A METHOD FOR SUPPLYING OUTSIDE ENERGY TO AN ONBOARD ELECTRICAL POWER NETWORK OF A SHIP, A SHIP WITH SUCH AN OUTSIDE ENERGY SUPPLY

The invention relates to a method for supplying energy to an onboard electrical power network of a ship as claimed in claim 1 and to a ship with an outside energy supply as claimed in claim 10. A method for retrofitting such an outside energy supply is the subject matter of claim 16.

An onboard electrical power network of a ship is known from WO 2004/028899 Al via which the electrical drive motors of the ship and other loads of diesel generators on board the ship are supplied with electrical energy. For this method of supplying energy to a ship the diesel generators and thus the energy sources for the operation of the ship's drive motors and the other loads are located on board the ship. The ship also has an additional diesel generator for operation when in port, which can be connected to the onboard network. Alternatively the onboard network can be supplied via a shore connection. For this type of outside energy supply of the onboard network the energy source which generates the current supplied via the shore connection into the onboard network is located outside the ship. The shore connection in such cases must supply a current with the voltage and the frequency of the onboard network. Such shore connections must thus be oriented specifically to the requirements (frequency and voltage) of the ship supplied with power and are thus not available in many ports.

When such a shore connection is retrofitted in a ship by being directly connected to the onboard network there continues to be the problem of a switching and supervision device for the shore connection having to be retrofitted in the ship. This normally also demands interventions into the existing switching and supervision devices and is thus expensive and often also is not possible for reasons of space.

The use of a current converter located on board the ship for the shore connection is already known from WO 2007/060244 A2 and WO 2007/060189 Al, in order to convert the current supplied by the shore connection with a frequency and voltage different from the onboard network into a current with the frequency and voltage of the onboard network. Sometimes however there is no current converter available on board the ship which is suitable for this purpose.

The object of the invention is to specify a method for the supply of outside energy to a ship's onboard power network with which the above-mentioned problems can be avoided. In particular the method should be able to be executed without any major changes in the existing switching and monitoring devices on board the ship being necessary. A further object of the invention is to specify a ship with which such a supply of outside energy to the ship's onboard network is possible. Furthermore a method is to be specified through which an outside energy supply can be retrofitted in a ship with a relatively low outlay.

The object relating to the method is achieved by a method as claimed in claim 1. The object relating to the ship is achieved by a ship with the features of claim 10. A method for retrofitting an outside energy supply is the subject matter of claim 16. Advantageous developments are the subject matter of the subclaims in each case.

In the inventive method for supplying outside energy to an onboard electrical network of a ship, with the ship featuring an electrical machine which, when the ship is being supplied with its own energy, is driven by at least one energy source on board the ship, for a supply of outside energy to the onboard network of the ship, the electrical machine is operated as a generator and is driven in this case with current from at least one energy source outside the ship such that it generates a current with the frequency and voltage of the onboard network for feeding into the onboard network.

Thus an electrical machine already present on board the ship and used for quite another purpose during the own energy supply of the ship is used for the supply of outside energy. The electrical machine is driven directly or indirectly with current from at least one energy source outside the ship and serves in this case to convert the voltage and frequency of the current delivered by this energy source into a current with the frequency and voltage of the onboard network. This enables the existing switching and monitoring devices of the electrical machine on board the ship to be used for the outside energy supply so that greater changes or upgrades in the ship are not necessary for this purpose. The electrical machine also achieves an electrical separation between the onboard network and the energy source arranged outside the ship. This means that overvoltage events and other influences in the energy source arranged outside the ship or in the electrical connection between the onboard network and the energy source arranged outside the ship which are damaging for the onboard network are not transmitted into the onboard network and vice versa.

The electrical machine can basically involve any electrical machine (i.e. motor or generator) on board the ship suitably dimensioned in respect of its power. When the ship is being supplied with its own energy, the electrical machine can be driven electrically or also mechanically in such cases by at least one energy source on board the ship. With an electrical drive, the power can be supplied from the energy source directly or via the onboard network.

The energy source located on board the ship can involve any type of energy source which generates mechanical or electrical energy from a primary energy carrier (e.g. a natural or artificial fuel, solar energy, wind) or a secondary energy carrier (e.g. waste heat of a machine) . Examples of this are diesel motors, gas turbines or also steam turbines (the latter for example in conjunction with waste heat utilization systems) , where necessary including a generator driven thereby for power generation.

Preferably an electrical machine is used on board the ship which, when the ship is being supplied with its own energy, is employed as a generator, especially as a generator of a waste heat utilization system or as a reactive power generator, since these machines are already dimensioned as required for the power requirements with an outside energy supply and additionally do not have to be operated during an outside energy supply.

As an alternative, an electrical machine is preferably used which, when the ship is being supplied with its own energy, is used as a motor for driving a device on board the ship, especially for driving a transverse thruster or a pump.

An energy source located outside the ship can involve any type of energy source which generates electrical energy from a primary energy carrier (e.g. a natural or artificial fuel) or from a secondary energy carrier, such as for example an electricity power station located on land, a floating power station, a floating port power supply or an offshore platform, with the last two typically having a generator for power generation and a combustion engine (e.g. a gas turbine or a diesel motor) driving said generator) .

The electrical machine can have a separate winding system in each case for driving it with the current of the outside energy source and for generating power for the onboard network. In accordance with an especially advantageous development the electrical machine will however be driven by a (separate) electrical motor for the outside energy supply of the onboard network of the ship, which is operated by current from the energy source arranged outside the ship, with the electric motor driving the electrical machine such that the latter generates the current with the frequency and the voltage of the onboard network.

When the electric motor decouples from the electrical machine for the supply of own energy to the ship and is only coupled to the electrical machine for the supply of outside energy, the electric motor does not have to be run at the same time when the ship is supplied with its own energy, whereby energy losses can be avoided.

Preferably, for the supply of outside energy to the ship's onboard network, the electric motor drives the electrical machine via a power transmission element which converts a rotational movement of the electric motor into a rotational movement of the electrical machine for the generation of the current with the frequency and voltage needed for the onboard network. This enables a low-cost standard motor, e.g. an asynchronous motor, to be used for the electric motor. The rotational speed of the electric motor can be adapted to the rotational speeds of the electrical machine needed for the generation of the current with the frequency and voltage of the onboard network in such cases by the power transmission element .

The power transmission element preferably involves toothed wheel gearing. In very low cost alternate developments a chain drive or a belt drive can also be used for the power transmission element. If the transmission ratio is able to be varied for the power transmission element, the electric motor can also be adapted for operation with currents of different voltage and frequency from different energy sources flexibly to the speed needed on the electrical machine side for generation of current with the voltage and frequency of the onboard network.

To avoid voltage interruptions in the onboard network right through to a blackout of the ship on transition from its own energy supply to an outside energy supply, the phase position of the onboard network voltage is preferably synchronized to the phase position of the voltage generated by the electrical machine before a transition from an own energy supply to an outside energy supply. This can be done for the onboard network by closed-loop or open-loop control interventions familiar to the person skilled in the art at the power generators running for supplying energy to the ship (e.g. by adapting speed and torque of diesel motors which drive the onboard network generators) .

Such open-loop or closed-loop control interventions can be avoided if conversely, before the transition from the own energy supply to the outside energy supply, the phase position of the voltage generated by the electrical machine is synchronized to the phase position of the onboard network voltage. If the electrical machine is driven by an asynchronous motor which drives the electrical machine with a slip drive, this can be made possible in an especially simple manner by precisely one repeating point in time being awaited for making the connection at which the phase position of the voltage generated by the electrical machine is synchronous with the phase position of the onboard network voltage. In other cases, e.g. in the case in which the electrical machine is driven by a synchronous machine, the synchronization can be undertaken by an open-loop or closed-loop control of the phase position of the current fed to the electric motor, e.g. by means of a current converter connected upstream from the electric motor.

In the event of the electrical machine being driven by an electric motor for the outside energy supply, the synchronization is also possible by the speed of the electrical machine and the speed of the electric motor being mechanically synchronized to each other. This can typically be done, in a first step in which the electrical machine and the electric motor are mechanically decoupled from one another, by the electrical machine driven by current from the onboard network and the electric motor driven by current from the energy source arranged outside the ship being started or operated independently of one another. The electrical machine is then already driven with the frequency and phase position of the onboard network. Subsequently in a second step the electrical machine and the electric motor are synchronized mechanically with each other in respect of their speed. This can be done by a mechanical coupling of the electrical machine and the electric motor by closing a switching coupling arranged between the electrical machine in the electric motor, which is preferably embodied for this purpose as a friction coupling. The phase position of the voltage and of the current with which the electric motor is driven is then of no importance .

This method is suitable for synchronizing the speed of both synchronous and also asynchronous machines. Synchronous machines can also be synchronized with asynchronous machines without any problem. When an outside energy supply is retrofitted, this method means that no interventions are required into existing synchronization sequences.

In an inventive ship with an onboard ship's network, an electrical machine and at least one energy source on board the ship for driving the electrical machine when the ship is supplied with its own energy, the electrical machine is able to be operated as a generator for supplying outside energy to the ship's onboard network, and when operated in this way, is embodied to be able to be driven with current from at least one energy source outside the ship such that it generates a current with the frequency and voltage of the onboard network for feeding into the onboard network.

In such cases the electrical machine is preferably embodied as a generator, especially as a generator of a waste heat utilization system or as a reactive power generator, which is used to supply power for the ship's own energy supply.

Alternatively the electrical machine can be embodied as a motor which, when the ship is being supplied with its own energy, drives a device on board the ship, especially a transverse thruster or a pump.

Advantageously the ship includes an electric motor for driving the electrical machine for supplying outside energy to the ship's own onboard network, with the electric motor able to be connected via an electrical connection with the energy source arranged outside the ship and being embodied and able to be operated with the current from this energy source, with the electric motor being embodied and able to be coupled or being coupled to the electrical machine such that, when it is operated with this current, the electrical machine driven by it generates a current with the frequency and voltage of the onboard network.

In an advantageous development a coupling, especially in an embodiment as a friction coupling, is available for operational coupling or uncoupling of the electric motor to or from the electrical machine. With a coupling embodied as a friction coupling - as already explained above - a mechanical synchronization of the speeds of the electrical machine and of the electric motor can be undertaken especially advantageously.

In accordance with an especially advantageous development, the ship includes a power transmission element, especially gearing, for converting a rotational movement of the electric motor into a rotational movement of the electrical machine needed for the generation of the current with the frequency and voltage of the onboard network.

The advantages stated for the inventive method and its advantageous developments apply equally to the inventive ship and its respective corresponding advantageous developments.

In an inventive method for retrofitting an outside energy supply for an onboard electrical network of a ship in a ship, with the ship having an electrical machine which, when the ship is being supplied with its own energy, is driven by at least one energy source on board the ship, and the electric motor is installed in the ship which is coupled or is able to be coupled to the electrical machine for driving it, with the electrical motor able to be connected via an electrical connection to at least one energy source arranged outside the ship and being embodied to be able to be driven by power from this energy source, with the electrical motor being embodied and being coupled or being able to be coupled to the electrical machine such that, when it is operated with this current, the electrical machine driven by it generates a current with the frequency and voltage of the onboard network.

For retrofitting the outside energy supply, this means that only an electric motor for driving the electrical machine in the ship has to be retrofitted. In such cases a low-cost asynchronous motor can be used. The existing supervision and switching devices of the electrical machine can be used so that greater changes or upgrades in the ship in respect of such devices can be avoided. This is a great advantage compared to retrofitting an outside energy supply with a direct connection of the onboard network to an outside energy source, since this makes an expensive retrofitting of an additional monitoring and switching device in the ship necessary, for which there is often no space. If there is already a starter motor for the electrical machine in the ship, this can also be replaced by the electric motor, whereby the outlay in space for the retrofitting of the electric motor can be reduced even further.

The invention as well as advantageous developments of the invention in accordance with features of the subclaims will be explained in greater detail below with reference to exemplary embodiments in the figures. The figures show:

FIG. 1 a use of a reactive power machine without starter motor for outside energy supply, FIG. 2 a use of a reactive power machine with starter motor for outside energy supply, FIG. 3 a use of a reactive power machine for outside energy supply, with the starter motor having been replaced by a larger electric motor, FIG. 4 a use of a generator of a waste heat utilization system for outside energy supply, FIG. 5 a use of a generator of a diesel generator set for outside energy supply, FIG. 6 a use of an electrical drive motor for a transverse thruster for outside energy supply, FIG. 7 an arrangement of an outside energy supply motor and the electrical machine driven by it in a line, FIG. 8 an arrangement of an outside energy supply motor on the electrical machine driven by it, FIG. 9 a right angled arrangement of an outside energy supply motor and the electrical machine driven by it.

A ship shown in a simplified manner in FIG. 1 comprises an onboard network with a rated voltage Ul and a rated frequency fl, a number of generators 4 connected to the onboard network 2 and each driven by one diesel motor 3 for generating power for the onboard network 2 as well as a load 5 connected to the onboard network 2. An electrical machine connected via a smoothing choke 21 to the onboard network 2 in the form of a reactive power machine (reactive power generator) 6 serves to generate reactive power for the onboard network 2. As an alternative the reactive power machine 6 can be connected directly to the onboard network 2.

An electric motor 7 is able to be coupled to the reactive power machine 6 via a gear 8 and a switching coupling 9. The switching coupling 9 allows operational coupling and uncoupling of the electric motor 7 to or from the machine 6. The electric motor 7 is able to be connected via an electrical line 11 with an onshore electrical network 12 and is able to be operated by current from this network 12. The onshore network 12 is supplied by an energy source 13 with a current which has a different voltage U2 and frequency f2 from the onboard network.

The reactive power machine 6, usually embodied as a synchronous motor, is a component of a shaft generator/motor system 20, which in addition to the smoothing choke 21, comprises a shaft generator/motor 23 coupled to the propeller shaft 22, a field rectifier 24, a starting current converter 25, a machine-side current converter 26 and a network-side current converter 27.

When the ship 1 is being supplied with its own energy, the diesel motors 3 on the one hand serve as an energy supply and drive the generators 4 which, synchronized with each other, feed currents with a voltage Ul and a frequency fl into the onboard network 2. A further energy source in the form of a main machine 28 (e.g. a large diesel motor) drives the propeller shaft 22 and thereby the shaft generator 23 which generates a current with a voltage U3 and frequency f3 different from the onboard network, which is converted by the converters 26, 27 into a current with the voltage Ul and frequency fl of the onboard network and is fed via the smoothing choke 21 into the onboard network 2. Since the shaft generator 23 cannot supply any reactive power, this must be provided by the reactive power machine 6. The reactive power machine 6 is operated in this case with current from the onboard network 2 or from the shaft generator 23 respectively. In this case the reactive power machine 6 is uncoupled from the motor 7.

The startup of the reactive power machine 6 up to the point of reaching the network frequency fl occurs in this case with an open switch 14 with current from the onboard network 2 via the startup current converter 26 and the network-side current converter 27.

For a supply of outside energy to the ship's onboard network 2 the reactive power machine 6 is operated as a generator generating effective power. To do this the shaft generator operation is stopped and the reactive power machine 6 is isolated by the switch 14 from the network 2. The electric motor 7 is connected by means of the line 11 to the onshore network 12. Subsequently the reactive power machine 6 is coupled to the electric motor 7 and driven by the latter. The electric motor 7 is driven in this case with current with a voltage U2 and a frequency f2 from the onshore network 12 and drives the reactive power machine 6 via the gear 8 such that this generates a current with voltage Ul and frequency fl of the onboard network 2.

The electric motor 7 and the transmission ratio of the gearing 8 are tuned in this case to the reactive power machine 6 such that, during operation of the electric motor 7 with a current with the voltage U2 and the frequency f2 from the network 12, the reactive power machine 6 is driven such that it rotates at a speed at which it generates a current with the voltage Ul and the frequency f1 of the onboard network 2.

To avoid voltage interruptions in the network during switchover from the own energy supply to outside energy supply, in a transitional phase there must briefly simultaneously be a power feed by one or more of the generators 4 and by the reactive power machine 6. To this end the phase positions of the voltage generated by the one or more generators 4 and the voltage generated by the reactive power machine 6 must be synchronized with each other.

Before a transition from own energy supply to an outside energy supply, i.e. before the reactive power machine 6 is connected to the network 2, the phase position of the voltage of the onboard network 2 is therefore synchronized, by a corresponding activation of the diesel motors 3, to the phase position of the voltage generated by the reactive power machine 6. Only after this synchronization will the reactive power machine 6 be connected via the switch 14 to the onboard network 2 and subsequently the generator or the remaining generators 4 will be disconnected from the onboard network 2.

Alternatively the phase position of the voltage generated by the reactive power machine 6 can also be synchronized with the phase position of the voltage of the onboard network 2. This is especially easy if the electric motor 7 is embodied as an asynchronous machine, since the phase position with such a machine constantly changes because of the slip and for the connection to the network 2 it is only necessary to wait for a time at which the phase positions are synchronous. In other cases, e.g. where the reactive machine is being driven by a synchronous machine, a synchronization can be undertaken by a closed-loop control or open-loop control of the phase position of the current fed to the electric motor 7, e.g. by means of a converter connected upstream from the electric motor 7.

In a transition from an outside energy supply to an own energy supply, to avoid voltage interruptions, in a similar manner either the phase position of the voltage generated by the generator 4 started first must be synchronized with the phase position of the voltage of the onboard network 2 or of the reactive power machine 6 supplied by it or conversely the phase position of the voltage of the onboard network 2 of the reactive power machine 6 must be synchronized with the phase position of the voltage generated by the generator 4 started first.

For the own energy supply of the ship 1, the reactive power machine 6 can also be uncoupled again by means of the coupling 9 from the electric motor 7.

In the two cases illustrated the reactive power machine 6 and the electric motor 7 are coupled to each other for the synchronization, with the switch 14 being opened however and thus the reactive power machine 6 being isolated from the onboard network 2. Only once electrical synchronization has taken place will the reactive power machine 6 be connected via the switch 14 to the onboard network 2 and subsequently the generator or the remaining generators 4 will be disconnected from the onboard network 2.

In addition to this type of "electrical" synchronization in respect of frequency and phase position, a "mechanical" synchronization is however also possible. Unlike for the electrical synchronization the switch 14 is closed for the mechanical synchronization, i.e. the reactive power machine 6 is connected to the onboard network 2 and the reactive power machine 6 is uncoupled mechanically by means of the coupling 9 from the electric motor 7. In a first step the reactive power machine 6 will then be driven with current from the onboard network 2 with the frequency fl and the electric motor driven with current from the onshore network 12 with the frequency f2 started and operated independently of one another. The reactive power machine 6 is then operated with the frequency and phase position of the onboard network 2. Subsequently in a second step the reactive power machine 6 and the electric motor 7 are synchronized mechanically with each other by closing the switching coupling 9. The switching coupling 9 is embodied as a friction coupling for this purpose so that the friction on the reactive power machine 6 side and the electric motor 7 side sets the same speed in each case. For retrofitting an outside energy supply this method means that no interventions into existing synchronization sequences are necessary.

Instead of being supplied from the onshore electrical network 12, the outside energy can also be supplied for example from a floating power station, a floating port power supply or an offshore platform.

A ship shown in FIG. 2 differs from the ship shown in FIG. 1 in that a small starter motor 29 is present for starting up the reactive power machine 6 for supplying energy to the ship 1 which is fed directly via a startup current converter 30 from the network 2. The reactive power machine 6 in this case is coupled at its one shaft end to the starter motor 29 and is able to be coupled at its other shaft end to the electric motor 7. The power of the electric motor 7 is far greater in this case than the power of the starter motor 29.

In the ship 1 depicted in FIG. 3 the starter motor 29 is replaced by the electric motor 7. The electric motor 7 thus takes over both the function of the starter motor for starting up the reactive power machine 6 for shaft generator operation, i.e. when the ship is being supplied with its own energy, and also the function of an outside supply motor for an outside energy supply to the ship 1. The electric motor 7 can optionally be connected in this case by means of a switch 31 to a startup current converter 30 or to the line 11. The coupling 9 can optionally in this case be embodied as a switching coupling or as a rigid connection coupling.

In the ship 1 depicted in FIG. 4 a generator 46 of a waste heat utilization system 40 of which only parts are shown is used for the outside energy supply, which converts waste heat of a combustion engine for driving the ship into electrical energy. The waste heat utilization system 40 comprises an exhaust gas turbine 42 for driving the generator 46 and a steam turbine 43, which are able to be coupled via a coupling 44 to one end of the shaft of the generator 46. Furthermore the generator 46 is able to be coupled at the other end of the shaft via a coupling 9 and gearing 8 to the electric motor 7. To supply the ship 1 with its own energy, the generator 46 is coupled to the exhaust gas turbine 42 and the steam turbine 43 and is driven mechanically by the latter, whereas it is uncoupled from the electric motor 7. This means that it is driven indirectly by the combustion engine as its energy source .

To supply outside energy, the generator 46 is separated by means of coupling 44 from the exhaust gas turbine 42 and the steam turbine 43 and instead is coupled by means of the coupling 9 to the electric motor 7. The electric motor 7 is connected via the line 11 to the onshore network 12 and is operated with power from this network. In this case it drives the generator 46 such that the latter generates a current with the voltage Ul and the frequency f1 of the onboard network 2.

In a ship 1 depicted in FIG. 5 a generator 56 of a diesel generator set 50 is used for supplying outside energy. The generator 56 is able to be coupled for this purpose at its one shaft end via a coupling 52 to a diesel motor 51 and is able to be coupled at its other shaft end via a coupling 9 and gearing 8 to the electric motor 7. To supply the ship 1 with its own energy, the generator 56 is coupled to the diesel motor 51 as its energy source and it is mechanically driven by the latter, whereas it is uncoupled from the electric motor 7. To supply outside energy, the generator 56 is disconnected by means of the coupling 52 from the diesel motor 51 and instead is coupled by the coupling 9 to the motor 7. The electric motor 7 is connected via the line 11 to the onshore network 12 and is operated by power from this network. In this case it drives the generator 56 such that the latter generates a current with the voltage Ul and the frequency fl of the onboard network 2.

In a ship 1 depicted in FIG. 6 the electrical drive motor 66 for a transverse thruster device 60 is used to supply outside energy. The drive motor 66 is able to be coupled at one of its shaft ends by the coupling 62 to a transverse thruster 61 and at its other shaft end via a coupling 9 and gearing 8 to the electric motor 7. When the ship is being supplied with its own energy the drive motor 66 is coupled to the transverse thruster 61 and drives the transverse thruster 61, whereby it is operated by power from the onboard network 2, i.e. with energy from one or more of the diesel motors 3 as its energy source (s) . In this case the drive motor 66 is uncoupled from the electric motor 7. For outside energy supply the drive motor 66 is uncoupled by means of the coupling 9 from the transverse thruster 61 and instead coupled via the coupling 9 to the motor 7. The electric motor 7 is connected via the line 11 to the onshore network and is operated by power from this network. In this case it drives the drive motor 66 operated as a generator in such a way that the latter generates a current with the voltage Ul and frequency f1 of the onboard network 2.

The method for transition from own energy supply to outside energy supply or vice versa with the associated synchronization processes can principally be undertaken in a similar way in the exemplary embodiments shown in FIG. 2 through FIG. 6 as in the cases explained in connection with FIG. 1.

As shown in FIG. 7 the electrical machines 6, 46, 56, 66, the electric motor 7 and the intermediate gearing 8 can be arranged in a line in the ship 1.

If the space available is very restricted - as shown in FIG. 8 - the electrical machine 6, 46, 56, 66 and the electric motor 7 can also be arranged at right angles to each other, with the power able to be transmitted for example via gearing 8 embodied as a right angled gear.

As an alternative - as shown in FIG. 9 - the electric motor 7 can also be arranged on or above the electrical machine 6, 46, 56, 66, with the power being transmitted for example via gearing 8 or a chain drive which is arranged on one of its end face surfaces.