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Monitoring and Controlling Power usingZigbee Communications

N. Javaid, A. Sharif, A. Mahmood, S. Ahmed♯, U. Qasim‡, Z. A. Khan§

COMSATS Institute of IT, Islamabad, Pakistan.♯Mirpur University of Science and Technology, AJK, Pakistan.

‡University of Alberta, Alberta, Canada§Faculty of Engineering, Dalhousie University, Halifax, Canada.

Abstract—Smart grid is a modified form of electrical gridwhere generation, transmission, distribution and customers arenot only connected electrically but also through strong communi-cation network with each other as well as with market, operationand service provider. For achieving good communication linkamong them, it is very necessary to find suitable protocol. Inthis paper, we discuss different hardware techniques for powermonitoring, power management and remote power controllingat home and transmission side and also discuss the suitabilityof Zigbee for required communication link. Zigbee has majorrole in monitoring and direct load controlling for efficient powerutilization. It covers enough area needed for communicationand it works on low data rate of 20Kbps to 250Kbps withminimum power consumption. This paper describes the userfriendly control home appliances, power on/off through theinternet, PDA using Graphical User Interface (GUI) and throughGSM cellular mobile phone.

Index Terms—Zigbee, monitoring, controlling, smart grid

I. I NTRODUCTION

in many countries, communication based controlling andmonitoring architecture is used in smart grid to save power.Communication network may be wired or wireless. Commu-nication through wired interface is very intricate and hardtoimplement or install. Wireless interfaces are chosen becausethey are easy to organize and install. Furthermore, Zigbee hassome technical advantages over bluetooth, WiFi, infrared raysetc. Zigbee is a kind of low power-consuming communicationtechnology for coverage area surrounded by200m, with a datarate ranging from20Kbps to 250Kbps, it is appropriate foruse in home area networks, mainly for the remote control ofelectric home appliances. Table. 1 shows the comparisons ofbluetooth, WiFi, Zigbee.

Standard Range Numberof Nodes

FrequencyBand

DataProtection

Poweruse

Bluetooth 10 m 8 2.4GHz 16 bitCRC

high

Wi-fi 100 m 32 3.1-10.6GHz

32 bitCRC

high

Zigbee 10-200 m More than25400

868/915Mhz 2.4GHz

16 bitCRC

low

TABLE I: Comparisons of bluetooth, wifi, zigbee.

In this paper, we discuss different options of hardwaretechnique for power controlling and monitoring architecture.

For Monitoring, hardware is based on current or voltage mea-suring circuits, Micro Controller Unit (MCU) relay and ZigbeeReduce Function Device (RFD). Current/voltage measuringcircuit measures the I/V and sends the information to MCU.Micro Controller checks abnormality of power and send theinformation to the home server where database is maintainedthrough Zigbee RFD. For controlling purpose, relay is addedin power monitoring hardware. In case of emergency foundby MCU, relay cuts the power supply to the electric homeappliances after receiving the control command. Graphic UserInterface (GUI) software is used as an interface betweenuser and end devices. User can control all electric appliancesthrough cell phone, computer or laptop.

II. RELATED WORK AND MOTIVATION

For remote power control and monitoring, many wirelesstechnologies are discussed; these are: Infrared rays, WLAN,Bluetooth, and Zigbee. However, Zigbee is suitable for remotepower control and monitoring due to large coverage area upto 200m and with transmission rate ranging from20Kbps to250Kbps. Typically home appliance has three power modes,normal, stand by and off. In normal mode, home appliancesuse maximum power, however, in stand by mode, homeappliances use almost10 percent of power consumption ascompared to normal mode. In [1], authors discuss architectureof automatic cut-off for home appliances during stand by modeto save power consumption.

In [2], [3] and [4], power monitoring module calculatespower consumption of electric home appliances in normalmode. Zigbee communication module is used to send mea-sured data of current and voltage to server module and storeit in computer. Embedded board is used instead of computerto reduce power consumption. In case of overload/abnormalityin power consumption, server module sends a control messageto MCU via zigbee modul. MCU cuts power to the load forsafety purpose. Authors design the GUI by using Visual Basic(VB) to provide user friendly environment. However, powersupply to power monitoring and controlling component is notdiscussed by authors.

In [5], Bluetooth is used for controlling electric home appli-ances. Bluetooth has low coverage area up to10m. Bluetooth

Fig. 1: Power Management Structure

is better option for short distance controlling, however, forlong distance controlling is not easy to achieve via bluetooth.

In [6], author discuss use of Zigbee communication inAdvance Metering Interface (AMI). Zigbee is used to transmitdetailed information of power consumption and also discussthe way of joining Zigbee network.

III. H ARDWARE

In this section, we discuss different hardware options withdifferent techniques for power monitoring and control purposein smart grid.

A. Power Management Structure

In [3], power management structure for electric outlet asshown in Fig. 1, has three main parts: Zigbee based powermonitoring module, home server and remote control section.Power monitoring module based on (MCU), Solid State Relay(SSR), a current measuring circuit and a Zigbee End Device(ZED). The home sever module has two parts: one is ZigbeeCoordinator (ZC) and other is embedded board. The remotecontrol section can be a personal Computer (PC) or PersonalDigital Assistant (PDA).

Sensor in Zigbee based power monitoring module senseselectric current being used by electric outlet. Current measur-ing circuit measures current and sends to MCU. MCU turnsthe electric outlet on/off. MCU based on two-way controlmechanism: one direction for on/off control and other forcurrent measurement. MCU handles ID of each end device,control electric outlets and send control message to homeserver through Zigbee coordinator. Through MCU, we candetect condition of all electric home appliances. Embeddedsystem stores data of all power outlets and serve the user whenthey want.

To minimize power consumption, traditional relay is re-placed by SSR for controlling on/off power outlets. In Zigbeebased monitoring module, embedded board is used instead of

PC to minimize the size, power consumption, and cost of homeserver.

B. Real-time Power Monitoring Architecture With Direct LoadControl

In [4], Zigbee based real-time power monitoring architectureconsists of three modules: power management module, Re-mote Monitoring Control Module (RMCM) and user module.Power management module contains Power Observing Side(POS) and Power Control Side (PCS). POS monitors powerconsumption from various facilities like power consumptionthrough switchboard and substation. Alternatively, largepowerutilization facilities such as central air conditioner, controlledby PCS. RMCM enclose major software components of POSand database. ZC is linked to RMCM through RS-232 interfacefor sending and receiving messages to Zigbee device on powermanagement module. On user side, user can remotely operatePOS through any web browser on notebook or PC, as shownin Fig. 2.

POS has three main parts Signal Transformation Circuit(STC), Digital Signal Processing (DSP) board and RFD. STCcollects power consumption data from switch/substation andscale the information to fit input scope of Analog to DigitalConverter (A/C) convertor of DSP board. DSP board is liableto calculate various power parameters and become awareof power omission in real time. This power information istransmitted to server side through Zigbee RFD. Zigbee RFDis an end device that can collect data through different sensorsor switches and send to gateway (coordinator or router).

In power control, Zigbee RFD is directly connected to relay.After finding power abnormality ZC sends command to ZigbeeRFD to unload assigned power facilities.

RMCS has following major functional components. Authen-tication and Authorization component (AA) verifying con-sumer identity and used for security purpose.Warning Mes-sage Transmission (WMT) component is capable of sending

Fig. 2: Real-time Power Monitoring Architecture with Direct Load Control

warning message to user through e-mails and mobile phoneshort message web service after finding abnormality in power.GUI component provides different user-friendly graphicalwebinterface to control system through general browsers. Throughremote control component, user can manually perform DirectLoad Control (DLC). Data management component managesdifferent data in system like user data, historical data of powerconsumption. The power demand forecasts component forecastthe best possible contract capacity based on historical powerconsumption data.

C. Power Observing Structure using Bluetooth, Ethernet andGSM

In [5], Bluetooth Controlled Power Outlet Module(BCPOM) is hardware architecture for power monitoring andcontrolling, as shown in Fig. 3. This hardware consists onseveral AC power sockets, vital control side, Protected DigitalCard (PDC) side, Scalable Source Routing (SSR), powermeasuring side and communication interfaces based on Zigbeeand GSM. SSR is used to turn on/off each sokets where electrichome machines/appliances can be pluged.

Vital control side is based on four functions:(i) dealing outcommands from communication interfaces bluetooth, ethernetand GSM,(ii) scheming the SSR on/off,(iii) observing thestatus of electric home appliances, and(iv) transmitting thepower status and measured data to the protected Digital CardSide. GSM interface is used to connect vital control side andalso allows to make a call by using GSM network. Bluetooth

side is a low power embedded bluetooth with a built-in high-output antenna.

The ethernet side connects electric home machines to in-ternet. PDC side is used for storing the measurement dataof electric home machines and also store status of theseappliances.

D. Power Monitoring and Controlling Architecture

In [2], proposed system for power monitoring is based onthree components: Data Acquisition (DA), Data Processing(DP) module and Application. Data acquisition consist ofwireless sensors which are used for measuring AC and controlpower outlets. A wireless sensor has three technical parts,MCU with A/C, a sensing unit and a Zigbee transceiver. DPmodule collects information from all sensors through Zigbeeand make a database of all collected information and respondsto appeal from users.

E. Power Controlling Architecture

Authors in [1] discuss the different techniques for control-ling power in different conditions. One is automatic power cutoff during standby mode. Architecture of automatic power cutoff during standby condition of power outlet is based on A/Cconversion, a two port relay, a micro controller and powerobserving circuit. AC input is connected to two port relay.One port of relay is directly connected to AC output electricpower outlet and other relay is connected to the output relaythrough power observing circuit. Power observing circuit hasthree major components: transformer, rectifying diodes and

Fig. 3: Power Observing Structure via Bluetooth, Ethernet and GSM

Fig. 4: Zigbee-based Transmission Line Monitoring

additional components. In micro controller unit Zigbee RFmodule is added to communicate with the coordinator.

Other is Zigbee controller with IR code Learning Function-ality. ZC is based on A/C conversion circuit, a MCU withZigbee RF module, IR receiver and several switches. Theseseveral switches have different tasks. First switch is assignedto the first power outlet; through this button first power outletwill be controlled. Next two buttons can be assigned for thelight control. One button is for ‘dark’ function and other isfor‘light’ function.

F. Zigbee Based Transmission Line Monitoring

In [7], authors propose a Zigbee based transmission linemonitoring system. The block diagram of the system is shownin Fig. 4. This system is based on Information Collection Unit(ICU), ZC and data management center. Information collectionunit consists of sensor A/C, DSP, Zigbee RFD. Sensors keepinformation of power consumption in analog form and A/Cconvert analog information into digital information and send to

DSP unit. DSP unit calculates variation in power consumptionor any abnormality in power utilization and send the informa-tion to ZC through Zigbee RFD. ZC sends all informationcoming from different sensor to data management center.

IV. SUITABILITY OF IEEE802.15.4FOR SMART GRID

There are various types of wired and wireless interfaces thatcan be used in smart grid for communication purpose similarto Bluetooth, WiFi, LAN, Zigbee, Ethernet, IEEE 1394, PLC,etc. Communication through wired interface in smart gridis very intricate and hard to implement and install; that iswhy wireless interfaces are chosen, since they are easy toorganize and install. Furthermore, Zigbee has some technicaladvantages over others. It is low-cost, low power consumingwireless communication standard with maximum number ofnodes. Zigbee has quicker response time. In [6], a new Zigbeebased power meters can easily join the Zigbee network. Powermeter sends the date and time synchronization command to theZigbee device which sends this command to ZC. ZC replies

with date and time data to the Zigbee device after completingthe date time synchronization power meter ready to send therequired data and become a part of Zigbee network. Belowwe tell the Open System Interconnection (OSI) model layeron which Zigbee protocol based and Zigbee based powermonitoring and controlling.

A. Zigbee

In [8], mound of Zigbee protocol is based on four layersof standard Open System Interconnection (OSI) model. Appli-cation Layer, Network Layer, Medium Access Control Layer(MAC) and Physical Layer. Application Sub layer layer isin charge for maintenance of required tables that match twodevices according to their desires and services. Network layeris responsible for creating network by adding and deleting thenodes and for the route discovery between devices and theirmaintenance. Zigbee has two standards for physical layersthat work in different frequency range: 868 MHz, 915 MHzand 2.4 GHz. MAC layer is conscientious to offer interfacebetween the Service Specific Convergence Sub layer (SSCS)and physical layer.

B. Zigbee Based Monitoring and Controlling

Zigbee technology can be implemented in generation, trans-mission, distribution, and in consumer sectors to providecontrol on power consumption and give accurate data to userand utility. Fig. 5 shows communication architecture, wheregeneration side, transmission side, distribution side andcon-sumers are not only connected electrically but also connectedby communication interfaces with markets, operations andservice providers. Zigbee based devices have two types: oneis Full Function Device (FFD) and other is RFD. FFD can becoordinator or router. It is liable to create the network, selectthe radio frequency channel and distinctive network identifierto avoid collision among data from different sensor nodes andfor security purpose. Zigbee RFD plays role of end device thatcollects variety of data from different switches and sensors.Here we discuss Zigbee based transmission lines monitoring,meter reading system and load control system.

1) Zigbee Based Transmission Lines Monitoring: In [7],transmission line monitoring system is based on environmentalparameters of lines and towers such as temperature, ice,wind lightening etc. Sensors are placed on transmission line.These Zigbee based sensors sense power passing through itand send to data center via Zigbee gateway that are fixedon transmission tower. Small blue boxes represent powermonitoring device as shown in Fig. 6.

2) Zigbee Based Meter Reading System: In [8], Zigbeebased meter reading system has two main parts: Zigbeenetwork and database unit. Zigbee network is constructedby Zigbee router, end devices and coordinator. Router andcoordinator must be FFDs and end devices can be RFDs.After calculating required information end devices send thisinformation to the relevant router. Router has function to syn-chronize service to other FFDs like coordinator. Coordinatorssend received data throughRS232 interface to database unit.

C. Zigbee Based Load Control System

In [1,4], for controlling purpose, Zigbee RFD is directlyconnected to relay. Relay is used for turning the switch on andoff. After finding any abnormality in power used by electrichome appliances control command is sent to the ZigbeeRFD by coordinator. Subsequently, relay turns off those homeappliances. ZC also receives the data from the end devicesthrough the zigbee RFD.

V. USER RESPONSIVE CONTROL SYSTEM

Zigbee based Smart meters are part of AMI which give allinformation about power to customer like showing peak hourstime, current running price, and real time power consumptionby electric home appliances. It involves user to control powerload at his end. This system provides reliable control systemto user through different ways.

A. Control by Internet

In [5], the software for remote controlling is install in PCor laptop and connect to internet. The network formation ofconnecting remote control by internet is a host-client structure.This remote control software sets IP address and ports andsends request to Power Monitoring System (PMS), createsa link between user and PMS. In [4], when PMS detects apower abnormality, warning message hurl to user through e-mail by means of Mail Transfer Protocol (MTP). In [2], underthe proposed system, functional schedules are implementedonjava Virtual Machine(VM). When user want to switch on/offan electric home appliance from a web interface, response timeis less than one sec.

B. Control by PDA with GUI

In [1], [3], [4] and [5], PDA is connected to power moni-toring module for controlling and monitoring electric homemachines. GUI is used in control area to create interfacebetween user and electronic devices. By making use of GUI,user can access condition of electric home appliances, timereaction and energy utilization made by electric power outlets.GUI provides effortless control of power status of electrichome machines. User can set each switch as on/off by sendingcommand. The remote control system offers to supervise andmanage power condition of electric home appliances.

C. Control by GSM Cellular Mobile Phone

In [5], consumer can examine and organize electric homemachines using GSM cellular mobile phone. User sends con-trol command message through GSM cellular mobile phone toPMS. After receiving control command PMS allows user tocontrol if sending command format match with system. Usercan be capable for supervise and organize power conditionof electric home appliances anytime and anywhere usingGSM cellular mobile. PMS can also send warning messageto consumer after finding unusual status of power

Markets Operations Service

Suppliers

Generation

Transmission

Distribution

Feeders

MetersCustomer side

Shows the wireless link

Shows the electrical link

COMMUNICATION ARCHITECTURE MODEL

Fig. 5: Communication Architecture

Fig. 6: Transmission Line Monitoring

VI. CONCLUSION

In this paper, we discussed power utilization, power orga-nizing and power controlling architecture for power savingpurpose. We also discussed the role of Zigbee in transmissionline monitoring, real time meter reading and direct load con-trolling of electric home appliances. This paper also describesthe user friendly control home appliances for power on/offthrough internet, PDA using GUI and through GSM cellularmobile phone.

REFERENCES

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[2] Kim, W.H. and Lee, S. and Hwang, J., “ Real-time Energy Monitoringand Controlling System based on ZigBee Sensor Networks”, ElsevierProcedia Computer Science(PCS), 2011.

[3] Bai, Y.W. and Hung, C.H., “Remote power On/Off control and currentmeasurement for home electric outlets based on a low-power embeddedboard and ZigBee communication”, IEEE 2008.

[4] Cheng, J.Y. and Hung, M.H. and Chang, J.W., “A zigbee-based powermonitoring system with direct load control capabilities”,IEEE Interna-tional Networking, Sensing and Control (INSC), 2007.

[5] Lien, C.H. and Bai, Y.W. and Lin, M.B., “Remote-controllable power

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[6] Luan, S.W. and Teng, J.H. and Chan, S.Y. and Hwang, L.C., “Develop-ment of a smart power meter for AMI based on ZigBee communication”,IEEE International Conference on Power Electronics and Drive Systems,2009.

[7] Zhang, Q. and Sun, Y. and Cui, Z., “Application and analysis of ZigBeetechnology for Smart Grid”, IEEE International Conferenceon Computerand Information Application (ICCIA), 2010.

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