robotics mointoring of power system

1. ROBOTICS MONITORING OF POWER SYSTEM
A PROJECT REPORT
Submitted by
Akshay Shinde
Guided by
Bachelor of Engineering
IN
Electrical and Electronics Branch
GOGTE INSTITUTE OF TECHNOLOGY,
BELGAUM-590008

2. Abstract
An electrical power system is a network of electrical components used to
supply, transmit and distribute electric power. There are various types of
faults that occur in a transmission lines due to various reasons and they
can be detected and monitored by various maintenance method. One of
them is by using a robot monitoring that system. The report contains in-
formation about the description, sensors and signal processing, and ad-
vantages of this method over conventional methods.

3. 1.0 INTRODUCTION
Monitoring of electric power systems in real time for reliability,
aging status, and presence of incipient faults requires distribut-
ed and centralized processing of large amounts of data from
distributed sensor networks. The power system in our country
is very complex and so monitoring of transmission lines is a dif-
ficult task for a human to perform. Managing overhead trans-
mission assets such as towers, conductors and insulators are
very costly and sometimes prove to be dangerous. Many lines
are located in remote and rugged environments. Usually the
workers who inspect these lines conduct helicopter surveys or
must climb the tower to check them in close proximity. As in-
spection of transmission lines at remote areas are very difficult,
a robot can act as an alternative to a human technician. The
main objective of robotic monitoring of power system is to de-
tect the various factors that cause the faults in the cables be-
fore the occurrence of the fault and monitor them by using a
mobile robot.
The design of platform consists of a acoustic sensors, Fringing
electric field sensing, infrared sensing and a multi-processor.
This method of monitoring of power system is the economically
effective maintenance and monitoring of power systems to en-
sure the high quality. Monitoring is justified by the reduction of
fault occurrence of electric power, damage to the equipment,
emergency equipment replacement cost.

4. 2.0 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 net-
work 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 mainte-
nance 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.

5. 3.0 TECHNOLOGICAL NEEDS
 Numerous problems have to be solved for this kind of a robot
i. Space confinement, size and weight re-
strictions
ii. Wireless design requirements
iii. Adverse environmental conditions
iv. With the continuing development of mems
and communications technologies.
 Mobile Monitoring of the power system involves the following is-
sues:
 Sensor fusion:-
i. Monitoring conditions of the cables
ii. Positioning
iii. Tactile sensors
iv. And other sensors aimed to support
the autonomy of robot movement
 Motion pattern:-
Inspection robot used in the
power system sub-divided into,
i. External robot
ii. Internal robot

6.  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 dif-
ferential 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 compen-
sate the errors introduced.

7. 4.0 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. shows the
conceptual design and a picture of the mobile platform.
Fig.1. Typical robot monitoring the power system
 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 ro-
bot 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 8MHz. Data is transmitted through a LINX TR-

8. 916-SC radio module, with a central frequency of 900 MHz
and 33.6 bps baud rate.
Fig.2. Information flow of robotics platform
 The current system allows a technician to control a remote, distrib-
uted network of power line inspection robots through a LAN or dial-
up connection. This goal was realized with a distributed cli-
ent/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.

9.  The second mode of operation the robot is fully controlled by the
central computer and does no data processing onboard.
5.0 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 ca-
ble, whether it is carrying current or not, Substantial second har-
monic (120-Hz) acoustic surface waves are generated. A piezoelec-
tric 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 non ambiguous classification.
 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 re-
duced 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 measure-
ment of electrical properties (dielectric conductivity and resistivity),

10. measurement of partial discharge activity, and thermal analysis of
insulation under stress.
o FRINGING ELECTRIC FIELD DIELECTROMETRY
 Inter digital dielectrometry is a subset of inter digital elec-
trode sensor applications that relies on direct measure-
ment of dielectric properties of insulating and semi-
insulating materials
Fig.3. Open Coaxial Resonator Type Microwave Dielectrometer
ACOUSTIC SENSING:
 Partial discharge (PD) measurement is an important diag-
nostic tool, especially for medium- and high voltage cables
 Acoustic sensing is very successful for switchgear and
transformers, because it is free from electrical interfer-
ence, very easy to apply, has no need to power down, and
does not require additional components, such as high-
voltage capacitors

11.  A broad range of PD measurement techniques includes
acoustic, current, time and frequency-domain reflectrom-
etry, 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 to75C increased the ca-
ble life by a factor of two for thermoplastic polyethylene,
and about 3.7 for cross linked polyethylene.

12. 6.0 ADVANATAGES OF ROBOTIC MONITORING
 Economically effective maintenance and monitoring of power sys-
tems to ensure high quality and reliability of electrical power sup-
plied to customers has been obtained.
 Replacing human workers for dangerous and highly specialized op-
erations, such as live maintenance of high-voltage transmission
lines.
 Operation in hazardous environments, such as radioactive locations
in nuclear plants, access to tight spaces, such as cable via ducts and
cooling pipes, and precise positioning of measurement equipment
is obtained.

13. 7.0 CONCLUSION:
 Review of monitoring technologies for maintenance of electric
power system infrastructure suggests numerous advantages of Ro-
botics monitoring of power system.
 Miniaturization of robot monitoring platforms is making realistic in
estimation of cable 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 distribu-
tion system have been presented. It includes acoustic sensing, dis-
crimination of energized cables, analysis of acoustic signatures of
partial discharges, fringing electric field sensing, and infrared sens-
ing