AN EFFICIENT MONITORING OF SUBSTATIONS IN POWER TRANSMISSSION LINES USING ZIGBEE IN EMBEDDED SYSTEM

AN EFFICIENT MONITORING OF SUBSTATIONS IN POWER TRANSMISSSION LINES USING ZIGBEE IN EMBEDDED SYSTEM

ABSTRACT

This project proposes an innovative design to develop a system based on microcontroller that is used for monitoring power of a distribution transformer in a substation and to protect the system from the rise in above mentioned parameter. Protection to the distribution transformer from the main station is done with the aid of the ZIGBEE Communication. Moreover the system displays the same on a LCD at the main station that will lead to avoid the damage in substation. The design generally consists of two units, one in the substation unit, called as transmitter unit, and another in the Main station called as controlling and receiver unit. The transmitter in the substation is where the power is monitored continuously by PIC microcontroller. A ZIGBEE is used for transmitting the signals that are obtained. The controlling unit in the main station receives the transmitted signals by means of ZIGBEE receiver and displays in LCD and LED and reacts in accordance to the received signal.

Keywords: PIC microcontroller, LCD, LED, ZIGBEE, Main-Substation.

INTRODUCTION

Electricity is a necessary and useful form of energy. It plays an ever growing role in our modern industrialized society. Maintenance of a transformer is one of the biggest problems in the Electricity Board (EB). The transformer may burn out due to the over load and short circuit in their winding. Power starts from the transmission grid at distribution substations where the voltage is stepped-down and carried by smaller distribution lines to supply commercial, residential, and industrial users.

Electric power systems can be divided into two stations, namely, Main station and Substation. Power to the substation is monitored using PIC Microcontroller and transmitted through ZIGBEE, then the main station receives the signal and compare with the reference voltage. Because of the microcontroller operation in the main station, if the increase in power rises higher than the desirable power, then that increased range is viewed by LCD and indicated using LED and BUZZER. And further damage can be avoided by shutting down the substation.

WORKING PRINCIPLE

The substation contains ZIGBEE transmitter and PIC microcontroller. The main station consists of PIC microcontroller, ZIGBEE receiver and LCD display. The power in the substation is continuously acquired by the PIC Microcontroller and transmits through the ZIGBEE transmitter to the main station. The ZIGBEE receiver in the main station receives the signal and compares it to the reference voltage. If the received signal is below the reference voltage it does not shows any variation or if it is above the reference voltage then that increased range is viewed by LCD and indicated using LED and further damage can be avoided by shutting down the substation using relay from the main station.

HARDWARE DESCRIPTION

 

Figure.1 Block diagram

A. PIC MICROCONTROLLER: The controller PIC 16f877A is used in this project. It is 8-bit CMOS microcontroller with flash program it is RISC PROCESSOR with performance, fully static design it has 5 ports. Port A, Port B, Port C, Port D and Port E with 33 I/O lines. The Controller has 8kx14 words of flash memory, 368x8 bytes for data memory and 256x8 EPROM data memory. It is programmable code protection. The user code will be stored in the flash memory. The 5V supply is given to VDD and VSS of the controller. Microcontroller is used for monitoring power of a distribution transformer in a substation and to protect the system from the rise in that parameter.

B. ZIGBEE: ZIGBEE is based on an IEEE 802.15.4 personal area network. The technology defined by the ZIGBEE specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZIGBEE is targeted at Radio Frequency (RF) applications that require a low data rate, long battery life, and secure networking. ZIGBEE has a defined rate of 250 kbps. In substation unit the power is continuously monitored and it is transmitted through ZIGBEE transmitter and the transmitted signal is received by ZIGBEE receiver.

 

Figure.2 Zigbee module

C. TRANSMITTER SECTION: Each of the two transmitters is a CMOS inverter powered by + 10V internally generated supply. The input is TTL and CMOS compatible with a logic threshold of about 26% of Vcc. The input if an unused transmitter section can be left unconnected: an internal 400KW pull up resistor connected between the transistor input and Vcc will pull the input high forming the unused transistor output low. The open circuit output voltage swing is guaranteed to meet the RS232 specification + 5v output swing under the worst of both transmitters driving the 3KW. The slow rate at output is limited to less than 30V/ms and the powered done output impedance will be a minimum of 300ohm with +2V applied to the output with Vcc =0V.The outputs are short circuit protected and can be short circuited to ground indefinitely.

D. RECIEVER SECTION: The two receivers fully conform to RS232 specifications. They’re input impedance is between 3KW either with or without 5V power applied and their switching threshold is within the +3V of RS232 specification. To ensure compatibility with either RS232 IIP or TTl\CMOS input. The MAX232 receivers have VIL of 0.8V and VIH of 2.4V the receivers have 0.5V of hysteresis to improve noise rejection. The TTL\CMOS compatible output of receiver will be low whenever the RS232 input is greater than 2.4V. The receiver output will be high when input is floating or driven between +0.8V and –30V.

E. CIRCUIT DIAGRAM EXPLANATION: Figure.3 shows the circuit diagram. The reference voltage is fixed in the c program coding. A potentiometer is connected to the reference pin-2 in U2 PIC Microcontroller. The signal is transmitted from U2 controller TX pin-25 via ZIGBEE transmitter. The transmitted signal is received by ZIGBEE receiver and fed to U1 controller RX pin-26. The port C and port D is connected to LCD Display. The LED and Buzzer is connected to port B Pin 33 and 34.

 

Figure.3 Circuit diagram

 

Figure.4 Final Hardware Arrangements

SOFTWARE DESCRIPTION

A. MPLAB: MPLAB IDE is an integrated development environment that provides development engineers with the flexibility to develop and debug firmware for various Microchip devices. MPLAB IDE is a Windows-based Integrated Development Environment for the Microchip Technology Incorporated PIC microcontroller (MCU) and PIC digital signal controller (DSC) families. In the MPLAB IDE, you can:

·       Create source code using the built-in editor.

·       Assemble, compile and link source code using various language tools.

B. CCS C COMPILER: It offers the most optimized Microchip PIC MCU and dsPIC DSC C Compilers for Windows and Linux, and a powerful integrated development environment. Our compilers support the PIC10, PIC12, PIC14, PIC16, PIC18 microcontrollers and now support Microchip PIC24/dsPIC chips. The CCS C Compiler includes generous libraries of useful routines and ready-to-run example programs for hardware peripherals. This compiler is used to compile the embedded c language program.

C. MPLAB SIMULATOR: PROTEUS is a discrete-event simulator for the running the hex code program. It’s used to debug the software before going to hardware.

D. PCB DESIGN: PAD 2 PAD is used to prepare the PCB schematic. Tracks are made in insulating base. PCB's are used to route electrical signal through copper. The performance of an electronic circuit depends up on the layout and design of PCB.

E. PCB PREPARATION: Layout is printed on a butter paper. It is screen printed on copper clad, etched by using ferric chloride solution, drilled using PCB driller, cut the unwanted materials and soldered the components.

 

Figure.5 PCB Design For PIC Microcontroller

CONCLUSION

This design based on PIC microcontroller is used to monitor and control the power in the distribution transformer continuously throughout its operation. If the microcontroller recognizes any increase in the level of desired value, then the unit has been made shut down in order to prevent it from further damages and also indicates the values throughout the process in LED and Buzzer and displays the value in LCD. Hence the distribution is made more secure, reliable and efficient by means of the proposed system.

REFERENCES

[1] Embedded C Programming and the Microchip PIC” by Barnett & Cox O’cull,Thomson, 2006.

[2] Design with PIC Microcontroller by John Bheat Man, Prentice Hall, 1997.

[3] PC-Based Instrumentation Concepts and Practice by N.Mathivanan, PHI Learning, 2007.

[4]The 8051 Microcontroller and Embedded Systems using Assembly and C by Muhammad Ali Mazidi, Pearson, 2009.

[5] P.Daponte, M. Di Penta and G.Mercurio, A Distributed Measurement System for Power Quality Monitoring, IEEE Transactions on Power Delivery, Vol. 19, Issue. 2, pp: 456-463, 2004.

[6] G. Pudlo, S. Tenbohlen, M. Linders and G. Krost, "Integration of Power Transformer Monitoring and Overload Calculation into the Power

System Control Surface", IEEE/PES Transmission and Distribution Conference and Exhibition, Vol. 1, pp: 470-474 Asia Pacific, 2002.

[7] Sen Ouyang and Jianhua Wang, "A new morphology method for enhancing power quality monitoring system", International Journal of Electrical Power & Energy Systems Vol.29, No.2, pp.121-128, February 2007.

[8] www.chipcon.com

[9] www.zigbeealliance.com

[10] www.microchip.com

[11] www.soselectronic.com

[12]www.silicontechnolabs.in

DESIGN OF A LOW-COST CONTACT-LESS DIGITAL TACHOMETER WITH ADDED WIRELESS FEATURE

DESIGN OF A LOW-COST CONTACT-LESS DIGITAL TACHOMETER WITH ADDED WIRELESS FEATURE

ABSTRACT

This paper proposes a hardware design of an “Digital Contact-less Tachometer” based on IR sensor for measuring the Revolutions Per Minute (RPM) of a rotating object. Conventional tachometers require direct contact with the rotating object which may affect its RPM and thus affecting the accuracy of the tachometer. This Tachometer design allows the measurement of the RPM without any direct contact with the rotating object. For more stable and accurate results a new algorithm is also proposed in this paper which allows the results to be displayed within a second. The design is also capable of sending RF signals which allows one to send the measured values to a distant place for its further processing. The RF feature also facilitates the data logging for monitoring and controlling the varying values of the RPM. The circuit design is simple, cheap and provide reliable results. Its stability and reliability has been verified through experiments.

Keywords – IR sensors; Opto-coupler; RPM; Tachometer; Rotating object.

INTRODUCTION

Tachometer is a device which is used to measure the rotational speed of a shaft or a disk in a motor or other machine. The word Tachometer came from Greek Ταχος, tachos, "speed", and metron, "measure". Tachometers are very useful in monitoring and controlling the Motors in industrial automation, such as in manufacturing plants of industries like chemical, pharmaceutical and textile or it may be a flat-belt and flow-control application .The conventional Tachometers require contact between the device and the rotating body, there are many situations where the direct contact between the tachometer and the device under investigation is not possible. To deal with such situations we need a tachometer which doesn’t require direct contact with the rotating body, such tachometers are known as Contact-less Tachometer. In some cases the contact-less tachometer solely does not serve the purpose, as in the case of applications where continuous monitoring of the RPM is required and the test object is placed far away from the monitoring station, in such cases we need a Tachometer which can send the measured values to a remote processing unit. Considering such situations, the capability of sending RF signals is also added to this design by using RF ICs whose typical range of transmission is about 30 meters, which can be easily increased by using more sophisticated ICs. This paper proposes the design of a low cost contact-less tachometer with added wireless feature to transmit the results at some distant place for further processing. This design also incorporates a new algorithm for calculating the RPM with higher precision.

THEORY

Digital Tachometers are used for precise measurement and monitoring of all time related quantities, which can be converted into a proportional frequency using appropriate sensor. For non-contact tachometers optical sensors are most suitable especially the reflective optical sensors. The design proposed in this paper makes use of the reflective IR sensor “TCND 5000”, which is used to convert the angular velocity of the rotating body into corresponding frequency. Once the Frequency corresponding to angular velocity is known it can be used to calculate the RPM using any one of the following methods.

1) Direct pulse counting,

2) Single pulse time measurement,

3) Constant elapsed time (CET),

4) Pulse times measurement using a variable number of counted pulses.

Results have shown that the first two methods are suitable only for low RPM whereas the third method is good for medium and high RPM. In this paper third method is used for calculating the RPM. An improvement to the CET method is adopted by counting the number of pulses for only 1/4th of a second and then averaging the three readings. The averaged value is then multiplied by 3 to make it RPS (Revolution per second) and then multiplying it by 60 to convert it into RPM. The averaging of the readings provides more accurate, stable and less fluctuating results. The whole calculation is done by the remote processing unit which comprises of a microcontroller “AT89C2051”. The results are displayed using the display unit which comprises of driver circuit and 4 digit 7-segment display. By using RF ICs the sensor unit and processing unit can be placed far from each other. In many applications where the object, whose RPM is to be measured is placed where the human entry is not possible and also, in applications where the RPM of different spinning objects or Motors need to be monitored and displayed at a common place requires the transmission of tachometer’s signal to a distant place.

 

Figure 1. Block Diagram of the Design

The addition of RF ICs to the tachometer design will fulfill the requirements of such applications. The design proposed in this paper uses TX-433 and RX-433, which uses ASK modulation technique, for transmission and reception of the Tachometer’s signal. The block diagram of the design is shown in Figure 1.

DESIGN AND ANALYSIS

The whole design is divided into two parts a transmitter section and a receiver section. The transmitter section comprises of sensor, Operational amplifier and ASK transmitter and the receiver section comprises of ASK receiver, Processing unit and Display unit. The circuit diagram of the Transmitter section and the Receiver section is shown in Figure 2(a) and 2(b), respectively. The sensor unit consists of an IR sensor “TCND 5000” manufactured by ‘Vishay Semiconductors’ and a NPN transistor BC 548 (Q1). The TCND 5000 is a reflective sensor that includes an infrared emitter and PIN photodiode in a surface mount package which blocks visible light and there is complete optical isolation between the emitter and the photodiode [2]. To convert angular velocity into the corresponding frequency a small reflective strip is placed on the rotating object which can then be detected by the sensor whenever it passes from its front. Whenever the reflective strip passes from the front of the sensor, some part of IR light gets reflected from it which increases the voltage across the Photo-diode. The output produced by the sensor is generally very low and needs to be amplified, which is done by the transistor Q1 and Q2. The emitter of the TCND 5000 has an absolute maximum forward current rating of 100mA, so for the reliable use of the device it is operated at 85mA using a current limiting resistor R1.

 

Figure 2 (a). Transmitter Section

The emitter is connected in current driven mode with forward biasing. The detector of the TCND 5000 is connected in reverse bias mode, it can withstand a maximum reverse bias voltage of 60V. Whenever some reflected light strikes on detector its output current increases appreciably but it is not large enough to drive the transistor Q1 into saturation region. Therefore a transistor Q2 is used which provides sufficient amplification to drive Q1 into saturation region. A voltage divider resistor network using R5 and R6 is used to set the reference voltage of the comparator at 3V, in this design CA3140 IC is used as a comparator. For wireless transmission of the comparator’s output, pin no.6 of the Op-amp is connected to the ‘DATA’ pin of the ASK transmitter IC “TX-433”, which transmits the signal at 433 MHz. For the reception of the transmitted ASK modulated signal RX-433 RF IC is used. Both TX-433 and RX-433 supports a data rate of upto 10Kbps, which is sufficient for this design. The demodulated output of the RX-433 is then fed to the processing unit, which consists of a microcontroller “AT89C2051” manufactured by ATMEL CORPORATION. The “AT89C2051” comes with an inbuilt analog comparator which reduces the hardware complexity. The data pin of RX-433 is connected to the pin no.13 and the reference voltage, which is set at 2 Volts using 4.7k preset, is fed to the pin no.12 of the microcontroller. The pin no.12 and pin no.13 of “AT89C2051” are non-inverting and inverting terminals of the inbuilt comparator, respectively.

 

Figure 2(b). Receiver Section

 

Figure3. Frequency based algorithm.

The input to the microcontroller is basically a train of pulses where each pulse corresponds to one revolution, thus the total number of pulses in one second corresponds to the Revolutions Per Second (RPS) of the spinning object. The inbuilt counter and timer of the AT89C2051 are used to calculate number of pulses in 1/4th of a second, such three values are first averaged and then converted into RPM. The flow-chart of the algorithm is shown in Figure 3. If the average value is ‘R’ i.e there are R number of pulses in 1/4th of a second then the RPS will be ‘4xR’ and the RPM will be ‘4xRx60’. The results obtained from the Processing unit are then fed to the display unit which consists of a Darlington Transistor array IC ULN2003 and common cathode 4 digit 7-segment display. The port P1 is connected to the pin no.1 to 8 of the ‘ULN2003’ which derives the 7-segments of the display. All four 7-segments are illuminated one by one with very short time delay, which cannot be perceived by human eyes, so that all four 7-segments appear to be illuminated simultaneously. Port P3 pins: P3.3, P3.2, P3.1 and P3.0 are used for selecting one of the four 7-segments at a time. P3.3 and P3.0 are connected to that segment which which displays the Most Significant Digit (MSD) and the Least Significant Digit (LSD), respectively.

CONCLUSION

The experiments have shown that this design is stable and feasible. The experiments have also proved that the results obtained using the proposed algorithm are better than the normally used algorithm which counts the number of pulses for 1 second. .For RPM values greater than 300 this algorithm works very well and the results are more accurate and stable. It’s major feature is that it does not require direct contact with the rotating object for measuring the RPM. This design can be extended by adding data logging feature to it, data logging is widely used in industries to keep the track of the varying RPM of the shaft of a Motor or any other rotating object. This Tachometer design’s capability of sending RF signals increases its area of application and makes it more versatile than the conventional Tachometers. Also, for data logging the RPM values can be sent to a distant ‘Monitoring unit’, using on board RF ICs. Many such Tachometer units can also be connected to a central ‘Processing Unit’ which will ease the simultaneous monitoring of different Motors, Turbines, and other spinning objects. It’s accuracy and capability of measuring high RPMs makes it an very good choice for different industrial applications. Beside, these advantages this design has few limitations, such as RPM values less than 300 cannot not be measured effectively using the proposed algorithm; this can be overcome by using different algorithm for different range of RPM values. For better results the ‘sensor unit’ needs to be place very near to the rotating shaft around 20 to 30 mm, this distance can be increased by using highly sensitive optical sensors. The capability of this design resides in the capability of the ‘Processing Unit’, for measuring RPM values greater than 1,25,000, microcontrollers such as AVR, with much faster processing speed can be used without changing the algorithm and other circuitry. It’s portable, easy to use and cheap design makes it suitable for the domestic and household applications. This design has great development potential and has a stable and reliable performance in long run. The features of the design are light weight, small size, low cost, high sensitivity and timeliness.

REFERENCES

[1] Bonert, Richard, "Design of a high performance digital tachometer with a microcontroller," Instrumentation and Measurement, IEEE Transactions on , vol.38, no.6, pp.1104,1108, Dec 1989

[2] TCND-5000 Optical sensor Datasheet,

http://www.vishay.com/docs/83795/tcnd5000.pdfVishay Semiconductors, United States

[3] Robert L. Boylested, Louis Nashelsky: Electronic devices and circuit theory, Pearson Prentice Hall, 2007.

[4] AT89C2051 Microcontroller Datasheet, www.atmel.com/images/doc0368.pdf  Atmel Corporation, United States.

[5] Ajay V Deshmukh, Microcontrollers: Theory and Applications, Tata McGraw-Hill, 2007.

DESIGN AND REAL PROTOTYPE FABRICATION OF A FREE SPACE OPTICAL TRANSMITTER AND RECEIVER

DESIGN AND REAL PROTOTYPE FABRICATION OF A FREE SPACE OPTICAL TRANSMITTER AND RECEIVER

ABSTRACT

We are communicating with each other’s for every purpose. Different modes of communication are used. Free space optics is one of the modes of communication. Free space optics is widely used by satellites for transmitting with each other. Design and real prototype fabrication of a low cost portable free space optical transmitter and receiver is presented in this paper. Using this prototype wireless communication is possible. Light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The transmitter circuit comprises of condenser microphone transistor amplifier BC548. The gain of the op-amp can be controlled with the help of 1-mega-ohm pot meter. The transmitter uses 9V power supply. The receiver circuit uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio Power amplifier. This paper deals with the designing of a very low cost free space optical system which is perfect for information transmission of general conversation, using an ordinary available Laser torch of cost. The circuit is designed using National Instrumentations Multisim11.0 (N.I. Multisim 11.0) and National Instrumentations UltiBoard11.0 (N.I. UltiBoard 11.0).

Keywords: Battery driven design, Free space optics, Laser torch, Low cost design, N.I. Multisim and N.I. UltiBoard Simulator, Voice or data transmission.

INTRODUCTION

This paper is based on the concept of Laser (Light Amplification by Stimulated Emission of Radiation) for transmitting analog as well as digital signals. As laser is stimulated radiation, problem of interference occurs in electromagnetic wave is eliminated, it can be a good substitution of present day communication systems and high deal of secrecy is available. Use of laser in communication systems is the future because of the advantages of the full channel speeds, no communication licenses required at present, compatibility with copper or fiber interfaces and no bridge or router requirements. Also it cannot be detected with use of spectrum analyzers and RF meters and hence can be used for diverse applications including financial, medical and military. Lasers can also transmit through glass. Laser transmitter and receiver units ensure easy, straightforward systems alignment and long-term stable, service free operation, especially in inaccessible environments. Optical wireless systems offer ideal, economical alternative to expensive leased lines for buildings. The laser can be commissioned in satellites for communication, as laser radar requires small aperture as compared to microwave radar. For voice transmission amplitude modulation of laser pulse was used to transmit the voice signal. Condenser microphone converts the voice into electric pulse which was then amplified and transmitted through laser. Photo detector at receiver detects the laser light and voice was output through loud speaker.

RELATED WORK

This paper presents the design and real prototype fabrication of a free space optical system. The circuits are simulated in N.I. Multisim 11.0 and checked for validity and routing for the P.C.B. design is done with N.I. UltiBoard 11.0. The given design is thus checked and routed as per „INDUSTRY STANDARDS‟ and the real prototype can thus be etched out and a P.C.B. can be made on which components can be easily soldered. This paper mainly focuses on checking the validity of my design and performing a routing for my design for making a P.C.B.

OBJECTIVES OF THE DESIGN

This paper aims to provide simple and cheap wireless communication design and real prototype fabrication for larger date rate with less distortion and to reduce the complexity for communication in the places where optical fiber or any wired communication is very difficult and expensive. The design is so easy, inexpensive and makeable with the available equipment’s that the technical as well as non-technical person can construct it by themselves for their personal use.

A. Block Diagram and Algorithm used for the Design

 

Fig. 1 Block Diagram for Voice and Data Transmission

The algorithm is as follows. The input voice is taken through condenser microphone or a plug-in is taken as the input. The voice signal is amplified through the preamplifier phase. Then, the signal is transmitted through laser light. The phototransistor at receiving side converts the signal into electrical signal. The electrical signal is passed through two transistor amplifier phases. Then LM386 audio amplifier amplifies the signal and drive speaker to generate voice output.

Flow Chart for Transmitter Circuit :

 

Flow Chart for Receiver Circuit :

 

EQUIPMENTS REQUIRED

TABLE I EQUIPMENTS REQUIRED

 

 

WORKING OF CIRCUIT DIAGRAM OF TRANSMITTER

The electret microphone converts sound waves to an electrical signal in the Tx circuit. R1 provides DC bias for the microphone and should be removed if you wish to connect any other input instead. This signal is coupled via C2 and amplified by two LM358 op amps, and converted to an optical signal by the LED emitter, driven from transistor Q1. R3 and R6 set the gain of IC1A to 1+R3/R6, or 221. Since IC1A is direct coupled, R4/R2 determine the DC input and thus the DC output level. IC1B is also direct coupled and provides both the DC base current for Q1 and the AC modulation current. R7 determines the DC bias current for Q1. The modulated collector current drives the LED emitter.

 

Fig. 2 Transmitter schematic in N.I. Multisim 11.0

REAL PROTO TYPE FABRICATION OF TRANSMITTER

After checking the validity of the circuit in N.I. Multisim11.0, now convert the circuit to UltiBoard 11.0. To do this check if all the components are blue in colour (i.e. they have a foot-print) and select „Transfer To UltiBoard 11.0‟ button.

 

Fig. 3 Basic View of the Converted Schematic in N.I. UltiBoard 11.0

Now, align the components on the workspace and perform „Routing‟.

 

Fig. 4 View after Performing Routing of the Schematic in N.I. UltiBoard 11.0 for Transmitter Design

The 3D View of the real prototype fabrication of my design is shown below.

 

Fig. 5 3D View of my Design Showing PCB Connectionsfor Transmitter Design

 

Fig. 6 3D View Showing Connections Appearing at the back-side of the PCB for Transmitter Design

WORKING OF CIRCUIT DIAGRAM OF RECEIVER

At the other end of the cable, the optical signal is directed at a photo-darlington detector in the receiver that converts it into an electrical signal again. The signal is amplified by op amp IC2 and power amp IC3 before being fed into a speaker where it becomes a sound wave. A voltage regulator has been used in the receiver gain stage to reduce DC supply ripple caused by the higher currents drawn in the power amplifier section. C1 and C2 are filter caps, C3 couples the detector voltage imposed across R1, into IC2. R2 and R4 set the op amp input to half the supply voltage, since only one supply is used rather than positive and negative supplies, as is usually the case. The gain of IC2 is adjustable by the pot in the feedback circuit. The range is therefore 1+1M/110k to 1+1M/10k, or 10 to 101. This is used as a volume control. IC2 output is coupled via C6 into an LM386 power amp IC with gain set to 20. R6 and C8 act as a low pass filter on the input. R7 and C9 form a network that provides a high frequency load to ensure stability.

 

Fig. 7 Receiver schematic in N.I. Multisim 11.0

REAL PROTOTYPE FABRICATION OF RECEIVER

After checking the validity of the circuit in N.I. Multisim11.0, now convert the circuit to UltiBoard 11.0. To do this check if all the components are blue in colour (i.e. they have a foot-print) and select „Transfer To UltiBoard 11.0‟ button.

 

Fig. 8 View after Performing Routing of the Schematic in N.I. UltiBoard 11.0 for Receiver Design

The 3D View of the real prototype fabrication of my design is shown below.

 

Fig. 9 3D View of my Design Showing PCB Connections for Receiver Design

 

Fig. 10 3D Side View of my Design Showing PCB Connections for Receiver Design

 

Fig. 11 3D View Showing Connections Appearing at the back-side of the PCB for Receiver Design

ADVANTAGES

Light from a laser torch is used as the carrier in the circuit instead of RF and FM signals. The laser transmission is very secure because it has a narrow beam. The main advantage of this system is high reliability as it is impossible to track the data on the way of transmission. This design of Laser voice transmission system can be made at anywhere with low cost and can be used for frequent conversation at free of cost instead of using cell phone.

CONCLUSION

This paper is completely based on wireless communication system. Presently there are various techniques which are being successfully used for transmission of data. The data transmission techniques employ RF, FM signals for transmission of data. Laser Torch Based Transmission and Reception are cheaper and simpler in construction than RF transmitter and receiver. Although, wireless communication predominantly means the use of radio frequency for communication, the use of light based carriers for transfer of information is explored in this paper. This design can be made and used successfully at political assembly, lecture halls and for general conversation between two houses. The main problem with lasers is the beam dispersion can occurs due to external factors. In order to overcome these problems most advanced powerful lasers are to be employed. Although the optical data communication technology is prevailing from last decade as optical fiber communication devices available in the market, this design was presented to get all ideas that are behind such wireless system.

REFERENCES

[1] I. Melngailis, “Laser development in Lincoln laboratory”, The Lincoln Laboratory Journal, vol. 3, no. 3, pp. 347, 1990.

[2] I. R. Sinclair and J. Dunton, “Practical Electronics Handbook”, 6thed. Oxford, U.K, Newnes, 2007, pp. 252-255.

[3] Sedra, Adel.S and Smith, Kenneth C, “Microelectronic Circuits”, Oxford University Press, 1998.

[4] T. L. Floyd, “Electronic Devices”, 6th ed. Singapore, Pearson Education, 2002, pp. 559-561.

[5] C. M. M. Paschoal, D. Do N. Souza, and L. A. P. Santo, “Characterization of three photo detector types for computed tomography dosimetry”, World Academy of Science, Engineering and Technology, no. 56, pp. 92-95, August 2011

[6] “Laser and its applications,” Popular Science & Technology Series, DRDO Publications, 2009.

[7] O. Bishop, “Electronics Circuits and Systems”, 4th ed. Oxford, U.K, Newnes, 2011, pp. 14.

[8] I. R. Sinclair and J. Dunton, “Practical Electronics Handbook”, 6th

ed. Oxford, U.K, Newnes, 2007, pp. 252-255.

[9] M. S. Islam and M. A. Rahman, “Design and fabrication of line follower robot,” Asian Journal of Applied Science and Engineering, vol. 2, no. 2, pp. 27-32, 2013.

[10] W. Tomasi, “Advanced Electronic Communication System”, 6th

ed.. New Jersey, U.S.A, Prentice-Hall, 2004, pp. 3, 41-42.

[11] S. Gibilisco, “The Illustrated Dictionary of Electronics”, 8th ed.

New York, U.S.A, McGraw-Hill, 2001, pp. 399.

[12] S. C. Singh, H. B. Zeng, C. L. Guo, and W. P. Cai, “Nanomaterials:

Processing and Characterization with Lasers”, 1sted. Wiley-VCH

Verlag GmbH & Co. KGaA., 2012, ch. 1, pp.1.

ON-LINE MONITORING AND ANALYSIS OF FAULTS IN TRANSMISSION AND DISTRIBUTION LINES USING GSM TECHNIQUE

ON-LINE MONITORING AND ANALYSIS OF FAULTS IN TRANSMISSION AND DISTRIBUTION LINES USING GSM TECHNIQUE

ABSTRACT

Increase in demand of electricity for entire applications in any country, need to produce consistently with advanced protection system. Many special protection systems are available based on volume of power distributed and often the load changes without prediction required an advanced and special communication based systems to control the electrical parameters of the generation. Most of the existing systems are reliable on various applications but not perfect for electrical applications. Electrical environment will have lots of disturbance in nature, Due to natural disasters like storms, cyclones or heavy rains transmission and distribution lines may lead to damage. The electrical wire may cut and fall on ground, this leads to very harmful for human beings and may become fatal. So, a rigid, reliable and robust communications like GSM technology instead of many communication techniques used earlier. This enhances speed of communication with distance independency. This technology saves human life from this electrical danger by providing the fault detection and automatically stops the electricity to the damaged line and also conveys the message to the electricity board to clear the fault. An Embedded based hardware design is developed and must acquire data from electrical sensing system. A powerful GSM networking is designed to send data from a network to other network. Any change in parameters of transmission is sensed to protect the entire transmission and distribution.

Keywords: Global System For Mobile Communication (GSM),Special Protection System (SPS), Embedded Systems

INTRODUCTION

With the growing population of India and its rising electric power needs, the demands on the power grid continue to rise. This demand necessitates additional grid reliability. Special protection systems (SPS) are an example of a class of protection schemes that can benefit from the use of communication to increase their accuracy and reliability. The job of an SPS is to detect system faults and take corrective action. Faults can be broadly classified into two main areas which have been designated “Active” and “Passive”. Types of faults in three phase system is shown in fig-1.

 

Fig-1 Types of Fault in Three phase system.

(A) Phase-to-earth fault.

(B) Phase-to-phase fault.

(C) Phase-to-phase-to-earth fault.

(D) Three phase fault.

(E) Three phase-to-earth fault.

(F) Phase-to-pilot fault.

(G) Pilot-to-earth fault.

The “Active” fault is when actual current flows from one phase conductor to another (phase to phase) or alternatively from one phase conductor to earth (phase-to-earth). This type of fault can also be further classified into two subgroup, namely the “solid” fault and the “incipient” fault. The solid fault occurs as a result of an immediate complete breakdown of insulation. Passive faults are not real faults in the true sense of the word but are rather conditions that are stressing the system beyond its design capacity, so that ultimately active faults will occur. Typical examples are: Overloading - leading to overheating of insulation

(Deteriorating quality, reduced life and ultimate failure). Over voltage - stressing the insulation beyond its limits.

FAULT CHARACTERISTICS WITH & WITHOUT FAULT CURRENT LIMITER:

Fig-2 shows the wave shape of a typical unlimited fault current [16] as well as the influence on this wave shape if FCL devices with and without fault current interruption capability are applied to the system. A distinction among the different types of FCL is made between passive and active fault current limiting measures. Passive measures make use of already initially high source impedance both at normal and at fault conditions whereas active measures bring about a fast increase of the source impedance at fault conditions only.

 

Fig-2. Typical fault current wave shape and characteristic data

Traditional SPS or special devices works with preplanning on load shedding. Many technologies were used in different periods like carrier power line communication, Radio frequency based control system, and Supervisory control and data acquiring systems, Distributed control systems and Internet based communications. Each of the above has merits and demerits. This paper is based on Robust GSM technology meets safety reliability and fastest in design. GSM is an open, digital cellular technology used for transmitting mobile voice and data services. It divides each 200 kHz channel into eight 25 kHz time-slots. GSM operates in the 900MHz and 1.8GHz bands. It has an ability to carry 64 kbps to 120 Mbps of data rates.

BACKGROUND AND LITERATURE REVIEW:

Many special protection systems are available based on volume of power distributed and often the load changes without prediction required an advanced and special communication based systems to control the electrical parameters of the generation.

CONVENTIONAL METHODS:

1. 1 The conventional remote operating and monitoring system:

 

Fig.3: The conventional remote operating and monitoring system

Fig.3 shows the example of a conventional remote operating and monitoring system (agent technology is not applied). In this system, the protection relay equipment serves as a server, the PC in an office serves as a client, and the PC and relay equipment communicate by 1 to 1. We can perform and follows some personal computer in an office; download of the voltage and current data stored in the relay equipment when relay equipment is activated by some power failure; checking and changing the setting values of the protection relay; detecting an abnormal occurrence and the relay activation caused by power system faults. As an excellent information terminal which can acquire the real time data from a power system. It is important that the information in a relay can be easily accessed from an office and of which mechanism for performing the function described above is simple. Because of the reason described above, the remote operating and monitoring system has expanded steadily. Thus, although the remote operating and monitoring system has outstanding features, the PC and protection relay equipment are connected with the relations of 1 to 1, and while operating this system, it is necessary that the operator looks at the PC browser continually all the time. Moreover, in order to acquire information from a numbers of relay equipment, an operator must specify the address of each relay to access them in turn, which is complicated and time consuming. Furthermore, in this system, even when relays are connected within the same network, the relays cannot communicate and cooperate with each other. That is to say, relay equipment works only as a server providing data to PCs located in the remote office.

1.2 POWER LINE COMMUNICATION (PLC):

It offers the possibility to use the well-developed infrastructure of the electrical energy distribution grid for data transmission. For the time being, there is no harmonized international standard for broadband PLC. But IEEE started standardization of PLC physical and MAC layer in June 2005. In Europe, broadband PLC is limited to frequencies between 1 and 30 MHz, because of restrictions regarding electromagnetic compatibility (EMC). Future communication systems are expected to use much higher data rates as today’s wireless local area networks (WLANs). In this paper, we study an approach to boost high data rate wireless communications by using existing power lines in a flexible and cost-efficient way. In wireless networks, spatial diversity and spatial multiplexing gains are achieved by multiple antennas at the transmitter and at the receiver. Using cooperative relaying strategies these gains are also possible for single-antenna nodes. Spatial multiplexing is mandatory to achieve the high bandwidth efficiency that is necessary for future Gigabit/s wireless Communication systems.

1.3 RADIO FREQUENCY (RF):

Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals. Electric currents that oscillate at radio frequencies have special properties not shared by direct current or alternating current of lower frequencies. The energy in an RF current can radiate off a conductor into space as electromagnetic waves (radio waves); this is the basis of radio technology. RF current can easily ionize air, creating a conductive path through it. One of the biggest disadvantages to radio communication technology is the limited range of a radio signal.

PROPOSED METHODOLOGY:

The proposed methodology is based on Robust GSM technology meets safety reliability and fastest in operation. It consists of a sensing system, signal conditioning electronic circuits, advanced embedded hardware for middle level computing, a powerful computer network for further transmission of data to various places. The above said system can able to communicate with one grid and its subsequent related actions. This system is an Advanced intelligent Electronic device (AIED). The Whole system must be employed to make perfect grid control system. The system design is shown fig 2. The Sub elements of proposed system are

• Sensing Transformers.

• Signal Conditioners.

• Embedded based electronic Hardware.

• GSM technology for Data transfer.

• Powerful software to generate control signal

 

Fig 4: Block diagram of robust communication based SPS for power system

Control switchgear refers to the combination of circuit breakers, fuses and other electrical disconnections to isolate electrical equipment.

The purpose of switchgear is to shut down or deenergize specific equipment, which will then allow work to be carried out further down the line. It is shown in Fig.4

 

Fig 5: Control switchgear

Signal conditioners are essential to improve received signals. Removing the unwanted frequencies during amplification. It consumes very low current from the source. It consists of voltage sensing, current sensing, Frequency sensing. The voltage sensing will senses any changes in the input voltage and output of the circuit is given to PIC. Shown in Fig 6.

 

Fig 6: Block Diagram of voltage sensing

Current Sensing will senses any changes in the input current converted in to voltage and given to the PIC shown in Fig 7

 

Fig.7: Block Diagram of Current sensing

Frequency Sensing will sense any changes in the frequency is converted into voltage and given to the ADC. Schmitt trigger is used to convert any waveform in to square waveform. XOR gate is used to double the frequency Shown in Fig 8

 

Fig 8: Block Diagram of Frequency sensing.

 

Fig 9: PIC Block diagram

Design Features

Fig 9 shows the block diagram of PIC 16F877A. Individual power supply for Analog and Digital circuits is required to avoid drift on analog portion. Double regulated filtered reference source is needed to ensure safest ADC operation. External clock source must be used which enables the user to design the required speed. External CPU Synchronous circuit must be designed in case of PC requirement. External RS-232 is used for data transmission. Power Supply Unit to Embedded consist of step down transformer to reduce the voltage, rectifier to convert AC to DC, filter to remove unwanted AC signal and voltage regulator to avoid the incoming voltage fluctuation and Keeps the output voltage(5V) as constant for embedded controller.

To perform the various operations and conversions required to switch, control and monitor the devices a processor is needed. The processor may be a microprocessor, micro controller or embedded controller. In this work an embedded controller has been preferred because of its industrial advantages in power electronics like built in ADC, RAM, ROM, ports, USART, DAC. And also the speed of embedded controllers is more compared to other processors. The embedded controller selected for this work is PIC16F877A due to its various features.

A Relay driver is an Electro-magnetic Switch which is useful for a low voltage circuit. The relays used in this work are compact, self-contained devices, which respond to abnormal conditions.

In personal computer, data transfer takes place serially. RS-232standard is used for serial communication. PIC Micro controller is linked to PC through the RS-232 port. The hardware design of the above system is shown Fig 10.

 

Fig. 10: Hardware Implementations of special protection systems

Algorithm without GSM

Step1: Initializing the PIC values i.e analog and digital values

Step2: Get voltage, Temp, Freq from PIC

Step3: Analog values from PIC will be read and display in the system

Step4: Plot voltage, Temp, Freq values

Step 5: Press the switch either in Kit or System

Step 6: If it checks for switch1 is pressed or not if sw1 is pressed then it is on otherwise it goes or switch2 conditions

Step7: Plot current values

Step8: It will check for overload condition, if it is overload and the circuit is tripped and shows the corresponding message in the system

Step9: If it is exists then end otherwise it goes to the step2

Algorithm with GSM

Step1: Initializing the PIC values i.e analog and digital values

Step2: Initializing the corresponding components of the GSM settings

Step3: Get voltage, Temp, Freq from PIC

Step4: Analog values from PIC will be read and display in the system

Step5: Plot voltage, Temp, Freq values

Step 6: Press the switch either in Kit or System

Step 7: If it checks for switch1 is pressed or not if sw1 is pressed then it is on otherwise it goes for switch2 conditions

Step8: Plot current values

Step9: It will check for overload condition, if it is overload and the circuit is tripped and then send the corresponding message to the mobile through the GSM

Step10: If it is exists then end otherwise it goes to the step2.

RESULTS

 

Fig 11: shows without GSM when the feeder1 is ON, in green color and the corresponding values are displayed

 

Fig 12: shows with GSM when the feeder2 is ON, in the green colour and the corresponding values are displayed.

 

Fig.13: shows the database results of voltage, incoming current, frequency, kvA, light and temperature for every second.

 

Fig 14: shows with GSM when the feeder2 is Tripped ; it shows in pink color and the message will be send to the mobile through the GSM when feeder2 is over loaded.

CONCLUSIONS:

This paper shows that a GSM technique can be successfully apply to the earlier developed communication based special protection systems to increase its reliability during network interruptions. The GSM enhances speed of communication with distance independentancy. A suitable authenticated hardware is designed to meet the credibility of the networking. An Embedded based hardware is designed to acquire data from electrical sensing system; it sends from one network to other and change in parameters of transmission to be sensed to protect the entire transmission and distribution. GSM enables bi-directional communication as a message or data.

Visual Basic software is used as interpreter among various tools and systems.

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