ISSN (Online) 2321 – 2004

ISSN (Print) 2321 – 5526

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING
Vol. 3, Issue 8, August 2015

Smart Transformer using Advanced Metering

Infrastructure (AMI) and Advance Sensor
Infrastructure (ASI)
Geeta Velhal1, Avani Pujara2, Vaishali Velhal3, Dr S.M.Bakre4, Dr V.Muralidhara5

Abstract: Transformer is one of the sensitive components of the smart grid. The transformers already installed, will be
in service for next 25 years .Very few transformers have ability to sense the parameters like voltage, current, and
temperature. The next generation of transformers will require implementation of remote monitoring of a system
parameters and wide range of transformers. Online transformer monitoring using advanced metering infrastructure
(AMI), Advance Sensor infrastructure (ASI) is necessary for efficient operation of the smart grid. An AMI system can
be effectively used as a low-cost distribution transformer monitor. The safety of the transformer plays a vital role in
smooth operation of a smart grid. Dissolved gas analysis, use of vegetable oil-based dielectric coolants, ensures
reliability and safety respectively of the transformer operation. Now a days many transformer manufacturers are
incorporating the real time monitoring of the temperature, pressure, vacuum especially for step up transformers. Real
time monitoring system consists of embedded system, GSM modem, mobile-users and GSM networks and sensors
installed at transformer site. Features of Solid State Transformer (SST), Bidirectional Intelligent Semiconductor
Transformer (BIST) for smart grid applications are discussed in this paper. Also, the different ways for improving
efficiency of the smart grid by ensuring the safety of the transformer are focused.
Keywords: Advanced metering Infrastructure (AMI), Solid State Transformer (SST), Bidirectional Intelligent
Semiconductor Transformer (BIST).

I. INTRODUCTION
Transformers installed already in distribution system are interconnecting transformer installations are the matter of
having single function, to increase or decrease the level of serious concern. These installations are prone to fire
voltage. Once the conventional grid becomes smart and because of several reasons such as internal faults,
topology changes in distribution system, bidirectional overheating, high order harmonics, failure of dielectric,
transformer would be needed to improve voltage profile lightening etc. This may result into loss of valuable assets.
and to solve power quality issues. Online monitoring of
transformer will help utility to detect fault in real time. Moreover such types of incidences may cause fatal or non-
Using advanced meter infrastructure, distribution fatal accidents to human being or stray animals. It has
transformer monitoring can be done in real time [6]. This been observed on number of occasions that there is a
can provide insight for taking action well in advance sudden blasting of porcelain bushings. The pieces of
before transformer fails. porcelain are scattered in the switchyard with high
velocity and cause damage to nearby equipments in the
The monitoring systems currently used has some problems switchyard. Therefore, it is highly desirable to protect
and deficiencies, like transformers from fire hazards.
1) Conventional transformer can detect a single parameter
like voltage, current or power. Online monitoring of transformer consists of GSM
2) Testing speed is not fast modem, mobile users GSM network and sensors [7].
3) Real time detection is not there In this paper working of nitrogen injection system is
discussed to understand smart way of operation of
We need a distribution transformer which is smart enough transformer under fire. Under occurrence of fire the smart
to monitor all the parameters at a time and with very good system of protection will quench the fire quickly and it
speed, this will help to identify overall health of will save transformer from severe damage. Online
transformer; which ensures safety of transformer before transformer monitoring using advanced metering
any serious fault occurs. A sensor is a device, which infrastructure (AMI), Advance Sensor Infrastructure (ASI)
responds to an input quantity by generating a functionally is necessary for efficient operation of the smart grid.
related output usually in the form of an electrical or optical
signal. A sensor's sensitivity indicates how much the An AMI system can be effectively used as a low-cost
sensor's output changes when the measured quantity distribution transformer monitor [8]. There are two
changes [4]. Sensors can be installed at transformer site principal ways to achieve this objective. The first calls for
which reads and measures the physical quantity from the the installation of a bellwether meter on the secondary
distribution transformer and converts it into analogue output of each device to be monitored. The bellwether
signal , it can sense load current, ambient temperature, meter will take advantage of the AMI infrastructure to
winding temperature, oil temperature , level of oil, return actual transformer loading and performance data.
humidity of oil ,dissolved gases in oil, partial discharge Such a solution may introduce a potentially significant
etc. Also fire hazards occurring at power transformer and extra cost at each transformer location.

Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2015.3802 5

 ISSN (Online) 2321 – 2004
ISSN (Print) 2321 – 5526

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING
Vol. 3, Issue 8, August 2015

II. DISSOLVED GAS ANALYSIS absorption level for commercialized palm oil-based
DGA is most important part of any transformer transformer oils and came to the conclusion that
maintenance which involves study of dissolve gases in oil ,compared to the other palm oil and mineral oil, PFAE
of transformer. (palm fatty acid ester oil) oil had the highest breakdown
The most important test that can be done on the liquid voltage even when the moisture content were increased up
insulation of a transformer is Dissolved Gas Analysis to 2500 ppm water added. It is due to the characteristic
(DGA). This test can give an early indication of abnormal that PFAE has greater electrical resistance to electrical
behaviour of the transformer oil. DGA test analyses the breakdown. Due to this, PFAE can be considered to
type and quantity of gases that are dissolved in the replace mineral oil in future completely [2].
transformer oil. DGA results would allow us to identify
the type of fault occurring in a transformer in service. IV. NITROGEN INJECTION SYSTEM
Generally the gasses found in the oil in service are The main parts of the system are briefly discussed below-
hydrogen (H2), methane(CH4), Ethane (C2H6), 1. Sensors- The sensors are usually provided at the top
ethylene(C2H4), acetylene (C2H3), carbon monoxide side of transformer tank. These units work as
(CO), carbon dioxide (CO2), nitrogen(N2) and temperature transducers. The temperature of transformer
oxygen(O2).[5] Manual DGA can be done in three steps oil is sensed by these sensors. Any abnormal rise in
 Oil sample extraction temperature due to fire hazards is detected by these
 Extraction of the gases sensors.
2. Valves- The valves are provided at three locations - a.
 Gases separation & measurement
between conservator and breather b. on oil drain pipe
Online DGA it is possible to increase operating safety and c. at nitrogen cylinder. In the event of fire hazards,
while simultaneously reducing costs. Online DGA can be the opening and closing of these valves takes place
used for maintenance and asset life management, for early automatically.
fault detection to enhance or monitor performance. 3. Pipelines- Basically two pipelines are provided, one for
oil evacuation and the other for nitrogen filling.
4. Control box- The control box receives signals from
sensors and accordingly sends command to operate the
system. In this paper, it is proposed to connect control
box to the existing tulip communication system through
RJ11 and Modbus.
5. Oil Pit- It is an underground pit below the soil in which
the small quantity of oil is drained from transformer
tank.
6. Outdoor cubicle- The outdoor cubicle is provided near
transformer installation. It comprises of nitrogen
cylinder and mechanism for operating the system.
7. Indoor Cubicle- The indoor cubicle is installed in the
control room. It is connected to the system through a
control cable. It comprises of fire switch, glass cover,
hammer, LED indicators, Fire alarm indicators etc.
FIG.1. DGA SYSTEM [1]

III. PALM OIL ENSURES SAFETY OF

TRANSFORMER
Liquid insulating material used in the transformer also acts
as a coolant. Since late nineteenth century, petroleum oil
has been used in electrical equipment [3].Mineral oil is
widely used because of its affordable cost and good
dielectric properties. But petroleum reserves are going to
deplete in near future; so we need to think of alternative
for it.When the fault occurs in the transformer e.g. rupture
of tank, oil leakage, the petroleum oil ,which is poorly
biodegradable, will be major environmental challenge for
the nature. In Malaysia, mineral oil is used in transformer
as the insulating medium. Because of the environmental
awareness raised rapidly, fully biodegradable vegetable
oils are used in the transformer [2]
Breakdown of the insulation in transformer is caused
because of the moisture content .Water leads degradation FIG.2. NITROGEN INJECTION SYSTEM
of the insulating material.NurSyamimi Murad, N. A. The overall working of fire injection system is as
Muhamad conducted an experiment , To study moisture described below. Whenever there is an occurrence of fire

Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2015.3802 6

 ISSN (Online) 2321 – 2004
ISSN (Print) 2321 – 5526

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING
Vol. 3, Issue 8, August 2015

hazards, obliviously there is rise in temperature. This Load Voltage Regulation

temperature rise is detected by the sensors as shown by Protection against Overload & Short Circuit
square packets in Fig. The sensors inform abnormal Operates on Distribution Voltage Level
condition caused because of rise in temperature, to the No Fire Hazard / Contamination
control box. In response, the control box performs Small size and light weight
following three actions in a sequential manner. Bidirectional power flow
Input to output isolation
The valve provided near buccholz relay is closed. This
stops circulation of transformer oil between conservator
and main tank.
The Oil drain valve is opened and a small quantity of oil
(usually 1%) is taken from top of the tank to the
underground pit as shown in figure 4. This forms a small
gap at top of the transformer tank.
Now the nitrogen valve is opened so that the nitrogen gas
is released from cylinder and gets injected inside the
transformer tank. The nitrogen gas is injected at the
bottom of tank. However, because of low density it goes
up and fills the gap created by evacuation of the oil. The
nitrogen quenches the fire immediately.

V.SOLID STATE TRANSFORMER FOR

BIDIRECTIONAL FLOW IN SMART GRID
SST and BITS ensure safety in smart grid:
The solid state transformer is a power electronic device
that replaces the traditional 50 Hz power transformer by
means of high frequency transformer isolated AC-AC FIG. 4. BIDIRECTIONAL TRANSFORMER
conversion technique, [5] This brings the promising
advantages such as the power flow control, voltage sag VI. GSM COMMUNICATION
compensation and fault current limitation. The basic The temperature acquisition module will sense the
diagram of a SST is given in Fig. Isolation is achieved transformer temperature. The data processing module
through SST. The grid voltage is converted into a higher mainly has microcontroller and its peripheral Circuits. It
frequency AC voltage through the use of power- processes the data and sends it to control module. When
electronics based converters to be applied to the primary the temperature goes high, out of the limit then the control
side of the transformer. The opposite process is performed module will send the temperature data and alarm signal to
on the transformer secondary side to obtain an AC and/or user by SMS [10].
DC voltage for the load. User receives the data by SMS then starts the cooling
system fan. GSM transceiver module is a link between
embedded system and user GSM network. The server is
attached to GSM modem and it sends SMS to mobile users
containing various parameters of distribution transformer
[6] [9].

FIG.3. SOLID STATE TRANSFORMER

For smart grid application bidirectional semiconductor
transformer is used to ensure safety. Following diagram of
BIST consists of high-voltage high-frequency ac/dc
converter, bidirectional low-voltage dc/dc converter, and
hybrid-switching dc/ac inverter. [6]
Functionalities and features of bidirectional transformer:
Voltage Harmonics / Sag Compensation
Outage Compensation FIG.5. OVERALL STRUCTURE GSM COMMUNICATION OF
TRANSFORMER
Protects Power System from Load Disturbance

Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2015.3802 7

 ISSN (Online) 2321 – 2004
ISSN (Print) 2321 – 5526

INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING
Vol. 3, Issue 8, August 2015

VII. CONCLUSION Dr. Shashikant M. Bakre completed

Online monitoring using Sensors, Advanced metering his bachelor’s degree in Electrical
infrastructure, and GSM Communication, transformer Engineering from Govt Engineering
safety can be ensured in smart grid. It also serves the College Amravati ( Nagpur University )
purpose of fast fault analysis and improves not only , followed by master’s degree in
overall health of transformer but the entire distribution engineering from COEP (Pune
system as well. University).He also completed MMS ,
With the implementation of Nitrogen injection system, master’s degree in management from Pune University .
Dissolved Gas Analysis and using Bidirectional Later , he completed his doctorate from Bharati
transformer it is easier to get safe and smart transformer Vidyapeeth Deemed University , Pune in the year 2011.
for upcoming smart Distribution System. He is the author of ten books on computer engineering
.Some of his books are Computer Fundamentals ,
ACKNOWLEDGEMENT Computer Master , Build your own website , OOPS and
Authors are grateful to Jain University, Bangalore for Core Java , Object Oriented Analysis and Design and
providing required research facilities and encouragement. Supply Chain Management. He has published about 25
research papers . His research work is focused on
REFERENCES applications of Information Technology in Power Quality .
[1] www.electricalenergyonline.com
He is working with Maharashtra State Electricity
[2] 2013 Annual Report Conference on Electrical Insulation and
Dielectric Phenomena Transmission Company as an Executive Engineer . He has
[3] Wilson, A.C.M., Insulating Liquids: Their Uses Manufacture and worked at 400 KV Lonikand SS , 400 KV Jejuri
Properties. 1980, IEEE Electrical and Electronic Materials and Substation and Testing Communication Circle. At present,
devices
he is posted at Major Stores, Baramati .The areas of his
[4] www.electrical4u.com
[5] Xiao-hui Cheng, Yang Wang,” The remote monitoring system of research are mobile computing based applications .He is
transformer fault based on the internet of Things”, 2011 also working as visiting faculty at Symbiosis Institute of
International Conference on Computer Science and Network Business ,Pune.
Technology
[6] Velhal, G. ; Pujara, A. ; Bakre, S.M. ; Muralidhara, V.On progress of
communication infrastructure for fault location and ABT Dr. V.Muralidhara Obtained B.E.
metering,IEEE 2014 in Electrical Engineering, M.E. in
[7] Avani Pujara , Geeta Velhal , Dr S.M.Bakre , Dr V.Muralidhara, A Power Systems from Mysore
Review on Smart Grid in India, International journal of innovative
University and PhD from Kuvempu
research in electrical, electronics, instrumentation and control
engineering, Vol. 3, Issue 3, March 2015 University. During the years 1975,
[8] Dr.S.M.Bakre,,Nakul Bakre “Object Oriented Approach for Sensing 1978 and 2012 respectively. He has
Measurement Communication and Control of Data using Numeric started his teaching career from PES
Meters”, March 2012
College of Engineering Mandya during 1976 and served
[9] Hahn Tram, “Technical and operation considerations in Using smart
metering for outage management”, IEEE 2008. there for 6 years and retired as Prof. and Head of EEE at
BIT, Bangalore and served there for 31 years. At present
[10] Zhang Luhua, Yi Zhonglin,Yuan Ruiming,Zhou Hui,Yin Qingduo
“Effects of Advanced metering Infrastructure on Relatons of power
serving the School of Engineering and Technology, Jain
supply and Application in smart Grid,” IEEE 2010.
University Bangalore as an Associate Director. Published
4 papers in International conferences and one paper in
BIOGRAPHIES
International Journal as a part of the research work. His
Velhal Geeta Vilas, Graduated in
field of interest is Power Systems and High Voltage
Electrical Engineering from
Engineering.
Government of College of Engineering,
Karad, in 2004 and had her Master’s
degree from Bharati Vidyapeeth
University, Pune. She is currently
pursuing PhD from Jain University,
Bangalore and she is with Trinity College of institute and
Research, Pune as an Assistant Professor. Her teaching
experience is six years. Her area of interest is Power
System protection and smart metering.

Avani Pujara has received her BE

Electrical Engineering degree from
Saurastra University. She earned her
ME power system from Pune
University and her teaching experience
is 9 years. She is currently a research
scholar at Jain University Bangalore.
Her interest revolves around power
system stability, smart grid and smart metering.

Copyright to IJIREEICE DOI 10.17148/IJIREEICE.2015.3802 8