METHODS OF OPERATING DUAL FED SYSTEMS

• US 20150035286A1
• Filed: 10/25/2011
• Published: 02/05/2015
• Est. Priority Date: 11/03/2010
• Status: Active Grant

• Current Assignee: GE Energy Power Conversion Technology Limited (GE Vernova, Inc.)
• Original Assignee: GE Energy Power Conversion Technology Limited (GE Vernova, Inc.)
• Inventors: Stephens, Richard Ian
• Granted Patent: US 9,318,894 B2
• Time in Patent Office: Days
• US Class Current: 290/4.A
• CPC Class Codes: B63H 21/22 the propulsion power units being controlled from exterior of engine room, e.g. from navigation bridge; Arrangements of order telegraphs
• CPC Class Codes: B63H 23/24 electric dynamo-electric machines H02K
• CPC Class Codes: B63H 25/42 Steering or dynamic anchoring by propulsive elements by jets B63H25/46; Steering or dynamic anchoring by propellers used therefor only; Steering or dynamic anchoring by rudders carrying propellers
• CPC Class Codes: H02J 2310/42 for ships or vessels
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 4/00 Circuit arrangements for mains or distribution networks not specified as ac or dc

Abstract

A method of operating a dual fed system is described where power is supplied to a electrical load from first and second ac busbars at a ratio that achieves a desired level of exhaust emissions such as nitrogen oxides (NO_x), carbon dioxide (CO₂) and other pollutants produced by the prime movers associated with generators. Preferably, the method may be used to operate a dual fed marine propulsion system wherein the electrical load is a thruster. Operating a dual fed marine propulsion system using the method of the present invention makes it possible to optimise thrust allocation between thrusters in a way that is similar to that used in conventional dynamic positioning (DP) systems and then share or allocate the required power between generators to minimise exhaust emissions.

Claims

1. A method of operating a dual fed system comprising:

a first busbar;

a second busbar;

at least one generator connected to the first busbar and having an associated prime mover that produces exhaust emissions;

at least one generator connected to the second busbar and having an associated prime mover that produces exhaust emissions; and

an electrical load connected to the first busbar by means of a first power converter and to the second busbar by means of a second power converter;

the method comprising the steps of selecting a desired level of exhaust emissions from the prime movers and supplying power to the electrical load from the first and second busbars at a ratio that achieves the desired level of exhaust emissions.

2. The method of claim 1, wherein the ratio at which power is supplied to the electrical load from the first and second busbars minimises exhaust emissions from the prime movers.

3. The method of claim 1, wherein the ratio at which power is supplied to the electrical load from the first and second busbars minimises operating costs associated with the prime movers.

4. The method of claim 1, wherein a measurement of the exhaust emissions from at least one prime mover is used to determine the ratio at which power is supplied to the electrical load from the first or second ac busbars.

5. The method of claim 1, wherein a measurement of the temperature of the exhaust gases produced by at least one prime mover is used to determine the ratio at which power is supplied to the electrical load from the first or second ac busbars.

6. The method of claim 1, wherein the dual fed system is an ac system, the first and second busbars are ac busbars and the at least one generator connected to the first busbar and the at least one generator connected to the second busbar are ac generators.

7. The method of claim 1, wherein the dual fed system is a marine propulsion system and the electrical load is a propulsion motor.

8. The method of claim 1, wherein the dual fed system includes a plurality of electrical loads, the method further comprising the steps of selecting a desired total power usage and allocating an output demand between the electrical loads to achieve the desired total power usage.

9. The method of claim 8, wherein the output demand is allocated to minimise total power usage.

10. The method of claim 8, wherein the dual fed system is a marine propulsion system, the plurality of electrical loads are a plurality of propulsion motors and the output demand is a thrust demand.

11. The method of claim 10, wherein the thrust demand is provided by a controller of a dynamic positioning system.

12. The method of claim 1, wherein the step of selecting a desired level of exhaust emissions from the prime movers uses a cost function.

13. The method of claim 12, wherein the step of selecting a desired level of exhaust emissions from the prime movers includes finding a minimum value for the cost function for which the sum of the power provided by the generators is equal to, or greater than, a total power requirement of the dual fed system.

14. A dual fed system comprising:

a first busbar;

a second busbar;

at least one generator connected to the first busbar and having an associated prime mover that produces exhaust emissions;

at least one generator connected to the second busbar and having an associated prime mover that produces exhaust emissions;

an electrical load connected to the first busbar by means of a first power converter and to the second busbar by means of a second power converter; and

a management system which selects a desired level of exhaust emissions from the prime movers and controls the dual fed system so that power is supplied to the electrical load from the first and second busbars at a ratio that achieves the desired level of exhaust emissions.

15. The fuel fed system of claim 14, wherein the first and second busbars are ac busbars and the at least one generator connected to the first busbar and the at least one generator connected to the second busbar are ac generators.

16. The dual fed system of claim 14, wherein the dual fed system is a marine propulsion system and the electrical load is a propulsion motor.

17. The dual fed system of claim 14, wherein the dual fed system includes a plurality of electrical loads, and the management system further selects a desired total power usage and allocates an output demand between the electrical loads to achieve the desired total power usage.

18. The dual fed system of claim 17, wherein the dual fed system is a marine propulsion system, the plurality of electrical loads are a plurality of propulsion motors and the output demand is a thrust demand.

19. The dual fed system of claim 18, wherein the thrust demand is provided by a controller of a dynamic positioning system.