Lecture notes on PLCC at MSETCL RTC Padghe Batch 7(Dt 12.7.13)

MSETCL RTC Padghe Batch 7 (dt.12/7/2013)

Power Line Carrier Communication

( B2B & D2D)

To communicate is Human Nature

We communicate to

Convey feelings.

Express agreements.

Express love.

Learn/ Teach

Share knowledge

Communico (Latin)

TelephoneA user end instrument that is used to transmit &

receive Voice frequency signals.

Voice frequency is audio range used for transmission of Speech. ( 300 Hz to 3400 Hz)

Telephone bandwidth for a Single voice frequency channel is 4 KHz.

Telephone Bandwidth is 4 KHz 1000 Hz

2000 Hz

3000 Hz

4000 Hz

5000 Hz

6000 Hz

Dialing Communication

Modulation & Demodulation

LINE IN LINE OUT (LILO) Arrangement

Existing PLCC link ABB make ETL

PLCC links after LILO

1. Line Section 1 use existing PLCTs(ABB)2. Line section 2 use new PLCTs (ABB or BPL)

Frequency plan

Freq. Band in KHz UFreq. Band in

KHzU

Freq. Band in KHz

UFreq. Band in

KHzU

Freq. Band in KHz

U Freq. Band in KHz U

100-104 168-172 236-240 304-308 372-376 440-444

104-108 172-176 240-244 308-312 376-380 444-448

108-112 176-180 244-248 312-316 380-384 448-452

112-116 180-184 248-252 316-320 384-388 452-456

116-120 184-188 252-256 320-324 388-392 456-460

120-124 188-192 256-260 324-328 392-396 460-464

124-128 192-196 260-264 328-332 396-400 464-468

128-132 196-200 264-268 332-336 400-404 468-472

132-136 200-204 268-272 336-340 404-408 472-476

136-140 204-208 272-276 340-344 408-412 476-480

140-144 208-212 276-280 344-348 412-416 480-484

144-148 212-216 280-284 348-352 416-420 484-488

148-152 216-220 284-288 352-356 420-424 488-492

152-156 220-224 288-292 356-360 424-428 492-496

156-160 224-228 292-296 360-364 428-432 496-500

160-164 228-232 296-300 U 364-368 432-436

164-168 232-236 300-304 U 368-372 436-440

Sr no. PLCC link Frequency in KHz Overlapping of allotted frequencies with the

available links.

1 400KV Pune PGCIL Lonikand S/S(with PC)

124/128U128/124U (400KV PGCIL- Padghe)

2 400KV Pune PGCIL Lonikand S/S(with PC)

160/168URx 160 (400KV PGCIL- Padghe)

Rx 168 (400KV PGCIL- Chakan

3 400KV Pune PGCIL Lonikand S/S

336/340UTx 340 (400KV PGCIL- Chakan)


352/356UCan be used.


228/232U228/232U (400KV PGCIL- Parali-II). Link

not yet commissioned. Hence can be used.


248/264UCan be used.

Approved Frequencies for 400 KV Lonikand I PGCIL line

Sr

no.

PLCC link Frequency in KHz Remarks

1 400KV Pune PGCIL Lonikand S/S ( With PC)

352/356U

2 400KV Pune PGCIL Lonikand S/S ( With PC)

228/232ULink not yet commissioned at

400KV Pune PGCIL- Parali-II.

Hence can be used.


248/264U


336/360U336KHz is already approved as

above.


328/348UBeing spare during shifting of

400KV Lonikand Parali I &

panel reduction at 400KV

Lonikand-II.


488/496U432/488UL is approved for 220KV

Lonikand I- VSNL. Can be

modified.

( 428/456 U KHz)Or (96/92 U KHz)

( 232/108 UL KHz)Or 480/ 488 UL KHz

RxTxRx TxRx Tx

Frequency space4 + 4 = 8 KHz required

Frequency space4 + 4 +4 +4 = 16 KHz required

For Single ch. Max 56 no. of PLCT & Twin ch. Max.28 no.of PLCTs can be used .

Rx

Tx

Rx

Tx

Speech signal

Protection signal

Data Signal Carrier

Amplitude Modulated Signal

AMsignal

fm

fm

fm fc

fc + fm

fc - fm

fc

PLCC link

PLCT are used as a pair one at each end

Each PLCT is designated for a set of Tx & Rx freq.

These freq may be Separate Or Adjacent.

The corresponding PLCT at the other end will be designated for the reverse value of Tx/Rx freq.

The ch freq. will be either in 4 KHz or 8 KHz BW depending upon single ch or Twin ch.

Features of PLCT

Mode of Transmission Amplitude Modulation (Single Sideband with Suppressed Carrier)

Carrier Frequency 50 to 500 KHz

Nominal carrier frequency band in either direction of transmission 4 KHz

Power output of PLC Terminal 20 or 40 Watt

Supply voltage- 48 V DC with + pole earthed

ProtectionFrequency

Guard Frequency

Pilot Frequency

Data Freq. Dial Freq. Speech Freq.

Carrier Frequency

Wave Trap or Line trap

Wave traps are series connected

Parallel tuned circuit.

Main components

L (main Coil)

Tuning pot

LA (protective device)

For a well designed Wave trap insertion loss is 1 to 3 dB & blocking attenuation is 8 to 10 dB

Do you know dB (decibel) unit ? Decibel dB denotes Logarithmic comparison between

two signals I/P & O/P.

Power ratio = 10 Log (P2/P1)

Voltage ratio = 20 Log (V2/V1)

Basic units dBm & dBu

dBm = Power levels above, below or at 1 milli watt.

One milli watt power w.r.to 600 ohms is referred as reference power.

dBu = Voltage levels above, below or at 775 millivolts.

Tuning Pot & LA

Pedestal WT

Exercise

Select Blocking Band for PLCT having Frequency 96/92 U KHz

Coupling Capacitor / CVT The main Purpose of CC is twofold

1. Protection of PLCC terminals from Extra HighVoltage.

2. Passing the HF signal with minimum attenuation.

One end of the CC must be securely connected to ground otherwise Over voltages up to the magnitude of the operating voltage may occur on the equipment side of the Capacitor.

Capacitive Voltage Transformer CVT

CVT consists of CC & Voltage transformer

CC for Carrier communication & Voltage Transformer for Monitoring or control.

CVT HF point

Line Matching Unit (LMU)

R

150E

125E

75E

To PLCC Terminal

22

21

20

19

18

17

24

23

28

27

MARSHALLING BOX A To CC/CVT

ESLADC

16

15

14

13

MARSHALLING BOX B

DC

LA ES

To CC/CVT

16

15

14

13

C S

MT

BT- Balancing Transformer

MT- Matching Transformer

DC- Drain Coil

ES- Earth Switch

LA- Lightning Arrestor

S- shield of Co-axial cable

C- Conductor of C-axial cable

LMU is mounted on the structure that supports the CC /CVT

ExerciseSelect the pass band of LMU for PLCT having frequency 96/92 U KHz.

Pass bands

35 90 KHz50 90 KHz

90 500 KHz

3 Elements Protection device

Drain Coil

LA

Earth switch

Insulated single Conductor Lead in wire To connect CC to the LMU, use an

insulted single conductor lead in wire.

Bare conductor & Co axial cable should not be used.

Stray capacitance & leakage to ground will increase the losses of LMU & bandwidth.

The connection between the CC & LMU is high impedance point in the series tuned circuit formed by the tuning inductor & CC.

HF Cable or Coaxial Cable

Coaxial cable is a Two conductor cable made of a single conductor surrounded by a braided wire jacket with a plastic insulating material separating the two.

The coaxial cable provides Shielding so that noise can not get into the cable and cause interference .

The characteristic impedance of the co ax cable is either

75 ohms or 125 ohms.

Characteristic Impedance

Ch impedance of a transmission line is defined as the ratio of the Voltage to the current of a traveling wave on a line of infinite length.

Ch impedance of line, Z = 276 Log (D/r)

where D distance between conductors & r is radius of conductor.

Ch. Impedance is also known as Surge impedance due to the temporarily resistive behavior of any length transmission line.

ABB Make Coupling device Connections

ExerciseFind the mistakes in this picture

Hints -

1. Make, Type & Frequency of PLCT.

2. Selection of Passband of LMU.

3. Selection of Blocking band of Line trap.

4. PLCC Phase to Phase coupling.

5. Main HF Cable & HF loop connections.

Coupling schemes---Economic ,Engineering & common sense

Mode 1 coupling

Center ph to Outer ph (No Mode 3)

Center ph to Ground ( No mode 2)

Outer ph to outer ph with Ground return (No mode 2)

Outer ph to Ground ( All 3 modes)

Inter circuit

Phase-to-Ground

LMU

Cc

LT

PLC

Cc

LMDU LMUPLC

Cc

LT

LT

Cc

LMDU LMUPLC

Cc

LT

LT

Phase-to-Phase

PLCC Coupling

Modal analysis Modal analysis is a mathematical tool similar to

symmetrical components used for analyzing unbalanced faults on three ph power system.

It can be shown that no. of natural Nodes is equal to the no. of conductors involved in the propagation.

For example, 3 nodes in the case of a single circuit line with 2 earth wires earthed at each tower.

The ph conductor V or I can be resolved into 3 sets of natural mode components at any point on a lossy, reflection free three ph line.

Mode distribution for a 3 ph line

Mode 1 is least attenuated & least frequency dependent

more frequency dependent & has more attenuation than Mode1

Mode 3 is the highest attenuated mode & is propagated on all 3 phases & returns via

the ground

Mode components for various types of coupling

a) Center phase to Ground couplingb) Outer phase to Ground coupling

c) Center to Outer Push Pull coupling

d) Outer to Outer Push push coupling

Substation A

Substation B

Zone 1 (A & B)Zone 1 (A)Zone 2 (B)

Zone 1 (B)Zone 2 (A)

Line Fault PUTTDistance relay( 21), Main I, Main II

Conductor snapping Tree fault Bird fault

In case of 400 KV line, Main I & Main II are parallel commands.M I ,M II should be operated simultaneously.

Substation A Substation B

Substation FaultDirect Trip Protection

Over Voltage LBB

Reactor Protection Busbar Hand trip

86ROV all commands are routed through 86ROV except Hand trip

85 LO receive command is routed through 85LO relay.

Conventional 3 Zone Protection

Distance Relay 21

Distance Relay 21

400 220

Z 1 0 0

Z 2 300 400

Z3 500 700

Carrier aided Protection

Distance Relay 21

Distance Relay 21

Protection Coupler

Protection Coupler

Trip logic Conventional & Carrier aided protection

Carrier aided Protection

In the absence of communication link, the operation of End zone fault is longer & auto reclosing is not possible.

Carrier aided protection scheme is used for simultaneoustripping of near & far end circuit breakers

Protection Coupler equipments can be used along with PLCC terminals for Tele protection requirements.

Principle of operation

Under normal conditions, i.e. when there is no fault in the line, guard frequency or frequencies G1 & G2 will be continuously transmitted through the PLC channel for monitoring the healthiness of the equipment.

In the event of operation of protection due to fault the guard signals will be cut & corresponding trip signals will be transmitted in the Speech band.

Speech & any other Data transmission are interrupted while the trip signals are being transmitted.

Relay Interface

1G4AC

Slot no. 15

Relay Interface

2G4AC

Slot no. 21

DSP

D A

D AD A

C

DSP Module G4AA Slot no.10Start A

Tx Command A AF Tx

BOOST

Pilot

Tx Speech

Relay Interface

1G4AC

Slot no. 15

Relay Interface

2G4AC

Slot no. 21

DSP

D A

D AD A

C

AlarmTx,Rx,COM 1,2

DSP Module G4AA Slot no.10

Rx command A

Rx aux O/P A

AF Rx

Rx Speech

AGC

ALARM

NSD 50 Trip Frequencies

Command A 872 Hz Command B 1090 Hz

A & B Permissive Trip/ Uncoded Commands

Command C 654 Hz / 1526 Hz Command D 654 Hz / 1745 Hz

C &D Direct Trip / Coded Commands

A,B,C & D Commands are transmitted in Speech band

Transmission time ,Security & Dependability

The Performance of a protection coupler is assessed by The Transmission time

The Security ( Unwanted command probability)

The Dependability ( Missing command probability)

Permissive & Direct

This scheme is used for protection of power line with Distance relay.

Tripping can only take place at the receiving end if a tripping signal is being received and local protection relay detects a fault.

Transmission Time 12ms

Command Prolongation (Trip Extension) time- 20ms

The tripping command from the protection coupler goes directlyto the circuit breaker.

Transmission Time 26 ms

Command Prolongation time- 100 ms

ABB ETL 41 ABB ETL 41 ABB ETL 41ABB ETL 41 ABB ETL 41

Main I Main II Direct Trip Sp Dialing Sp Express

M I Own M II Own Direct trip Own

M I Parallel

M II Parallelv

Utilization of PLCC panels (3P+2S)

A AB B C

Modified Utilization (2P+2/1S)

ABB ETL 41 ABB ETL 41 ABB ETL 41ABB ETL 41

Channel I Channel II Speech Dialing

A AB B

M II Own Direct trip Own

v

v

v

M I Parallel

M II Parallel

Direct trip Parallel

Speech Express

C C

OR

ABB ETL 41 ABB ETL 42A AB B

M II Own

v

v

v

M I Parallel

M II Parallel

Direct trip Parallel

C C

Channel I Channel II Speech Dialing/Express

Twin Channel Panel

M I Own

M I Own

Direct trip Own

ABB ETL 41

Relay Interface 2

Opto coupler

Solid state C

Alarm Contact

Opto coupler

Solid state C

Relay Interface 1

Opto coupler

Solid state C

Opto coupler

Solid state C

DSP Card

G4AA G4AC G4AC

Protection Coupler ABB Make NSD 50

Alarm Contact

Slot no. 10 Slot no. 15Slot no. 21

DSP

Relay Panel Protection coupler

Opto coupler

Solid state

Contact

Alarm Contact

Trip Send Contact in RP

Carrier Receive Relay in RP

Carrier Healthy relay in RP

85X

30X

RP K102

RP K877

RP K173

RP K169

RP K161

RP K169

Distance

Relay 21

ETL 41 84/80 KHzwith

NSD 50

ETL 41 80/84 KHz with

NSD 50

M I

M II

DT

M I

M II

DT

ETL 41 96/92 KHzwith

NSD 50

ETL 41 92/96 KHz with

NSD 50

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Lecture notes on PLCC at MSETCL RTC Padghe Batch 7(Dt 12.7.13)