Power Line Carrier Communication 1q485l

NANDA

Prepared By :

1

Power Line Carrier Communication System LT Power Line (50Hz)

C RF carrier C (40-500kHz) PAX

RT U PLCC TERMINAL

(AB-ETL41)

Transmission line

2

PLCC Technology 

PLCC system uses the same High Voltage transmission line connecting two sub-stations for telecommunication purpose too.



PLCC is used in all power utilities as a primary communication service to transmit speech, telemetry and protection tripping commands. This is economic and reliable for inter grid message transfer as well as low bit rate RTU signals.



The voice/data are mixed with radio frequency carrier (40-500kHz), amplified to a level of 10-80W RF power and injected in to high voltage power line using a suitable coupling capacitor. The power line as a rigid long conductor parallel to ground, guides the carrier waves to travel along the transmission line. Point to point communication takes place between two SSB transceivers at both ends.

3

Line diagram Sub-display Station bay1

To other S/S

Line Isolator

Circuit Breaker

Bus Isolator 1

Bus Isolator 2

Single Line digm

Bus Bar #1 Bus Bar #2

4

H.V Line

Line Trap

Coupling

capacitor

Components PLCC terminal

LMU Coaxial cable

PLCC Terminal = Translates voice and data into High Frequency Carrier. Output Power =10 to 80W LMU = Line Matching Unit = For impedance matching between line and coaxial cable, includes high voltage protection devices like drainage coil(20mH), lightening arrestor(500V) and an earth switch. Coupling Capacitor = Couples high frequency carrier with Power Line ( 4000 to10000pF) Line Trap = Do not allow the transmitted HF carrier to enter inside the sub-station. (L = 0.5 to 2mH) With out Line trap HF carrier get by-ed to some other line on the same bus bar and may leak to ground ( a earth switch inside the yard provided for each bay is kept closed during maintenance) 5

Coupling Scheme Behind

Front

Line Trap

To remote Coupling Capacitor

Line Matching Unit

•Transformer (s) •BusBar

Coaxial

Local substation

substatio

The PLC n signal is routed to H.V Line

The PLC signal is not absorbed by the substation

PLC terminal

6

Line trap function

= PLC signal Blocking HV Line Power energy PLC Signal

Substatio n

Line Trap = High Impedance for PLC signal Low Impedance for Power energy

7

Line Trap Components

Corona ring Liftinglug Terminal Main coil Tuning device Pedestal Protective device Tie rod

8

Line Trap is a parallel LC circuit Inductance of main Coil

Lightning Arrester

Series resistance Tuning Capacitor

Damped single

Line Trap 9

Line Traps Mounting Options

Vertical Pedestal

Horizontal Pedestal

Suspension

10

CVT : CAPACITIVE VOLTAGE TRANSFORMER

11

LMU function Line Trap

LMU = impedance matching Transformer

+ high voltage Protection Coupling

 To prevent dangerous potential on the

Capacitor s/s

PLCC connection

LMU

To match PLCC set & transmission Line

PLC

Coaxial

Matching

+

Protection

LMU 12

Modular Coupling Device ABB make MCD-80

13

Elements of Coupling Device • Drain coil for draining of HV leakage currents to earth. •Lightning arrester at the line terminals of coupling device for transients protection

• Transformer for impedance matching and galvanic isolation between line and PLCC terminal.

• • •

Earth switch for grounding of line terminals during maintenance. High- or band- filter elements for efficient matching. connectivity to equipment room through coaxial cable.

14

LMU functional blocks HV -line

Substation Line trap

Coupling capacitor Tx

ABB MCD 80

or

Coax cable

Rx

PLC Cabinet 15

HF Coupling modes

LT

LT

Cc

PLC

LT

Cc

LMU

PLC

LT

LMDU

Cc

LMU

LT

Cc

Phase-to-Ground PLC

LMDU

Cc

LMU

Inter circuit

Phase-to-Phase 16

Function of PLCC terminal IF AF

Signal

IF

IF

(0 to 4 kHz)

(40 to 500 kHz) H

H

Side

R.F Signal

PA RF

AF

RF A

Line Side

IF

AF IF

gain

RF

H= hybrid

IF

Translation : audio signals into radio Spectrum Amplification : To compensate the line attenuation 17

PLCC ( type: ABB ETL 41/42)

Cabine t

Module s 18

Multiplexing speech & data in 4 kHz raster Speech 3.4 kHz

Programmable speech bandwidth

Speech 3.4 kHz

Speech 2.0 kHz

plus

0.3

3.6

4.0 kHz

3.6

4.0 kHz

tele protection (4 trip commands) 0.3

2.0

plus Speed

Tele metering (FSK modem)

300 Bd Center frequency 120 Hz steps 1200 Bd 0.3

3.6

4.0 kHz

19

ABB PLCC terminal

ETL- 41 System data -- complies to IEC 495 Operating mode : Single side band Suppressed carrier Frequency range: 40 to 500kHz (programmable in 4 kHz Steps) AF Bandwidth: 4 kHz (Speech band=300 – 3400 Hz) Transmitter RF output power : 40W ( +46 dBm) Spurious suppression > 60 dB Pilot channel : 3780 + 30 Hz Receiver RF sensitivity : - 24 dBm Receiver Selectivity : 70dB ( 300Hz from band limit) Receiver Image rejection > 80 dB Receiver IF rejection > 80 dB

20

Installation

LT

LT

cc

cc C FAX

ETL

ETL

FAX

M

M

PR

PC

MS

PAX

FAX

MS = Master station PAX = Private automatic exchange PR = Protection relay PC = Computer M = Modem

PR

PC

RTU

FAX

PR= Protection relay FAX = Facsimile equipment M = Modem RTU = Remote terminal unit

21

Effect of bad weather on PLCC communication Losses increase for all inclement weather conditions 

The worst offender is when heavy frost is formed on the line 

Because of the skin effect, the carrier signal tries to propagate on the ice instead of the conductor.



The attenuation can change as much as 4:1 depending on the frequency.



The contaminats (on the insulators) have a larger effect when it is raining than when the line is dry.



The worst condition is a light rain with the presence of contaminants on the insulators

22

RF Noise RF noise in HV line  two mains effects Impulsive Noise = Caused by atmospheric discharges, breakers and isolator close/open operation Corona effect = Due to sequences of pulse streams caused by arcs over conductors. It appears during positive-going half-cycle of the Line voltage (occurrance frequency for a 50Hz 3-phase system is 150 Hz)

The corona noise could be subject to considerable variations due to differences in the design parameters of the overhead line.

Other variations are possible due to the construction, altitude and age of the line

Weather effect can also be significant

23

Corona Noise

Bad weather Noise

Voltage Correction (kV) (dB) 33

- 14

132

-4

220

0

400

+4

500

+5

Typical average Noise on a 220 kV line and for a 3 kHz Bandwidth

24

PLCC test instrument: Selective Level Meter

25

PLCC test instrument : Selective Level Oscillator

26

THANK YOU ALL

27