Power Line Communicationfrom Home Automation

toSolar Farm Monitoring

Ekachai LeelarasmeeChulalongkorn University, Bangkok

Thailand funded by Ratchadaphiseksomphot Endowment Fund

of Chulalongkorn University (RES560530056-EN)

Power Line Communication (PLC)• Since 1988 • Utilize existing AC power lines to carryhigh freq data signal

• Data rate from 1Kbps – 200Mbps

www.prime-alliance.org

230KVac

23KVac

220Vac

PLC signal on AC 220V

622V

80kHz

0.4V

PLC

PLMPLMPLM

Device Device

Voltage (Parallel) Mode PLC

Device

Device = Appliance, Computer, ADSL, etc

AC line

data

PLM = Power Line communication Module

PLM 80-90kHz

64Kbps, OFDM

10μF

100Ω

15nF 470μH

470nF

.6 8μH:10 1Tx

Rx

ac220VFilter

DataDSP

Type Narrow Band Broad Band

Freq. 3-500kHz 2-25MHz Data 2-128Kbps 10-200MbpsRange > km < 300m Uses Monitor/Control High Speed DataSTD PRIME,G3,X10 Home Plug AvApp Smart Grid Home Network

PLC classification

www.sentec.com

Home Automation (narrow band < 500kHz)

X10, LonTalk

Low speed <128kbpsControl &Monitor

www.aztech.com

internet

Home Area Network Broadband <25MHz

Home PlugHome Plug AV

High speed<200Mbps

www.smartlighting.com

Street Lighting

Lamp maintenance & dimming

Long range

EV Charging station

www.greenvity.com

Smart Grid

MDMOMDSMetc

Narrow band, Long range

PRIME, G3

Problems with PLC1) Noises

1.1) Motor & Switch (intermittent)1.2) Switching Power Supply

(Periodic impulse)

2) Unknown Topology2.1) Line characteristic varies 2.2) Frequency & Time dependent2.3) Multiple reflection (coupling loss)

Smart Grid Technologylow data rate (32kbps), real time, long range

PoweRline Intelligent Metering Evolution

Open International PLC Standardfor Advance Metering, Grid Controland Asset Monitoring applications

2,500,000 meters deployed worldwide

PRIME TreeTopology

BN: Base Node (DCU)SW: Switch Node (Meter)SN: Service Node (Meter)

Smart Meter

PLC (PRIME)

RF (Zigbee)

220V AC in 220V AC out

RF, Optic

Advance Metering Infrastructure (AMI)

CorporateUtility Network

DataConcentrature(BN)

PLC

SN SW

SW SN

SN

Internet

PRIME Protocol Layer

41.992KHz – 88.867KHz 128Kb/Sec OFDM

PRIME OFDM

PRIME MAC Frame Structure

Solar Farm Monitor

8MW 86668 PV panels: fixed topology

+ -20-100V50-200W

World Bank 2012 Renew energy projects

Global (MW) Thailand (MW)

Bio 1277 39

Hydro 31060 0

Wind 28900 127

Solar 7695 326

Blackout22 May 2013

Lightning strike on 500KV

Not enough localPower generation

Multi-String Topology

PV’s are not identical but must operate at the same current un-optimal

8 20 PVs− AC

8 20 PVs−

AC

AC

DC

DC

InverterI I

1P nP

Mismatched PV panelsdefect, cloud, trees, airplane, directioncrack, dust, leaves, aging, temperature

P1 + P2 < P1m + P2m 20% loss

P1 P2

I

P1m

P2m

weak

I

P1

P2

Effect of Mismatched PVs

I

Solar Farm (Health) Monitoring

MU

CUMUMU

MU

DCUDC

DC

AC

AC

Controlcenter

CUCU

CU

DCU

MU : Monitor Unit (V,I,Temp)CU : Communication UnitDCU: Data Concentrator Unit

RF 433MHz or 2.4GHz

Expensive, Fragile & Complicate

MUMU

MU MU

CU CU

CUCU

DCU

DCU

Controlcenter

DC

DC

AC

AC

Serial Mode PLC

MU

CUMUMU

MU

DCUDC

DC

AC

AC

CUCU

CU

DCU

AC Current Mode PLC (analog tech)

Low cost: uses current transformer for couplinghigh frequency current signal

MU MU

MU MU

CU

CU

CU

CU

DCU

DCU

DC

DC

AC

AC

ControlCenter

Pulse PLC (digital tech)

Low cost. Toggle switch to transmit data

MU

MUMU

MU CU

CU CU

CU DCU

DCUDC

DC

AC

AC

ControlCenter

MU MUTx Rx Rx

acI

Superimpose AC Current onto DC Current

1) AC Current Mode PLC

o

PV & INV must be short circuit at carrier frequency ω

TxiV

acI

Rx oVoIiI oZ =∞ iZ 0=

PLC Current Coupling Circuit

m kL ,L

iV oV2C

1C

1L

acI acI

Tx Mode

o1 m 2

1ω(L L )C

=

oZ to couple current=∞

2o

1 m k 2

1ω(L (L L ))C

=+

kL

iV2C 1L

acI acI

mL

Ideal

oZ

2C1L

acI acI

mL

Ideal

i 2 iI jωC V=

oZ

Rx Mode

ac 2o o i

o 1 11 1

jI C1ω ; V Vω C CL C−

= = =

iZ 0 to avoid loading DC line=

22 o k 2o 2

1 k 1 o 1 k 2

1 ω L C1ω(L L )C 1 ω (L L )C

−= •

+ −

mL

oV2C

1C

1L

acI acIIdeal

kL

iZmL

oV

2C

1C1L

acI acIIdeal

iZ

50W Amorphous PV panels

3Ω

250kHz

Carrier frequency

PVZ

oω0.81A 9802.2 0.8μ

pvZ

m

k

s

L

L 84μL 36μR 50R 10k

=

=

=

=

m kL ,L

iV oV2C

1C

1L

acI acI= =

= =

=

= =

=

1 1

2 s

L

i ac ac ac

L 220μH ; C 5.22nFC 1.39nF; R 50R 10K ; V 1V ; I 2.18mAEnergy loss per PV 14μW

Test Experiment for simulation

MU MUCU CU DCU

#1 #8

3Ω 3Ω

Monte Carlo Simulation 50 simulations, 20% over 3 sigmaGaussian Distribution

o

i

VV

Amplitude Shift Keying (ASK)

Data Rate = 25kbit/sec

40μS40μS40μS 40μS

1 0 1 1

4μS

250kHz

MU & CU Circuit

Consume 50uA (2.5mW) while idle

CU

MCUoD

iDADC

iV oV1MΩ

10kΩ

50V + −

3V REG

GND

Low Power MU & CU Circuit

M1 is on to wake up MCUMCU turns on/off M2 to keep power on/off

to save power

CUMCU

oD

iDADC

iV oV

50V + −

toADC

M1M2

3V

Gnd

M1 M1on on

Low Power Communication Protocol

CU DCUwake (111)addr & instrackresponsesleep

MUMU CUCU DCUDC

AC

Pulse PLC

A switch closes temporarily to create a pulse thatpropagates through the DC Power Line.

DV (n 1)V if one PV switch closesV 0 for all PV if DCU switch closes

= −

=Thus DCU can broadcast data to all PVs

PV can reply to DCU only

MU

#1 #n

VMU CUCU DCU

DC

ACV

DV

Ideal Waveforms: 8 x (50V) PV

DCUV

pvVPV DCU→

DCU PV→400V

300μ 600μ

0 01

8μ

50V

Pulse shaping due to PV Capacitor

pv

ph

C 65nFV 50V

I 0.015 0.5A

==

= →

r

r

T 6.5 220μSData Rate

1 <8μ T

4.4kpulse / s

= →

+

=

MU+

−

pv pvr

ph

C VT

I=

V

CloseV

pvCphI

PV

8μS

Open

DC Line

Close

AC

DCTransmission Line

μL 1.475 H / m, C 11.3pF / m= = DCUV+

−

Ringing due to transmission line effect

cause ringing

Ringing through DC Line

15m cable35m cable

1.8MHz

close

R 10; L= ; C=

Ringing Suppression at DCU

Y o

Y

R 410Ω to match ZC 2nF to block DC

=

=

oZ DCUV+

−

YR

YC

Ringing Suppression at the Switch

pvV

+ −pvV + −pvV

C R

Hard Switch

pvV

Soft Switch

50W Amorphous PV panels

DCUV

a) Hard Switch (IRFS630)b) Terminate DCU with 410 + 2.2nFc) Soft Switch with 1.5K & 150pFd) Soft Switch under weak sunlight

Negative edge detectorQ is OFF when idle (zero power)

ON when there is a neg. pulse

1C

2C

2R

1R

3VPVVDC line

PVpanel

μC/ON OFF

Switch

pT

Q

PT

in

out

1P PV

1

2∆ ;

C C∆C

=+

2

1 2P

R∆ ∆ 0.7R R

≈ ≤+

( )2 2 1P 2(R R )(C C )lnT ∆ / 0.7= + +

DesignEq.

1C

2C

2R

1R

pT

QΔPV

ΔP

Δ3

3V

3

3V

1 2 1 2 PV

PP

R R 10KΩ; C 470pF; C 4.7nF; ∆ 80V∆ 7.27V T 170μ; ∆ 3.6 S3V;

= = = = =

== =

Experimental Result

Strong Weak

Broadcast by DCU

One MUresponses

Edge Detector with Regulator

1C

2C

2R

1R

3V40VDC line

PVpanel

MCU

Q

Edge Detector with Regulator

1C

2C

2R

1R

3V40VDC line

PVpanel

MCU

Q 3V

MCU Self Bias

P 3

DC

T is long to allow MCU to turn on Qand keep V supply to MCUMCU turns off S to shut down (All transistors OFF)

1C

2C

2R

1R

PVV

2R

1R

MCUpT

pT

3V

3VC

DCV

1Q 2Q 3Q

P1 + P2 < P1m + P2m 20% loss

P1 P2

I

P1m

P2m

weak

I

P1

P2

Effect of Mismatched PVs

Future Work: Integrated Converter

DC/DC maximizes energya) from PV. b) to DC/AC.

Communication Unit (CU) shares information.

Centralcontrol

DC/DC

DC

ACMU/CU

DC/DC

MU/CU

Advantages of usingPLC for solar farm

1) No extra wire2) Simple Circuits low cost3) Low power4) Fixed topology5) Low noise6) Low power protocol

Thank You

This research is supported by Ratchadaphiseksomphot Endowment Fund

of Chulalongkorn University (RES560530056-EN).