Technical Field The invention relates to high reliability vessels in general and more specifically a system for a dynamic positioning vessel using redundancy zones.

Background Art From prior art one should refer to traditional vessels capable of dynamic positioning of IMO class 3 divided into two redundancy zones by a longitudinal bulkhead. The problem is that flooding or fire in one redundancy zone will render half the vessel in- operational. Also splitting the engines into two separate engine rooms adds complexity to the vessel design.

Disclosure of the Invention

Problems to be Solved by the Invention

Therefore, a main objective of the present invention is to provide an improved system for a high reliability vessel that overcomes the above problems.

It is particularly desirable to overcome the problems relating to the lack of flexibility that comes with the solutions known from prior art.

Means for Solving the Problem

The objectives are achieved according to the invention by a vessel as defined in the preamble of claim 1 , having the features of the characterising portion of claim 1 .

The present invention attains the above-described objective by providing an energy storage system located in a first zone, a generator system located in a second zone, wherein at least one of the first zone and the second zone is a redundancy zone.

In one aspect of the invention an improved system for a high reliability vessel is provided, comprising a plurality of redundancy zones, a thruster system comprising at least two thrusters to create transversal thrust, and a main power supply system comprising a generator system, and a main electrical distribution system comprising a switchboard system, characterized in the vessel further comprises an energy storage system comprising a plurality of energy storage sub systems, wherein at least one of the thrusters with an operatively connected energy storage subsystem is located in a first redundancy zone, and another of the thrusters and the generator system is located outside said first redundancy zone.

In a preferred embodiment the generator system is centralised in a single compartment. In a more preferred embodiment the generator system is centralised in a redundancy zone.

In an embodiment the energy storage system is centralised. In a preferred embodiment the energy storage system is centralised in a redundancy zone.

In another preferred embodiment the energy storage system comprises a plurality of energy storage subsystems and is decentralised. In a more preferred embodiment the energy storage system is located local to at least one thruster. In an even more preferred embodiment the energy storage system is located local to all thrusters.

In an embodiment the switchboard system is centralised. In a preferred embodiment the switchboard system is centralised in a redundancy zone.

In another preferred embodiment the switchboard system comprises a plurality of switchboard subsystems and is decentralised. In a more preferred embodiment the switchboard system is located local to at least one thruster. In another preferred embodiment the switchboard system is located local to at least one energy storage system. Effects of the Invention

The technical effects of the invention are that redundancy is achieved without the use of a longitudinal bulkhead in a vessel and that one can instead use redundancy zones around various parts. These effects provide in turn several further advantageous effects:

• Generators will not have to be partitioned into more than one separate

generator compartment, thus reducing complexity and cost.

• Improved redundancy in that all generators can fail without loss of

manoeuvrability.

· Bulkheads can be kept smaller and thus not affect the structural properties of the vessel. Bulkheads do not have to reach all the way up to the ceiling but can be kept lower.

In some embodiments the switchboard does not have to be split

Redundancy can exceed that of prior art without added complexity.

Design and structures can be simplified since redundancy zones can group parts having same functionality, e.g. reduced piping for a single generator compartment.

Provide maximum dynamic positioning capability. Brief Description of the Drawings

The above and further features of the invention are set forth with particularity in the appended claims and together with advantages thereof will become clearer from consideration of the following detailed description of an exemplary embodiment of the invention given with reference to the accompanying drawings.

The invention will be further described below in connection with exemplary embodiments which are schematically shown in the drawings, wherein: Fig. 1 shows a vessel according to prior art

Fig. 2 shows an embodiment of the present invention wherein a generator system is enclosed in a redundancy zone

Fig. 3 shows an embodiment of the present invention wherein generator system and energy storage system are enclosed in separate redundancy zones Fig. 4 shows an embodiment of the present invention with local energy storage subsystems and comprising a switchboard similar to that of prior art, wherein the generator system is located in a redundancy zone

Fig. 5 shows an embodiment of the present invention with local energy storage subsystems without a switchboard

Fig. 6 shows an embodiment of the present invention with local energy storage subsystems and comprising local switchboard subsystems

Fig. 7 shows an embodiment of the present invention with local energy storage subsystems and comprising a switchboard similar to that of prior art Description of the Reference Signs

The following reference numbers and signs refer to the drawings:

Redundancy zones are indicated by enclosure in dashed lines.

Detailed Description

An underlying principle of a high reliability vessel is that functions are divided into redundancy zones, wherein total loss of one zone should not prevent the vessel from operating, at least within a defined performance envelope that also comprises operational time in degraded mode. For IMO class 3 there is a requirement that loss of position is not to occur in the event of a single fault in any component or system including fire and flooding.

For comparison, Fig. 1 shows a vessel according to prior art, wherein the vessel is divided into two redundancy zones by a longitudinal bulkhead. Loss of one side will allow the other side to maintain operations. Single failure criteria comprise:

• Any static component or system (generators, thrusters, switchboards, remote controlled valves etc.)

• Any normally static component (cables, pipes, manual valves etc.)

· All components in any one watertight compartment, from fire or flooding

• All components in any one fire sub-division, from fire or flooding.

It should be noted that in this design the switchboard is split into two switchboard subsystems connected with a bus tie. When operating in redundancy mode the bus tie is kept open to achieve electrical isolation between the two zones.

A generator system typically comprises at least one engine driving a generator. For redundancy and/or the ability to deliver sufficient power, the generator system comprises a plurality of engines, each driving a generator. Each generator is in turn connected to the switchboard system. Principles forming the basis of the invention

An underlying principle of the present invention is that when one part is enclosed in a compartment in redundancy zone, there is actually a second implied redundancy zone defined by the area outside the compartment and within the hull of the ship. Throughout this disclosure a redundancy zone means an enclosed area unless otherwise stated, nevertheless the implied redundancy zone should always be kept in mind for failure mode analysis.

Fig. 2 shows an embodiment of the present invention wherein a generator system is enclosed in a redundancy zone. It should be noted that placing an energy storage system in a redundancy zone is also within the ambit of this basic

embodiment, as is having both parts, i.e. generator system and energy storage system, enclosed in separate redundancy zones as shown in Fig. 3. Should one or the other of said parts be lost the vessel can draw energy from the part not lost and operate with all thrusters. This embodiment has some limitations such that a loss of the implied redundancy zone will lead to the vessel no longer being operational.

Placing the generator system in a single compartment in a redundancy zone has many advantages e.g. in that fuel, exhaust, cooling and power lines can be kept close together, significantly reducing complexity. The generator system with flammable fuel, high temperature and high power electric system represents many entries into various failure modes that can result in loss. A separate energy storage system outside the single engine compartment will overcome such a loss.

The energy storage system represents electrical power at standby, ready to use should the generator system fail. It can be embodied by a single accumulator or battery system or by a plurality of accumulators or batteries that are separately fused for improved reliability.

The present invention allows for many embodiments for the energy storage system. It is possible to use centralised as well as decentralised energy storage systems. It is found that placing energy storage system local to all thrusters, wherein the local energy storage system and the respective thruster is compartmentalised in a redundancy zone provides particularly high reliability. In such a system the worst case single failure is loss of a single thruster which is a significant improvement over the loss of half of the power system and half of the thrusters in prior art

configurations.

Fig. 2 shows such a system wherein each thruster redundancy zone receives power through a switchboard. In normal mode the thruster is powered by the generator system providing power through the switchboard. Also the energy storage system can be recharged or trickle charged and maintained by the same provided power. In case of failure wherein provided power fails, due to failure in the generator system, the switchboard or other reasons, emergency power is fed from the energy storage system into the thruster.

Local power makes it also possible to combine provided power from the generator system e.g. with boost energy from the energy storage system for emergency situation, requiring extra large amounts of power. Having local energy storage makes it simpler to draw extra thick power cables for such peak power.

With local power it will also be possible to operate thrusters without powering up and operating the entire system.

The switchboard system routes power from the generator system to the thrusters and the energy storage system. In prior art as shown in Fig.1 the switchboard system is divided into 2 subsystems connected with a bus tie. The divided

switchboard system with bus tie represents added complexity that is no longer required according to the present invention for all embodiments.

The present invention allows for many embodiments of the switchboard system. It is possible to use centralised as well as decentralised switchboard system.

In the embodiment shown in Fig. 2 and Fig. 3, the switchboard system connects to the generator system and also the energy storage system. Thus the switchboard system has to be able to route power from the generator system to the thrusters and preferably also be able to route power when charging and receiving power from the energy storage system.

In the embodiment shown in Fig. 4 the switchboard delivers power for charge and discharge of the energy storage system taking place in the thruster zones.

In the embodiment shown in Fig. 5 the switchboard is distributed between 2 of the thruster zones. This allows a compact solution for the distribution panel in the thruster zones but also adds some complexity in that the switchboard subsystems also have to feed another thruster zone. Also having the switchboard subsystems in redundancy zones can improve availability.

The bus tie provides means for connecting and disconnecting switchboard

subsystems in a switchboard system. Under certain operations such as IMO class 3 it is mandated to be in a disconnected state.

Best Modes of Carrying Out the Invention The embodiment of the apparatus according to the invention shown in Fig. 4 and 5 comprises a single engine room in a redundancy zone and an energy storage subsystem local to each thruster wherein each thruster is in separate redundancy zones together with respective energy storage subsystem. Thus any single redundancy zone can fail without loss of operational capability. In fact a single failure will leave maximum one thruster unavailable, a clear improvement over prior art where one half of the ship can fail. This embodiment can take on further variations.

Fig. 4 shows a system comprising a switchboard similar to that of prior art. When operating in IMO class 3 mode a bus tie inside the switchboard is kept open and each switchboard subsystem is powered separately from the generator system. This has the advantage of operating flexibility between IMO class 3 mode and a non- IMO class 3 mode with lower running costs by operating fewer engines to drive the generators. The system also negates the requirement to have generators capable of double the power required for dynamic positioning operating associated with the baseline design in order to have sufficient power available following a single failure. Operating fewer engines at higher load has both fuel consumption and emissions benefits. Generators can be in a redundancy zone as shown in Fig. 4 or not in a separate redundancy zone as shown in Fig. 7

Fig. 5 shows an embodiment with a switchboard co-located with the

generators, where separate power cables from the single engine room feed each thruster redundancy zone. This has the advantage of simplicity.

These modes should comply with IMO class 3 requirements.

It is preferred that the fire-proof sub-divisions are implemented according to the A60 standard.

Alternative Embodiments

A number of variations on the above can be envisaged. For instance one can use a hybrid system where the switchboard system is split into switchboard subsystems that are local to at least two thruster redundancy zones.

Fig. 6 shows such an embodiment wherein the switchboard subsystems route power from the generator system to the redundancy zone local to the switchboard subsystem as well as to other thruster redundancy zones.

Fig. 2 and 3 show a single cable from the single engine room and from the energy storage unit. Nevertheless one can also envisage a system where there instead are two cables from these, where a first cable from a first group of engines and a first cable from a first part of the energy storage system are connected to a first switchboard subsystem and a second cable from a second group of engines and a second cable from a second part of the energy storage system are connected to a second switchboard subsystem. A bus tie can be provided to selectively connect the first and second switchboard subsystems.

It is also within the scope of the invention to also provide a thruster in the single engine compartment embodiment, also when this single engine compartment is a redundancy zone.

It is also possible to provide a redundancy zone having an energy storage unit and a thruster further comprising a sub division between the energy storage system and the thruster. Said sub division can be provided to avoid fumes mixing, or to provide extra barrier against fire or flooding. Such divided compartments still provide the same effect as a normal redundancy zone and thus still fall within the ambit of the invention.

Industrial Applicability

The invention according to the application finds use in high reliability vessel with improved capability in case of single and multiple point of failure.