GB2546766A

GB2546766A - DC communication on power

Info

Publication number: GB2546766A
Application number: GB1601555.4A
Authority: GB
Inventors: Puchianu Silviu
Original assignee: GE Oil and Gas UK Ltd
Current assignee: Baker Hughes Energy Technology UK Ltd
Priority date: 2016-01-28
Filing date: 2016-01-28
Publication date: 2017-08-02
Also published as: GB201601555D0

Abstract

The invention is applied to a transmission line 30 containing two conductors (24, 25). First 26 and second direct current (DC) supply means supply current to the first and second conductors respectively. Modulator means 27, 28 are coupled with one of the supply means to modulate the output from the DC supply with a data signal 23 to provide a communications on power transmission. The modulator may be an H-bridge. The invention finds particular application in the field of hydrocarbon wells and can be used to transmit power and communications between a topside device and subsea equipment. The supply means may include and AC/DC converter. The invention may be adapted to provide bidirectional communication.

Description

DC COMMUNICATION ON POWER

Field of the Invention

This invention relates to transmitting data by communication on power, for example in a control system for a subsea hydrocarbon well facility.

Background of the Invention

Communication on power (COP) systems are electrical power and data transmission systems where an analogue data waveform is superimposed on a power waveform at one end and, at another other end, power and data filters are used to separate the power waveform from the data waveform.

For long offset power and data transmission systems (for example tens or hundreds of miles), this method allows for bi-directional transmission of power and data on the same copper wires.

These systems are widely used in control systems for subsea hydrocarbon well facilities. A known system 1 is illustrated in Fig. 1. The system 1 comprises a housing 2 which is connected to an AC mains input line 3 and a data input line 4. The AC mains input line 3 is connected to a power conditioning front end 5 which outputs conditioned power. The conditioned power is then fed to a transformer 6 which raises the voltage of the conditioned power. The electrical power output by the transformer 6 then into a diplexer 7. The diplexer 7 comprises a communications blocking filter to prevent communication signals from travelling up to the AC mains input line 3.

The data input line 4 is connected to an analogue modem 8. A data signal is passed from the modem 8 to the diplexer 7. The diplexer combines the data signal and the electrical power received and the resultant COP signal is fed to the topside end of an umbilical 10.

As prior art, there may be mentioned US-A-4 398 178, WO 00/46923, EP-A-2 104 240, GB-A-2 441 811, WO 2004/028064, EP-A-0 463 341, US 2006/079971 and GB-A-2 352 376.

Summary of the Invention

According to the present invention from one aspect, there is provided a communication system for use in transmitting electrical power and data from a first end of a transmission line to a second end of the transmission line comprising: first supply means for supplying a first direct current (DC) signal; second supply means for supplying a second direct current (DC) signal; and modulator means coupled with said supply means for modulating the first DC signal with a data signal; wherein, the modulator means is coupled to supply the modulated first DC signal to a first conductor in the transmission line at the first end, and the second supply means is coupled to supply the second DC signal to a second conductor in the transmission line at the first end.

According to the present invention from a second aspect, there is provided a communication on power system comprising: a transmission line having a first end and a second end, comprising first and second conductors; first supply means for supplying a first direct current (DC) signal; second supply means for supplying a second direct current (DC) signal; and first modulator means coupled with said supply means for modulating the first DC signal with a data signal; wherein, the first modulator means is coupled to supply the modulated first DC signal to the first conductor in the transmission line at the first end, and the second supply means is coupled to supply the second DC signal to the second conductor in the transmission line at the first end, the communication on power system further comprising: third supply means for supplying a first direct current (DC) signal; fourth supply means for supplying a second direct current (DC) signal; and second modulator means coupled with said supply means for modulating the third DC signal with a data signal; wherein, the second modulator means is coupled to supply the modulated third DC signal to the first conductor in the transmission line at the second end, and the fourth supply means is coupled to supply the fourth DC signal to the second conductor in the transmission line at the second end.

According to the present invention from a third aspect, there is provided a method of transmitting electrical power and data from a first end of a transmission line to a second end of the transmission line, the method comprising, at said first end: using first supply means to supply a first direct current (DC) signal; using second supply means to supply a second direct current (DC) signal; using modulator means to modulate said first DC signal with a data signal; coupling the modulated first DC signal to a first conductor in the transmission line at the first end; and coupling the second DC signal to a second conductor in the transmission line at the first end.

The modulator means could comprise an H-bridge. The supply means for supplying the first DC signal could comprise an AC/DC converter. The supply means for supplying the second DC signal could comprise an AC/DC converter.

At said second end, there could be a means for receiving from said transmission line the data signal from said first end. At said first end, there could be a means for receiving from said transmission line a data signal from said second end.

The system could comprise a control system for a subsea hydrocarbon well facility, said first end being topside and said second end being subsea.

Brief Description of the Drawings

Fig. 1 is a block diagram of a known topside control system;

Fig. 2 is a block diagram of a topside control system according to an embodiment of the invention; and

Fig. 3 is a schematic diagram of a COP system according to an embodiment of the invention.

Detailed Description of the Invention

Fig. 2 is a block diagram of a topside control system 11 according to an embodiment of the invention.

The system 11 comprises a housing 12 which is connected to a data input line 13 and first and second AC mains input lines 14a, 14b. The first mains input line 14a is connected to a first AC/DC converter 15a and the second mains input line 14b is connected to a second AC/DC converter 15b. The DC output from the first AC/DC converter 15a is connected to the power input for a communications signal H-bridge 16. The DC output from the second AC/DC converter 15b is simply output from the system 11 on a second output line 20.

The data input line 13 is connected to a computer 17 which comprises a pulse width modulation (PWM) control 18. In the system 11 shown in Fig. 2, the PWM control 18 is a field programmable gate array (FPGA). The PWM control 18 controls the switches of the communications signal H-bridge 16 to encode the data received from the data input line 13 on the power input received by the H-bridge 16. The resultant COP signal is output from the H-bridge 16 on a first output line 19.

The first output line 19 is connected to a first conductor in an umbilical, and the second output line 20 is connected to a second conductor in an umbilical.

Fig. 3 schematically shows a communication on power (COP) system 21 according to an embodiment of the invention.

The system 21 comprises a topside control system connected to a subsea control system via an umbilical 30. The components to the left of the umbilical 30 as shown in Fig. 3 are topside and the components to the right of the umbilical 30 as shown in Fig. 3 are subsea.

The topside control system comprises a computer 22. This may be located within a master control station (MCS) of a topside control platform for an underwater hydrocarbon extraction facility. The computer 22 comprises a PWM modulator 23 which controls the gates 27, 28 of an H-bridge in response to instructions received from the computer 22. The H-bridge has a low voltage power input 24, 26, for example +/- 30 volts DC. Such DC power could be derived from a mains AC power source which has been passed through an AC/DC converter. The output of the H-bridge is connected to a first conductor in the umbilical 30 as shown. A DC power input line 25 is connected to a second conductor in the umbilical 30 as shown.

At the subsea end, the first and second conductors are connected to a subsea load 32. This could be any powered component in an underwater hydrocarbon extraction facility that requires DC power, such as a subsea electronics module or a subsea control module.

The first conductor is also connected to a subsea discriminator 32. This receives the communication on power (COP) signal produced by the topside H-bridge and carries the data carried by the COP signal to a subsea processing means (not shown). Said subsea processing means is also connected to a PWM modulator 34, which controls the gates 35, 36 of a subsea H-bridge in response to instructions received from the subsea processing means. The subsea H-bridge is provided with a power input 33, and so a COP signal can also be communicated from the subsea H-bridge to a topside discriminator 29 via the first conductor in the umbilical. The topside discriminator is further connected to the topside computer 22, so that received data may be processed by the topside computer 22 and displayed to an operator of the underwater hydrocarbon extraction facility at the master control station.

Advantages of using the Invention 1) A significant hardware reduction compared with prior art solutions. As a result the physical size of the new topside COP system is reduced by approximately half. This is due to the removal of the power conditioning front end, the transformer and associated circuitry, the communications blocking filter and diplexer and the modem (which is replaced by a single PWM control integrated circuit). 2) The subsea COP system is also reduced in size. Again, this is due to the removal of the power conditioning front end, the transformer and associated circuitry, the comms blocking filter and diplexer and the modem. 3) The new system may use off-the-shelf standard and modular components which reduces cost of manufacture. 4) Higher reliability, availability and maintainability, due to the potential for a higher level of redundancy. For example, multiple parallel H-bridges could be used.

Claims

CLAIMS:

1. A communication system for use in transmitting electrical power and data from a first end of a transmission line to a second end of the transmission line comprising: first supply means for supplying a first direct current (DC) signal; second supply means for supplying a second direct current (DC) signal; and modulator means coupled with said supply means for modulating the first DC signal with a data signal; wherein, the modulator means is coupled to supply the modulated first DC signal to a first conductor in the transmission line at the first end, and the second supply means is coupled to supply the second DC signal to a second conductor in the transmission line at the first end.

2. A system according to claim 1, wherein the modulator means comprises an H-bridge.

3. A system according to claim 1 or 2, wherein the supply means for supplying the first DC signal comprises an AC/DC converter.

4. A system according to any preceding claim, wherein the supply means for supplying the second DC signal comprises an AC/DC converter.

5. A system according to any preceding claim, wherein, at said second end, there is means for receiving from said transmission line the data signal from said first end.

6. A system according to any preceding claim, wherein, at said first end, there is means for receiving from said transmission line a data signal from said second end.

7. A system according to any preceding claim, comprising a control system for a subsea hydrocarbon well facility, said first end being topside and said second end being subsea.

8. A communication on power system comprising: a transmission line having a first end and a second end, comprising first and second conductors; first supply means for supplying a first direct current (DC) signal; second supply means for supplying a second direct current (DC) signal; and first modulator means coupled with said supply means for modulating the first DC signal with a data signal; wherein, the first modulator means is coupled to supply the modulated first DC signal to the first conductor in the transmission line at the first end, and the second supply means is coupled to supply the second DC signal to the second conductor in the transmission line at the first end, the communication on power system further comprising: third supply means for supplying a first direct current (DC) signal; fourth supply means for supplying a second direct current (DC) signal; second modulator means coupled with said supply means for modulating the third DC signal with a data signal; wherein, the modulator means is coupled to supply the modulated third DC signal to the first conductor in the transmission line at the second end, and the fourth supply means is coupled to supply the fourth DC signal to the second conductor in the transmission line at the second end.

9. A method of transmitting electrical power and data from a first end of a transmission line to a second end of the transmission line, the method comprising, at said first end: using first supply means to supply a first direct current (DC) signal; using second supply means to supply a second direct current (DC) signal; using modulator means to modulate said first DC signal with a data signal; coupling the modulated first DC signal to a first conductor in the transmission line at the first end; and coupling the second DC signal to a second conductor in the transmission line at the first end.

10. A method according to claim 9, wherein the modulator means comprises an H-bridge.

11. A method according to claim 9 or 10, wherein the supply means for supplying the first DC signal comprises an AC/DC converter.

12. A method according to any of claims 9 to 11, wherein the supply means for supplying the second DC signal comprises an AC/DC converter.

13. A method according to any of claims 9 to 12, wherein, at said second end, there is means for receiving from said transmission line the data signal from said first end.

14. A method according to any of claims 9 to 13, wherein, at said first end, there is means for receiving from said transmission line a data signal from said second end.

15. A method according to any of claims 9 to 14 performed in a control system for a subsea hydrocarbon well facility, said first end being topside and said second end being subsea.