2015 International Conference on Advanced Technologies for Communications (ATC) A Practical Implementation of Wireless Sensor Network based Smart Home System for Smart Grid Integration Minh-Triet Nguyen, Lap-Luat Nguyen, Tuan-Duc Nguyen International University of Vietnam National University, Vietnam Email: ntduc@hcmiu.edu.vn Abstract—This paper presents a hardware design of smart grid home gateway that integrates smart home network to be compatible for smart grid integration In this network, a Smart Grid Home Gateway can control the electrical appliances based on the programming schedule or data received from control center Moreover, some low cost wireless transceivers for Smart Grid are investigated and a simple wireless network topology based on star routing protocol for Smart Grid Home Network is also proposed Final, demonstration results display an actual SGHG prototype to verify the system Index Terms—Smart grid, electricity meter, wireless communication, WSN, home network, saving energy consumption I I NTRODUCTION Electricity becomes the most important thing in modern life Today, a chain effect with serious consequences can be occurred in case of the interruption such as a power failure affecting the banking system management, communications, transportation and security Because the sustainable growth must be ensured in the future, people need a new kind of power grid This technology is not only built from the current architecture platform that can handle the signal bit of modern digital devices, but also capable of automatic control, monitoring and managing the complexity of the electrical system as well as the growing demand for electricity One of the main developments and important technologies in the power system is the Smart Grid [1] The Smart Grid can be known as an integration of the modern systems as information technology and communication networks into the traditional grid This combination allows providers and consumers to communicate two-way via better controlling and management of electrical energy in the transmission, distribution and consumption In addition, the Smart Grid also unlocks enormous potential of the current power grid such as: push of the renewable energy source, improve the safety and stability of the power supply with the participation of consumers [2] Given that the relative studies in [3], [4] and [5], the smart grid system consists of two main layers known as smart grid system layers and network layers Figure shows components which are contained by two main layers This research focuses on the design of a smart grid system in the home area network (HAN) Especially, a hardware prototype (smart grid home gateway) for the central control circuit of the household is introduced A smart grid home gateway (SGHG) has to response functions as optimal power distribution and limitation overload on the grid system, increase energy production efficiency and 978-1-4673-8374-5/15/$31.00 ©2015 IEEE Fig Smart grid architecture reduce wasteful consumption of energy for fake load Moreover, it also helps effective utilization of renewable energy sources, decreases cost of energy consumption and contributes environmental protection [6] [7] To reach these requirements, the SGHG is designed with the following capabilities: 1) Communication and monitoring a) Noting continuity energy consumption in real time b) Collecting data of electricity prices or the state of the grid from the center control c) Management of the operational of the electrical equipment in the home 2) Intelligent Control a) Self-adjusting power usage mode according to information received b) Change the power usage based on time (programming schedule) Basically, there are two types of data infrastructure that is essential for the data transmission in a smart grid system The first pathway is between the sensors and the electrical appliances with the SGHG, the second one is from the SGHG to control center According to the development of the innovative wireless technologies, recent research studies [8] [9] present the wireless sensor networks (WSNs) technology as a key solution for monitoring and securing the electrical transmission and distribution The advantages of the WSN in the Smart Grid: low-cost infrastructure, rapid deployment and flexible connection to difficult areas, aggregate intelligence via parallel processing [10] [11] These are reasons why the WSN has emerged as a safe and effective concept [12] 604 2015 International Conference on Advanced Technologies for Communications (ATC) The paper describes an efficient hardware design of smart grid home network for integrating the electrical appliances to the smart grid system, in particular the smart grid home network The paper also presents the pratical test for SGHG and SHGN to verify their ability in real life The rest of this paper is organized as follows In Section II, we describe in more details about components of the smart grid system in household Section III - IV then looks at the prototype hardware design and wireless module selection and some basic information of software designs respectively The practical implementation is described in Section V In section VI, the performance is evaluated Finally, section VII has the conclusion 2) SGHG: Smart grid home gateway is technically capable of delivering the functionality of monitoring and controlling energy consumption in household Furthermore, it can also receive information remotely, such as from the control center to update price information or status of current grid In the field of WSN, this design is used to send control signals to connected end-devices node i Receiving data from smart energy meter ii Analyzing requested data and sending command due to the programming scenarios iii Storing the data in case want recheck iv Communicate with users via LCD or PC using FT232 port 3) Wireless home network: Derived from the system requirements, a star topology network is chosen In this topology, every node communicates directly with the gateway or the data collector Due to a simple communication of networking, this topology simplifies the network wherever it is realizable Although the quality connection between controlling-device nodes with the gateway is weak with large distance, this topology is still the best choice for network in household where the coverage area is around 30 to 50 meters The most important advantage of the star topology, which decides it as key topology of this study, is independent ability of network In case of errors, when one node is cut off, there is no effect on other nodes and whole network still operates normally Fig represents the network topology for the SGHN for a normal apartment II S MART GRID NETWORK ELEMENTS The smart grid home network (SGHN) gives users the ability of monitoring in real time Every 60 minutes, number of power consumption will be reported on the SGHG by the electricity meter SGHG also controls the electrical equipment in the home wireless network and wireless control button Besides that, the SGHN provides the option of using alternative energy sources By this way, a system of renewable energy generators like solar energy and a windmill generator will be equipped and used as replaced energy in the household Moreover, the SGHG collects data about the status of the power grid as the update of electricity price via a service portal energy through WSN or GPRS connection Fig Smart grid home area A model of SGHN is presented in figure In order to meet the above features, the SGHN builds on three parts named as: (1) the electricity meter, (2) the SGHG and (3) the wireless home network Each of them contains some information or characteristics, which integrate different units or active functions between them They can be further defined as follows: 1) Electricity meter: It is next generation of an energy meter, a replacement for existing meters Data from electricity meter to house display, which gives users the real-time feedback on the power consumption and how much it cost The electricity meter works by communicating with control center in a variety of different ways, including using wireless technology to send data Fig Home network topology III H ARDWARE D ESIGN A Electricity meter Electricity meter structure is designed based on the same platform of meter node structure in the world In this study, accuracy in measurement and low cost material are considered as the important factors for the electricity meter platform Figure shows the block diagram of the platform It composes of power supply module which includes AC and DC 605 2015 International Conference on Advanced Technologies for Communications (ATC) Fig Hardware structure of electricity meter power supply modules; Counter energy meter and Calibration module Fig Electricity meter platform Figure presents the prototype of the energy metering circuit, which is based on the Microchip MCP3905 energy metering IC MCP3905 is a DSP-based instantaneous power integrator that supplies a pulse output which is proportional to the amount of energy consumed It uses an internal 14bit ADC to sample the voltage and current The MCP3905A design is specified with an energy measurement error of 0.1% typical across 1:500 dynamic ranges for high accuracy energy meter designs B Smart Grid Home Gateway The prototype hardware block diagram of the SGHG is displayed in Fig The main processor is based on 8-bit AVR Microcontroller Atmega1284A Its functionality analyzes Fig the complicated events, operates the firmware, and processes the control algorithms In addition, this circuit integrates both function modules and wireless communication module Function modules have to ensure not only the accuracy operation in real time but also the backup storage of system That is the reason why it composes Real-time clock, SD card and Keyboard A Texas Instruments Sub-GHz RF CC1110 is used as the major transceiver of Wireless communication group Next part will show the explanation of this choice In case of error in Wireless network, module GPRS/3G is designed as backup option The power group is a combination between a 12V-1.5A SMPS and a power regulator With objective as easy installation and operation, human interface group, which consists of RS-232/FT232 and LCD module, is also developed An interesting issue in design is the size of the circuit Figure shows the design of smart grid home gateway platform Hardware structure of SGHG Fig Smart grid home gateway platform C Wireless module selection The most advantage of modern wireless transceiver is optimal wireless communication among sensor nodes Some useful common features of transceivers can be listed as: error detection and correction, received signal strength indicator (RSSI), advanced encryption standard (AES) for security issue, automatic acknowledgment (ACK), etc Table I gives the comparison between some popular wireless transceivers in the market such as: MRF24J40MC and XBee, Bluetooth and CC1110 As can be seen clearly, CC1110 from Texas Instrument is not the best transceivers in the outdoor condition However, in scope of this study, CC1110 satisfies some key requirements namely: Standard of Frequency Band, Sensitivity at Max Data Rate, Indoor Transmission Range, Battery Life and Price It needs to notice that frequency band of CC1110 is based on the standard frequency for smart grid in the world Hence, system using this module can combine with the other systems as unification Furthermore, the Sleep Mode Current of CC1110 supports the longer battery time-life than the others Finally, low cost is a strong point of this module Following these reasons, in our work, CC1110 is confirmed as the best transceiver to design wireless platforms for SGHN 606 2015 International Conference on Advanced Technologies for Communications (ATC) TABLE I C OMPARISION AMONG POPULA WIRELESS TRANSCEIVERSR Features Example Frequency Band Max Data Rate Sensitivity at Max Data Rate Transmission Indoor Range ZigBee/ IEEE 802.15 MRF24 XBee J40MC Bluetooth/ IEEE 802.15.1 Sub-Ghz Standard TI CC1110 2.4Ghz 2.4Ghz 2.4Ghz 250 Kbps 250 Kbps 800 Kbps 333/433/ 868Mhz 500 Kbps -108 dBm -92 dBm -82 dBm -110 dBm 50m 20m 10m 150m Star Topology Star, Mesh Star, Mesh Point to point, Star Battery Life (days) Max No of Nodes 100 1,000+ 100 1,000+ -7 1,000+ 64000 1000+ 10-100 Security AES (128bit) AES (128bit) SAFER (64/128bit) SoC(8bit) Price/ 1K 10 USD 15 USD USD 2.3 USD Fig Flowchart of energy saving algorithm IV S OFTWARE D ESIGN Algorithms control of the SGHG are programed in 8bit MCU ATMEGA1284A by CodeVision AVR compiler A basic scenario about automation control of the SGHG will be displayed in figure Fig shows the sequence of operation steps that will be taken by SGHG On receiving messages about equipment status, the SGHG checks permission from the user After checking, it will analyze these messages by the schedules operation time and advertised energy level of devices Finally, the SGHG decides these devices will operate or not As an example, in case of rush hour, all of devices in level and (high power consumption) will be advised to turn off For all cases, as soon as the SGHG command instruction is decided, it will be sent to control devices node for next operating step Moreover, some module functions such as: LCD interface, UART communication, SD Card and Real-Time integration are also embedded by this complier Fig Implementation of energy monitoring smart grid home system TABLE II PARAMETERS OF ELECTRICAL DEVICES IN EXPERIMENT V P RACTICAL IMPLEMENTATION Figure shows a prototype system has been implemented in a typical experiment, an electricity meter, a SGHG and controls located in different places of the house to set up the system The electricity meters deployed in power measurement input data to record the energy consumption of the entire house and through SGHG to monitor and manage the status of electricity devices This gateway connects to other devices via the wireless home network and Sub-GHz distribution center via 3G communication Beside the ability to collect and process the information from the distribution center, SGHG also has responsibility to maintain the operation of electrical equipment according to the pre-programmed scenarios to reduce to the lowest level of power consumption To prove the feasibility of the study, a test script was conducted as described below Table II shows some common devices using household electricity for the power levels and different time use There Name of Devices Compact Light Incandescent Lamp Electrical Fan Fluorescent Lamp Level of Energy Quantity Time (h) Power Consumption (W) 14 200 2 15 55 12 36 are three levels of equipment, which specify based on energy consumption capacity of device In this experiment, six controlling nodes are connected to twelve devices According to profile of Vietnam Electricity (EVN) , Fig.10 presents a distribution of time and price energy using in normal 607 2015 International Conference on Advanced Technologies for Communications (ATC) much energy From the result of table III, that we could analyze 16% of energy and 18% of price were saved TABLE III COMPARE OF ENERGY CONSUMPTION Type Total Price 5645 Wh 17,389 (VND) 100% 100% 4757 Wh 14,385 (VND) 84% 82% Home energy consumption without energy saving algorithm applied Home energy consumption with energy saving algorithm applied Fig 10 Distribution of price and hour energy using in VietNam Saving Rate Energy Price Total Energy Consumption B Delay performance day There are three kinds of time namely: low, normal and rush hour The price of energy consumption also change with the kind of time The purpose of this demonstration was conducted distributed power consumption over time in the logical way Thus, the system will reduce the overload on the network during rush hours and the energy wasted on false load in low hours Moreover, it also helps users reduce energy cost VI PERFORMANCE EVALUATION A Energy consumption saving algorithm testing We carry out the delay performance evaluation of the system by measuring the time latency Time latency is defined as the taken time for a packet sent from SGHG to a determined controlling node and then sent back to the SGHG The packet delay is calculated by the time latency divided by two One hundred of packets have been sent and received for calculation the average delay of the system When the distance is more than 15m or two walls the delay raises very fast because weak signal strength that make the packet error rate increase, more packets have been resent that lead to the quick increase of delay time The result is presented in table IV TABLE IV Fig 11 shows the result for energy consumption from the demonstration system of electricity appliances in the table II during a normal day The blue columns present system which has applied energy saving algorithm while the red columns are inverse system it’s important to note that, the peak of blue column is much lower than the red column and the difference between blue column is not as large as the red column Based on this result, we can proves that the system with energy saving algorithm is better than the other one PERFORMANCE OF WIRELESS NETWORK IN SMART GRID HOME AREA Node Distance(m) 11 13 17.5 15.7 Latency(ms) 100 100 400 450 600 500 Stability(%) 100 100 100 100 99 99 VII C ONCLUSION Fig 11 The result of energy consumption in demonstration Table III presents that it is possible to reduce to 84% level of energy when the SGHG with energy saving algorithm is applied than a situation without it The usage time of energy also reduced because of distributing the time for the Incandescent lamp and Fluorescnet lamp, which consume In this paper, an efficient hardware design of SGHG has been developed for integrating the electrical appliances to the smart grid system The SGHG can be operated with the SGHN based on programmed scenarios We have also developed a practical system to verify functions of the SGHG which is attached to the electricity devices From the experiment results, we have shown that the energy consumption can be controlled due to the load change and time usage Then we compared the performances between with and without the this system Energy can be saved effectively, with the smart grid system Moreover, the low cost and low power wireless hardware based on Texas Instrument CC1110 SoC is selected for SGHN to create a simple but efficient star routing wireless network Through a practical test, the reliability of data transmission of this module for SGHN is proved R EFERENCES [1] Hafeez, Ayesha, Nourhan H Kandil, Ban Al-Omar, T Landolsi, and A R Al-Ali ”Smart Home Area Networks Protocols within the Smart Grid Context.” Journal of Communications 9, no (2014) 608 2015 International Conference on Advanced Technologies for Communications (ATC) [2] Zhang, Yichi, Lingfeng Wang, Weiqing Sun, Robert C Green, and Mansoor Alam 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