FIELD OF THE INVENTION
This invention relates to a method of controlling and monitoring the parameters
of power transformers. More particularly, the invention relates to an apparatus to
control and monitor all the parameters of an operating transformer including
associated sensors in a power plant through a redundant system with seamless
communication under SCADA system using IEC61850 communication protocol.
BACKGROUND OF THE INVENTION:
Transformers are the most expensive and most important equipment of the high-
voltage transmission system. They need to be monitored continuously to not only
prevent any potential faults, but also to ensure optimal utilization and an
improved performance.
A few related examples on Transformer Monitoring System can be found in the
earlier patents mentioned below:
1) US20050223782A1 2005-10-13 Transformer monitoring system (en) :
This invention relates to a system that has an oil temperature calculation
device to calculate the transformer oil temperature using measurements
from a transformer current measuring device and an ambient temperature
measuring device. The transformer monitoring system also has an oil
temperature measuring device and compares an output value from the oil
temperature calculation device with an output value from the oil
temperature measuring device to detect any anomaly.
2) EP1786083A1 2007-05-16 Method and system for monitoring power
transformers (en) :

This invention relates to a method and a system of monitoring power
transformers, intended to detect incipient failures in a transformer. The
detection of the incipient failures is carried out based on mathematical
models of behavior, so that for the identification of the fault conditions a
set of measured variables is compared, with some adaptive threshold
values for each variable calculated from the operating conditions of the
transformer.
3) 2008-10-02-ICSA DISTRIBUTION TRASFORMER MONITRING SYSTEM(en)
The present invention relates to ICSA Distribution Transformer Monitoring
System (DTMS), Distribution Transformer Monitoring System is used to
monitor and control the Distribution transformers and sub-station feeders.
The DTMS is also useful in energy audit, load survey and fault analysis.
This will communicate the alarm conditions, energy parameters and other
data to a central control station using a communication link.
4) US20100188240A 2010-07-09 Continuous monitoring of transformers (en)
This invention relates to a device and method for monitoring the condition
of an electrical power transformer in an electrical power grid which
synchronously measures current and voltage data at both the high voltage
side of the transformer and the low-voltage side of the transformer and
computes from this measured data the corresponding transformer
impedance data. These measurements and computations are repeated
continuously in real time at rates upto 30 Hz to provide a sequence of
real-time transformer impedance data.
5) WO201300824A1 2013-01-17 AN INTELLIGENT TRANSFORMER
MONITORING SYSTEM (en) :

This invention relates to an intelligent transformer monitoring system
being equipped with artificial intelligence in order to process and interpret
said second stream data in relation to pre-defined parameters and models
in order to obtain predictions of transformer performance parameters and
servicing calls in relation to said predicted performance, thereby obtaining
a condition based servicing model.
6) US20130158897A1 2013-06-20 SYSTEM AND METHOD FOR MONITORING
AND CONTROLLING A TRANSFORMER (en) :
This invention is concerned with a system, a method and computer
program to monitor a plurality of transformer operating parameters, as
well as to accurately control one or more of the transformer operating
parameters, calculation of loss of life, give diagnosis for recovery and
provide maintenance notification and monitor the operation of the LTC.
7) US20140036958A1 2014-02-06 HYBRID MECHANICAL AND ELECTICASL
TRANSFORMER MONITOR (en) :
In accordance with the present invention, there is provided a hybrid
mechanical and electrical transformer temperature monitor. The
mechanical sensing mechanism drives mechanical switches, local display
and a sensing input to the electrical side of the monitor. The electrical of
the temperature monitor has the ability to calculate winding temperature
(with an additional current sensor) data log, actuate electrical switches
and has a local display for winding temperature.
8) WO2015183298A1 2015-12-03 SYSTEMS FOR MONITORING POWER
TRANSFORMERS AND METHOD OF OPERATIG THE SAME (en) :
This invention relates generally to power transformer monitoring systems
and, more particularly, to a fiber optic- based probe to monitor a position

of the windings and / or the top ring assembly of a power transformer,
thereby determining a clamping force induce on the windings by the top
ring assembly.
9) WO2015149593A1 2015-10-08 IEC 61850-BASED COMMUNICATION
SIMULATION METHOD FOR TRANSFORMER GROUNDING ON LINE
MONITORING DEVICE (en) :
The invention relates to an IEC61850 based communication simulation
method for a transformer grounding on-line monitoring device by starting
an IEC61850/MMS communications service and querying values of analog
quantities pre-stored in an SQL database, of an analysis on a transformer
grounding on-line monitoring intelligent electronic device to be simulated.
10) CN1032681088B 2016-08-03 Transformer load intelligent management
system : The invention discloses an intelligent transformer load
management system. The system measures the oil temperature of the top
layer of a transformer in real-time and predicts temperature changes of
the transformer according to external environment factors and current
operation conditions and also provides corresponding predicted overload
operation time so as to improve the utilization rate of the transformer to
the greatest degree, and enables the transformer to operate in an energy
saving and efficient mode.
11) CN105241497A 2016-01-13 Transformer monitoring system and fault
diagnosis method (en) :
The invention proposes a transformer monitoring system and a fault
diagnosis method. Mainly this invention involves the measurement of oil
gas colour, oil moisture, temperature, partial discharge, grounding
current, load voltage adjustment switch monitoring unit which can also
diagnose a fault based on all these continuous measurements.

OBJECTS OF THE INVENTION:
An object of the invention to propose an apparatus to control and monitor
all the parameters of an operating transformer including associated
sensors in a power plant through a redundant system with seamless
communication under SCADA system using IEC61850 communication
protocol.
Another object of the invention is to focus towards making the complete
system including two separate units (indoor and outdoor units) connected
to each other through a high speed and reliable fiber optic armored link.
A further object of the invention is to provide 100% redundancy in the
outdoor unit, the indoor unit and the communication link.
SUMMARY OF THE INVENTION:
The present invention is concern with the Transformer monitoring system,
in particular with a method of controlling and monitoring of an actual
transformer through a redundant system. The said system comprises of
two separate units (indoor and outdoor) connected to each other through
a redundant, high-speed, reliable fiber optic armored cable. The outdoor
unit contains input/output electronic modules through which all the field
inputs are sensed, conditioned and converted into digital data to be sent
to the indoor cubical. To make the communication between indoor and
outdoor unit more reliable and compatible to present power plant trends,
MODBUS over TCP/IP protocol is implemented. The indoor unit houses a
controller/processor module which is equipped with multiple
communication capabilities including communication with SCADA using the
IEC61850 communication protocol. It also has two serial ports
connectivity with laptops and touch-screen HMIs located on the cubical for

parameter monitoring, archiving and control. The processor module is
developed with a flash disk so as to store transformer data up to 2 years.
To make the system highly reliable and robust, redundancies at each and
every level of the architecture have been incorporated in the system. The
outdoor unit contains two sets of redundant field input / output modules
such that each Input or Output is conditioned, monitored and controlled
twice in parallel. The fiber optic communication link and power supplies
are also redundant. Furthermore, the indoor unit also contains two
processor modules which process the data independently but in sync with
each other in MASTER / SLAVE configuration. In case of any failure the
system automatically detects the fault through intensive diagnostics
algorithms and smoothly changes over to the slave set without any bump
in the input / output. This makes the system highly reliable and gives
ample time for service and maintenance of the faulty set without any
interruption of service in the system.
The redundancy is provided starting from the field I/O card level including
the fiber optic communication to the Composite Monitoring System
including the redundant DC power supply. This facilities seamless
automatic change over from the faulty system to the healthy system
without any manual intervention.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS :
The invention is described with the help of figures 1 to 7 where:
Figure 1 shows a Block diagram of the composite monitoring System
Figure 2 depicts Redundancy in Binary inputs
Figure 3 depicts Redundancy in Binary Outputs
Figure 4 depicts Redundancy in Analog Inputs

Figure 5 depicts Redundancy in PT signals
Figure 6 depicts Redundancy in CT signals
Figure 7 depicts Redundancy in Power Supply Modules
DETAIED DESCRIPTION OF THE INVENTION
Referring now to Figure 1, the complete system comprises of two
separate units:
1. Outdoor Unit (IOD – Input Output Device)
2. Indoor Unit (CMS – Composite Monitoring System)
IOD [101] contains input/output electronic modules through which all
the field inputs are sensed, conditioned and converted into digital data
to be sent to the indoor cubicle. The Binary I/Os, 4-20mA signals from
various sensors and analog Input (AI) signals from the field
Marshalling box and Cooling Control cubical are directly terminated in
the IOD cubical. The outdoor unit contains two sets of redundant field
input / output modules – Primary IOD [102] and Secondary IOD
[103] such that each input or output is conditioned, monitored and
controlled twice in parallel. Each module [102] & [103] has 72 nos. of
Digital inputs, 20 nos. of digital outputs, 16 nos. of 4-20 mA signals,
and 3 nos. each of CT/PT signals for communication with CMS. Data
communication between the IOD cubicle and the CMS cubicle is with
MODBUS TCP/IP protocol over redundant, armored optical fiber cable
[104]. The self-Diagnostics feature has been provided for al the I/O
hardware modules for detection of any module level fault.

The CMS [105] is a high speed processor based system which collects
the field from module [101] on a fiber optic cable through MODBUS
protocol and stores into internal memory or transfer into SCADA [109]
system and also controls the output connected to module [101]. In
this configuration module [101] acts as MODBUS TCP slave and
module [105] acts as MODBUS TCP Master. There is 100% redundancy
in the module [105] system i) Primary CMS [106] and ii) Secondary
CMS [107]. During operation if anything unusual occurs in module
[106] or module [102] then the module [106] switches its role and the
module [107] system takes total control seamlessly and gets the data
from module [103] and sends it to the SCADA [109] system
accordingly. The logic processing decision – Making and data-logging is
done in the CMS module. Estimation of remnant life as per IEC-60076-
7 based on thermal model Guide for loading mineral oil immersed
transformers, calculation of hotspot temperature ageing rate, loss of
life etc. is also done in the module [105].
The indoor unit can communicate serially with a front end display
designed with the graphic terminal having touch screen facility as well
as PC based HMI. Several pages have been designed for the display of
the measured parameters, tap changer control, life estimation,
Diagnostics and configuration. Events and alarms are also displayed
and stored for operator use.
The CMS communicates to module [109] over the IEC61850
communication protocol. Both the modules [106] and [107] are
physically connected to Ethernet switch [108] through RJ45 LAN cable
and SCADA will communicate with either module [106] or module
[107] which one is primary at that time. Redundancy logic has also

been incorporated between SCADA and CMS – Primary & Secondary,
so that in case of any failure in primary unit (either CMS or IOD)
seamless transition should happen between CMS-Secondary [107] and
SCADA [109].
All the 72 available Binary inputs are connected to redundant IOD
[101] through separate sets of cables from single input coming from
the field. Referring to figure 2 single cable for BI – 1 digital input is
coming from the field to the TB interfacing card [201] of IOD cubical.
From here, same signal is connected to the redundant digital cards of
module [101] through separate parallel cables.
Referring to figure 3, the binary output card of IOD has been designed
with various features. Out of the total of 20 binary output channels
available in the card, 12 channels are available with extra relay
contacts at the output of the channel specifically for cases where both
NO and NC contacts of the main relay of the channel are being used
to energize different circuits (in case of cooling fans for latch and reset
coils). However, provisions have been kept to bypass this extra contact
when only a single contact (either NO or NC) of the main relay of
channel is used. All these features have been implemented to realize
100% redundancy and smooth changeover between primary and
secondary CMS system. Each contactor coil is provided with two coils
namely coil [302] and reset coil [303]. These coils can be energized
through NO and NC contacts of the main relay in the binary output
card of IOD rack. However, to ensure that only one output is
transmitted to the output coils, an extra NO relay contact is provided
between [302] / [303] and the output relay as shown in the figure
below. The extra relay can be operated by IOD active signal [301] this

signal is generated by CMS indoor rack and is also checked at IOD rack
level. For example, if both the IODs are healthy and generating BO=1,
then 110V will be available at point A1 and A2. Therefore, the BO of
only one IOD shall be transmitted to the latch coil depending on the
[301] signal.
If module [102] is healthy, then CMS shall provide the IOD1_ACTIVE
as high (1) and IOD2_ACTIVE shall be low (0). If IOD primary is not
healthy, then IOD1_ACTIVE shall be made 0 and IOD2_ACTIVE shall
be made high and thereby module [103] shall be operating the binary
outputs.
Referring to figure 4 redundancy in 4 to 20 mA analog signal has been
realized through implementation of 4 to 20 mA current signal isolator
and splitter device module [401]. Through this two isolated and 1:1
equivalent 4 to 20 mA current signals are generated based on the
input 4 to 20 mA analog signal coming from the field. The two
generated redundant signals are connected to redundant 4 to 20ma
analog input electronics cards of module [101] through separate
cables. In case of disturbance in any of the two signals, the other
signal shall remain unaffected and thereby maintaining 100%
redundancy.
All the 3 available analog PT inputs are connected to redundant IOD
cards (Primary/Secondary) through separate sets of cables from single
inputs coming from the field. This interconnection from field input to
redundant rack has been realized through TB interfacing card [501]
mounted on the TB panel of IOD cubicle. Referring to figure 5, single
cable for PT-1 analog input comes from the field PT to the TB
interfacing cad of IOD cubicle. From here the signal is connected to

the redundant analog input cards through separate parallel cables.
Referring now to figure 6 redundancy for analog inputs from CT has
been realized through series connection of the input current signals to
module [102] and module [103]. The input from the field CT is
connected to the TB interfacing card [501] of the IOD cubicle, from
here, the signal is sent in series. 24V relays have been placed in the
cards from which inter connections to the incoming and return path of
the signal as shown in the diagram below are present. So if both the
cards are OK and present in the designated slot, no relay shall operate
and the signal shall flow and then return back to TB interfacing card
module [501]. However, in case of a fault or if one of the card is pulled
out, the corresponding relays shall operate through the IOD/P_FAIL or
IOD /S_FAIL signal and the current signal shall not enter the faulty
card thereby maintaining redundancy.
Referring to fig 7 the racks for indoor as well as outdoor units are
equipped with 2 no. or redundant power supply electronics cards. Each
power supply card energizes independently a singe set of cards of the
redundant rack. So, in case of any disturbance in the power supply or
any I/O of that set, the system shall change over to the standby set.
The power supply card works with both DC as well AC input supply.
With this 100% redundancy is maintained for each electronics rack.

WE CLAIM :
1. An apparatus to control and monitor all the parameters of an operating
transformer including associated sensors in a power plant through a
redundant system with seamless communication under SCADA system
using IEC61850 communication protocol, the apparatus comprising :-
- One each outdoor unit ad indoor unit connected to each other
through a redundant high speed fiber optic armored cable, wherein
the outdoor unit contains two sets of redundant field Input/output
modules such that each input or output is conditioned, monitored
and controlled twice in parallel, wherein the indoor unit contains
two processor modules which process the data independently but
in sync with each other in MASTER/SLAVE configuration, and
wherein if any failure in the primary system automatically
detects the fault through intensive diagnostics algorithm and
smoothly changes over to the secondary set without any bump in
the input/output.
2. The Apparatus as claimed in claim 1 wherein the fiber optic
communication link is also redundant,
3. The Apparatus as claimed in claim 1, wherein the input / output electronic
modules of the outdoor unit enables sensing conditioning and converting
all the field inputs into digital data to be sent to the indoor unit.
4. The apparatus as claimed in claim 1 wherein the power supplies are also
redundant.

5. The Apparatus as claimed in claim 1 wherein the indoor unit has a
controller/processor module configured with a flash – disk and equipped
with multiple communication capabilities including SCADA using the
IEC61850 communication protocol.