switch yard & protection

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Presented By: Mr. MANOJ KUMAR MAHARANA

Sr. Engineer [ Dept. Of Electrical ]BLA Power Pvt. Ltd

BLA Power Pvt. Ltd

SWITCHYARD &

PROTECTION

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SWITCHYARD

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DEFINATION• A switchyard is a part of an electrical Generation, Transmission, and

Distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions.

• Switchyards generally have Breakers, Isolators , CTs ,PTs , Bus bars, protection and control equipments, transformers ,grounding wires and switches, disconnects and metering devices, etc.

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132 KV Switchyard

• Constructional Overview• Testing• Operation & Maintenance• Protection• Conclusion

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Constructional Overview • Two main Bus-1& 2 bars – ACSR TWIN MOOSE Conductor.

Both are used to energize any abnormality with Bus-coupler for un interruption Operation.

• Current rating 2000A,Fault Level 40KA for 3 Sec.• Bay Equipment to Equipment Connection-ACSR Moose

Conductor.• CTs are connected in Series , PTs are connected across supply.• STG Generator Transformer Bay -01 No.• Start-up S.A.T. Bay -01 No.• 132 KV overhead line circuit Bay -02 No.s• 132 KV Transfer Bus coupler Bay - 01 No.s• Fully Equipped Bus PT Bay -02 No.s

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GEN. TRFO. BAY

TRNSFER BUS COUPLER BAY

BUS PT

O/G OHL #1 BAY

STN. TRFO. BAYO/G OHL # 2 BAY

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• Total no. of Towers- 28 (A/B/C/D/E)• Total no. of SF6 CB- 5• Total no. of PT-12• Total no. of CT-12• Total no. of LA-12• Total no. of Wave Trap -2• Total no. of Isolators- 22• Total no. of CVT- 6• Total no. of BPI- 18• Total no. of EMPT -6

Constructional Overview

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GEN BAY SAT BAY

9B/C BAY

Line# 1 & 2 BAY

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Bus Bar Protection Scheme

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• Rated Voltage 145 KV • Rated Current 1250 A Frequency 50 Hz • Breaking Capacity 40 KA • Making Capacity 100 KVP• Short Time Rating 40 KA for 3 sec• Operating sequence O-0.3 sec - CO- 3 MIN- CO • Trip and Closing Coil Voltage 110V DC • Motor Supply 240 V

These are used to operate on the fault on line or X-mer depending upon where it is connected. This isolates the faulty line or equipments from the live portion of the sub station by opening automatically through protective relays; control cables etc. in definite time.

Testing for SF6:- Applied Volt 5KV DC•IR Value > 20 GΩ CB ON [R(Y+B+E),Y(R+B+E),B(R+Y+E)] > 50 GΩ CB OFF [R-R’,Y-Y’,B-B’]•Applied current 100 A DC Contact Resistance test: R-ø ,Y-ø B-ø < 34 μΩ•SF6 Gas pressure setting 5.4 bar.•Breaker , Closing Time 72 ms Opening Time -29 ms Each Phase

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Make CGLType OutdoorNo of Core 2 CoreRatio 400-800/1-1AClass 0.25/0.25Burden 30 VAISF <= 5

Make CGLNo of Core 2Ratio 132KV/√3/110V/√3/110V/√3Class 0.2/3PBurden 100 VA/100 VA

a) Measurement of voltageb) Provide secondary voltage for

protection.

a) Measurement of currentb) Protection current circuits when currents

passed through protective relays like Distance protection, Backup protection.

Common Testing's Required for CT & PT:- •IR Test : Applied Volt 5KV DC > 10 GΩ [Prim – Earth, Prim – Core] Applied Volt 1KV DC > 500 MΩ [Core-Earth]•Winding Resistance Test: < 5-6 Ω [Ex: R-ø ,1s1-1s2,1s1-1s3]

•Ratio Test : [Prim current 400-800]/ [Sec. current 1-1A] [Ex: R-ø ,1s1-1s2,2s1-2s2]•Polarity Test : [Ex: R-ø ,1s1-1s2,2s1-2s2] •Knee voltage Test:[Only For Protection Class CT ]is significance of saturation level of a current transformer core mainly used for protection purposes. The sinusoidal voltage of rated frequency is applied to the secondary terminals of CT, with other winding being open circuited which increased by10%, cause the exiting current to increase by 50%.

NEXT

Press

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P1 P2

S1 S2

Battery 9V

Press Back

•Polarity Test :

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Make OBLUM ELECTRICAL

Type METAL OXIDELD DISCHARGE CLASS Class-3Rated Voltage 60 KVRated Frequency 48-62 HZMaximum continuous Operating Voltage 102 KV

Nominal Discharge Current 10 KAMFD 2010

Make OBLUM ELECTRICAL

Wave trap is an instrument of Low pass filter, when power frequency currents are passed to switchyard & high freq. signals are blocked. Line trap also is known as Wave trap. Shapes like a DRUM.Use for Carrier Communication (PLCC) systems for communication among various substations without dependence on the telecom company network located in substation control room (through coupling capacitor and LMU).

To discharge the switching & lighting voltage surges to earth to protect instrument in the station. These are high pass filters (50 KHZ to 500 KHZ) pass carrier.

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Make CGLNo of Core 3Ratio 132KV/√3/110V/√3/110V/√3/110VClass 0.2/3P/3PBurden 100 VA/100 VA/100VA

> CVT is a transformer used to step down extra high volt. Signals & provide low volt. Signals either for measurement or to operate protective relays. CVTs are typically 1-ø devices where stack of capacitors are connected in series result voltage drop.

Make S & S POWER SWITCHGEAR EQUIPMENT LTD.

Type Drive Motor/Manual,415 v,3øRated Voltage 145 kvRated Current 1250 AFrequency 50 HzShort Time Rating 100 KA for 3 secLightning Impulse with stand Across voltage 650 kv

> Isolators are used to isolate the high Volt. from flow through the line into the Bus. It allows only needed voltage and rest is earthed by itself if required.

Bushing

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•Bus: is a line in which the incoming feeder come into & get into the instruments for further step up or step down.•Double line in the bus so that if any fault occurs in one the other can still have the current and the supply will not stop.•Two lines are separated by a little distance by a conductor [spacer] having a connector between them .

Spacer

ClampTension

Suspension

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OPERATIONAL MODES• Normal Operation :Synchronization Start Up / Import

• Inter -Transfer Mode Operation:Inter Transfer Mode

By Pass change over Scheme:

Press

Press

Move Next

Press

Press

19G

DS-1 DS-2

CB

CB

DS-4

DS-3 DS-2

CB

DS-4

DS-3 DS-1

DS-2

CB

DS-3

DS-4

DS-1 DS-2

CBDS-4

DS-1 DS-3

OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY

BUS COUPLER CUM TRNSFER BREAKER

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS <--- GT BAY <--- STN. TRFO BAY

GENERATOR

G. TRFO STN. TRFO

DS-5 DS-5

U.A.TRFO

DS-1 DS-2

Gen CB

LOAD

20G

DS-1 DS-2

CB

CB

DS-4

DS-3 DS-2

CB

DS-4

DS-3 DS-1

DS-2

CB

DS-3

DS-4

DS-1 DS-2

CBDS-4

DS-1 DS-3

OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY

BUS COUPLER CUM TRNSFER BREAKER

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS <--- GT BAY <--- STN. TRFO BAY

GENERATOR

G. TRFO STN. TRFO

DS-5 DS-5

U.A.TRFO

DS-1 DS-2

LOAD LOADPress Back

21G

DS-1 DS-2

CB

CB

DS-4

DS-3 DS-2

CB

DS-4

DS-3 DS-1

DS-2

CB

DS-3

DS-4

DS-1 DS-2

CBDS-4

DS-1 DS-3

OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY

BUS COUPLER CUM TRNSFER BREAKER

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS <--- GT BAY <--- STN. TRFO BAY

GENERATOR

G. TRFO STN. TRFO

DS-5 DS-5

U.A.TRFO

DS-1 DS-2

LOAD LOADPress Back

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CB

DS-2

CB

DS-4

DS-3 DS-1

BUS COUPLER CUM TRNSFER BREAKERS

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS

DS-1 DS-2

Tripping Prt.

OUTGOING OHL #1 BAY

1. Close DS-3 2. Open DS-3 & DS4

Close DS-3

Tripping Prt.

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CB

DS-2

CB

DS-4

DS-3 DS-1

BUS COUPLER CUM TRNSFER BREAKER

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS

DS-1 DS-2

Press Back

Tripping Prt.

OUTGOING OHL #1 BAY

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CB

DS-2

CB

DS-4

DS-3 DS-1

BUS COUPLER CUM TRNSFER BREAKERS

MAIN -1 BUS

MAIN -2 CUM TRANSFER BUS

DS-1 DS-2

Tripping Prt.

OUTGOING OHL #1 BAY

1. Open DS-12. Close DS-1

Tripping Prt.

Protection Tripping fuse Out

Press Back

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Maintenance

• CTs, PTs ,all auxiliaries terminal tightness.• SF6 Breaker Gas pressure monitoring &

maintain.• Stone,metnal layer maintain across the area.• Monitoring & diagnosis using Hotspot

detector or temperature scanner .• Isolator & contact cleaning on scheduled.

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Thermal Sensor / Hot Spot Detector

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PROTECTION

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Protection

CR Panel

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Protection System

• A series of devices whose main purpose is to protect persons and primary electric power equipment from the effects of faults.

Why A System Needs Protection?

• There is no ‘fault free’ system.• It is neither practical nor economical to build a ‘fault free’

system.• Electrical system shall tolerate certain degree of faults.• Usually faults are caused by breakdown of insulation due to

various reasons: Short Circuit, High Voltage, system aging, lighting, etc.

Protection System Elements

• Protective relays• Circuit breakers• Current and voltage transducers• Communications channels• DC supply system• Control cables

Three-Phase Diagram of the Protection scheme

CTs

VTs

Relay

CB

Control

Protected Equipment

How Do Relays Detect Faults?

• When a fault takes place, the current, voltage, frequency, and other electrical variables behave in a peculiar way. For example:– Current suddenly increases– Voltage suddenly decreases

• Relays can measure the currents and the voltages and detect that there is an overcurrent, or an undervoltage, or a combination of both

• Many other detection principles determine the design of protective relays

Main Protection Requirements• Reliability

• Selectivity

• Speed

• Sensitivity

Typical Short-Circuit Type Distribution

Single-Phase-Ground: 70–80%Phase-Phase-Ground: 17–10%Phase-Phase: 10–08%Three-Phase: 03–02%

Following type of Protection Curve used in our plant

1. INSTANTANEOUS/High Speed 2. DMT: (Definite Mean Time-I>>/high set)3. IDMT: (Inverse Definite Minimum Time)a. SI - Standard Inverse (I>) b. VI - Very Inversec. EI - Extreme Inverse d. LTI - Long Time Inverse

Formula for Relay Operating Time calculation

Operating Time: = A X TMS Ir C - 1 o A=0.14 & C=0.02 for SIo A=0.13.5 & C=1.0 for VIo A= 80 & C= 2.0 for EIo A=120 & C=1.0 for LTIo Ir= I(multiple of fault current) / Iset

Example:

• If FLC=100A, % setting =105, • Operate time = 10sec Then TMS=? If CTR =150/1A, In=150, Isec=1A

As per CTR % set= 0.7*In.Relay Iset= 700mA, Ir=1.05/1.0=1.05=>TMS will be 0.136

IDMT:SI

IDMT:

Basic Requirement for Relay Setting

• Equipment Full Rating(V, Amp, Z)• CT/PT Ratio installed on that feeder• Identification of CT/PT for Particular

protection.• Breaker opening & tripping time. • Equipments Factory Test report/Curve

Relay Setting Adopted for our system:

1. OC: 105% to 120% - SI, 2. EF: 10% to 30%. - SI3. OV: 110%, U/V: 80% - DMT4. SEF: more than EF and time >0.8to1.0sc.5. REF/Diff : 08 to12% -Inst.6. DPR (Z1-inst. Z2-300ms, Z-800ms)

Protection used for different System

• For Transmission Line :a. Distance Protection b. Backup Direction OC/EF c. Lightning Protection• For Transformer: a. Differential Protection b. Overfluxingc. O/C & E/Fd. Restricted E/F

e.Sensitive or standby E/F f. Buchholz

g. Pressure Release Valve h. Winding/ oil Temperature & LA • For LT Motor (up to 35KW) a. Thermal Overload b. Fuse• For LT Motor (Above 35KW) a. Thermal Over Laodb. O/C & E/F

• For HT Motors:

a. Thermal Over Loadb. O/C & E/F c. Locked Rotor d. Negative Phase Sequence e. Start supervision f. Restart Inhabit • For Generator :a. Differential Protectionb. Stator Earth Fault (100% & 90 %)

c. Rotor E/Fd. NPSe. Backup Impedance f. Backup O/C & E/Fg. Loss of fieldh. Reverse Power (Short Time /Long time)i. Thermal Overload Alarmj. Dead Machine k. Winding temperaturel. O/V & U/V

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SUMMARY

• The Operative Direction for Directional OC Relays are as follows: – GT bay relay is having operative direction towards GT. – Line bay relay is having operative direction towards Line. – Station Transformer. Relay is having operative direction towards Station Transformer.

• Grading margin of 0.3 seconds has been considered between different levels of protective devices.

• In case of a fault on Line, Distance relay will operate instantaneously. If it fails to Operate than Directional OC relay will operate as backup.

• If the fault is still found persisting than GT bay and other line bay relay will give further backup and will trip their respective breakers to clear the fault.

• In case of a fault on Bus, Bus differential relay will operate instantaneously. If this relay fails to clear the fault , all other feeders including two line bays and GT bay relays will trip their respective breakers to clear the fault .

• In case of a fault in Generator Transformer (GT),Differential protection for GT will operate instantaneously. And Directional relay looking towards GT will give backup to it. If the fault is still found persisting than all other feeders including two line bays will trip their respective breaker to clear the fault.

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Forward Path

• For Trouble Free Operation.• Longevity of System.• 2 No.s Upcoming Bays for Unit-II

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Special Thanks

• for Guidance Mr. U.P. Sharma Sr. Manager [ Dept. Of Electrical ] • for Co-ordination Mr. Nilesh Malviya Mr. Dhanajya Ray Engineer [ Dept. Of Electrical ]

Thanks To AllPrepared By:

Mr. MANOJ KUMAR MAHARANASr. Engineer [ Dept. Of Electrical ]BLA Power Pvt. Ltd