Fault Protection System For A Power System Of Dynamically Positioned Vessel

• US 20130270902A1
• Filed: 04/16/2013
• Published: 10/17/2013
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: Siemens Energy AS (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Blystad, Svein, Radan, Damir, Andersen, Rune B., Haukaas, Inge, Koenig, Gunnar, Settemsdal, Stig Olav
• Granted Patent: US 9,543,748 B2
• Time in Patent Office: Days
• US Class Current: 307/9.1
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• 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: B63J 2003/002 by using electric power
• CPC Class Codes: H02H 3/08 responsive to excess current responsive to abnormal temperature caused by excess current H02H5/04
• CPC Class Codes: H02H 3/081 and depending on the direction
• CPC Class Codes: H02H 3/28 involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus for transformers H02H7/045
• CPC Class Codes: H02H 7/26 Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured locating faults in cables G01R31/08

Abstract

A fault protection system for a power system of a dynamically positioned vessel is provided. The power system is separated into two or more power system sections, each including a bus section of a power distribution bus. The bus sections are connected by bus ties in a ring configuration. Each bus section includes a connection to a generator and a connection to a thruster drive of the dynamically positioned vessel. The fault protection system includes a fault isolation system which includes for each power system section a bus tie circuit breaker for breaking the connection provided by the bus tie.

Claims

1. A fault protection system of a power system of a dynamically positioned vessel, wherein the power system is separated into two or more power system sections each comprising a bus section of a power distribution bus, wherein the bus sections are connected by bus ties in a ring configuration, and wherein each power system section comprises two or more power system subsections each comprising a bus subsection of the power distribution bus, the bus subsections of the same power system section being connected by one or more bus couplers, wherein each bus section comprises a connection to a generator and a connection to a thruster drive of the dynamically positioned vessel, wherein the fault protection system comprises:

a fault isolation system including for each power system section a bus tie circuit breaker for breaking the connection provided by the bus tie and one or more bus coupler circuit breakers for breaking the connection provided by the one or more bus couplers, the fault isolation system being configured to implement a differential over-current protection scheme for operating at least the bus tie circuit breaker and the bus coupler circuit breaker,

a generator ride through system comprising for each power system section an excitation limiter for the generator coupled to the respective bus section, the generator ride through system being adapted to limit the excitation field current provided to the generator upon occurrence of a fault, and

a thruster drive ride through system configured to provide electric energy to a DC bus of a variable frequency drive of the thruster drive of each power system section upon occurrence of a fault so as to maintain the voltage on the DC bus above a predetermined voltage threshold,

wherein the fault protection system is configured, upon the occurrence of a fault in the power system, to isolate the fault by tripping the component of the power system in which the fault occurred and/or by opening one or more circuit breakers in the power system subsection in which the fault is located, and to continue operation of the power system with the remaining bus tie circuit breakers and bus coupler circuit breakers closed.

2. The fault protection system of claim 1, wherein the fault isolation system is configured to implement a differential over-current protection and/or a directional over-current protection against faults for at least the bus ties and the bus subsections.

3. The fault protection system of claim 2, wherein the fault isolation system comprises protection relays for operating at least the bus tie circuit breakers and the bus coupler circuit breakers, the protection relays implementing the differential over-current protection and/or the directional over-current protection for the bus ties and the bus subsections.

4. The fault protection system of claim 2, wherein the fault isolation system is further configured to implement a short circuit and over-current protection as a back-up by means of at least the bus tie circuit breakers and the bus coupler circuit breakers.

5. The fault protection system of claim 1, wherein the fault isolation system further comprises for each power subsection, a generator circuit breaker for breaking the connection to the generator and a thruster drive circuit breaker for breaking the connection to the thruster drive.

6. The fault protection system of claim 1, further comprising an automatic voltage regulator containing the excitation limiter, the automatic voltage regulator being adapted to automatically adjust the voltage provided by the respective generator to keep the voltage within an operation band.

7. The fault protection system of claim 6, wherein the automatic voltage regulator is adapted to detect the occurrence of a fault by detecting a drop in the voltage at the generator output or at the power distribution bus, the automatic voltage regulator being adapted to decrease a voltage setpoint for the generator after the detection of a fault and to control the output voltage of the generator in accordance with the reduced voltage setpoint, so as to limit voltage overshoot after the occurrence of a fault.

8. The fault protection system of claim 1, wherein the thruster drive ride through system comprises a variable frequency drive controller for the variable frequency drive of each thruster drive, the variable frequency drive controller being adapted to decrease the output frequency of the respective variable frequency drive upon a drop in voltage on the DC bus of the variable frequency drive, thereby causing the variable frequency drive to operate in a generating condition in which electric energy is generated by an electric motor of the thruster drive and is fed back to the DC bus to maintain the voltage on the DC bus above the voltage threshold.

9. The fault protection system of claim 1, wherein the thruster drive ride through system comprises a power storage device, such as a battery, which is coupled to the DC bus of the variable frequency drive, the power storage device being adapted to supply electric power to the DC bus in case of a drop of voltage on the DC bus in order to maintain the voltage on the DC bus above the voltage threshold.

10. The fault protection system of claim 1, wherein the power system further comprises for each power system subsection a connection to a thruster utilities switchboard electrically coupled to the generator of the respective power system subsection for providing electric power to utilities of the thruster drive, and a connection to an engine support switchboard electrically coupled to the generator of the respective power system subsection for providing electric power to utilities of the engine operating the generator of the power system subsection, and

wherein the fault protection system further comprises for each power system subsection a circuit breaker for breaking the connection to the thruster utilities switchboard and the engine support switchboard.

11. The fault protection system of claim 10, further comprising an uninterruptable power supply for each power system subsection, the uninterruptable power supply being coupled to the thruster utilities switchboard and/or the engine support switchboard.

12. The fault protection system of claim 11, further comprising an electric interlink connection from the thruster utilities switchboard or the engine support switchboard of one power system subsection to the uninterruptible power supply of another power system subsection.

13. A power system of a dynamically positioned vessel, comprising:

two or more power system sections, each comprising a bus section of a power distribution bus, wherein the bus sections are connected by bus ties in a ring configuration, and wherein each power system section comprises two or more power system subsections each comprising a bus subsection of the power distribution bus, the bus subsections of the same power system section being connected by one or more bus couplers, wherein each bus section comprises a connection to a generator and a connection to a thruster drive of the dynamically positioned vessel, and

a fault detection system comprising;

a fault isolation system including for each power system section a bus tie circuit breaker for breaking the connection provided by the bus tie and one or more bus coupler circuit breakers for breaking the connection provided by the one or more bus couplers, the fault isolation system being configured to implement a differential over-current protection scheme for operating at least the bus tie circuit breaker and the bus coupler circuit breaker,

a generator ride through system comprising for each power system section an excitation limiter for the generator coupled to the respective bus section, the generator ride through system being adapted to limit the excitation field current provided to the generator upon occurrence of a fault, and

a thruster drive ride through system configured to provide electric energy to a DC bus of a variable frequency drive of the thruster drive of each power system section upon occurrence of a fault so as to maintain the voltage on the DC bus above a predetermined voltage threshold,

wherein the fault protection system is configured, upon the occurrence of a fault in the power system, to isolate the fault by tripping the component of the power system in which the fault occurred and/or by opening one or more circuit breakers in the power system subsection in which the fault is located, and to continue operation of the power system with the remaining bus tie circuit breakers and bus coupler circuit breakers closed.

14. The power system according to claim 13, further comprising for each power system subsection a connection to a thruster utilities switchboard for providing electric power to utilities of the thruster drive, and a connection to an engine support switchboard for providing electric power to utilities of the engine operating the generator of the power system subsection, and

the power system further comprising a transformer for each power system subsection connected to the respective bus subsection, the transformer providing electric power to a respective thruster drive coupled to the bus subsection, wherein the transformer comprises an additional secondary winding electrically coupled to the thruster utilities switchboard and the engine support switchboard of the power system subsection for providing electric power to both switchboards.

15. A method of operating a fault protection system of a power system of a dynamically positioned vessel, the method comprising:

detecting a fault in the power system,

localizing the fault in the power system, electrically isolating a component in which the fault occurred from the remaining power system by opening a circuit breaker coupled to the component or isolating a power system subsection in which the fault occurred from the remaining power system by opening bus tie and/or bus coupler circuit breakers of the respective bus subsection, and

continuing operation of the power system with the remaining bus tie circuit breakers and bus coupler circuit breakers closed.