Powerline Communication based Home Automationand Electricity Distribution System

Harshad V. DangeDepartment of Electronics and

Telecommunication EngineeringMaharashtra Academy of Engineering

Pune, Maharashtra 411–015Email: harshadhere@gmail.com

Vamsi K. GondiMission10x

Wipro TechnologiesBangalore 560–100

IndiaEmail: vamsi.gondi@wipro.com

Abstract—Home automation is a common field of interest forengineers, researchers and of course, consumers. Today, homeautomation systems are commonly found in many homes acrossmany countries around the world. Such systems not only offer ahigh level control over home appliances, but also try to reducethe wastage of electricity. Powerline communication (PLC) is apopular technique employed in home automation systems thatreuses household electrical wiring for communication. But thecurrent systems have some drawbacks and need improvement.Our paper describes the design of a next generation homeautomation system that will provide great features to consumersas well as electricity distributors. The main features of this systemare web based control and data-logging facility.

I. INTRODUCTION

Electricity is the biggest bringer of comfort to our homes.An average household, today has over a hundred electricaland electronic appliances installed. These increase our inhome productivity. Home automation systems allow maximumcontrol over these appliances. A generic home automationsystem will allow the user to control all the home appliancesfrom a single console. Home automation systems have existedfor decades, in some form, in many homes around the world.Automatically opening garage doors, burglar alarms, etc. areall forms of home automation systems.

A. Applications of home automation

The application areas of home automation range from basiccomfort to security and energy conservation. Some of theseare as follows. The concept of a “Smart Home” is shown inFigure 1.

1) Heating Ventilation and Air Conditioning (HVAC): Itincludes the control of heaters, air conditioners and fans.These appliances are responsible for maintaining a properenvironment in the home. Moreover, they are usually the mostpower hungry appliances and hence, must be used wisely.Home automation systems use sensors to detect the presence ofa person in the room and the room temperature to automate theswitching of HVAC appliances. This reduces power wastagewithout sacrificing comfort.

2) Lighting: This is the most common application of homeautomation systems. The lighting needs of different rooms inthe home are different. Living/reading rooms are generally

brightly lit whereas bedrooms will use calm lights. Automationsystems use ambient light sensors and presence detectorsto automate switching of lamps. Proper switching of lampsensures less wastage of electricity.

Lighting control

Smoke sensor

Music system turns offwhen no one is inthe room

Controller forthe system

Surveillancecamera

TV switches off whennobody is present

Air conditioner switched according to temperature

Automatically dimminglamp

Control overkitchenappliances

Sprinklers turn on whenmoisture level of the soildrops down

Fig. 1. A “Smart Home”. The home automation system automaticallyswitches appliances as needed.

3) Safety and security: Safety and security are an integralpart of modern home automation systems. Video surveil-lance is provided with the help of video cameras andCCTV networks. Sensors to detect fire/smoke, breakage ofdoors/windows, etc. are commonly used for security. To furtherenhance this scenario, these systems can be integrated withthe local police and fire departments, to ensure quick actionin case of emergencies.

B. Architecture of home automation systems

The architecture of a home automation system is shown inFigure 2. It is similar to a generic automation/control system.As seen from the figure, the architecture consists of sensors,actuators and communication interfaces forming a network.The figure shows just a basic simplified architecture of ahome automation system. Modern systems are much morecomplicated. Let us discuss the basic functional units of ahome automation system one by one.

978-1-61284-764-1/11/$26.00 ©2011 IEEE

1) Sensors: Sensors are used to automate common in-hometasks. The commonly used sensors are presence detectors,ambient light sensors, motion detectors, temperature sensors,smoke detectors, etc. A modern home automation system usesarrays of such sensors mounted in every room of the homeand uses their signals as basic parameters for automation.

Communication Interface

Communication Interface

System Controller

Actuators

Appliances

Light Sensor

Camera

Wired/Wireless Channel

Fig. 2. The architecture of a generic home automation system showing thevarious components.

2) System controller: The system controller is the centralcontrol unit for home automation systems. The controllerreceives signals from the sensors and performs necessarycontrol actions. Controllers are usually micro-controller basedembedded systems. However, a common desktop computermay also be used as a controller. Controllers are responsi-ble for providing a friendly interface for the end user. Atypical controller will have a display screen and a set ofbuttons/keypad to help the user control the system. Controllersare usually installed in an easily accessible place in the home.

3) Actuators: Actuators are directly connected to the endappliance. They are responsible for switching applianceson and off. In general, they function as remote controlledswitches. Actuators receive commands from the system con-troller. Depending on these commands, they perform necessaryswitching actions on the appliance. TRIACs and relays arepopularly used as actuators.

4) Communication channel: The sensors and actuators areconnected with each other through a communication channel.The communication channel may be wired or wireless. Datarates as low as 100 bps are sufficient for home automation.But for video streams, higher bandwidth in the Mbps rangeis required. The physical channel can be UTP cables, co-axialcables, etc. in case of wired systems. In case of wireless sys-tems, the ISM band is generally used. Common technologiesusing this band are Zigbee, WiFi, Bluetooth, etc.

5) Communication interfaces: Communication interfacesare used to connect the various functional units of the homeautomation system to each other. Communication interfacesprovide a standard interface such as USB, RS232, Ethernet,etc. to the home automation equipment. They are responsiblefor modulation/demodulation, signal transmission and errordetection/correction, wherever necessary.

C. Drawbacks of current systems

Home automation systems today, are very advanced. Butthere still is room for improvement, as with every othertechnology. Todays systems are capable of offering totalautomation with least human intervention. But, they are stillviewed as consumer commodities. The systems do not playany significant role beyond the walls of the home they areinstalled in. To change this scene, we are proposing a new,next generation system. But before that, let us mention somedrawbacks of current home automation systems.

1) Installation troubles: Home automation systems havenot yet completely achieved the plug-n-play form factor. Mostsystems require extra wiring and surgeries to install actuatorsand sensors. This is typically painful when installing in fur-nished homes, or when upgrading/replacing existing systems.Wireless systems may be easy to install, but they have theirown problems. For one, they have a limited range, which is notgood in case of large homes with multiple floors. Secondly,weak wireless signals cannot penetrate thick concrete walls.And of course the cost of wireless technologies is almostalways higher than their equivalent wired solutions.

2) Cost: Cost is one of the primary reasons why homeautomation systems fail to appeal to the masses. The termcost is referred to as the combined expenses incurred for in-stallation, maintenance and replacement of components. Overthe recent years home automation systems have become muchmore affordable. Many companies provide low-cost solutions,but these systems are not that advanced in nature.

3) Compatibility with home appliances: Apart from thecommon home appliances such as CFLs, TVs, etc., there area large number of appliances that operate on variable powerlevels or feature some automatic switching mechanisms inthem. For example, a refrigerator contains a temperature sensorand a switching mechanism, which turns off the compressorwhen the compartment temperature falls below a certainthreshold. Same is the case with air-conditioners, microwaveovens and water heaters. Compatibility with these must bemaintained. Consumers residing in areas that experience fre-quent power-cuts usually have inverter/UPS systems installedin their homes. Home automation systems must detect powercuts and switching of UPS systems and try to lower powerconsumption when on backup.

4) Compatibility with other systems: A single technol-ogy/manufacturer cannot cater to everyones needs. Hence,consumers may need to install products from different manu-facturers. These must be compatible with each other and mustnot cause problems in each others functioning. Unfortunately,

there is not an international standard regarding sensors, actu-ators or system controllers.

But systems can be designed using the existing internation-ally accepted standards. For example, a USB/RS232 interfacecan be used for expansion or inter- connections instead ofa custom/proprietary connector. If compatibility with othersystems is not maintained, consumers will be tied up to thesame manufacturer.

5) Not yet web-ready: The internet has changed our world.One of the best applications of internet in monitoring/controlsystems is remote access. With web publishing, a automa-tion/control system can be accessed from anywhere.

Today, almost every home has access to the internet. Buthome automation systems offering web publishing are rarelyseen. With web publishing and remote access, concerns aboutsecurity and unauthorized access also come into picture.

6) Fail to create awareness about energy conservation:Most of the current systems are designed with just comfortand convenience in mind. Such systems do not inform theuser about the electricity consumed by an appliance duringits operation. So consumers are unaware of the amount ofelectricity they use everyday. This is why these systemsfail to create awareness about energy conservation amongstconsumers.

7) Provide no features to the electricity distributor: Homeautomation systems do not play any significant role outside thehomes they are installed in. From the electricity distributorsside, there is no change in the way electricity is distributed.With the advent of smart grids, the electricity distributionscene is changing rapidly. Home automation systems must becompatible with smart grids and related technologies.

II. POWERLINE COMMUNICATION

Powerline communication (PLC) is a technique in whichexisting electricity supply networks are re-used for communi-cation. The primary benefit of PLC is the reduction of costs inthe realization of new communication networks. The techniqueof PLC has been in use since the early twentieth century.

PLC supports a wide range of communication frequencies,starting from a few kHz to more than 100 MHz. Broadly,we can classify PLC in two categories: narrowband andbroadband PLC. Narrowband PLC offers low data rates andis typically used for home automation and metering pur-poses. Broadband PLC is popularly used for home networking(LAN).

PLC has a natural application in home automation. Alarge number of home automation solutions currently availableare PLC based. The sensors, controllers and actuators areconnected to each other through the electrical wiring of thehome. The concept of PLC based home automation is shownin Figure 3. Many communication standards exist for in-homePLC. Some of them are X10, HomePNA, LonWorks andHomePlug. The X10 protocol is particularly popular. Let usnow discuss the merits and de-merits of using PLC in homeautomation.

A. Advantages of using PLC in home automation

The biggest advantage of using PLC in home automationis that it reduces re-wiring as it uses existing electrical wiringfor communication. This eases installation as most componentsare designed to be of the plug-n-play type. Hence PLC basedsystems are more portable, i.e., they can be removed from onehome and installed into another without much trouble.

Less re-wiring also means less cost and hence, PLC basedsystems tend to be much more affordable.

B. Limitations

The power lines were not designed for communication.Hence, some problems are faced when using power linesfor communication. Signal loss and attenuation are amongstthem. At some point, use of signal repeaters becomes essential,increasing cost and complexity. Moreover, the power lines con-tain a fair amount of high frequency noise usually generatedby SMPS systems. PLC signals may get contaminated due tothis and hence, power line filters must be used.

In the low voltage power supply network, a single trans-former supplies power to a number of homes. Hence, highfrequency PLC signals from one house may pass to otherscausing interference.

System controllersends commands

Power lines(power + data)

Appliances receive commands throughpower cables

Fig. 3. PLC based home automation. Existing electrical wiring is reused forcommunication between the components of the home automation system

III. SYSTEM ARCHITECTURE

Our goal is to design a next generation home automationsystem that will try to overcome some of the drawbacks ofcurrent systems as mentioned in Section I-C.

The system architecture is as shown in Figure 4. Thesystem controller is responsible for the UI and all the in-home automation tasks. The controller is interfaced to variouscomponents that build up our system. Let us discuss them oneby one.

A. Controller

The controller (also system controller) is the heart of thesystem. The entire system is divided into four major subsys-tems – appliance control, surveillance, web publishing and

data logging. The controller is responsible for managing allthese systems. Apart from this, the controller also plays animportant role in creating a friendly user interface for the user.

Controller

Web Interface

User Interface

PoE InterfaceIP Camera

PoE Interface

PLC

Inte

rfac

e

PLC

Inte

rfac

ePL

C In

terf

ace

Actu

ator

Actu

ator

Appliance 1

Appliance 2

BPL Interface

Internet

Local User

Remote User

To Server

Pow

er L

ines

CAT5 Cable

Fig. 4. The architecture of our system. The blocks within the dashedboundary are installed in the home.

B. Appliance control subsystem

The appliance control subsystem is responsible for control-ling the home appliances using PLC. The controller sendscommands and trigger signals to the actuators using PLC.For this, PLC interfaces are provided for both controllerand actuators. These interfaces are responsible for providingstandard connection interfaces for actuators and the controller.

C. Video surveillance subsystem

The video surveillance subsystem consists of video camerasand Power over Ethernet (PoE) interfaces. PoE is a techniqueby which Ethernet cables (CAT5/6) can be used to supplypower to a device. This enables us to use the same cable topower the device and for communication. The PoE standardis described in IEEE 802.3af.

Two PoE interfaces are provided for the video surveillancesubsystem. At the controller end, the PoE interface providesstandard Ethernet interface whereas at the camera side, thePoE interface provides a standard Ethernet interface as wellas a power supply cord.

D. Web publishing subsystem

The web publishing subsystem allows remote access andmanagement. The web interface is responsible for this. Thesystem controller will run a web server that allows access tothe system from any place around the world.

E. Data logging subsystem

The data logging subsystem keeps a track of the timeand date when an appliance was switched on or off. Thisdatabase is maintained in the system controller. Furthermore,this database can be accessed from a remote location.

With this, the system can be further extended for multiplehomes. This is as shown in Figure 5. As shown in the figure,multiple homes are managed by a central server. Each homehas a system controller installed in it. Each system controllerkeeps the appliance usage database in it. The central servercan access this database at any time. This data base can beused for load shedding/balancing, identifying peak hours ofelectricity usage and generating itemised electricity bills.

For this, a Broadband over Power Lines (BPL) interfaceis provided for the controller as well as for the server. Thecommunication between the server and controller is carriedover the low voltage power supply network. Internet accessfor all homes in the grid can also be easily provided usingBPL.

Controller Controller Controller Controller

Controller Controller Controller Controller

Central Server

Power Lines (power + data)

Fig. 5. Extension of the system for multiple homes. The central servercommunicates with the controllers installed in each home using the powerlines.

IV. IMPLEMENTATION MODEL

Let us now discuss how the system can be realized inpractice. To design the system, we chose technologies that arepopular, readily available and least expensive. We deliberatelysteered away from technologies that are yet to arrive in themarket because we want to deploy our system as soon aspossible. The implementation model of our system is as shownin Figure 6.

The system controller is an embedded system designedaround the ARM9 micro-controller. The controller uses a touchscreen LCD display for user interaction.

A. Appliance control subsystem

The appliance control subsystem is realized using the X10standard. X10 is the de-facto standard for PLC in homeautomation. Majority of the home appliance products in usetoday are X10 based. This will make our system compatiblewith the existing home automation solutions.

The micro-controller (ATmega168) is used solely for trans-mitting X10 commands. It is interfaced with the main con-troller via USB. The XM10 is a X10 powerline trans-receiverthat accepts X10 codes from the ATmega168, modulates them

with 120 kHz X10 signals and injects them into the powerlines. The XM10 also isolates the ATmega168 (and hencethe controller) from the power lines. In the X10 standard, theactuators that are connected to the home appliances are calledas modules. They extract/receive X10 codes/commands fromthe power lines and perform necessary switching actions. Wehave used two modules in our prototype – AM12 and LM12.The AM12 acts as a remote controlled relay and is suitablefor on/off operations (TV sets, CFLs, cellphone chargers, etc.)whereas the LM12 also supports dim/bright commands and isused for incandescent bulbs.

ATmega 168

LM12

Lam

p M

odul

eA

M12

App

lianc

e M

odul

e

Lamp

TV

PoE Injector

Power

Router

Internet Web Browser

On Off

Appliance

On

Dim

Off

Bright

Lamp

Camera Footage . . .

Power Lines

CAT5 Cable(Power + Data)

IP Camera

PoE Splitter

Power Data

Electricity Distributor

Terminal

Remote User

USB

DataLogging

WebPublishing

VideoSurveillance

ApplianceControl

System Controller

XM

10

Pow

erlin

e In

terf

ace

GPIO

Ethernet

Fig. 6. The implementation model of our system showing how the varioussubsystems are realized

B. Video surveillance

The PoE injector and splitter form the simple interface forthe IP camera. We deliberately chose IP cameras because theythemselves can work as standalone surveillance systems. Soin case the main controller fails, the surveillance subsystemwill still work as it is directly connected to the internet router.The footage from the camera can be viewed from popular andstandard web browsers.

In CAT5 cables, two pairs of wires are unused. The PoEinjector uses these to transmit DC power to the camera. Thepower supply and injector are placed near the controller.

The CAT5 cable between the injector and the splitter carriesboth the power and data from the camera. The PoE splitterworks exactly opposite to the injector. The splitter routes theDC power to the camera power input socket. The remainingwires in the CAT5 cable are connected as usual at both, thecontroller and the camera side.

C. Software

The software of our system is tightly integrated with theunderlying hardware. The simplified architecture is shown inFigure 7.

1) OS kernel: The system runs a custom kernel made fromthe generic Linux kernel. At the lowest level, the OS providesbasic services required for proper functioning of the device.The main components here are:

• Device drivers: They are required for interfacing vari-ous components of our system to the controller. Devicedrivers for touch-screen displays, USB devices, network-ing devices, speakers, etc. are included in the kernel.

• Networking: Networking support is an important require-ment of our system. The system has a networking stackand supports many popular and standard protocols suchas Telnet, HTTP, FTP, etc.

• File system: We have also provided a standard Linux filesystem in our controller. The file system is required fordata logging, saving user preferences, system logs, etc.

ApplianceControl

VideoSurveillance

DatabaseManagement

WebPublishing

User Experience

Application Frameworks

Qt 4

QtGui QWebView

BoaWeb Server

QProcessSQLite 3

AApppplliiccaattiioonn FFrraammeewwoorrkkss

Linux File System Networking Drivers

Custom KernelCCuussttoomm KKeerrnneell

Fig. 7. Software architecture of the system

2) Application frameworks: Proper application frameworksstreamline the process of software design. In our system, theentire user interface is designed using the open source Qtframework for C++. Qt 4 provides a standard desktop-likeinterface while being light enough to run on an embeddedsystem. The important Qt classes that we have used in oursystem are:

• QtGui: This class provides the basic UI environment.Buttons, scroll-bars, tabs, etc. are all a part of this class.

• QWebView: This class provides the essential HTTP func-tions required to communicate with the IP camera. TheIP camera footage is displayed using this class.

• QProcess: This class is used to manage processes and runbash scripts from within Qt. This is used to integrate theappliance control subsystem and SQLite with Qt.

Apart from Qt, the system uses SQLite 3 for data logging (asdescribed in Section III-E.) and Boa web server (as describedin Section III-D) for web based control.

V. CONCLUSION

Though our prototype is still under development, we haveachieved most of the features we mentioned above. We wereable to establish reliable communication over the power linesat a frequency of 120 kHz and for distances up to 300 m. The

prototype, apart from being a feature rich home automationsystem, also forms a solid base for future systems. We havekept room for expansion and improvement throughout thearchitecture. The system is currently capable of controlling 256home appliances, from anywhere around the world. Interfacesto attach sensors are provided and the software for them isready. The snapshots of our prototype are shown in Figure 8and Figure 9.

Fig. 8. The system controller, showing the touch screen interface and theappliance control UI.

Fig. 9. The daughterboard of our system. The system controller connects tothe board using the USB interface.

Apart from surveillance and appliance control, the featureof our system that we are very proud of is the data loggingprovision. The system will collect very valuable data aboutelectricity usage in every home. This data can be used toidentify peak hours of electricity consumption, average elec-tricity consumption and for generating itemized electricitybills. Itemized electricity bills will tell consumers the runningcost of their appliances. Consumers, themselves, will identify

which of their appliances are the most power hungry and willuse them carefully and switch them on only when needed.This means lower bills and less power consumption.

The electricity distributor can efficiently monitor everyhome in his grid. He can easily identify high load areas andperform necessary load balancing and load shedding. He canalso identify unjustified usage of electricity by a consumer(such as use of air-conditioners in winters) and penalize himfor it. Itemized billing will increase transparency in billing andimprove relations between consumers and distributors.

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