Self-contained transportable electric heave compensation system

Abstract

A mobile active heave compensation system (10) provided with a first attachment device (12) allowing said mobile active heave compensation system (10) to be suspended from a load bearing device (14) and provided with a second attachment device (16) allowing said mobile active heave compensation system (10) to carry a payload (18), said mobile active heave compensation system (10) comprising: - a control unit (20), - a heave compensation part (22) comprising an electrically driven actuator (24), - a sensor arrangement (26) producing input signals for said control unit (20) to control the heave compensation part (22), - an electric power source (28) provided with supercapacitors (30), such that, in a first heave compensation phase, when the heave compensation part (22) generates energy, electric power is stored in said supercapacitors (30) and, in a second heave compensation phase, when the heave compensation part (22) requires energy, electric power stored in said supercapacitors (30) is supplied to said electrically driven actuator (24).

Description

TECHNICAL FIELD

[0001] The present invention relates an active heave compensation system.

[0002] The present invention relates more particularly to an in-line active heave compensation system.BACKGROUND

[0003] Heave compensation systems may comprise heave compensators that are connected between a load bearing device and the load. The compensation is in-line with the load and will be referred to as in-line active heave compensator (IAHC).

[0004] The purpose of heave compensators is to keep a load, held by equipment on a moving vessel, motionless with regard to the seabed, a fixed structure, or another vessel. Additionally, dynamic behavior and force control need to be managed during splash zone transition.

[0005] Transfer of load needs also to be managed. During load transfer there is a period of time where heave compensator needs to be force controlled, as position is defined by vessel movement and the load is still on the moving vessel, and there is a period of time, during hoisting and approaching of a vessel, where heave compensator needs to be position controlled, as the full load is in the hook.SUMMARY

[0006] The scope of protection is set out by the claims.

[0007] The invention propose a mobile active heave compensation system provided with a first attachment device allowing said mobile active heave compensation system to be suspended from a load bearing device and provided with a second attachment device allowing said mobile active heave compensation system to carry a payload, said mobile active heave compensation system comprising: a control unit, a heave compensation part comprising an electrically driven actuator, a sensor arrangement producing input signals for said control unit to control the heave compensation part, an electric power source provided with supercapacitors, such that, in a first heave compensation phase, when the heave compensation part generates energy, electric power is stored in said supercapacitors and, in a second heave compensation phase, when the heave compensation part requires energy, electric power stored in said supercapacitors is supplied to said electrically driven actuator.

[0008] According to various embodiments of the mobile active heave compensation system: the system comprises at least one of an auxiliary battery and an auxiliary power cable which are controlled by an energy management system; the electrically driven actuator uses spur gear mounted electric motors; the electrically driven actuator is supported by a non-adjustable passive system; the electric power source comprises a brake resistor device able to consumes excess of energy supply during the first heave compensation phase; each supercapacitor is provided with a bypass circuit to control pre-charge and discharge; the auxiliary battery is provided with a DC / DC converter to allow a bigger discharge of the auxiliary battery; an electric filter circuit is provided to protect the electrically driven actuator.

[0009] It is also proposed a control method for the mobile active heave compensation system mentioned above, comprising the steps of: storing electric power in said supercapacitors during a first heave compensation phase, when the heave compensation part generates energy, and supplying electric power to said electrically driven actuatorduring a second heave compensation phase, when the heave compensation part requires energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Example embodiments will be more fully understood from the detailed description provided herein and the accompanying drawings, which are given by way of illustration only. In the present description and in the drawings. FIG.1 is a schematic view showing a vessel equipped with a mobile active heave compensation system; FIG.2 is a schematic view showing a mobile active heave compensation system in accordance with the present invention and able to equip the vessel of FIG.1; FIG.3 is a schematic view showing an electrically driven actuator to be used in the mobile active heave compensation system of FIG.2 and comprising spur gear mounted electric motors; FIG.4 is a schematic view similar to the one of FIG.2 showing an alternative embodiment of the mobile active heave compensation system comprising additional components; FIG.5 is a schematic view showing an alternative embodiment for the compensator wherein the electrically driven actuator is supported by a non-adjustable passive system.

[0011] It should be noted that these figures are intended to illustrate the general characteristics of methods, structure and / or materials utilized in the described exemplary embodiments. The drawings are not to scale and should not be interpreted as limiting the range of values or properties encompassed by the exemplary embodiments.DETAILED DESCRIPTION

[0012] As shown on figures 1 and 2, the present invention proposes a mobile active heave compensation system 10 provided with a first attachment device 12 allowing said mobile active heave compensation system 10 to be suspended from a load bearing device 14. The mobile active heave compensation system 10 is provided with a second attachment device 16 allowing said mobile active heave compensation system 10 to carry a payload 18.

[0013] In the present application, mobile for the active heave compensation system 10 refers to the fact that the system is self-contained and can be swapped between load bearing devices. In the present case, the active heave compensation system 10 is an independent, separate unit that is not made as an integral part of a crane or a lifting unit. It may be transported between different lifting vessels if and when required. It can be temporarily suspended from a lifting device.

[0014] The mobile active heave compensation system 10 comprises: a control unit 20, a heave compensation part 22 comprising an electrically driven actuator 24, a sensor arrangement 26 producing input signals for said control unit to control the heave compensation part 22, an electric power source 28 provided with supercapacitors 30, such that, in a first heave compensation phase, electric power is stored in said supercapacitors 30 and, in a second heave compensation phase, electric power stored in said supercapacitors 30 is supplied to said electrically driven actuator 24.

[0015] During the first heave compensation phase, the heave compensation part 22 extends and generates electric energy. During the second heave compensation phase, the heave compensation part 22 retracts which consumes electric energy.

[0016] Advantageously, the mobile active heave compensation system 10 comprises an auxiliary battery 32. It allows for longer period of operation of the system 10 and compensate for energy losses. Additional power sources can also be provided to the system 10 as additional batteries, a generator, etc.

[0017] Advantageously, the mobile active heave compensation system 10 comprises an energy management system 34 which implement different strategies regarding the supply of electricity to the electrically driven actuator 24. The electricity can be supplied by the auxiliary battery 32 or by the supercapacitors 30. Also, electricity generated during the first heave compensation phase can be supplied to the auxiliary battery 32 or to the supercapacitors 30, or to both, depending on the strategy and charging status of these components.

[0018] In the present embodiment, electrical power is supplied by the electrical power source 28 to the heave compensation part 22 through a DC / AC converter 35 in order to supply alternative current.

[0019] The mobile active heave compensation system 10 is provided with at least one heave compensation part 22. Alternatively, additional heave compensation parts 22 could be included in the system 10. The system 10 is regulated by a sensor arrangement 26 and is driven by the electric driven actuator 24. Lowered load energy can be recovered and stored in the supercapacitors 30 in combination with the auxiliary battery 32.

[0020] Low loads can be hoisted using a rack-and pinion design. Higher loads can utilize a winch design or a rocker design where a pipe is bended over a radius.

[0021] Preferably, the electrically driven actuator 24 uses spur gear mounted electric motors 36 as shown on figure 3.

[0022] An alternative embodiment is shown on figure 4 wherein the electric power source 28 comprises additional components allowing more flexibility for managing the system power supply.

[0023] A power cable 38 connects the electric power source 28 of the system 10 to an external power source such as the power source of the vessel. It makes the system redundant and / or provides an auxiliary source for charging the auxiliary battery.

[0024] The electronic control unit 20 and the energy management system 34 are able to control force and / or position of the heave compensation part 22. The energy management system 34 manages the energy flow.

[0025] Advantageously, the electric power source 28 comprises a brake resistor device 40 which can consume energy excess during the first heave compensation phase by converting it into heat. This brake resistor device 40 is controlled by the energy management system 34.

[0026] Preferably, a bypass circuit 42, controlled by the energy management system 34 is connected to each supercapacitor 30 to control pre-charge and discharge of the supercapacitors 30.

[0027] According to the embodiment shown, a DC / DC converter 44 is arranged in the circuit to generate a voltage step between the auxiliary battery 32 and the remaining of the electric circuit, which allow better management of battery discharge phase.

[0028] According to the embodiment shown, an electric filter circuit 46 is provided between the electric power source 28 and the heave compensation part 22 to remove harmful harmonics and to prevent damage to the electrically driven actuator 24 by overheating.

[0029] Advantages of the mobile active heave compensation system 10 include: No need to load gas springs which provides for increased uptime, increase in operational availability of the system and facilitate fast transfer of loads, The energy system can be shared with the vessel via umbilical, Almost instantaneous torque / force on the system, Simple design allows for quick engineering process for new loads, Less complex system, therefore reduction in maintenance time and amount of spare parts required.

[0030] The mobile active heave compensation system 10 is characterized in that the compensator is powered by an electric power source in combination with the energy storage capacity of supercapacitors 30 that allows bi-directional energy flow to the electrically driven actuator 24.

[0031] The mobile active heave compensation system 10 allows to get rid of a complex passive compensation system using adjustable gas pressure systems. The mobile active heave compensation system 10 allows to recover the potential energy due to vessel motions in the supercapacitors 30.

[0032] In addition, the kinetic energy of the moving components can be stored in the supercapacitors 30 as well.

[0033] The mobile active heave compensation system 10 can do quick lifts, the process is reversable as long as power is available.

[0034] The mobile active heave compensation system 10 is simpler, not prone to leakage (environmental spillage) and requires less maintenance. Additionally, the response time of the system is almost instantaneous.

[0035] Other sources of energy can be connected to make the power supply redundant. This can be an auxiliary power cable 38 from the crane hook to vessel's deck or a battery system in the hook.

[0036] Another alternative embodiment is shown on figure 5 wherein the electrically driven actuator 24 is supported by a non-adjustable passive system 52. Said non-adjustable passive system 52 may comprise for example a gas spring cylinder 48 and a gas reservoir 50. This gas spring cylinder 48 could be very simple and calibrated to compensate only part of the load, for example 50% of the regular load for which the system 10 is designed. Such gas spring cylinder 48 is not adjustable like some complex and expensive device that are designed to compensate for approximately 100% of the load to be hoisted.LEGEND

[0037] 10 : mobile active heave compensation system 12 : first attachment device 14 : load bearing device 16 : second attachment device 18 : payload 20 : control unit 22 : heave compensation part 24 : electrically driven actuator 26 : sensor arrangement 28 : electric power source 30 : supercapacitors 32 : auxiliary battery 34 : energy management system 35: DC / AC converter 36: spur gear mounted electric motors 38: power cable 40: brake resistor device 42: bypass circuit 44: DC / DC converter 46: electric filter circuit 48: gas spring cylinder 50: gas reservoir 52: non-adjustable passive system

Examples

Embodiment Construction

[0012]As shown on figures 1 and 2, the present invention proposes a mobile active heave compensation system 10 provided with a first attachment device 12 allowing said mobile active heave compensation system 10 to be suspended from a load bearing device 14. The mobile active heave compensation system 10 is provided with a second attachment device 16 allowing said mobile active heave compensation system 10 to carry a payload 18.

[0013]In the present application, mobile for the active heave compensation system 10 refers to the fact that the system is self-contained and can be swapped between load bearing devices. In the present case, the active heave compensation system 10 is an independent, separate unit that is not made as an integral part of a crane or a lifting unit. It may be transported between different lifting vessels if and when required. It can be temporarily suspended from a lifting device.

[0014]The mobile active heave compensation system 10 comprises:

a control unit 20, a ...

TECHNICAL FIELD

[0001] The present invention relates an active heave compensation system.

[0002] The present invention relates more particularly to an in-line active heave compensation system.BACKGROUND

[0003] Heave compensation systems may comprise heave compensators that are connected between a load bearing device and the load. The compensation is in-line with the load and will be referred to as in-line active heave compensator (IAHC).

[0004] The purpose of heave compensators is to keep a load, held by equipment on a moving vessel, motionless with regard to the seabed, a fixed structure, or another vessel. Additionally, dynamic behavior and force control need to be managed during splash zone transition.

[0005] Transfer of load needs also to be managed. During load transfer there is a period of time where heave compensator needs to be force controlled, as position is defined by vessel movement and the load is still on the moving vessel, and there is a period of time, during hoisting and approaching of a vessel, where heave compensator needs to be position controlled, as the full load is in the hook.SUMMARY

[0006] The scope of protection is set out by the claims.

[0007] The invention propose a mobile active heave compensation system provided with a first attachment device allowing said mobile active heave compensation system to be suspended from a load bearing device and provided with a second attachment device allowing said mobile active heave compensation system to carry a payload, said mobile active heave compensation system comprising: a control unit, a heave compensation part comprising an electrically driven actuator, a sensor arrangement producing input signals for said control unit to control the heave compensation part, an electric power source provided with supercapacitors, such that, in a first heave compensation phase, when the heave compensation part generates energy, electric power is stored in said supercapacitors and, in a second heave compensation phase, when the heave compensation part requires energy, electric power stored in said supercapacitors is supplied to said electrically driven actuator.

[0008] According to various embodiments of the mobile active heave compensation system: the system comprises at least one of an auxiliary battery and an auxiliary power cable which are controlled by an energy management system; the electrically driven actuator uses spur gear mounted electric motors; the electrically driven actuator is supported by a non-adjustable passive system; the electric power source comprises a brake resistor device able to consumes excess of energy supply during the first heave compensation phase; each supercapacitor is provided with a bypass circuit to control pre-charge and discharge; the auxiliary battery is provided with a DC / DC converter to allow a bigger discharge of the auxiliary battery; an electric filter circuit is provided to protect the electrically driven actuator.

[0009] It is also proposed a control method for the mobile active heave compensation system mentioned above, comprising the steps of: storing electric power in said supercapacitors during a first heave compensation phase, when the heave compensation part generates energy, and supplying electric power to said electrically driven actuatorduring a second heave compensation phase, when the heave compensation part requires energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Example embodiments will be more fully understood from the detailed description provided herein and the accompanying drawings, which are given by way of illustration only. In the present description and in the drawings. FIG.1 is a schematic view showing a vessel equipped with a mobile active heave compensation system; FIG.2 is a schematic view showing a mobile active heave compensation system in accordance with the present invention and able to equip the vessel of FIG.1; FIG.3 is a schematic view showing an electrically driven actuator to be used in the mobile active heave compensation system of FIG.2 and comprising spur gear mounted electric motors; FIG.4 is a schematic view similar to the one of FIG.2 showing an alternative embodiment of the mobile active heave compensation system comprising additional components; FIG.5 is a schematic view showing an alternative embodiment for the compensator wherein the electrically driven actuator is supported by a non-adjustable passive system.

[0011] It should be noted that these figures are intended to illustrate the general characteristics of methods, structure and / or materials utilized in the described exemplary embodiments. The drawings are not to scale and should not be interpreted as limiting the range of values or properties encompassed by the exemplary embodiments.DETAILED DESCRIPTION

[0012] As shown on figures 1 and 2, the present invention proposes a mobile active heave compensation system 10 provided with a first attachment device 12 allowing said mobile active heave compensation system 10 to be suspended from a load bearing device 14. The mobile active heave compensation system 10 is provided with a second attachment device 16 allowing said mobile active heave compensation system 10 to carry a payload 18.

[0013] In the present application, mobile for the active heave compensation system 10 refers to the fact that the system is self-contained and can be swapped between load bearing devices. In the present case, the active heave compensation system 10 is an independent, separate unit that is not made as an integral part of a crane or a lifting unit. It may be transported between different lifting vessels if and when required. It can be temporarily suspended from a lifting device.

[0014] The mobile active heave compensation system 10 comprises: a control unit 20, a heave compensation part 22 comprising an electrically driven actuator 24, a sensor arrangement 26 producing input signals for said control unit to control the heave compensation part 22, an electric power source 28 provided with supercapacitors 30, such that, in a first heave compensation phase, electric power is stored in said supercapacitors 30 and, in a second heave compensation phase, electric power stored in said supercapacitors 30 is supplied to said electrically driven actuator 24.

[0015] During the first heave compensation phase, the heave compensation part 22 extends and generates electric energy. During the second heave compensation phase, the heave compensation part 22 retracts which consumes electric energy.

[0016] Advantageously, the mobile active heave compensation system 10 comprises an auxiliary battery 32. It allows for longer period of operation of the system 10 and compensate for energy losses. Additional power sources can also be provided to the system 10 as additional batteries, a generator, etc.

[0017] Advantageously, the mobile active heave compensation system 10 comprises an energy management system 34 which implement different strategies regarding the supply of electricity to the electrically driven actuator 24. The electricity can be supplied by the auxiliary battery 32 or by the supercapacitors 30. Also, electricity generated during the first heave compensation phase can be supplied to the auxiliary battery 32 or to the supercapacitors 30, or to both, depending on the strategy and charging status of these components.

[0018] In the present embodiment, electrical power is supplied by the electrical power source 28 to the heave compensation part 22 through a DC / AC converter 35 in order to supply alternative current.

[0019] The mobile active heave compensation system 10 is provided with at least one heave compensation part 22. Alternatively, additional heave compensation parts 22 could be included in the system 10. The system 10 is regulated by a sensor arrangement 26 and is driven by the electric driven actuator 24. Lowered load energy can be recovered and stored in the supercapacitors 30 in combination with the auxiliary battery 32.

[0020] Low loads can be hoisted using a rack-and pinion design. Higher loads can utilize a winch design or a rocker design where a pipe is bended over a radius.

[0021] Preferably, the electrically driven actuator 24 uses spur gear mounted electric motors 36 as shown on figure 3.

[0022] An alternative embodiment is shown on figure 4 wherein the electric power source 28 comprises additional components allowing more flexibility for managing the system power supply.

[0023] A power cable 38 connects the electric power source 28 of the system 10 to an external power source such as the power source of the vessel. It makes the system redundant and / or provides an auxiliary source for charging the auxiliary battery.

[0024] The electronic control unit 20 and the energy management system 34 are able to control force and / or position of the heave compensation part 22. The energy management system 34 manages the energy flow.

[0025] Advantageously, the electric power source 28 comprises a brake resistor device 40 which can consume energy excess during the first heave compensation phase by converting it into heat. This brake resistor device 40 is controlled by the energy management system 34.

[0026] Preferably, a bypass circuit 42, controlled by the energy management system 34 is connected to each supercapacitor 30 to control pre-charge and discharge of the supercapacitors 30.

[0027] According to the embodiment shown, a DC / DC converter 44 is arranged in the circuit to generate a voltage step between the auxiliary battery 32 and the remaining of the electric circuit, which allow better management of battery discharge phase.

[0028] According to the embodiment shown, an electric filter circuit 46 is provided between the electric power source 28 and the heave compensation part 22 to remove harmful harmonics and to prevent damage to the electrically driven actuator 24 by overheating.

[0029] Advantages of the mobile active heave compensation system 10 include: No need to load gas springs which provides for increased uptime, increase in operational availability of the system and facilitate fast transfer of loads, The energy system can be shared with the vessel via umbilical, Almost instantaneous torque / force on the system, Simple design allows for quick engineering process for new loads, Less complex system, therefore reduction in maintenance time and amount of spare parts required.

[0030] The mobile active heave compensation system 10 is characterized in that the compensator is powered by an electric power source in combination with the energy storage capacity of supercapacitors 30 that allows bi-directional energy flow to the electrically driven actuator 24.

[0031] The mobile active heave compensation system 10 allows to get rid of a complex passive compensation system using adjustable gas pressure systems. The mobile active heave compensation system 10 allows to recover the potential energy due to vessel motions in the supercapacitors 30.

[0032] In addition, the kinetic energy of the moving components can be stored in the supercapacitors 30 as well.

[0033] The mobile active heave compensation system 10 can do quick lifts, the process is reversable as long as power is available.

[0034] The mobile active heave compensation system 10 is simpler, not prone to leakage (environmental spillage) and requires less maintenance. Additionally, the response time of the system is almost instantaneous.

[0035] Other sources of energy can be connected to make the power supply redundant. This can be an auxiliary power cable 38 from the crane hook to vessel's deck or a battery system in the hook.

[0036] Another alternative embodiment is shown on figure 5 wherein the electrically driven actuator 24 is supported by a non-adjustable passive system 52. Said non-adjustable passive system 52 may comprise for example a gas spring cylinder 48 and a gas reservoir 50. This gas spring cylinder 48 could be very simple and calibrated to compensate only part of the load, for example 50% of the regular load for which the system 10 is designed. Such gas spring cylinder 48 is not adjustable like some complex and expensive device that are designed to compensate for approximately 100% of the load to be hoisted.LEGEND

[0037] 10 : mobile active heave compensation system 12 : first attachment device 14 : load bearing device 16 : second attachment device 18 : payload 20 : control unit 22 : heave compensation part 24 : electrically driven actuator 26 : sensor arrangement 28 : electric power source 30 : supercapacitors 32 : auxiliary battery 34 : energy management system 35: DC / AC converter 36: spur gear mounted electric motors 38: power cable 40: brake resistor device 42: bypass circuit 44: DC / DC converter 46: electric filter circuit 48: gas spring cylinder 50: gas reservoir 52: non-adjustable passive system

Examples

Embodiment Construction

[0012]As shown on figures 1 and 2, the present invention proposes a mobile active heave compensation system 10 provided with a first attachment device 12 allowing said mobile active heave compensation system 10 to be suspended from a load bearing device 14. The mobile active heave compensation system 10 is provided with a second attachment device 16 allowing said mobile active heave compensation system 10 to carry a payload 18.

[0013]In the present application, mobile for the active heave compensation system 10 refers to the fact that the system is self-contained and can be swapped between load bearing devices. In the present case, the active heave compensation system 10 is an independent, separate unit that is not made as an integral part of a crane or a lifting unit. It may be transported between different lifting vessels if and when required. It can be temporarily suspended from a lifting device.

[0014]The mobile active heave compensation system 10 comprises:

a control unit 20, a ...

Claims

1. A mobile active heave compensation system (10) provided with a first attachment device (12) allowing said mobile active heave compensation system (10) to be suspended from a load bearing device (14) and provided with a second attachment device (16) allowing said mobile active heave compensation system (10) to carry a payload (18), said mobile active heave compensation system (10) comprising: - a control unit (20), - a heave compensation part (22) comprising an electrically driven actuator (24), - a sensor arrangement (26) producing input signals for said control unit (20) to control the heave compensation part (22), - an electric power source (28) provided with supercapacitors (30), such that, in a first heave compensation phase, when the heave compensation part (22) generates energy, electric power is stored in said supercapacitors (30) and, in a second heave compensation phase, when the heave compensation part (22) requires energy, electric power stored in said supercapacitors (30) is supplied to said electrically driven actuator (24).

2. The mobile active heave compensation system (10) according to claim 1 comprising at least one of an auxiliary battery (32) and an auxiliary power cable (38) which are controlled by an energy management system (34).

3. The mobile active heave compensation system (10) according to claim 1 or 2 wherein the electrically driven actuator (24) uses spur gear mounted electric motors (36).

4. The mobile active heave compensation system (10) according to any of the preceding claims, wherein the electrically driven actuator (24) is supported by a non-adjustable passive system (52).

5. The mobile active heave compensation system (10) according to any of the preceding claims, wherein the electric power source (28) comprises a brake resistor device (40) able to consumes excess of energy supply during the first heave compensation phase.

6. The mobile active heave compensation system (10) according to any of the preceding claims, wherein each supercapacitor (30) is provided with a bypass circuit (42) to control pre-charge and discharge.

7. The mobile active heave compensation system (10) according to any of the preceding claims, wherein the auxiliary battery (32) is provided with a DC / DC converter (44) to allow a bigger discharge of the auxiliary battery (32).

8. The mobile active heave compensation system (10) according to any of the preceding claims, wherein an electric filter circuit (46) is provided to protect the electrically driven actuator (24).

9. A control method for a mobile active heave compensation system (10) according to any of the preceding claims, comprising the steps of: - storing electric power in said supercapacitors (30) during a first heave compensation phase, when the heave compensation part (22) generates energy, and - supplying electric power to said electrically driven actuator (24) during a second heave compensation phase, when the heave compensation part (22) requires energy.

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