Abstract. 2. Web based Data Acquisition and Control System. 1. Introduction

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1 Web based Data Acquisition and Control System for Thermal Power Plants 1 Soniya Sunny, 2 1 PG Student, Believers Church Caarmel Engineering College, Perunad, 2 Asst. Professor, Believers Church Caarmel Engineering College, Perunad 1 soniyasunny1210@gmail.com, 2 kuruvilla08@gmail.com Abstract Wireless sensor network technology is emerging as an important field in process monitoring and controlling applications. In thermal power plants, various environmental conditions have to be continuously monitored. This paper presents a web-based data acquisition and control system for thermal power plants. The system is implemented using Raspberry Pi and ZigBee protocol. Different sensor nodes are placed at different locations in the power plant. A coordinator node is designed with Raspberry Pi as the main controller. All sensor nodes are interconnected using ZigBee communication protocol. Raspberry Pi communicates with all sensor nodes in the wireless sensor network and collects the values sensed by these sensor nodes. It will then upload all information to the internet so that the user can monitor data from distant location through web browser. A threshold value is set at sensor nodes, and if the sensed value crosses the threshold limit, a buzzer will beep in order to provide control signal. 1. Introduction Data acquisition is the process of sampling a real world signal that is used to measure certain environmental conditions and converting those sampled signals into digital numeric values so that it can be manipulated by a computer. Industrial and commercial fields require more automated systems with remote monitoring and controlling capability. Remote accessing capability can be provided by using Wireless Sensor Network (WSN) technology [1]. A Wireless Sensor Network creates a network of multiple devices having capability of sensing, communication and computation [3]. WSN consists of spatially dispersed and dedicated autonomous devices that consists of sensors which are used to measure various physical or environmental parameters. In thermal power plants, combustion of coal in the boiler converts the water into steam in boiler tubs. This steam with high pressure and temperature flows into turbine and rotates turbine shaft. This turbine shaft is connected to the generator shaft. By rotating turbine shaft, generator shaft also rotates and power will be generated. In such cases, it is a major concern to monitor and control various parameters like temperature, humidity, pressure etc. Accurate and reliable measurement of these parameters from each main location of a plant is essential for operational excellence. There will be a limit for these parameters for ensuring proper operation of the power plant. If such parameters cross the specified limit, it may result in damage of equipment, severe accidents or even unscheduled plant shut down. All process control applications are mission critical and have stringent requirements [2]. In order to avoid catastrophic conditions, various sensor nodes can be designed to communicate with a main coordinator node. Coordinator is connected with internet and it will upload all sensor data to the web [3]. 2. Web based Data Acquisition and Control System Figure 1. Architecture of proposed system Figure 1 shows the basic architecture of our proposed system. The whole system is developed using open source hardware platforms Raspberry Pi and ZigBee. The system consists of one coordinator 343

2 node and many sensor nodes. Raspberry Pi acts as the main embedded system based coordinator which connects all node sections, collects and stores data and analyses the stored data. The ZigBee module connected to the Raspberry Pi is set as the coordinator node. Different sensors like temperature sensor, humidity sensor, moisture sensor etc. are placed at each sensor nodes. Sensor nodes which are placed at different locations will collect different parameters and send to the coordinator node through wireless communication. The user can monitor the system remotely [4], [5], [6] Linux Operating System A lot of the advantages of Linux are a consequence of Linux' origins, deeply rooted in UNIX, except for the first advantage, of course: Linux is free: As in free beer, they say. If you want to spend absolutely nothing, you don't even have to pay the price of a CD. Linux can be downloaded in its entirety from the Internet completely for free. No registration fees, no costs per user, free updates, and freely available source code in case you want to change the behavior of your system. Most of all, Linux is free as in free speech: The license commonly used is the GNU Public License (GPL) [9]. The license says that anybody who may want to do so has the right to change Linux and eventually to redistribute a changed version, on the one condition that the code is still available after redistribution. In practice, you are free to grab a kernel image, for instance to add support for teletransportation machines or time travel and sell your new code, as long as your customers can still have a copy of that code. Linux is portable to any hardware platform [14] Raspberry Pi The Raspberry Pi is a very powerful, small computer having the dimensions of credit card which is invented with the hope of inspiring generation of learners to be creative [10], [11]. This computer uses ARM (Advanced RISC Machines) processor, the processor at the heart of the Raspberry Pi system is a Broadcom BCM2835 system-on-chip (SoC) multimedia processor. The general hardware structure of the remote I/O data acquisition and control system based on Raspberry Pi processor. The remote I/O data acquisition and control system based on embedded ARM platform has high universality. Sensors are used for process monitoring and for process control [10]. Each I/O channel can select a variety of electrical and nonelectrical signals like current, voltage, resistance etc. Multiple sensors can be used to measured data are stored in external memory, we can directly show this data on LCD display connected to port 0 & the memory is act as a data base during accessing web server. We can interface GUI with this processor [11], [16] Zigbee ZigBee is a specification for a suite of high-level communication protocols used to create wireless networks built from small, low-power digital radios [12]. ZigBee is based on an IEEE standard. It is a simple, efficient, reliable, and low cost, low-power standard of wireless technology. Though its low power consumption limits transmission distances to meters line-ofsight, depending on power output and environmental characteristics, ZigBee devices can transmit data over long distances by passing data through a mesh network of intermediate devices to reach more distant ones. ZigBee is typically used in low data rate applications that require long battery life and secure networking (ZigBee networks are secured by 128-bit symmetric encryption keys.) ZigBee has a defined rate of 250 Kbit/s, best suited for intermittent data transmissions from a sensor or input device. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other wireless personal area networks (WPANs), such as Bluetooth or Wi-Fi. For example, DigiXbee series modules S1 and S2 implement the IEEE radio and ZigBee networking protocol. Here we used XBee series module S1 from Digi international which fully implement Zigbee protocol [12], [13] PIC Microcontroller PIC16F877A is a 40 pin microcontroller IC. It consists of two 8-bit and one 16-bit timer. Capture and compare modules, serial ports, parallel ports and five input/output ports are also present in it. PIC16f877A finds its applications in a huge number of devices. It is used in remote sensors, security and safety devices, home automation and in many industrial instruments. An EEPROM is also featured in it which makes it possible to store some of the information permanently like transmitter codes and receiver frequencies and some other related data. The cost of this controller is low and its handling is also easy. It is flexible and can be used in areas where microcontrollers have never been used before as in coprocessor applications and timer functions etc [14] Web Interface A channel is created by the user through ThingSpeak IoT platform. ThingSpeak is an open source Internet of Things application and API to store and retrieve data from things using HTTP over the internet or via a Local Area Network. 344

3 Raspberry Pi collects all data from different sensor nodes and uploads these data to the following base URL: ' Sensors Temperature Sensor: LM35 is used in sensor nodes for sensing temperature. It is a precision IC temperature sensor with its output proportional to the temperature (in o C). The sensor circuitry is sealed and therefore it is not subjected to oxidation and other processes. With LM35, temperature can be measured more accurately than with a thermistor. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼ C at room temperature and ±¾ C over a full 55 C to 150 C temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low-output impedance, linear output and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy [14] Humidity Sensor SYH-1 is used for sensing humidity of the sensor node. The humidity sensor is of capacitive type, comprising on chip signal conditioner. The humidity sensor used in this system is highly precise and reliable. It provides DC voltage depending upon humidity of the surrounding in RH%. This work with +5 Volt power supply and the typical current consumption is less than 3 ma. The operating humidity range is 30% RH to 90% RH. The standard DC output voltage provided at 250C is 1980 mv. The accuracy is ± 5% RH at 250C. The humidity dependent voltage is obtained and subjected for further processing [14]. (PAN). PAN ID is same for every Xbee device working on the same network Coordinator Node: Coordinator node ZigBee is connected to Raspberry Pi through USB cable. It continuously collects the data sent by all sensor nodes through ZigBee. Raspberry Pi processes the data and make available to view for the users through web interface. It connects clients by external network so that they can monitor all sensor nodes and send information to the sensor nodes. Figure 2. Coordinator node setup Coordinate node contains Xbee transceiver and Web interface. It collects the sensor data continuously and stores it in ThingSpeak IoT platform. Two sensor node never transmits the data simultaneously, because the ZigBee protocol having the mechanism of collision detection. The python serial programming is used in raspberry Pi to open the serial port connected to the Xbee device and read data over it. Python script continuously reads the data, stores in ThingSpeak channel and simultaneously checks the threshold value. If sensor data crosses the threshold value coordinator node sends commands to the sensor node. Figure 2 shows the setup of coordinator node 3. System Operation We deploy the two sensor node separated from each other. Each sensor node contains one temperature sensor, one humidity sensor and one ZigBee transceiver. The programming on the PIC microcontroller board is such way that after every minute sensor node sends parameter data to coordinator node via the ZigBee wireless communication protocol [3], [4], [5], [6]. The XBee transceiver device has a unique 64-bit serial address and 16-bit personal area network address 345

4 Figure 4. Sensor node setup Figure 3. Coordinator node flow chart Figure 3 shows the flow chart of coordinator node. ThingSpeak enables sensors to send data to the cloud where it is stored in either a private or a public channel. Once data is in a ThingSpeak channel, we can analyze and visualize it. It provides the web interface to the user to monitor and control the system remotely. The user can access the system status using an internet access device like personal computer, laptop, and smart phone Sensor Node The sensor nodes constitute a wireless sensor network which cooperatively monitor physical or environmental conditions, such as temperature, vibration, pressure, motion, moisture, light, or pollution at different location. These smart sensors constitute a network topology through selforganization. The sensors nodes can transmit the data detected by their own sensor and can also pass the data to the adjacent nodes. Figure 5. Sensor node flow chart Figure 4 shows the setup of sensor node. Figure 5 shows the flow chart of sensor node. PIC16F877A is used as the microcontroller in the sensor node. Multiple sensors can be connected to the sensor node. The ZigBee module encapsulates RF transceivers and ZigBee protocol stacks. Xbee can be easily integrated into any microcontroller or microprocessor systems such as Raspberry Pi through UART serial communication interface. The XBee module is configured as a router on the sensor nodes. Router can relay messages in a tree or mesh network and Coordinator has the capability to control the entire network. 4. Experimental Test Results The sensor node circuits are placed at different locations where the parameters are to monitored. On each circuit, temperature and humidity sensors are placed. ZigBee module is also connected with both nodes. The temperature and humidity values are read by corresponding sensors and those values 346

5 are given to the PIC microcontroller. It processes the data and transmits the data serially to the coordinator node. ZigBee connected to the Raspberry Pi receives the data from the sensor nodes. Python code is used to open the serial port for enabling serial communication, and to receive the data from sensor nodes serially. These parameters are displayed on the web page using ThingSpaek channel. It facilitates web interface so that the user can monitor and control all sensor nodes remotely. Also, threshold limits are set for both temperature and humidity values. Raspberry Pi checks these threshold limits, and if the sensed data exceeds the limit, a control signal is sent to the corresponding sensor node. Thus user can monitor and control the system from any location. Figure 7. Output graph of temperature at sensor node A Figure 7 shows the output graph of temperature at sensor node A. 5. Conclusion Figure 6. Web page displaying the sensed data Figure 6 shows the web page displaying temperature and humidity values of sensor node 1 and sensor node 2. A channel is created by the client with two different fields, ie. temperature and humidity. Data of various sensor nodes are updated to the channel by Raspberry Pi. Webpage of the particular channel shows the output graphs of various fields. Temperature and humidity values of different sensor nodes can be acquired from the output graphs. This paper designs a web based monitoring system for thermal power plants based on Raspberry Pi and ZigBee. Various sensor nodes are designed and implemented at different locations and the sensed values are continuously transmitted to the coordinator node, that is connected to the Raspberry Pi. ZigBee module connected to the Raspberry Pi acts as coordinator node, thus enabling Raspberry Pi to join the whole network and provide access to all sensor nodes. Raspberry Pi collects data from these sensor nodes and saves it in an IoT platform. At the same time, it provides web interface so that the user can monitor the network from remote location. The user can also send control information to the sensor nodes if the sensed values exceed a particular limit. 6. References [1]Soumya Sunny P, Roopa.M (2012), Data Acquisition and Control System Using Embedded Web Server, International Journal of Engineering Trends and Technology, Volume3, Issue3, pp [2] Dhanajay A. Sabale, Sushil M. Sakhare, Roshan A. Lende, Piyush C. Mankar, Vaibhav V. Wagare (2014), Wireless Sensor Network for Industrial Process Controlling & Monitoring, International Journal of Electronics Communication and Computer Technology, Volume 4 Issue 4, pp [3] Pandurang H. Tarange, Rajan G. Mevekari, Web based Automatic Irrigation System using wireless sensor network and Embedded Linux board, International Conference on Circuit, Power and C omputing Technologies,

6 [4] Prachi Sharma, Wireless Sensor Networks for Environmental Monitoring, International Journal of Scientific Research Engineering & Technology, IEERET Conference Proceeding, 3-4 November, [5] Christos G. Panayiotou, Despo Fatta, Michalis P. Michaelides, Environmental Monitoring Using Wireless Sensor Networks, InternationalJournal of Scientific Research Engineering & Technology, November 2014 [6] Mr. Sudhir G. Nikhade, Dr. Mrs. A. A. Agashe, Wireless Sensor Network Communication Terminal Based on Embedded Linux and Xbee, International Conference on Circuit, Power and C omputing Technologies, [7] Sudhir G. Nikhade, Wireless Sensor Network System using Raspberry Pi and Zigbee for Environmental Monitoring Applications, International Conference on Smart Technologies and Management for Computing, Communication, Controls, Energy and Materials, May pp [8] Sheikh Ferdoush, Xinrong Li Wireless Sensor Network System Design using Raspberry Pi and Arduino for Environmental Monitoring Applications, Elsevier The 9th International Conference on Future Networks and Communications (FNC-2014). [9] Pachpande, Internet based data acquisition system, IJEECS, Vol. 2, Issue 1, January 2014 [10] [11] RaspberryPi,webpage: wiki/raspberry_pi [April20, 2014]. [12] ZigBee Specification.ZigBee Alliance [13] DigiInternational Inc., available at [14] [15] Kochlan, M.; Hodon, M.; Cechovic, L.; Kapitulik, J.; Jurecka, M., WSN for traffic monitoring using Raspberry Pi board, Computer Science and Information Systems (FedCSIS), 2014 Federated Conference on, vol., no., pp.1023,1026, 7-10 Sept [16] Powers, Shawn. The open-source classroom: your first bite of raspberry pi. Linux Journal