Intelligent Relay for Power System Protection

Guide
Manjari Asutkar Mahesh G. Shende
Asst. Professor, Electrical Department Student, Electrical Department
Abha Gaikwad Patil College of Engineering Abha Gaikwad Patil College of Engineering

Yogesh O. Kolhe Vikas F. Kambalkar

Student, Electrical Department, Student, Electrical Department,
Abha Gaikwad Patil College of engineering Abha Gaikwad Patil College of Engineering

Harshal B. Maskar Akhil Fulbhoge

Student, Electrical Department, Student, Electrical Department,
Abha Gaikwad Patil College of engineering Abha Gaikwad Patil College of Engineering

Abstract- In any system the protection its normal mode of operation. However,
is most important part, because the natural events such as lightning, wind, ice,
reliability of the system depends on which earthquake, fire, explosions, falling trees,
type of protection is provided in a system a flying objects, physical contact by animals
system. In this system we are using relay or humans, contamination, and personnel
because its play vital role in faulty errors can result in short circuits. Faults
condition. They are intended to quickly sometimes can be very dangerous to the
identify a fault and isolate it do the balance machines being used during generation,
of the system continue to run under normal distribution and utilization of electricity.
condition. Relays are an important part of Short circuits, also known as faults, will
the power systems and are responsible for change the status of a power system from a
the control of any overload voltage or normal state to an abnormal state. Protective
current and protection of the devices from relays are in wide use throughout power
these parameters. The main function of the systems to detect abnormal modes of
relay is to persistently monitor the parameter operation. They are relatively small
to be controlled and if it exceeds the electromechanical, solid‐state, or computer
percentage range set by the controller then it (microprocessor‐based) devices that sense
sends a signal to the circuit breaker to break the abnormal modes of operation through
the connection and isolate the faulty part. instrument transformers.
A protective relay identifies short circuits or
other problems quickly, and initiates circuit
INTRODUCTION- Today's electric breaker tripping to isolate the faulty
power system consists of large and small component. Consequently, a minimum
generating stations, transformers, amount of the circuit is disconnected and a
transmission lines, distribution lines, high level of service continuity is achieved.
reactors, capacitors, and induction motors. Protective relays do not prevent failures, but
Most of the time a power system operates in
they mitigate undesirable effects of faults
and failures and minimize failed equipment
damage. Well‐designed protective relay
equipment have high levels of reliability,
speed, sensitivity, selectivity, and
economics.
A secondary function of protective relays is FIGURE. 1.1 Logic representation of an
to provide information regarding the electric relay.
location and type of failure. This
information assists in locating and repairing Logic representation of an electric relay is
faulty equipment. It also provides a means shown in Figure 1.2. The components can be
for assessing the effectiveness of a electromechanical, electronic, or both. The logic
protection scheme based on the level of functions are general in nature, so that in any
damage that occurred. particular unit they may be combined or, on
occasion, not required. Specific designs and
RELATED WORK-
features vary widely with application
All Power-system protection is a branch of requirements, different manufacturers, and the
electrical power engineering that deals with the time period of the particular design. Originally,
protection of electrical power systems from
all protective relays were of the
faults through the isolation of faulted parts from
the rest of the electrical network. The objective electromechanical type. Electromechanically
of a protection scheme is to keep the power type relays are still in widespread use and
system stable by isolating only the components continue to be manufactured.
that are under fault, whilst leaving as much of
the network as possible still in operation. Thus, The relay function can be better understood by
protection schemes must apply with very explaining the following diagram given below.
pragmatic and pessimistic approach to clearing The diagram shows an inner section diagram of
system faults. The devices that are used to a relay. An iron core is surrounded by a control
protect the power systems from faults are called coil. As shown, the power source is given to the
protection devices. electromagnet through a control switch and
through contacts to the load. When current starts
flowing through the control coil, the
BASIC DESIGN OR OPERATION OF electromagnet starts energizing and thus
RELAY intensifies the magnetic field. Thus the upper
contact arm starts to be attracted to the lower
The Institute of Electrical and Electronic fixed arm and thus closes the contacts causing a
Engineers (IEEE) defines a relay as “an electric short circuit for the power to the load. On the
other hand, if the relay was already de-energized
device that is design to respond to input
when the contacts were closed, then the contact
conditions in a prescribe manner and after move oppositely and make an open circuit.
specified condition are met, to cause contact Relays are mainly made for two basic
operation or similar abrupt change in associated operations. One is low voltage application and
electric control circuits.” the other is high voltage. For low voltage
applications, more preference will be given to
reduce the noise of the whole circuit. For high
voltage applications, they are mainly designed to
reduce a phenomenon called arcing.
 a) Electromechanical Relay

b) Static Relay (Solid State Relays)

c) Numerical Relays

FIGURE 1.2 Basic relay operation .

PROPOSED MODELING

The main f of the relay is the sensing unit which

basically is an electrical coil. AC or DC current
can be used to power the coil. When applied
current/ voltage increases from the threshold
value, the armature of the relay gets activated by
the coil, which is used to close the open
FIGURE1.3 Block diagram of intelligent
contacts. The switch mechanism is actuated by a
relay protection.
magnetic force that is generated when power is
supplied to the coil. When coil is energized it The above block diagram represents the actual
sends information to the circuit breaker that block diagram of the GSM based protection of
breaks the circuit till the fault clearance or power system. It consists of various blocks such
isolates the faulty part. The relay compares the as microcontroller, measurement devices and
current or voltage from the transformer sensor unit along with interfacing IC. The
connected before the relay and send information parameters for e.g. VOLTAGE, CURRENT,
to the circuit breaker. The coil opens when the TEMPERATURE, by using microcontroller
circuit breaker disconnects the faulty part. which is further connects with a GSM this
collected data will further send to server which
The basic functions performed by the relay are
will situated at any part of world through SMS.
On/Off Control- For example, in motor control,
In further connection in case of fault such as
relay is used to limit and control the speed limit
unbalanced voltage, under voltage, overvoltage
which is a high power load. Limit Control In
etc the fault is being analyzed by microcontroller
this, relay is used to control a set of parameters
programming and the signal is being send to the
and disconnect the device if the value of these
driver relay to disconnect the contactor and
parameters goes above or below the set value.
isolate the substation.
For Example in Motor Speed Control, motor
gets disconnected if the desired speed increases As shown in the figure the power
or decreases beyond the limit. transformer is used to step down the voltage of
230V single phase to 12V. The 12V supply is
Types of Relays Relay can be broadly classified
being rectified to 12V by using the full wave
on the basis of construction and application.
rectifier. This rectified supply is regulated to 5V.
There are three types of relay based on
This 5V of supply is need for the working of
construction which are Electromechanical, Static
MICROCONTROLLER, GSM, and the various
and Numerical.
equipped sensors. The P.T. and the current
transducer are energized by the line conductors.
The LCD used to display all the parameters such
as voltage and current of all phases . The driver
IC is used as a current booster to amplify the
current from the microcontroller, used to drive
the relay. The microcontroller is being
programmed to certain limits. The oil
temperature, oil level and the humidity within
the transformer. Whenever the fault occurs such
as overvoltage, over current, under voltage,
phase failure etc. The direct effect will be
developed on the transformer. So in case of fault
condition the microcontroller will give the
command to driver IC, so that the relay is to be
tripped and the transformer will be isolated, i.e.
the power system will be protected. The GSM is
used to send fault notification on mobile to
operate fastly.

RESULT AND CONCLUSION:

If voltage less than 230v trip on current took

2.3sec. and in case voltage greater than 230v trip
on current took 1.2 sec. Zero voltage switching
tooks less than 1sec. single phase tooks less than
2.8 sec. sending and receiving SMS time may
varying all to network provider.

REFERENCES

1) Relay system by I.T. Monseth and

P.H.Robinson, McGraw-Hill Book Co.,
New York 1935
2) S.J. Tikhe Asst. professor,electrical
department, DES COET Dhamangaon
Rly. India