7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
1/23
23/05/2012. power system protection 1
Power system Protection
Visited Grid stations1) 500 KV Sheik Muhammadi Grid Station.2) 220 KV Grid Station near khazana Sugar Mill .
Group members
Zahid ur RehmanShaiq Ali.Najib Ullah Afridi.Shabir Asghar.
Dept: of Electrical Power Engineering UET Peshawar.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
2/23
23/05/2012. power system protection 2
Why protection system is Necessary .
Impossible and uneconomical to build faultfree Power system.
Small disturbances handled by controlsystem.Severe disturbance can jeopardize P.S
Needs a separate protection for handlingthese faults.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
3/23
23/05/2012. power system protection 3
Protection system basic
goal.Detection & disconnection of faulty section.
Reasons:-Unnecessary interruption to consumers.
Prevention of Spreading of fault. Assures System stability .
Consumer devices are not made to carry faultcurrent for longer period of time.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
4/23
23/05/2012. power system protection 4
Schemes of Protection.1) Generators.2) Low tension Switch gear.3) Transformer.4) High tension Switch gear.5) Transmission lines.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
5/23
23/05/2012. power system protection 5
General Introduction.500kv S/C 4 bundled conductor Line fromtarbela.
Two auto transformer 500/220kv each rated450MVA .220KV line from Ghazi Brotha.
220kv/132kv khazana grid.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
6/23
23/05/2012. power system protection 6
Essential Elements.Power Line Carrier Traps.Mainly used for telecomm: , teleprotection & telemonitoring.Frequency Range: 272kHz-700kHz.
CCVT:Step down the EHV signals for measurmentand protection.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
7/23
23/05/2012. power system protection 7
Continue
Surge arresters:To protect against the lightning andswitching strokes.
Always on the live wireBased on metal oxide varistor.Eearthing of switchyard.Increased safety.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
8/23
23/05/2012. power system protection 8
Continue
Isolating switches:Used for de-energizing of the lines formaintenance.Earth switches.Circuit Breakers:
Used for the disconnection of the faultyelement from the PS.SF6 is used as a quenching media.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
9/23
23/05/2012. power system protection 9
Continue.
INSULATORS:Porcelain and glass insulators are used.The dielectric strength is as follow;Porcelain:11.5kv/disc.Glass:110kv/disc.
One and half breaker scheme .To increase reliability.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
10/23
23/05/2012. power system protection 10
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
11/23
23/05/2012. power system protection 11
Components of Protection.
Fuses.C.Ts & P.Ts
Circuit breaker.Relays.
Auto reclosers.
Spark gap and surge arrester.Isolaters and earth switches.FACTS , SVC, TPSC,SCCL..
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
12/23
23/05/2012. power system protection 12
Transmission lines ProtectionDistance Protection.Total length 117 km.Primary protection ( static distancerelays).L-G, L-L , L-L-L-G faults .
Back up protection (Electromechanicaldistance relays).Grid faults or system fault indications.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
13/23
23/05/2012. power system protection 13
Transmission lines ProtectionCarrier current protection.Carrier added protection.Pilot protection.Optical fibre / shielding line protection.
O.C relay coupled with distance relay .
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
14/23
23/05/2012. power system protection 14
Transmission line zonesZone 1: 85% of total length.Zone 2: 50 % of total length.Zone 3: 25 % of total length.Zone 4: 15 % of total length.
No pet rule for zoning .Zoning based on importance of TX-line.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
15/23
23/05/2012. power system protection 15
Bus Bar protection.High impedance differential relay.
Voltage based protection.No C.T on busbars.Dangreous protection scheme.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
16/23
23/05/2012. power system protection 16
Transformer Protection.
Over current protection.Differential Relay.Earth fault relay.Restricted Earth fault.
Tertiary O.C protection.Over flux protection.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
17/23
23/05/2012. power system protection 17
Transformer Protection.
Bucholz protection.Current inrush protection.T/F fire protection.Nitrogen used mostly.
Thermal protection.Temp > 95C initiates alarm signal.Temp> 110C trips.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
18/23
23/05/2012. power system protection 18
Transformer Testing
Megger Testing.DGA of T/F oil.
Vacum dehydration.TTR Testing.
Capacitance & dissipation factor testing.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
19/23
23/05/2012. power system protection 19
Transformer Testing
Bushing tests.DC- winding resistance test.Polarity tests.Earth resistance test.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
20/23
23/05/2012. power system protection 20
Miscellaneous protection.
Frequency metering & Triping.
Frequency less than 48.80HZ.132kv line is tripped.
Frequency less than 48.60HZ.220kv lines may b tripped.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
21/23
23/05/2012. power system protection 21
Miscellaneous protection.
Check synchronizing relay.Maximum voltage difference on L.T side of transfomer may be 20kv.Phase difference is 30.Ensure above feature before closing of
breaker.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
22/23
23/05/2012. power system protection 22
Miscellaneous protection.
Over voltage .Under voltage.Power swing blocking relay.Over load protection.
Interface relay for PLC.
7/31/2019 Power System Protection Basics..a Visit to Sheik Muhammadi Grid Peshawar.
23/23
23/05/2012. power system protection 23
End..
Top Related