Claims:WE CLAIM:
1. A system for tapping power from an earth wire of a transmission line, wherein the system comprising:
an earth wire;
a power potential transformer;
a transmission line;
wherein the earth wire of a transmission line is insulated by providing suspension/tension polymer insulators strings in between tower and earth wire in order to tap voltage induced in the polymer insulated earth wire within a span of predetermined distance, and wherein the polymer insulated earth wire feeds the induced voltage to the power potential transformer designed to generate a predetermined power output at a secondary winding of the power potential transformer, wherein the power potential transformer is designed such that a High Tension (HT) and a Low Tension (LT) winding are wounded on the separate limbs of core, wherein the High Tension (HT) and Low Tension windings further comprises equal number of turns wounded on the separate limbs of core referred to as balancing windings in order to generate the predetermined power output considering voltage fluctuations in the earth wire and losses occurred due to the distance covered by the wire, wherein the power potential transformer is protected by connecting the polymer insulated earth wire with a lightning arrestor.

2. The system of claim 1, wherein the transmission line is either Single Circuit (three phase) or Double circuit (six phase) power transmission line.

3. The system of claim 1, insulates one of the two earth wires in 2.35 kms section of line by using the suspension and tension insulator strings.

4. The system of claim 1, wherein the voltage is induced in earth wire due to electric field generated by transmission lines.

5. The system of claim 1, wherein the polymer insulated earth wire is connected to the power potential transformer and the lightning arrestor near a gantry or at a tower location.

6. The system of claim 5, wherein the polymer insulated earth wire connected to the power potential transformer and lightning arrestor by putting a jumper with a clamp and a connector.

7. The system of claim 1, wherein the power potential transformer designed to generate 3.5kw output at secondary winding of power potential transformer.

8. The systems of claim 1, wherein the High Tension (HT) wires and Low tension (LT) wires are connected in parallel in order to ensure zero leakage flux.

9. A method for tapping power from an earth wire of a transmission line, wherein the method comprising:
insulating earth wire of transmission line for a predetermined distance by providing suspension/tension polymer insulator strings between earth wire and tower;
Inducing voltage in polymer insulated earth wire of transmission line due to electric field of transmission line;
feeding the voltage induced in the polymer insulated earth wire to the power potential transformer wherein the power potential transformer is designed to generate predetermined power output from the secondary winding of the power potential transformer wherein the power potential transformer is designed such that a High Tension (HT) wire and a Low Tension (LT) wire are wounded on the separate limbs of core, wherein the High Tension (HT) wires and Low Tension wires further comprises equal number of turns wounded on the separate limbs of core along with balancing windings in order to generate the predetermined power output considering voltage fluctuations in the wire and losses due to the distance covered by the wire; and protecting the power potential transformer by connecting the polymer insulated earth wire with the lightning arrestor.
, Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
SYSTEM AND METHOD FOR TAPPING POWER FROM AN EARTH WIRE OF A TRANSMISSION LINE

APPLICANT:
M/S SHYAMA POWER INDIA LTD.,
An Indian entity having an address as,
Naga Cottage, Circular Road,
Dimapur - 797112, Nagaland
(India)

The following specification describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

The present application does not claim priority from any other patent application(s).
TECHNICAL FIELD
The present subject matter described herein, in general, relates to power generation system, and more particularly, to a power generation system and method thereof enabling tapping of power from an earth wire of a transmission line.
BACKGROUND
In a developing country like India the majority of the population lives in remote rural areas therefore after independence successive governments have tried to improve the rural infrastructure including energy infrastructure. Mostly, the power generation plants are remotely located away from the rural areas and therefore, transmission lines are used to transmit power to such remote places. Further, high-voltage transmission lines comprise of overhead conductors installed on Transmission line towers with the help of Disc/Long Rod Insulators Strings, Earth wire installed on tower directly and provided above conductors at a suitable distance so as to protect Conductors against lightning.
Earth wire on each tower is earthed properly with the help of GI Flat, pipe or counterpoise earthing. With the development taking place at a very fast pace in each sector i.e. Power, Telecom, Infrastructure, Agriculture, Automobile etc. the demand in every field is increasing by leaps and bounds. In the telecom sector also, more and more operators are entering into communication business resulting into installation of large number of antennas on telecom towers in the length and breadth of the country including remote areas. Many telecom operators are facing problem in getting reliable power supply for telecom towers and repeater stations located in remote areas from the state 11kV/0.415kV feeders due to long distance transmission.
Therefore, there is long standing need of the system and method for making reliable power available to telecom operators in remote areas by utilizing the voltage induced in the earth wire in order to avoid loss of the power and further solves the problem of getting power at remote areas.
SUMMARY
This summary is provided to introduce concepts related further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
In one implementation, a system for tapping power from an earth wire of a transmission line is disclosed. The system may comprise a Double circuit transmission line with earth wires, Power Potential transformer, and Lightning arrestor. Further, one out of two earth wires may be insulated by putting Polymer insulator suspension/tension string (depending upon type of tower involved) in between Tower and earth wire at each tower location for predetermined distance of length of the line. Insulation of earth wire may have to be done from tension tower to Tension tower only i.e. if the predetermined distance is 2.0Kms and tension tower is not available at 2.0Kms then earth wire has to be insulated till the next tension tower location. On charging of line, a voltage may induce in the insulated earth wire due to electric field. As insulated earth wire is connected with Power Potential transformer, therefore, the polymer insulated earth wire feeds the induced voltage to the power potential transformer, which is designed such that a High Tension (HT) wire and a Low Tension (LT) wire are wounded on separate limbs of core, and wherein the High Tension (HT) wires and the Low Tension wires includes equal number of turns wounded on the separate limbs of core along with balancing winding to generate a predetermined power output at its secondary winding of the power potential transformer under various conditions of voltage fluctuations in the earth wire and losses occurred due to the distance covered by the wire. The power potential transformer is protected by connecting the polymer insulated earth wire with a lightning arrestor.
In another implementation, a method for tapping power from an earth wire of a transmission line is disclosed. The method may comprise connecting a Double circuit transmission line with earth wires to Power Potential transformer and Lightning arrestor. Further, one out of two earth wires are insulated by putting Polymer insulator suspension/tension string (depending upon type of tower involved) in between Tower and earth wire at each tower location for predetermined distance of length of the line. In the charged line, due to electric field, a voltage is induced in the insulated earth wire. The method may comprise feeding the voltage induced in the polymer insulated earth wire to the power potential transformer. In an aspect, the power potential transformer may be designed to generate a predetermined power output from the secondary winding of the power potential transformer. Further, the power potential transformer may be designed such that a High Tension (HT) winding and a Low Tension (LT) winding are wounded on separate limbs of core. Further, equal number of turns wounded on the separate limbs of core referred to as balancing winding are also wound in addition to HT & LT winding, in order to generate the predetermined power output, considering voltage fluctuations in the wire and losses due to the distance covered by the wire. The power potential transformer may be protected by connecting the polymer insulated earth wire with the lightning arrestor.

BRIEF DESCRIPTION OF DRAWINGS
The detailed description is described with reference to the accompanying Figures. In the Figures, the left-most digit(s) of a reference number identifies the Figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.
Figure 1 illustrates an implementation of a system for tapping power from an earth wire of a transmission line near a gantry, in accordance with an embodiment of the present subject matter.
Figure 2 illustrates an implementation of a system for tapping power from the earth wire of the transmission line at a tower location, in accordance with an embodiment of the present subject matter.
Figure 3 illustrates a design of the power potential transformer, in accordance with an embodiment of the present subject matter.
Figure 4 illustrates an implementation of infrastructure for tapping power from the earth wire, in accordance with an embodiment of the present subject matter.
Figure 5 illustrates a method for tapping power from the earth wire, in accordance with an embodiment of the present subject matter.
Figure 6(a) illustrates sectional arrangement of the 66kV out door oil cooled power potential transformer in accordance with an embodiment of the present subject matter.
Figure 6(b) illustrates top view of the sectional arrangement of the 66kV out door oil cooled power potential transformer in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION
Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
In one embodiment, the present subject matter is directed to a system and method for tapping power from an earth wire of a transmission line. The system comprises a polymer insulated earth wire of transmission line, a power potential transformer and a lightning arrestor. In one embodiment, the transmission line may either be Single Circuit (three phase) or Double circuit (six phase) power transmission line. The transmission lines may be supported by the transmission tower or power tower which is a tall lattice structure.
In one embodiment, the polymer insulated earth wire is part of the transmission line. In one embodiment, the conductors of the transmission line may induce voltage in the polymer insulated earth wire due to electric field. The polymer insulated earth wire may tap the induced voltage within a span of predetermined distance. In one exemplary embodiment, the polymer insulated earth wire may tap the induced voltage within the range of two to three kms from the tower. In one embodiment, the voltage may be tapped by installing suspension insulator string or tension insulator string. In one embodiment, the polymer insulated earth wire feeds the induced voltage to the power potential transformer which may be designed to generate a predetermined power output at a secondary winding of the power potential transformer. The power potential transformer may comprise a High Tension (HT) winding and a Low Tension (LT) winding winded on separate limbs of core. In one embodiment, the balancing winding may be placed with the High tension(HT) and the Low Tension(LT) winding. Further, the balancing windings may be tuned apart from the HT & LT winding to ensure the desired characteristics of the power potential transformer. & be connected in parallel in order to ensure zero leakage flux. In one exemplary embodiment, the power potential transformer may be designed to generate 3.5kw output at secondary winding of power potential transformer.
In one exemplary embodiment, the power potential transformer may be designed to generate the predetermined power output considering voltage fluctuations in the earth wire and losses occurred due to the distance covered by the wire. In one embodiment, the power potential transformer is protected by connecting the polymer insulated earth wire with a lightning arrestor.
In one exemplary embodiment, the polymer insulated earth wire may be connected to the power potential transformer and the lightning arrestor near a gantry or at a tower location.
Now referring to figure 1, an implementation of the system for tapping power from an earth wire of a transmission line near a gantry is illustrated. The system comprises double circuit tower 101 which is used for support the transmission lines. In one embodiment, the transmission lines may comprise three phase (not shown in the figure 1) or six phase lines. In one embodiment, the polymer insulated earth wire 102 may be connected to the transmission lines near the gantry. In one embodiment, the polymer insulated earth wire 102 may be connected to the power potential transformer 104 and the lightning arrestor 103 near the gantry location. In one embodiment, the polymer insulated earth wire may induce voltage due to the electric field of the conductors of the transmission lines. The polymer insulated earth wire 102 may tap the voltage induced. The polymer insulated earth wire 102 may feed the induced voltage to the power potential transformer 104.
Now referring to figure 2, an implementation of the system for tapping power from an earth wire of a transmission line near at a tower location is illustrated. The system comprises double multi-circuit tower 101 which may provide support the transmission lines. In one embodiment, the polymer insulated earth wire 102 may be connected to transmission line at the tower. In one embodiment, polymer insulated earth wire 102 may be connected to the power potential transformer 104 and lightning arrestor 103 at the tower lattice structure. In one embodiment, the polymer insulated earth wire may induce voltage due to the electric field of the conductors of the transmission lines. The polymer insulated earth wire 102 may further tap the voltage induced. The polymer insulated earth wire 102 may feed the induced voltage to the power potential transformer 104.
In one embodiment, the power potential transformer may generate predetermined power output at the secondary of the power potential transformer 104. The power potential transformer 104 may be designed to generate predetermined power output considering voltage fluctuations in the earth wire and losses occurred due the distance covered by the wire. In one example, the power potential transformer 104 may generate a power output within a range of 2.5-3.5KW.
In one exemplary embodiment, the power potential transformer may be configured to deliver desired wattage over a wide voltage variation range. The power potential transformer may further be configured to maintain the voltage regulation. The power potential transformer may be designed to operate continuously with desired regulation & wattage over the input operating range of 20kV to 75kV. In one embodiment, the power potential transformer may be designed with graded High Tension (HT) winding along with specially designed balancing windings.
Now referring to figure 3, a design of the power potential transformer is illustrated. In one embodiment, specially designed balancing windings may be placed along with High Tension (HT) and Low Tension (LT) windings, wherein the specially designed balancing windings are tuned to ensure the desired characteristics. In one embodiment, the High Tension (HT) and Low Tension (LT) windings are wounded on the separate limbs of core. In one embodiment, the High Tension (HT) wires and Low Tension wires may include equal number of turns wounded on the separate limbs of core.
Now referring to figure 4, an infrastructure for tapping power from the earth wire is illustrated. In one embodiment, the voltage induced in the polymer insulated earth wire may be tapped within a span of predetermined distance. In one exemplary embodiment, the polymer insulated earth wire may tap the voltage induced within range of two to three kms. In one embodiment, one of the two earth wires insulated in 2.35 kms section of line by using the suspension and tension insulator strings.
Now referring to figure 5, a method for tapping power from the earth wire is illustrated, in accordance with an embodiment of the present subject matter. At step 501, the earth wire of transmission line may be insulated for a predetermined distance by providing suspension/tension polymer insulator strings between earth wire and tower.
At step 502, the polymer insulated earth wire 102 may induce voltage due to an electric field of the transmission lines. In one exemplary embodiment, the polymer insulated earth wire 102 may tap the induced voltage within the range of two to three kms. from the tower.
At step 503, the polymer insulated earth wire 102 may feed induced voltage to the power potential transformer 104. In one embodiment, the power potential transformer 104 may be designed to generate predetermined power output from the secondary winding of the power potential transformer 104. The power potential transformer 104 may be designed to generate the predetermined power output considering voltage fluctuations in the wire and losses due to the distance covered by the wire.
At step 504, the polymer insulated earth wire 102 with the lightning arrestor may be connected to the power potential transformer in order to protect the power potential transformer 102 from the lightning strikes.
In one exemplary embodiment, the output of the potential transformer is tested by measuring a secondary output of power potential transformer with connected variable load to the circuit. In one embodiment, testing meters are used for the measurement.
In one exemplary embodiment, Double Circuit (six-phase) transmission line comprises a of two circuit each of three phase transmission line circuit. Both the circuits of the transmission lines i.e. circuit 1 (ckt 1) and circuit 2 (ckt 2) were charged at 400KV. In an exemplary embodiment, one earth-wire of double circuit line was insulated for a distance of 2.35km. The power potential transformer output is connected with the variable load. The induced voltage output as-well-as leakage current was measured at the secondary of the Power Potential transformer and a lightning arrestor respectively. The tested results observed are depicted in table 1 below.
Case 1: ckt 1 is ON, ckt 2 is ON and insulated earth wire above ckt 2 is loaded.
66kV Class LA leakage current was 0.1mA
Power PT voltage Ratio is 66kV/v3kV:230V
S. No. Connected Load at PT secondary in Amps 66kV PT AC voltage at secondary terminals Primary Voltage
(Kilovolts) Total load in KVA
1 No Load 207.3 34.35 0
2 3.6 201.6 33.40 0.73
3 5.3 197.8 32.77 1.05
4 6.8 195.2 32.34 1.33
5 8.1 191.5 31.73 1.55
6 8.3 189.6 31.41 1.57
7 9.7 187.3 31.03 1.82
8 10.9 183.7 30.44 2.0
9 11.1 181.7 30.10 2.02
10 12.1 179.1 29.67 2.17
11 13.2 175.6 29.09 2.32
12 13.4 173.9 28.81 2.33
13 14.4 169.9 28.15 2.45
14 18 154.5 25.60 2.78
Table 1
In another exemplary embodiment, for the Double circuit (six-phase) transmission lines, ckt. 1 was switched off and ckt. 2 was only charged at 400KV wherein one earth wire above ckt. 2 was insulated for 2.35 Kms. The tested results are given in the following table 2.
Case II: ckt 1 is OFF, ckt 2 is ON and insulated earthwire above ckt 2 is loaded.
66kV Class LA leakage current was 0.5mA
Power PT voltage Ratio is 66kV/v3kV:230V
S.No. Connected Load at PT secondary in Amps 66kV PT AC voltage at secondary terminals Primary Voltage Total load in KVA
1 No Load 294 48.71 0
2 4.9 284 47.05 1.39
3 7.3 278 46.06 2.03
4 9.3 274 45.40 2.55
5 9.4 274.9 45.55 2.58
6 11.6 266 44.07 3.09
7 18.4 243 40.26 4.47
8 24.5 216 35.79 5.29
Table 2
From the above readings, it is observed that primary and secondary voltage is varying from 48.71kV to 25.60KV and 154.9V to 294V respectively. Therefore, in order to take care of high voltage variation, the power potential transformer may be designed with graded HT winding having specially designed balancing winding apart from usual HT & LT windings, which further delivers desired power of the order of 3kVA continuously over a wide range of primary voltage variation i.e. 20kV to 75kV and maintaining regulation of +/- 5%. In one exemplary embodiment, the power potential transformer is designed to develop 230 volts output at 50kV, its thermal rating was 32.6 Amps at 20kV input voltage.
In another exemplary embodiment, the power potential transformer is designed for 66kV. Now referring figure 6(a) and 6(b) sectional arrangement of 66kV out door oil cooled power potential transformer is illustrated. The 66kV out door oil cooled power potential transformer may comprise a HT terminal 601, an oil level indicator 602, an oil expansion chamber 603, a Bushing clamp 604, a Bushing(IEC/ABIL/WSI/Modern) 605, a Lifting Lug 606, a Tank with cover 608, an oil drain plug 609, an earthing terminal 610, a secondary and earthing terminal box 611, a nitrogen valve 612, an oil filling plug 613, a dome 614, pressure release device 615, bushing gasket 616 and stack lamination 617.
In one embodiment, High Tension (HT) terminal 601 is a primary terminal. In one embodiment, the High Tension (HT) primary terminal may be made up of aluminium. In one embodiment, a secondary and earthing terminal box 611 may provide secondary winding terminal along with a provision for earthing. The 66kV out door oil cooled power potential transformer may comprise insulating oil to insulate the primary and secondary windings. In one embodiment, the oil filing plug 609 and the oil drain plug 613 may assist in maintaining the level of the oil. In one embodiment, the oil level indicator 602 may be used to maintain the correct oil level in the transformer. In one embodiment, the bushing 605 may provide central passage for conductors with a provision for mounting a barrier. In one embodiment, the bushing gasket 616 may be employed for avoiding leakage of oil. Further, the nitrogen valve 612 may facilitate to reduce the risk of the fire hazards in the oil cooled power potential transformer. In one embodiment, the 66kV out door oil cooled power potential transformer comprises two separate limbs of a magnetic core. In one embodiment, the primary HT winding may be wounded on one of the limbs of the magnetic core along with the balancing winding. Further, the secondary LT winding may be wounded on the other limb of the magnetic core along with the balancing winding. In one embodiment, the High Tension (HT) wires and the Low Tension (LT) wires may include equal number of turns wounded around separate limbs of magnetic core. In one embodiment, the High Tension (HT) wires and the Low tension (LT) wires may be connected in parallel in order to ensure zero leakage flux.