Presented by:

jashuva kiran 1691210067

ROBOT MONITORING OF POWER SYSTEMS

CONTENTS LAYOUT

• Introduction

• Back ground

• Technological needs

• Robot platform

• Sensors and signal processing

• Conclusion

• References

INTRODUCTION

• Monitoring of electric power systems in real time for reliability, aging status, and presence of incipient faults requires distributed and centralized processing of large amounts of data from distributed sensor networks.

• The design of platform consists of a multi-processor control board, a 900 MHz wireless with

(i) Acoustic sensors

(ii) Fringing electric field sensing

(iii) Infrared sensing

• Economically effective maintenance and monitoring of power systems to ensure the high quality.

• Monitoring is justified by the reduction of fault occurrence of electric power, damage to the equipment, emergency equipment replacement cost.

EASE BACKGROUND OF THE LIVE WORKING:

• Manual Live Working Techniques

Live working, or working on energized circuits, is the preferred method of maintenance where system integrity, system reliability, and operating revenues are at a premium and removal of the circuit from service is not acceptable.

The common tasks to be carried out in electrical network are shown as follows:

(i) Changing insulator sets

(ii) Inspect the line equipment

(iii) Hot stick working

(iv) Insulating glove working

(v) Bare hand working

• Why Robotized Live Working Maintenance ? Live working is physically strenuous and dangerous and can expose workers to

musculoskeletal disorders, such as low back pain and shoulder tendonitis. The risks associated with the maintenance task on live working are:

(i) Electric shock,

(ii) The radiation of electromagnetic fields

(iii) Fall from the high working place

All these aspects have been widely studied in order to reduce the hazardous conditions of the workers. Moreover, the aspects improved by the adaptation of a new technology, the robot, which may eliminate the risk of electric shock, falls, and also increase the comfort of the worker during the maintenance task..

TECHNOLOGICAL NEEDS

• Numerous problems have to be solved for this kind of a robot

(i) Space confinement, size and weight restrictions

(ii) Wireless design requirements

(iii) Adverse environmental conditions

(iv) With the continuing development of mems and communication technologies.

Mobile monitoring of the power system involves the following issues:

• Sensor fusion :-

(i) Monitoring conditions of cables

(ii) positioning

(iii) Tactile sensors

(iv) And other sensors aimed to support the autonomy of robot movement

• Motion pattern :-

inspection robots used in the power system sub divided into

(i) External robots

(ii) Internal robots

Fig. 1. Miniature robotic platform for monitoring of transmission anddistribution power cables. (a) Internal platform. (b) External platform.Fig. 2. Robot Negotiation of tower.

Control strategy:

It includes object tracking, collision, avoidance and prevention of short circuits The control system receives initiating commands from the operator for the global tasks

Communication:

The module exchanges the data between the master computer and the mobile robot. Including data originating from differential streams on both sides of the communication link.

Positioning system:

It should work like the global positioning system (gps) used to estimate the location of the robot. In most applications, two basic position estimations are employed:

relative and absolute positioning. Relative positioning can provide rough location estimate, the absolute one can compensate the errors introduced.

ROBOT PLATFORM:

A unique segmented configuration allows the robot to traverse cables with a diameter of four to eight centimeters and negotiate obstacles along its path. The design of platform consists of a custom multi-processor control board, a 900 MHz wireless communication module and multiple sensor arrays. Fig. show the conceptual design and a picture of the mobile platform.

• The system control architecture is divided into two parts:

(i) Remote host computer control

(ii) On-board robot control

The host computer communicates with the robot via a radio transmitter module connected to the host computer serial port.

The radio communication module is comprised of two AVR AT90s8535 micro-controllers (MCU) operating at 8 MHz.

Data is transmitted through a LINX TR-916-SC radio module,with a central frequency of 900 MHz and 33.6 bps baud rate.

• The current system allows a technician to control a remote, distributed network of power line inspection robots through a LAN or dial-up connection. This goal was realized with a distributed client/server model

• Multiple instances of remote robot control can be established by creating bi-directional asynchronous socket connections from the central computer to each server, using standard TCP/IP protocol

• The first mode places the robot into fully autonomous operation, with all data processing done onboard.

• The second mode of operation the robot is fully controlled by the central computer and does no data processing onboard.

SERVER USER INTERFACE AND CENTRAL COMPUTER USER INTERFACE.

SENSORS AND SIGNAL PROCESSING

Discrimination of Energized Cables:

Consequently, maintenance personnel often need to determine the energization status of underground cables. A mobile monitoring system should be capable to do the same task.

In an energized cable, Whether it is carrying current or not, Substantial second harmonic (120-Hz) acoustic surface waves are generated. A piezoelectric accelerometer responds to both surface acoustic waves and power frequency electric fields of an energized conductor.

The strong presence of the 120-Hz component is fairly easy to detect however, the presence of other energized cables in the vicinity of the cable under test makes the discrimination task more difficult. Surface imaging is necessary for nonambiguous classification.

FOURIER TRANSFORM OF ACOUSTIC SIGNATURES OF UNDERGROUND POWER CABLES. (A) NONENERGIZED CABLE. (B) ENERGIZED AND LOADED CABLE.

EVALUATION OF THE ELECTRICAL INSULATION STATUS:

• Maintenance of aging power cables is a major cost item of the total maintenance of an electric network, which can be significantly reduced by a more accurate prediction of the remaining lifetime of cable insulation.

• Several methods are used to evaluate the aging status of electrical insulation, including eddy currents, acoustic sensing, and X-rays.

• The most useful and commonly used methods rely on measurement of electrical properties (dielectric conductivity and resistivity), measurement of partial discharge activity, and thermal analysis of insulation under stress.

FRINGING ELECTRIC FIELD DIELECTROMETRY

• Inter digital dielectrometry is a subset of inter digital electrode sensor applications that relies on direct measurement of dielectric properties of insulating and semi-insulating materials

ACOUSTIC SENSING:

• Partial discharge (PD) measurement is an important diagnostic tool, especially for medium- and high voltage cables

• Acoustic sensing is very successful for switchgear and transformers, because it is free from electrical interference, very easy to apply, has no need to power down, and does not require additional components, such as high-voltage capacitors

• A broad range of PD measurement techniques includes acoustic, current, time and frequency-domain reflectrometry, and optical sensing.

INFRARED SENSORS• Thermal analysis plays an important role in the evaluation of insulation status, The lifetime of electrical insulation is reduced when it is subjected to continuous overheating.

• Generally, overheating occurs due to overload, physical damage, insulation aging factors, or conditions of crossing regions.

One experiment showed that reducing the accelerating aging test temperature from 90C to 75C increased the cable life by a factor of two for thermoplastic polyethylene, and about 3.7 for cross linked polyethylene.

CONCLUSION:

• Review of monitoring technologies for maintenance of electric power system infrastructure suggests numerous advantages of mobile sensing.

• Miniaturization of mobile monitoring platforms is making realistic in estimation of cabe remaining life, operating conditions, and failure modes.

• A deeper understanding of physical nature of aging processes may be achieved through distributed sensing.

• Several critical sensor technologies relevant to monitor the distribution system have been presented. It includes acoustic sensing, discrimination of energized cables, analysis of acoustic signatures of partial discharges, fringing electric field sensing, and infrared sensing.

REFERENCES :• M. Tsutsui, H. Tsuchihashi, K. Satoh, M. Mukaida, H. Watanabe, S. Mori, Y. Kojima, and S. Yokoyama,

“Manipulator system forconstructing overhead distribution lines,” IEEE Trans. Power Delivery, vol. 4, pp. 1904–1909, July 1989.

• S. Nio and Y. Maruyama, “Remote-operated robotic system for live-line maintenance work,” in Proc. 6th Int. Conf. Transmission and Distribution Construction and Live Line Maintenance, 1993, pp. 425–435.

• M. Nakashima, H. Yakabe, Y. Maruyama, K. Yano, K. Morita, and H. Nakagaki, “Application of semi-automatic robot technology on hot-line maintenance work,” in Proc. IEEE Int. Conf. Robotics and Automation, vol. 1, 1995, pp. 843–850.

• Y. Kawaguchi, I. Yoshida, H. Kurumatani, T. Kikuta, and Y. Yamada, “Internal pipe inspection robot,” in Proc. IEEE Int. Conf. Robotics and Automation, 1995, pp. 857–862.

• A. V. Mamishev, S. X. Short, T. W. Kao, and B. D. Russell, “Non-intrusive sensing techniques for the discrimination of energized electric cables,” IEEE Trans. Power Delivery, vol. 45, pp. 457–461, Apr. 1996.

• A.V. Mamishev,Y. Du, B. C. Lesieutre, and M. Zahn, “Development and applications of fringing electric field sensors and parameter estimation algorithms,” J. Electrostatics, vol. 46, no. 2, pp. 109–123, 1999.

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