FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Remote telemetry unit for transformers
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Singh Vivek of Crompton Greaves Limited, Distribution Automation Research Centre (DARC), Global R&D Centre, Kanjurmarg, Mumbai-400042, Maharashtra, India, Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

Field of the Invention:
This invention relates to the field of substation automation and electrical devices.
Particularly, this invention relates to remote telemetry unit for transformers in substation automation.
Background of the Invention:
A transformer is a device which can transfer electrical energy from one circuit to another through inductively coupled conductors i.e. the transformer's coils. The transformer coil has a primary winding and a secondary winding which allows stepping up or stepping down of the voltage through a transformer. However, when a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (Fs) is in proportion to the primary voltage (Fp), and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be stepped up by making Ns greater than Np, or stepped down by making Ns less than NP.
However, the above can also be achieved by including a transformer tap which can enable in performing the above function and at the same time facilitating both stepping up and stepping down of voltage. A transformer

tap is a connection point along a transformer winding which enables a transformer to select a certain number of turns.
In the field of substation automation, multiple transformers need to be monitored with respect to their tap position so that the outputs of the transformers are obtained as rated.
Though there are some systems which can monitor the position of the transformer tap and later can adjust it with the help of received data, these systems do not estimate the ideal tap position which may be required in runtime environment in near future based on the rise or decline in the voltage trends. Also, these systems can either perform monitoring related functions periodically or utilize parameters or methodologies which are not robust or fully configurable as per the requirement of the transformer.
Hence, the above mentioned technique is not as accurate as required for enabling proper functioning of transformer or increasing the shelf life of a transformer.
Therefore, the objective of the present invention is to overcome the above mentioned problems, details of which have been provided below,
Objectives of the Invention:
An object of the invention is to provide a system with a Remote Telemetry Unit (RTU) which can enable the users to estimate the ideal position of tap in a transformer in run time environment.
Yet another object of the invention is to provide a system which when combined with a RTU can enable users to continuously estimate the ideal

position of the tap position in a transformer based on rise or decline in the trend of the transformer voltage rating, bus voltages and power calculated in MVA on secondary side.
Still another object of the invention is to provide a system which can be combined with a RTU for real time estimation of tap position of a transformer in a continuous manner in real time.
Yet another object of the present invention is to provide a system with a RTU which can be applied to plurality of transformers at the same time.
Another objective of the invention is to estimate time of the ideal tap position in milliseconds, hence, enabling SCADA personnel to guickly change the tap position manually as per the requirement.
Still another object of the present invention is to provide a highly cost-effective system unlike the current systems being utilised which provide the similar estimation function, but, when incorporated with an additional hardware, cost can go up to several times.
Yet another object of the present invention is to avoid wastage of time and user inconvenience associated with installation of hardware in multiple transformers or in a common communication unit.
Summary of the Invention:
According to this invention, there is provided a remote telemetry system for transformers in substation automation, said system comprises:

a. monitoring means adapted to monitor current tap position of at
least one transformer, in a pre-determined manner at preset time
intervals;
b. parameter defining means adapted to define plurality of parameters
in relation to obtaining current tap position for each of said
transformers being monitored;
c. tap position calculation means adapted to calculate tap position
parameters for each of said monitored transformers;
d. tap selection means adapted to selected tap position parameter in
relation to said calculated tap position parameters and in reference
with said defined parameters at said preset time intervals; and
e. tap changer mechanism adapted to change tap position for each of
said selected tap position parameter for each of said transformers at
said preset time intervals.
Typically, said parameter defining means includes selection means adapted to select each field for defining each of said field in terms of user input, said fields being selected from a group of fields consisting of Tag field, Transformer Rating field, Transformer Reactance field, Low BUS Voltage Rating field, High BUS Voltage Rating, Primary Transformer Voltage rating field, Secondary Transformer Voltage rating field, Bus 1 Voltage field, Bus 2 Voltage field, Real Power Bus 2 field, Reactive Power Bus 2 field, and Enable field.
According to this invention, there is provided a method for remote telemetry for transformers in substation automation, said method comprises the steps of: i. monitoring current tap position of at least one transformer, in a predetermined manner at preset time intervals;

ii. defining plurality of parameters in relation to obtaining current tap
position for each of said transformers being monitored; iii. calculating tap position parameters for each of said monitored
transformers; iv. selecting tap position parameter in relation to said calculated tap
position parameters and in reference with said defined parameters
at said preset time intervals; and v. changing tap position for each of said selected tap position
parameter for each of said transformers at said preset time
intervals.
Typically, said step of defining plurality of parameters includes a step of selecting each field for defining each of said field in terms of user input, said fields being selected from a group of fields consisting of Tag field, Transformer Rating field, Transformer Reactance field, Low BUS Voltage Rating field, High BUS Voltage Rating, Primary Transformer Voltage rating field, Secondary Transformer Voltage rating field, Bus 1 Voltage field, Bus 2 Voltage field, Real Power Bus 2 field, Reactive Power Bus 2 field, and Enable field.
Brief Description of the Accompanying Drawings:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic of the system;
Figure 2 illustrates a transformer with tap and bus lines;

Figure 3 illustrates a schematic flowchart of the working of the system of Figure 1.
Detailed Description of the Accompanying Drawings:
According to this invention, there is provided a remote telemetry unit for transformers in substation automation.
It also provides a method of estimation of ideal tap position of transformer in a real time environment. The monitoring is enabled to be continuous and not periodic in nature.
Figure 1 illustrates a schematic of the system.
In accordance with an embodiment of this invention, there is provided a monitoring means (MNM) adapted to monitor current tap (10) position of a transformer (Tl, T2, ...., Tn) or a plurality of transformers. This monitoring may be adapted to be conducted periodically or in a continuous manner. The reception of data from the monitoring means is transmitted to a remotely located processing unit which makes this system a Remote Telemetry Unit. The Remote Telemetry Unit (RTU) enables a person to continuously keep receiving the estimation of an ideal position of tap in a transformer based on various parameters apart from the current tap position which is being continuously or periodically monitored.
It is known that a transformer tap is a connection point along a transformer winding that allows a certain number of turns to be selected. By this means, a transformer with a variable turns' ratio is produced, enabling voltage regulation of the output.

In accordance with another embodiment of this invention, there is provided a parameter defining means (PDM) adapted to defined a plurality of parameters in relation to obtaining a current tap position for each of the transformers being monitored. The parameters include the following fields:
Tag field: The Tag field identifies the Transformer Tap Estimation pseudo point. This will be the identifier for the calculated transformer tap value which can be mapped into slave protocols to send to the master station.
Transformer Rating (MVA) field: This field defines the transformer rating expressed in Mega VA.
Transformer Reactance (p.u.) field: This field is used for Transformer reactance expressed in per unit value.
BUS Voltage Rating (kV) (Low) field: This field defines the voltage rating in kV for the lower end.
BUS Voltage Rating (kV) (High) field: This field defines the voltage rating in kV for the higher end - Higher Voltage.
Transformer Voltage rating (kV) (Primary) field: This field defines the primary / low voltage rating for the Transformer in kV.
Transformer Voltage rating (kV) (Secondary) field: This field defines the secondary / higher voltage rating for the Transformer in kV.

Bus 1 Voltage field: This field is a ref TAG mapped to read in the Bus 1 Voltage from digital multifunction meters / transducers.
Bus 2 Voltage field: This field is a ref TAG mapped to read in the Bus 2 Voltage from digital multifunction meters / transducers.
Real Power (kW) Bus 2 field: This field is a ref TAG mapped to read in from digital multifunction meters/transducers the Real Power injected into Bus 2.
Reactive Power (MVA) Bus 2 field: This field is a ref TAG mapped to read in from digital multifunction meters / transducers the Reactive Power injected into Bus 2.
Enable field: Yes/No to indicate whether to process this record and do the estimation or not.
Figure 2 illustrates a transformer (T) with tap (10) and bus lines (BUS 1, BUS 2).
In accordance with yet another embodiment of this invention, there is provided a tap position calculation means (TPCM) adapted to calculate tap position for each of the transformers being monitored.
In accordance with still another embodiment of this invention, there is provided a tap selection means (TSM) and a tap changer mechanism (TCM). Once the tap position is calculated, the result can be monitored remotely at SCADA end which can do the tap selection using the tap

changer mechanism. . This replaces the use of extra hardware module e.g. Digital Relays, Program Logic Controller (PLCs) and the like.
With the help of above mentioned system, it is possible to estimate the ideal tap position of the transformer or plurality of transformers which can further help in better functioning of the transformer, power quality at distribution level as well as increase the overall life of the transformer.
Figure 3 illustrates a schematic flowchart of the working of the system of Figure 1.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A remote telemetry system for transformers in substation automation, said system comprising:
a. monitoring means adapted to monitor current tap position of at
least one transformer, in a pre-determined manner at preset time
intervals;
b. parameter defining means adapted to define plurality of parameters
in relation to obtaining current tap position for each of said
transformers being monitored;
c. tap position calculation means adapted to calculate tap position
parameters for each of said monitored transformers;
d. tap selection means adapted to selected tap position parameter in
relation to said calculated tap position parameters and in reference
with said defined parameters at said preset time intervals; and
e. tap changer mechanism adapted to change tap position for each of
said selected tap position parameter for eac;h of said transformers at
said preset time intervals.
2. A system as claimed in claim 1 wherein, said parameter defining means includes selection means adapted to select each field for defining each of said field in terms of user input, said fields being selected from a group of fields consisting of Tag field, Transformer Rating field, Transformer Reactance field, Low BUS Voltage Rating field, High BUS Voltage Rating, Primary Transformer Voltage rating field, Secondary Transformer Voltage rating field, Bus 1 Voltage field, Bus 2 Voltage field, Real Power Bus 2 field, Reactive Power Bus 2 field, and Enable field.

3. A method for remote telemetry for transformers in substation
automation, said method comprising the steps of:
i. monitoring current tap position of at least one transformer, in a predetermined manner at preset time intervals; ii. defining plurality of parameters in relation to obtaining current tap
position for each of said transformers being monitored; iii. calculating tap position parameters for each of said monitored
transformers; iv. selecting tap position parameter in relation to said calculated tap
position parameters and in reference with said defined parameters
at said preset time intervals; and v. changing tap position for each of said selected tap position
parameter for each of said transformers at said preset time
intervals.
4. A method as claimed in claim 3 wherein, said step of defining
plurality of parameters includes a step of selecting each field for
defining each of said field in terms of user input, said fields being
selected from a group of fields consisting of Tag field, Transformer
Rating field, Transformer Reactance field, Low BUS Voltage Rating
field, High BUS Voltage Rating, Primary Transformer Voltage rating
field, Secondary Transformer Voltage rating field, Bus 1 Voltage
field, Bus 2 Voltage field, Real Power Bus 2 field, Reactive Power
Bus 2 field, and Enable field.