT -2023 Page 2 of 7  At 17:18:34:052 GT synchronized after clearance from process.  At 18:15:54:563 TG#1 synchronized after clearance from process. TG-1 & GT GPR Relay events: Time Duration Event Setting 17:04:13:342 00:00:00.000 TG-1 isolated from Grid_ON. 17:05:52:607 00:01:39.265 81-1 Picked up_ ON 17:05:53:753 00:01:40.411 81-1 Picked up_ Off 17:06:02:766 00:01:49.424 81-1 Picked up_ ON 48 HZ & 1 Sec. 17:06:04:828 00:01:51.486 81-2 Picked up_ ON 17:06:14:826 00:02:01.484 81-2 Trip_ ON 47.5 HZ &10Sec 17:06:15:615 00:02:02.273 86T Trip_ ON 17:06:21:791 00:02:08.449 27-1 Under voltage V < picked up_ ON 87.3 % V 17:06:22:046 00:02:08.704 24-1 v/f> warning stage_ ON V/F -1.10 & 10 sec. 17:06:22:691 00:02:09.349 27-1 Under voltage V < trip_ ON 17:06:23:052 00:02:09.710 27-2 Under voltage V << Picked up_ ON 17:06:24.000 BFP-1 Tripped on process from DCS 17:06:26:051 00:02:12.709 27-2 Under voltage V << Trip_ ON 83.6 % & 3.09 sec. 17:06:26:051 00:02:12.709 27-2 Under voltage V << Trip_ ON 83.6 % & 3.09 sec. 17:06:26:078 00:02:12.736 86 U1U2 optd_ ON 17:06:26:145 00:02:12.803 TG1_FLCB&EXCON_ OFF 17:06:26:190 00:02:12.848 TG1_52G1 Close_ OFF 17:06:27:055 00:02:13.713 TK fan-3 trip on over load GT DCS Event
  • 3. ABNORMALITY REPORT -2023 Page 3 of 7 17:06:27:055 00:02:13.658 TK fan-1 trip on over load GT DCS Event 17:06:28:494 00:02:15.152 11kV IC-1 Tripped on 27-1& BC Closed 53% @1000ms 17:10:22:066 00:06:08.724 GT_Reverse power picked_up_ON 17:10:32:064 00:06:18.722 GT_Reverse power trip_ON -1.5% @ 10 secs 17:10:32:065 00:06:18.723 GT_86 G1 trip relay_optd_ON 17:10:32:068 00:06:18.726 GT_86 G2 trip relay_optd_ON 17:10:32:151 00:06:18.809 GT_52G1 Open_ON 17:12:02:000 00:07:48.658 TK fan#2 started and clearance given for Sync. GT DCS Event 17:14:16:962 00:10:03.620 TG-1 isolated from Grid_OFF. 17:18:34:052 00:14:20.710 GT_52G1 Close_ON GT Syncronised 17:40:14:231 00:36:00.889 11kV IC-1 MCO & BC OFF 18:15:54:563 01:11:41.221 TG-1 _52G1 Close_ON TG-1 Syncronised Analysis:  TG#1 came on AFR as per CCB open contact received from MRS as per scheme. Hunting in frequency was observed and subsequently Turbine tripped on 86T relay actuated from 81-2 (47.5 HZ &10Sec). Further Generator CB & Field CB tripped on 27-2 (83.6 % & 3 sec.)  Since MRS Bus –B was isolated from MT-02 and TG#1was the only generation source available, after tripping of TG1 MRS Bus B got dead and 11kV I/C-1 of CPP that is from MRS Bus B got tripped on under voltage (27- 1, 53% @1000ms). A/C/O taken place successfully as per scheme.  During frequency hunting, running TK Fan-1 & Fan-3 tripped on overload. Both motors were on MRS Bus –B on which TG#1 was connected. Hence, motors were tripped during frequency hunting. Due to unavailability of TK-
  • 4. ABNORMALITY REPORT -2023 Page 4 of 7 1/ 2 & 3 GT unload command given after 15 sec by MARK-VI as per logic. Auto start command of standby TK-2 was after 60secs from running fan trip, as per logic in MARK VI.  Refer Annexures for Trend view. Remedial action:  System worked as per scheme. QEHSEn (ISO 14001, 45001, 9001 & 50001) related impact:  Nil Sr. EE(AAS) Through: SM(PLP)------->SM(BGS) ------->CM(KKB) ------->AGM(RPT) BFP-1 tripped from DCS on process at 17:06:16.591 as per event list from REM620.
  • 5. 45 46 47 48 49 50 51 52 53 54 55 0 10 20 30 40 50 60 17:02:01 17:02:11 17:02:21 17:02:31 17:02:41 17:02:51 17:03:01 17:03:11 17:03:21 17:03:31 17:03:41 17:03:51 17:04:01 17:04:11 17:04:21 17:04:31 17:04:41 17:04:51 17:05:01 17:05:11 17:05:21 17:05:31 17:05:41 17:05:51 17:06:01 17:06:11 17:06:21 17:06:31 17:06:41 17:06:51 17:07:01 17:07:11 17:07:21 17:07:31 17:07:41 17:07:51 17:08:01 17:08:11 17:08:21 17:08:31 17:08:41 17:08:51 17:09:01 17:09:11 17:09:21 17:09:31 17:09:41 17:09:51 17:10:01 17:10:11 17:10:21 17:10:31 17:10:41 17:10:51 17:11:01 17:11:11 17:11:21 17:11:31 17:11:41 17:11:51 17:12:01 17:12:11 17:12:21 17:12:31 17:12:41 17:12:51 17:13:01 17:13:11 17:13:21 17:13:31 17:13:41 17:13:51 17:14:01 17:14:11 17:14:21 17:14:31 17:14:41 17:14:51 17:15:01 17:15:11 17:15:21 17:15:31 17:15:41 17:15:51 17:16:01 17:16:11 17:16:21 17:16:31 15/05/2023: TG1 Turbine tripped on 81-2 (47.5@10s) followed by GCB tripped on 27-2 (83.6%@3.09s) GT trunloaded to FSNL by TK1 & TK3 tripping on overload. Import Power GT Load TG#1 Load Total Load TG#1 Frequency GT Unloaded To FSNL CCB OPEN To TG#1, TG1 changed to AFR 86T ON_due to 81-2 Turbine Tripped TG-1 GCB Tripped on 27-2 ACO in CPP 11kv & MRS-B o/g feeders Annexure-A Note: Refer secondary axis for TG#1 frequency trend