Methods of operating dual fed systems

Patent metadata

Field	Value
Publication number	US-9318894-B2
Application number	US-201113882212-A
Country	US
Kind code	B2
Filing date	Oct 25, 2011
Priority date	Nov 3, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

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 (CO 2 ) 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 optimize 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 minimize exhaust emissions.

First claim

What is claimed is:

1. A method of operating a dual fed system comprising a first busbar, a second busbar, (i) 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:
selecting a desired level of exhaust emissions from the prime movers, the selecting including minimizing, according to a power constraint, a cost function formed from estimated nitrogen dioxide and carbon dioxide emission rates of 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 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 one of the first busbar and the second busbar.

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 one of the first busbar and the second busbar.

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 (DP) system.

12. The method of claim 1 , further comprising determining the estimated nitrogen dioxide and carbon dioxide emission rates of the prime movers.

13. The method of claim 12 , wherein the cost function includes a weighted sum of the estimated nitrogen dioxide and carbon dioxide emission rates of the prime movers, and weights of the weighted sum represent relative contributions of different types of emissions.

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 (i) selects a desired level of exhaust emissions from the prime movers by minimizing, according to a power constraint, a cost function formed from estimated nitrogen dioxide and carbon dioxide emission rates of the prime movers and (ii) 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 (DP) system.

Assignees

• Stephens Richard Ian
• Ge Energy Power Conversion Technology Ltd

Inventors

• Stephens Richard Ian

Classifications

• H02J4/00 Primary

  Circuit arrangements for mains or distribution networks not specified as AC or DC; Circuit arrangements for mains or distribution networks combining AC and DC sections or sub-networks (arrangements using intermediate DC-AC-DC conversion H02J1/002; arrangements using high-voltage DC [HVDC] links H02J3/36) · CPC title

• H02J3/38

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title

• B63H21/22 Primary

  the propulsion power units being controlled from exterior of engine room, e.g. from navigation bridge; Arrangements of order telegraphs · CPC title

• B63H23/24

  electric {(dynamo-electric machines H02K)} · CPC title

• B63H25/42

  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 title