A Flexible Data Acquisition System for EnergyInformation

Guan Wah UngSchool of Electrical and Electronic Engineering

Nanyang Technological University,Nanyang Avenue, Singapore 639798.

(now with Water Supply Network, Public Utilities Board, Singapore)Email: ungg0002@ntu.edu.sg

Peng Hin LeeSchool of Electrical and Electronic Engineering

Nanyang Technological University,Nanyang Avenue, Singapore 639798.

Email: ephlee@ntu.edu.sg

Liang Mong KohSchneider Electric Singapore Pte Ltd

10, Ang Mo Kio Street 65, 02-17/20, TechPoint, Singapore 569059.Email: Liang-Mong.Koh@sg.schneider-electric.com

Fook Hoong ChooSchool of Electrical and Electronic Engineering

Nanyang Technological University,Nanyang Avenue, Singapore 639798.

Email: efhchoo@ntu.edu.sg

Abstract—This paper proposes a system for the monitoringand data acquisition of information that are associated withthe energy consumed by an equipment or facility. The acquireddata are stored in a relational database and can be retrievedfor further processing and analysis by the energy managementpersonnel. Various scheduler functions can be carried out to easethe tasks of energy management for the facility. The proposedsystem is integrated with a programmable logic controller forthe monitoring and control of equipment. The status of theequipment are displayed through a SCADA platform to providea visual interface for the operator. Through the mobile phone’sShort Message Service (SMS) function, an online condition-basedmaintenance monitoring alert function is provided. Alarm signalsfrom faulty equipment or plant malfunctions and commandsignals as SMS messages sent by the user is routed through thesystem and the PLC, thereby allowing remote communicationsamong the equipment and the user.

Keywords : Data acquisition, energy management system,programmable logic controller, energy consumptions mea-surements, energy audit.

I. INTRODUCTION

With the rising oil prices and increasing electrical tar-iffs charged by the electric utilities companies, electricity-dependent industries are faced with the challenges of min-imizing or reducing the electricity bills while at the sametime not sacrificing performance and human comfort. Due tothe increasing competitive nature of conducting businesses,many companies have found it worthwhile to invest in someform of energy management system to monitor energy usageand trend energy consumption patterns in their facilities asa means to reduce business costs through the identificationsand implementations of energy savings projects. These effortswould also lead to the reduction of the emissions of greenhousegases that is a major contributing factor to global warming.In addition, the interest in green buildings for a sustainableenvironment has also increased significantly in many countriessuch as North America, Europe and Asia. Many governments

are encouraging the use of renewable sources of energy andassist companies to reduce the energy costs. In Singapore, forexisting buildings, part of the costs of replacing inefficientequipment such as old inefficient chillers and replacing themwith more energy efficient ones can be absorbed by the govern-ment. New building owners are also encouraged with subsidiesto incorporate energy efficient, environmental friendly andsustainable features into the design and constructions of thenew buildings. Electrical energy is needed in every householdsand buildings that require heating, cooling and lighting. Incommercial buildings, the lighting system, the HVAC systemand lift operations are areas that consume very significantamount of energy. A major part of the electricity bills is due tothe need to operate motors and compressors in the industries.

Energy efficient operations and energy consumptions areimportant considerations in an energy efficient environmentand this can be established by measurements with an energymonitoring and management system. Such a system promotesthe economical operations of the equipment in the facility andis useful for energy audits purposes ([1], [2]) as it facilitatesthe identifications of energy savings opportunities.

Over the years, significant changes have taken place in theway the energy consumptions are being measured, whether athome or in the industries, see e.g. ([3], [4], [5], [6], [7], [8])Different means in the acquisition of the energy informationhave been described. In [9], the application of wireless sensorsnetworks to a plant energy managements system is adopted,replacing wired systems formed by communication cables andsensors. Some research work on the development of an energymanagement system based on using the electric utilities powerlines for the transmission of data were reported in [10]. Others,such as, Young et al. [11] proposed a universal serial busapproach, Chung et al. [12] utilized the zig-bee technologyand Sabat et al. [13] adopted an neural network approach fordata acquisitions. Energy conservations efforts were also seen

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to be implemented in some campuses. For example, a low costpower monitoring system using the Rogowski coil is describedin Jansson et al. [14] and Nagata [15] described an electricpower energy monitoring system using the Internet for themonitoring of energy consumptions in a campus. In [16], aportable three phase energy consumption acquisition system isproposed. It consists of a notebook, clamp-on ammeters, dataacquisition card and signal interfaces to analyze the energyconsumption in the authors university and to identify energywaste areas.

A relatively low cost and flexible data acquisition systemthat is integrated with real time data logging capability andcontrol functions is described in this paper. In the oil andgas industries, LabVIEW-based data acquisition systems withreports generation capabilities are carried out with advancedand accurate flow meters for measurements so that customersare billed according to the actual amount of gas or oil that theybought from the supplier. The proposed system described hereis similar to the LabVIEW-based systems in the oil and gasindustries with respect to the necessity of parameters sensing,data acquisitions and report generations, except that the mainfocus here is on energy monitoring, energy management andcontrol. The proposed system uses the iFix SCADA software[17] as a software platform for development of a user friendlygraphical interface and data acquisition system for energymanagements. It is integrated with data logging features andcapable of consumptions and trends reports generations. Sen-sors are connected to the system to monitor environmentalfactors such as temperature and humidity. Other types ofsensors can also be easily connected to the available I/O portsfor a more comprehensive monitoring system. The systemacquires the energy and relevant parameters information frompower meters and sensors that are connected to the system.

Besides the acquisition of energy information, a controlfunction via a PLC connected to the system is also demon-strated. Applications functions are developed in programminglanguages such as VB.Net and visual basic to monitor theequipment’s status in real time, whether it is in an alarm stateor in a normal functioning state. These functions could allowthe plant management to take correction actions, if necessary.Remote monitoring and control is possible with the use ofthe Short Message Service (SMS) function found in mobilephones. Alarms text messages can be sent out to alert theresponsible personnel of possible faulty equipment or whena situation requires attention. The text messages can be sentdirectly to any mobile phone in the event of, for example,an overflow, pump failure, link error, etc. The authorized usercan initiates corrective actions from a remote location via textmessages and SMS alerts with a mobile phone. For example,in the manipulation of temperature, there are several remedialactions possibilities such as the switching on of a fan, resettingthe circuit breakers, shutting down the air-conditioner or evenmodifying the fan speed. The authorized user is also able toreceive accurate reports on the performance of the plant orequipment via SMS. The capability to receive alerts and relaycommands via text messaging and SMS commands makes the

system cost effective as there is no additional expenditure forspecific controller devices. It allows the users to be in controleven when they are away from the plant. The alarm alerts andcommand signals are routed through the system.

Using the scheduler functions developed, the system canperforms the switching of the lighting, air-conditioners andequipment to their desired states at the pre-defined timings withthe aim of energy conservation. Various communication meth-ods are put in place to carry out the information monitoring andacquisition. For example, a wireless communication modulewas built for areas where the laying of cables or hard wiringis not feasible. In the system developed, a total of 137 relevantsystem parameters are to be read from the power meters,sensors and the simulated equipment components such as airhandling units, lifts and fans connected to the system via thePLC. The acquired energy information is stored in a relationaldatabase and the data can be extracted to generate daily, weeklyor monthly reports for analysis. In the next section, the systemdeveloped is discussed in details and Section three concludesthe paper.

II. SYSTEM DESIGN

In this section, the design of the proposed system for dataacquisition of energy information is discussed.

A. Design Considerations

From the viewpoint of energy managements, the maindesign consideration is that energy information should be ableto be monitored and acquired by the system. In addition, todemonstrate the control function, a PLC is integrated to thesystem and is to be programmed to perform simple controlfunctions such as the simple switching ON-OFF functions ofdevices. The communication protocols that the various devicesemployed need to be known so that the appropriate interfacescould be designed. The system developed must also haveuser-friendly graphical interface so that users of the proposedsystem can operate it without much technical difficulties. Thefollowing main equipments are used in the system developed:

∙ QuadStar power meters with Modbus protocol∙ Temperature and humidity sensors with electrical signal

outputs∙ Signal converters including wireless and Ethernet types∙ Analog input module with Modbus protocol∙ Omron PLC

B. System Design and Architecture

The architecture of the data acquisition system is as shownin Figure 1. It showed the communication links between thesingle host PC and the various devices and equipment. Mostof the equipment have serial communications and as the serialports on the PC is limited, some of the acquired signalsare converted to Ethernet and/or wireless signals using signalconverters.

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Fig. 1. Architecture of system.

C. System and Reporting structure

The system acquires the required information through theI/O communication drivers, which will poll and request in-formation from the external devices. The data are stored ina database and are to be displayed in numerical or graphicalanimations for the users. The iFix SCADA software [17] isused as the software platform for the designs of the graphicaluser interface and the data acquisition part of the system.Reports, such as energy consumptions trends, based on thedata collected can be easily created by the Visual Basic forApplication software that is embedded in the iFix SCADAsoftware. The data stored in the relational database can be usedto generate Web reports using the Microsoft SQL ReportingServices package. In this way, the energy information or otherdata can be retrieved through the Internet almost anywherein the world. The reports can also be used for verificationor to dispute the bills sent by the electric utilities company.A diagnostic report on the working conditions of the variousequipments used can also be generated for the user. Figure 2show the reporting system architecture.

D. Schedulers

A scheduler application function was set up to demonstratethe tasks of energy managements in the facility.

a) Lighting scheduler. Lighting can be scheduled to beswitched ON or OFF at pre-defined times. The scheduler, seefigure 3, makes use of the time-based triggered event functionin the visual basic script. Upon reaching the user pre-definedtime, the script function will send a signal to the PLC controllerto set the lighting to the respective ON/OFF status. In this way,energy costs can be minimized.

b) Transfer data scheduler. This scheduler transfers theacquired data into a relational database using the MicrosoftSQL Server Express Edition. However, due to the limited

Fig. 2. Reporting system architecture

Fig. 3. Light Scheduler Configuration

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data storage size, regular maintenance, for e.g. at half yearlyintervals, may be required.

c) Reports scheduler. The purpose of this scheduler is togenerate reports such as trend charts from the historical datathat have been acquired. These reports can be used by theenergy management team to identify possible energy savingsopportunities. Another example of the use of this scheduleris that the reports generated can serve as part of the billingreports to different vendors, for the case of a building whichis occupied by many vendors. To generate the reports, upon atime triggered event, the system will automatically request forthe desired data that are stored in the relational database andhave them recorded onto an Excel spreadsheet. As the Excelspreadsheet is first designed as a template report, once the dataare recorded in the cells, the required charts as shown in figure4 will be generated and they can be saved into the system.

E. Additional useful features of the proposed system

The proposed system also consists of the following cus-tomized applications:

∙ The SCADA driver function is customized to handle theon-demand scanning of the equipments that are connectedto the system for monitoring.

∙ The Source Connector” allows connecting to a device’sreport-data upon request at the relational database. Itretrieves the devices historical data from the HistorianDatabase, summarized them and then archived it to thea Relational Database server. It also checked whether thedevices parameters are within the set tolerance limits. Thevalidity signal will be given based on the tolerance limitand the logics are based on the tolerance limits that canbe developed by any programming tool.

F. Remote monitoring and control

The remote monitoring and control of equipments canbe demonstrated through the use of a mobile phones SMSfunction (see figure 5) . Alarms alerts from a faulty equipmentand command signals sent by the user via SMS are routedthrough the system and the PLC. The application makes useof a GSM modem to send and receive the SMS messages andthe decoded SMS message allow the user to control or checkon the equipment or certain functions of the plant. When a userreceives the alert message, he can either send an acknowledgemessage back to the system or he can send an action SMSmessage to the system to control the respective devices andcarry the appropriate actions to be taken. In this way, the usercan choose to rectify the problem even before he arrives at thesite station or he could just simply acknowledge the alarms ifit is known to be not a result of a serious problem.

G. System salient features

The salient features of the proposed system are as follows:

∙ Feasibility of project planning and development∙ Integrated software wizard∙ Able to integrate with other systems

∙ Standard programming languages (VBA,VB, C++, etc)for easy programming

∙ Support generation of online web billing reports, mainte-nance reports and equipment faults reports

∙ Support embedded custom activeX control∙ Support SQL query by other systems∙ Runtime changes on site∙ Support data browsing remotely via GSM modem∙ Monitor equipment status locally and remotely

H. Discussions

New changes or developments can be achieved via thesoftware evaluation mode which supports all the functionalityof the system. The system can contain customized modules thatallow developers to key in new indexes for new equipmentand this will then automatically creates a whole new set ofgraphics, database, etc, if there are changes to the system to bemonitored. The system uses the Visual Basic for Application(VBA) which is a standard embedded programming platformthat acknowledges all the open standard protocols or anycustomised protocols if known. The system interfaces canbe connected to the web servers, relational database, etc, bymaking use of the standard internet information services andcustomized driver toolkit for configurations and developments.Furthermore, the relational database servers that are connectedto the system can have imported stored procedures that canbe programmed to run at pre-defined intervals to check forany inactive activities. The inactive monitoring points may bedisabled, if required. All the features that are described abovemay not be found in other existing systems in the market andadditional costs will be incurred for the systems to integrateall these features. If maintenance is required, the need toseek expertise assistance from different platform developersis avoided as there is only one platform used in our proposedsystem. In this sense, the maintenance time required will beshorter.

III. CONCLUSIONS

This paper presents a system for the data acquisition ofenergy information. The proposed system is flexible in thesense that changes can be made to the system with relativeease. A laboratory model was set up to test the control func-tions of the PLC and the various sensors with the system. Thesystem is able to log various kinds of data through differentcommunication mediums, which allows flexible accessibility tothe equipment in the field. The friendly graphical user interfacedeveloped allows the user to operate the system and at the sametime monitor the status of the equipment without technicaldifficulties. With the reports that can be easily generated, it alsoallows the energy management team to analyze and implementpotential energy savings measures to reduce energy cost andminimize energy consumptions. The proposed diagnostic andreporting system is still under further improvements to ensurea more accessible billing system and to be tested in the fieldin future.

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Fig. 4. Samples of charts and data reports

REFERENCES

[1] W. C. Turner and S. Doty, Energy management handbook. FairmontPress, 6th edition, 2006.

[2] A. Thumann and W. J. Younger, Handbook of energy audits, FairmontPress, 7th edition, 2007.

[3] W. J. Lee and R. Kenarangui, Energy management for motors, systemsand electrical equipment, IEEE Transactions on Industry Applications,38 (2), 2002, pp 602-607.

[4] D. R. Munoz, D. M. Perez, J. S. Moreno, S. C. Berga, E. C. Montero,Design and experimental verification of a smart sensor to measure theenergy and power consumption in a one-phase AC line. Measurement42, 2009, pp 412-419.

[5] F. Libano, I. Paranhos, J. Melchiors, O.Mano, R. Fehlberg, R. Braga,S. Muller, Power energy meter in a low cost hardware/software. InIEEE International Symposium on Industrial Electronics, 9-12 July 2006,Montreal, Quebec, Canada, pp 1712-1715.

[6] P. A. V.Loss, M. M.Lamego, G. C.D. Sousa, J. L. F.Vieira, A singlephase microcontroller based energy meter. In Proceedings of the IEEEInstrumentation and Measurement Technology Conference, Vol. 2, 1821 May 1998, St. Paul, Minnesota, USA, pp 797-800.

[7] Inoue M., T. Higuma, Y. Ito, N. Kushiro and H. Kubota, Networkarchitecture for home energy management system, IEEE Transactionson Consumer Electronics, 49 (3), 2003, pp 606-613.

[8] A. T. de Almeida and E. L. Vine, Advanced monitoring technologies forthe evaluation of demand-side management programs, Energy, 19 (6),1994, pp 661-678.

[9] B. Liu, T. H. Habetler, R. G. Harley and J. A. Gutierrez, Applyingwireless sensor networks in industrial plant energy management systemsPart I: A closed-loop scheme, In Proceedings of the 4th IEEE Conferenceon Sensors, Irvine, CA, 2005, pp 145-150.

[10] G. K. Papagiannis, T. A. Papadopoulos, C.D. Dovas Non, D. A. Tsi-amitros and P. S. Dokopoulos, A Power line communication based energyconsumption management system- power line performance analysis: field

Action Reply

Alert Message

Data Query

Fig. 5. SMS Application

tests and simulation results. In Proceedings of the IEEE conference onpower tech, St. Petersburg, Russia, 2005, pp 1-7.

[11] C. P. Young, M. J. Devaney, A. C. Wang, Universal serial bus enhancesvirtual instrument-based distributed power monitoring, IEEE Transac-tions on Instruments and Measurements. 50 (6), 2001, pp 1692-1697.

[12] J. Y. Chung, M. H. Hung, J. W. Chang, A zig-bee based power moni-toring system with direct load control capabilities, In IEEE InternationalConference on Networking, sensing and control, 15-17 April 2007,London, UK, pp 895-900.

[13] S. L. Sabat, S. K. Nayak, S. Mahapatra, WNN based intelligent energymeter, Measurement, 41, 2008, pp 357-363.

[14] P. M. Jansson, J. Tisa, W. Kim, Instrument and Measurement Tech-nology Education - A case study : Inexpensive student-designed powermonitoring instrument for campus sub-metering, IEEE Transactions onInstrumentation and Measurement, 56 (5), 2007, pp 1744-1752.

[15] T. Nagata, An electric power energy monitoring system in campus usingthe internet, In Proceedings of IEEE Power Engineering Society Meeting,Quebec, Montreal, Canada, 2006.

[16] A. Lang and H. Weiss, Portable three phase energy consumption acqui-sition system, In proceedings of the 12th International Power Electronicsand Motion Control Conference, EPE-PEMC 2006, Portoroz, Slovenia,2006, pp 13301334.

[17] Proficy HMI SCADA iFix Electronic Book,www.gefanuc.com/products/3311.

[18] UPM6100 Portable Energy Meter Technical Information, Algodue Elec-tronica s.r.l., Italy.

[19] SYSMAC CQM1 Series Programming Manual.http://www.crystal-pix.com/Ebay/CX − ProgrammeManual2.1.pdf

[20] J. M. Figueiredo and J. M. G. Sa da Costa, An efficient system to monitorand control the energy production and consumption, In proceedings ofthe 5th International Conference on European Electricity Market, EEM2008, Lisboa, pp 1-6.

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