Method for determining the crane or jib operating envelope on a jack-up unit, jack-up unit

Abstract

The present application provides a method for determining an actually achieved preload value by monitoring outrigger load characteristics during preloading. The method further includes determining an actual crane or jib operating envelope considering the actually achieved preloading. The method further includes considering other data such as environmental loads or crane or jib movements.

Description

Technical Field

[0001] The present application relates to a jack-up vessel having mission equipment installed on a deck. The mission equipment can be at least one crane or a cantilever. The crane can be installed on a jack-up platform unit and can be movable relative to the deck. For example, the crane boom angle and / or outreach can vary during operation. The crane can be installed, for example, on the deck, around a leg, on a ceiling, etc. The cantilever can be movably installed on the deck and can move, for example, between an extended position where the cantilever extends substantially outward from the deck and a retracted position where the cantilever is substantially on the deck. Background Art

[0002] Jack-up platform units or jack-up vessels are well-known and typically include a floating hull and a plurality of movable legs. The legs can be movable relative to the hull and can extend through the hull. Typically, a jack-up platform unit can have three, four, or six legs. The legs can be adjusted between a sailing position where the legs extend substantially above the hull. In the sailing position of the legs, the hull floats on the water and the platform unit can be moved from one location to another. The legs can also be adjusted to an installation position where the legs extend substantially below the hull and the hull is above or just above the water level. In this position, the legs contact the seabed and rest on and / or in the seabed. In another position, namely the operating position, the legs extend substantially below the hull and are fixed to the seabed while the hull is raised above the water level to an operating level to allow sufficient clearance between the water level and the bottom of the hull, particularly to allow waves to pass underneath. The legs are moved relative to the hull by a jacking system.

[0003] Such jack-up platform units can be self-propelled or self-mobile, but can also be towed. Jack-up platform units are typically used for offshore operations, such as for drilling operations, maintenance operations, or wind turbine installation operations. Jack-up platform units are typically provided with a crane for lifting and / or installation operations, for example installed around one of the legs.

[0004] In the installation position of the jack-up platform unit, the legs are lowered to the seabed and need to be firmly installed on the seabed so that the jack-up platform is stable and firmly positioned in the operating position to allow safe operation. To firmly ground the legs to the seabed, it is common practice to sequentially apply a relatively high load to each of the legs, for example individually or in pairs, such as applying loads of thousands of tons, while the other legs are only slightly loaded. This process is generally referred to as "preloading".

[0005] Various preloading procedures are possible, the most common being active preloading or passive preloading, but a combination of active and passive preloading is also possible. In the case of active preloading, a set force is continuously applied to the legs at predetermined time intervals. The active load is applied repeatedly until the jacking operator, based on his experience and expertise, deems that the legs have settled sufficiently and the foundation is stable. In the case of passive preloading, the force is applied to the legs in a discrete manner, as opposed to being applied continuously during the active process. The discrete force is applied repeatedly until the jacking operator, based on his experience and expertise, deems the foundation to be stable enough. Only the expert knowledge and human judgment of the jacking operator are relied upon to determine whether the foundation is stable and the preload value. There is no reproducible determination of the preload value.

[0006] The jacking operator is responsible for the preloading operation and ensures that sufficient preloading is provided on the legs and a stable foundation for the platform unit is obtained. After this preloading step, the hull is further raised to the required operating height above the sea surface, for example, to a height of 10 to 15 m above the sea surface, which substantially avoids the hull being continuously hit by waves. Before or after further raising the hull, the loads on the legs can be substantially equal or balanced. In this way, a relatively stable platform position is considered to be established, from which operations can be carried out almost independently of the water flow and / or wave action.

[0007] During the operation, operators such as crane operators or jib operators rely on pre-set procedures and plans, such as lifting plans or jib plans or deck loading plans, and believe that the operation can be safely completed without endangering the stability of the platform unit when the preload value is not exceeded during the operation.

[0008] In particular, for offshore wind turbine installations, when the platform is frequently raised and lowered at consecutive construction positions, time may be limited and the operator may not wait long enough to observe whether the applied load has stabilized to a stable value. Thus, the safety relied upon during offshore operations on a jack-up platform unit is determined by the skills of the jacking operator.

[0009] Additionally, particularly on a jack-up platform unit used for wind turbine installation operations, a crane is provided on the jack-up platform unit, for example around one of the legs, for lifting and / or hoisting operations. The maximum crane capacity is defined by the crane characteristics and stated in the crane operation manual. The crane operator ensures that the crane is operated within its defined boundaries. Thus, the crane operator uses the preload value that has been given to him by the jacking operator. For some jacking operations, the operator may overload the legs through his operations, even though he has not exceeded the preload value received from the jacking system operator. This can endanger the safety and stability of the platform unit. For example, this may cause additional, uncontrolled settlement of the legs in the seabed, or penetration, and / or crane collapse, or even loss of the platform unit. Consequently, it may happen that the crane operator sometimes leaves too much safety margin in his operations, but may have too little safety margin in other operations. This results in safety risks during the operation of the jack-up platform unit and / or during the unused capacity of the crane.

[0010] Therefore, safer and more reliable operations are needed on offshore jack-up platform units. Summary of the Invention

[0011] To this end, a method for determining the crane or jib operation envelope of a crane or jib installed on a jack-up platform unit according to claim 1 is provided.

[0012] The method includes: applying a preload to at least one leg of the jack-up platform unit; monitoring at least one characteristic of the leg, such as the leg load value and / or the leg penetration value, during a predetermined time interval; monitoring the leg characteristic and / or the gradient of the leg characteristic during the time interval; evaluating whether the leg characteristic is stable during the time interval; repeating the above steps until the leg characteristic is stable during the time interval, whereby the leg characteristic remains within a predetermined threshold and the gradient of the leg characteristic remains within a predetermined limit; wherein the actually achieved preload value is the leg load value associated with such obtained stable leg characteristics; determining the actual crane or jib operation envelope by calculating the leg bearing capacity of each leg based on the actually achieved preload value and converting the calculated leg bearing capacity into crane or jib operation capacity.

[0013] Advantageously, the determination of the crane or jib operation capacity is completed according to the crane or jib movement, the crane or jib load, where the crane or jib load is, for example, a lifting load or a deck load, an environmental load, the jib outreach, etc. When determining the crane or jib operation capacity by converting the calculated leg load capacity into crane or jib operation capacity, all these parameters can be considered together or individually.

[0014] The leg load value can be considered as the load value on the leg and can be monitored, for example, by a jacking system. Of course, different jacking systems, hydraulic systems, rack - and - pinion systems or electric systems, have different devices for directly or indirectly applying and monitoring the leg load value. The leg penetration can be considered as the depth at which the leg penetrates the seabed. The leg penetration can also be referred to as leg settlement or leg displacement and can be monitored directly or indirectly in various ways, such as by measuring the displacement of the leg relative to the hull and by measuring the distance between the hull and the seabed, etc.

[0015] A crane mounted on a jack - up unit or a cantilever on the deck typically can have an operating state in which the crane or the cantilever has an overhanging part outside the hull profile. In particular, when the actual operating conditions exceed the theoretically determined operating plan due to inaccurate pre - load data, such an operating situation endangers the stability of the jack - up unit. Therefore, a more precise determination of the operating envelope may be related to the crane or cantilever operation.

[0016] By now determining in a structured and objective manner the pre - load value actually achieved on the legs, preferably by using an algorithm executable by a computer program, the subjective human judgment of the jacking operator can be made independent of the determination of the actually achieved pre - load. This gives a more reliable pre - load value, resulting in safer operation on the jack - up platform unit. In particular, when the actually achieved pre - load value is used to determine the actual crane operating envelope, precise, reliable and safe crane operation can be carried out on the jack - up platform unit. In this way, the jacking operation can be combined with and integrated into the crane operation, resulting in safer crane operation because the actual margin of the crane operation can now be precisely determined. Similarly, feedback for the cantilever operation can be carried out. Thus, when the crane operator operates the crane within the actually determined crane operating envelope, the risk of leg and / or platform failure can be eliminated. Therefore, instead of the prior - art open - loop method, in which a great deal depends on human judgment and on the theoretically determined operating envelope, according to the present application, not only is the pre - load more precisely determined, but the precisely defined pre - load value is fed into the operating envelope. In this way, a closed - loop method with more precise input is obtained, resulting in a more reliable operating envelope and thus safer operation, in which human judgment is minimized.

[0017] When the legs have sufficiently settled into the seabed, especially when the leg characteristics are stable during pre - loading, typically when the leg characteristics are poor and / or the gradient of the leg characteristics is less than a corresponding predetermined threshold, the legs are considered stable.

[0018] When the difference in leg characteristics and / or the gradient of the leg characteristics is greater than the corresponding predetermined threshold, the leg characteristics are considered unstable. In this case, it is considered that the legs have not yet settled stably into the seabed.

[0019] According to this method, at least one leg is preloaded. For a four-leg jack-up platform unit, typically two diagonally opposite legs are preloaded simultaneously while the other two legs are unloaded. During preloading, a load as large as possible is preferably applied to the legs. For example, for a 20,000 metric ton jack-up platform unit, applying the total weight to two legs would theoretically result in a preload of 10,000 metric tons. In practice, due to friction or other losses, seabed characteristics, environmental loads, etc., it is never possible to achieve this theoretical maximum. Then, the jacking operator attempts to apply as high a load as possible to the legs. This can be done actively when the jacking system applies such a high load to the legs for preloading. Or, it can be done passively when the jacking system holds the legs to be preloaded while the other legs are released and the weight of the platform is suspended on the legs, thus using gravity for preloading. Which method is used is independent of the preload value achieved. The actual load on the legs can be monitored by the jacking system and presented to the jacking operator at its operator interface, but can alternatively or optionally be input into the control unit. It is observed that the actual load on the legs decreases over time due to factors such as seabed settlement, friction, hydraulics, etc. According to this method, during a predetermined time interval, e.g., during 30 minutes or 40 minutes, the actual load on the legs is monitored. This predetermined time interval is preferably settable by the jack-up platform unit designer, but can also be set by the platform unit operator. During this predetermined time interval, the value of the actual load on the legs is monitored, preferably by the control unit. It is monitored whether the load value on the legs remains above a predetermined threshold and whether the gradient of the load value on the legs is less than a predetermined limit. Preferably, the control unit is configured to automatically monitor the load value on the legs. The minimum threshold and the maximum gradient are advantageously set by the platform unit designer, but can also be determined by the jack-up platform unit operator. When the drop in the leg load value is higher than the predetermined threshold, or when the gradient of the leg load value is too high, then the preloading must be repeated. The control unit can send an alarm signal to the jacking operator, i.e., the jacking operator can stop the current preloading and must re-perform the preloading of at least one leg with the same preload value or a slightly higher preload value. By providing an alarm signal, a visual signal, an audible signal, or a tactile signal, the operator knows that the preloading step has failed and needs to repeat the preloading step with the same preload value or a higher preload value. The control unit can give a suggestion or indication of the preload value for the subsequent preloading step. The steps of applying the preload and monitoring the load value are performed until the legs are considered to have settled stably onto the seabed, i.e., when the drop or decrease in the leg load value of the preloaded legs is below the predetermined threshold and the gradient of the load value remains below the maximum predetermined gradient limit during the predetermined time interval for monitoring the load value. Then, the actually achieved preload value is determined as the minimum load value reached during the predetermined time interval. Preferably, the control unit determines this actually achieved preload value.When the actually achieved preload value is determined, it can be used to calculate the crane operating envelope for a crane mounted on a jack-up platform unit, e.g., around one of the legs. The crane designer provides a crane operating manual which also defines the crane operating envelope. However, this crane operating envelope treats the crane as a static item, i.e., a static crane operating envelope, and does not at all take into account that the crane is mounted on a dynamic platform unit where the foundation is relatively unpredictable or difficult to predict. Now, by combining the actually achieved preload value with the crane operating envelope, an actual, accurate, and reliable crane operating envelope that takes into account site-specific conditions is obtained. For example, after preloading, the loads on the legs can be levelled, balanced, or at least they can be stabilized to the installed load value. The difference between the actually achieved preload value and the installed load value provides an operating load margin and a safety margin. The remaining operating load value can then be used to integrate with the theoretical crane operating envelope. Depending on the lift load, outreach, slewing angle, and / or boom angle, a particular crane operation may fall within the theoretically determined crane operating envelope but outside the operating load margin of the jack-up platform unit, making the particular crane operation unsafe to perform. Thus, the actual crane operating envelope can be determined considering the actually achieved preload value as well as the actual crane operation. Advantageously, the actual crane operating envelope can be determined in real time, providing the crane operator with a real-time and practical understanding of a particular crane operation, so that the particular crane operation can be safely performed or not performed. Preferably, this actual crane operating envelope is output to a crane operator display which is available to the crane operator in his operator cabin. The crane operator can then track in real time the operation and the operating boundaries of his crane. This can be done in a similar way to determine the actual jib operating envelope available to the jib operator, preferably by outputting the jib operating envelope to a jib operator display which is available to the jib operator in his operating cabin. Thus, the actual jib operating envelope may differ from the theoretical jib operating envelope in that the actually achieved preload value is taken into account. The theoretical crane or jib operating envelope is typically provided by the engineer who designed the crane or jib considering theoretical values and safety margins.

[0020] This application also relates to a system for determining the actual crane operating envelope of a crane on a jack-up platform unit.

[0021] Another aspect of this application relates to a computer program product and / or to a non-transitory signal storage medium storing the computer program product.

[0022] Other advantageous embodiments are set forth in the dependent claims. Description of the Drawings

[0023] The present application will be further described below with reference to the accompanying drawings of views with exemplary embodiments. Corresponding elements are denoted by corresponding reference numerals. In the drawings:

[0024] Figure 1 is a flowchart of a method according to one aspect of the present application.

[0025] Figure 2 is a flowchart of a method using passive preloading according to one aspect of the present application.

[0026] Figure 3 is a flowchart of a method using active preloading according to one aspect of the present application.

[0027] Figure 4 is a schematic representation of a system according to one aspect of the present application.

[0028] Figure 5 is a schematic view of a jack-up platform unit, where a crane is mounted around one of the legs of the jack-up platform unit.

[0029] Figure 6 shows a representation of a preloading step.

[0030] Figure 7 is a schematic representation of the leg load value.

[0031] Figure 8a 、 8b is a schematic view of a dynamic crane operation envelope. Detailed Description of the Invention

[0032] Note that the accompanying drawings are given by way of exemplary embodiments and should not be construed as restrictive, nor as drawn to scale.

[0033] Figure 1FIG. 0 shows a flowchart of an embodiment of a method according to the present application. Method 100 not only provides a more accurate determination of the preload value actually achieved on the outriggers, but also combines the jacking system data with the crane system data to determine the actual, and sometimes even real-time, dynamic crane operating envelope. In step 101, method 100 begins with a preloading process in which a preload is applied to the outriggers. For some jack-up platform units, preloading is performed simultaneously on two diagonally opposite outriggers. The preload is a relatively high load, and in some cases, the preload is the actual possible high load applied to the outriggers to seat them on the seabed. The preloading can be done actively, passively, or in a combined active / passive process. In step 102, the value of an outrigger characteristic is monitored during a predetermined time interval t. The outrigger characteristic can be, for example, the outrigger load or the outrigger penetration. Then, in step 103, during the time interval t, it is monitored whether the outrigger characteristic remains stable, which indicates the stability of the outrigger and finally the stability of the foundation. Once it is determined that the outrigger characteristic is stable, the preload value can be established in step 105. The preload value is associated with the outrigger characteristic value determined to be stable. For each outrigger, these steps 101, 102, 103, 105 are repeated until, for each outrigger, the outrigger characteristic value is determined to be stable and the associated preload value can be established (step 106). In step 107, when the actually achieved preload values have been determined for all outriggers, the actual load on each outrigger can be determined. The actual load is also referred to as the installation load and can only be established when the platform is lifted to its operating level. Then, after bringing the hull to its operating level, some jacking operators may attempt to distribute the platform load approximately equally among the outriggers, while other jacking operators may leave the load as it is. Regardless of which method is used, after bringing the hull to the operating level, the installation load value for each outrigger can be determined in step 107. This is the load actually installed on each of the outriggers. Thus, this actual installation load can be different for each outrigger. The step of bringing the hull to its operating state between step 106 and step 107 is not shown in the flow scheme.

[0034] This installation load value is less than the achieved preload value, and simply put, the difference between the achieved preload value and the installation load on the outrigger defines the operating margin of the outrigger, which is determined in step 108. Then, in step 109, the operating margin of each outrigger can be input into the operating margin of the crane or jib operating envelope. Then, in step 110, using the actually achieved preload value and the actual installation load value, the actual crane or jib operating envelope can be determined, thereby obtaining an accurate and reliable crane or jib operating envelope.

[0035] Figure 2 and Figure 3 shows when using Figure 2 the passive preloading inFigure 3 during active preloading in Figure 1 The method. Any mix between active preloading and passive preloading is also possible. In Figure 2 , for passive preloading, the monitored outrigger feature is the outrigger load value. In Figure 3 , the monitored outrigger feature is the outrigger penetration value. These methods are largely similar, so Figure 2 and Figure 3 will be discussed together.

[0036] In step 101, alternatively, a preload is applied passively, where a force is applied in discrete fashion and then the load value is monitored during a predetermined time interval t ( Figure 2 step 102 of Figure 3 ). Alternatively, a preload is applied actively, where a force is applied continuously and then held at a constant value. Then, in step 102, during the predetermined time interval t (

[0037] In Figure 2 step 102, during time t, during a predetermined time interval, the load value of the outrigger being preloaded is monitored. The time t can be 20 minutes, 30 minutes, or sometimes 50 minutes, and can be set by the jacking system operator and / or by the jacking platform unit designer. During time t, it is monitored whether the decrease in the outrigger load value (Δoutrigger load value) is greater than a predetermined threshold - question 103, and whether the gradient of the decreasing load value (Δoutrigger load value / Δt) is greater than a predetermined gradient limit - question 104. The decrease in the outrigger load value is the difference between the outrigger load value at time t and the outrigger load value at time 0 at the start of the monitoring time interval. Similarly, in Figure 3 step 103, it is checked whether the increase in the outrigger penetration value (Δoutrigger penetration value) is greater than a predetermined threshold, and whether the gradient of the outrigger penetration value (Δoutrigger penetration value / Δt) is greater than a predetermined limit. If the decrease in the outrigger load value is too high, or if the increase in the outrigger penetration value is too high, this is an indication of an unstable state. Alternatively, when the gradient of the outrigger load value or the gradient of the outrigger penetration value is too high, this is also an indication of an unstable state. Thus, in either case, the stable condition is not reached and the preloading step is repeated until the stable condition is reached. Thus, if the response to either of questions 103, 104 is "yes", the preloading can be abandoned and it is necessary to start over at step 101.

[0038] By monitoring whether the leg characteristics become stable, it is possible to detect when the preload value of the leg has stabilized to a certain value. A decrease in the leg characteristic value, especially the load value, or an increase in the penetration value gives an indication of leg settlement. The gradient or slope of the decreasing load value or the increasing leg penetration value gives an indication of the leg settlement speed. If the load value on the leg decreases too quickly, or the penetration value of the leg increases too quickly, this indicates that the leg has not settled stably into the seabed. When applying the preload, the decrease in the load value on the leg or the increase in leg penetration may be due to seabed characteristics, such as mud being different from sand or rock, friction, environmental loads, etc. When the response to both questions 103 and 104 is "no", the leg has settled stably to the seabed, and the actually achieved preload value can be determined in step 105. During the time t, the actually achieved preload value on the leg is considered to be the minimum obtained load value. The actually achieved leg penetration value is related to the actually achieved preloading and indirectly gives an indication of the actually achieved preloading. Contrary to traditional preloading, in which the applied preloading is usually taken as the preload value, by using this method, it is now possible to establish the actually achieved preload value for each leg. The preloading is carried out for each leg or for each pair of legs, and the actually achieved preload value is determined until the actually achieved preload value is established for each leg of the jack-up platform unit, as shown in step 106. Then, after the preloading is completed, some crane operators may equalize the platform loads on the legs of the platform unit, also called load equalization on the legs. This is no longer strictly necessary for this method. It may happen that one leg holds a heavier load than the other legs. After preloading and lifting the hull to its operating level above sea level, the crane operator can create additional torque in the hull by applying additional loads to two diagonally opposite legs. Thus, after preloading and after bringing the hull to its operating level, the actual load on each of the legs can be determined in step 107. This actual load is called the so-called installation load value. Here, the step of bringing the hull to its operating level between step 106 and step 107 is also not shown. The installation load value is less than the achieved preload value, and simply put, the difference between the achieved preload value and, for example, the installation leg load value is the operating load margin of the leg, as will be combined with Figure 7It is explained and determined in step 108. This operating load margin can be determined based on the installation leg load values after preloading and after lifting the hull to the operating position. Advantageously, a safety factor is also considered. In this case, the operating load margin is a static value. Alternatively, the operating load margin can be determined based on the actually measured leg load values measured by the jacking system or any other measuring unit on the legs. In this case, the operating load margin is a dynamic value that changes during the operation on the platform unit. Then, this operating load margin can be integrated into the crane operating envelope or the jib operating envelope to obtain an integrated crane or jib operating envelope that takes into account the additional load that a single leg can bear. This is done in step 109. It can be seen that in certain crane operations with a certain lifting load, outreach angle, slewing angle, and / or boom angle, such high loads are applied on a single leg that the leg load will become higher than the actually achieved preload value, thus using up all the operating load margin for this crane operation. Such crane operations are no longer safely possible, although the specific crane operation itself may be within the static crane operating envelope. The static crane operating envelope is the operating conditions or operating boundaries given by the crane designer, usually without considering that the crane is installed on a dynamic foundation, i.e., a jack-up platform unit. For jib operations with a large jib extension and / or heavy jib loads, a similar situation is possible. Although the jack-up platform unit settles stably on the seabed, it is considered a dynamic foundation due to the operations on the platform unit, or wind and / or wave loads or bottom characteristics, etc., as opposed to a static foundation on shore. Thus, in step 110, the actual crane operating envelope for a specific crane operation using the lifting load, outreach, slewing angle, and / or boom angle can be determined. This provides the crane operator with a more reliable view of what he can do with the crane. Additionally, preferably, the actual crane operating envelope is adjusted in real time, so that when the crane slews, for example, the envelope is adjusted and presented to the crane operator, enabling the crane operator to immediately evaluate whether his operation is still safe. This is a great advantage for the crane operator because the crane operator can now monitor and evaluate the safety of the operation during the operation. In the prior art operations, the crane operator does not have an integrated crane operating envelope with the actually achieved preload value integrated into it. In traditional operations, the crane operator may have a preload value, which is also not the actually achieved preload value but is usually the applied preload value, and the crane operator also does not have any information about the actual leg loads. Similarly, the actual jib operating envelope can be determined in step 110, possibly in real time, considering the actual platform conditions, environmental conditions, jib outreach, and / or jib load. This also provides an advantage for the jib operator.

[0039] Figure 4 Figure 4 schematically shows a system 200 according to the present application. The system 200 includes a jacking system 201 and a crane system 202 that communicate with a control unit 203. The jacking system 201 is arranged to jack the relevant legs up and down relative to the hull of the jacking platform unit and is arranged to hold the legs in a specific position. The jacking system 201 is operated by a jacking operator who provides input to the jacking system 201 via a jacking operator user interface 204. The jacking system 201 receives input data from the jacking operator user interface 204, but can also provide data to the jacking operator user interface 204, such as measured load data. The jacking operator user interface 204 can be a display and / or an operation panel through which the operator provides input to the jacking system, such as the load to be set. Data from the jacking system 201, such as the measured load, the position of the legs, etc., can be presented to the jacking operator on the display of the jacking operator user interface 204. The jacking system 201 can be arranged to measure the load on the legs. Alternatively, separate load measuring units can be provided on the legs to determine the actual load on the legs.

[0040]

[0040] The crane system 202 communicates with the control unit 203 and is operated by a crane operator from a crane operator cab. The crane operator has a crane operator user interface 205 at his disposal through which the crane operator can handle crane operations. The crane system 202 receives input data from the crane operator user interface 205, but can also provide crane data to the crane operator user interface 205. The crane operator interface 205 can include one or more displays on which crane operation data, such as the lifting load, outreach, slewing angle or boom angle, is displayed. The crane operator interface 205 can also include an operator panel that, for example, includes one or more joysticks for providing instructions to the crane system 202.

[0041] According to the present application, the control unit 203 communicates with the jacking system 201, the jacking operator user interface 204, the crane system 202, and the crane operator user interface 205. The control unit 203 receives data from the jacking system 201, in particular the measured outrigger load data. The measured outrigger load data is input into the control unit 203, specifically into the first sub-control unit 206, which is configured to determine the actually achieved preload value on the outriggers. Once the actually achieved preload value is determined, it can be fed back to the jacking operator user interface 204. Additionally, according to the present application, the actually achieved preload value is input into the second sub-control unit 207. The second sub-control unit 207 is configured to determine the actual or dynamic crane operating envelope. The actual crane operating envelope takes into account the actually achieved preload value to determine the crane operating envelope. By using the actual lifting load and / or outreach and / or slewing angle and / or boom angle and using the actual crane data, the actual crane operating envelope can be obtained. Advantageously, the crane operating envelope can be calculated in real time, thereby providing the crane operator with a real-time envelope based on which the crane operator can operate. More advantageously, the actual measured outrigger load is used to calculate the actual crane operating envelope, so that the second sub-control unit 207 can also communicate with the jacking system 201 to receive the actual measured outrigger load. The crane operating envelope thus determined can be fed back to the crane operator, in particular to the crane operator user interface 205, such that the actual crane operating envelope can be displayed to the crane operator.

[0042] Figure 5 A self-elevating platform unit 300 having a hull 301 and four outriggers 302 is schematically shown. The outriggers 302 can be adjusted relative to the hull 301. In this figure, the self-elevating platform unit 300 shown is in an operating state, in which the hull 301 is at an operating height above sea level. The four outriggers 302 are settled on the seabed. Each outrigger 302 is provided with a jacking system 201 to move the outrigger up and down. The jacking system 201 is operated by a jacking operator from a jacking operator's cabin having a jacking operator interface. Around one of the outriggers, a crane 303 is positioned, which is arranged for heavy offshore lifting operations, such as for wind turbine installation operations. The crane 303 is operated by a crane operator in a crane operator's cab having a crane operator user interface. As described above, the jacking system 201 and the crane system 202 communicate with the control unit 203 to determine the actual crane operating envelope using the actually achieved preload value.

[0043] Figure 6Schematically shows the leg load data measured during the preloading step. Here, the preloading step of a four-leg platform unit is shown. From the situation of the four legs on the ground, i.e., position 401, a high load is applied to two diagonally opposite legs, with the applied preload value 410, lines 402 and 403, while the other pair of legs is approximately unloaded. During a predetermined time interval, for example 30 minutes, the decrease in the measured load value of the legs represented by lines 402 and 403 is monitored. It is monitored whether the decrease in the measured leg load remains above a predetermined load threshold Lt. Additionally, it is monitored whether the slope or gradient g of the leg load value lines 402 and 403 is less than a preset limit g1. Here, in this embodiment, the leg load values of the legs represented by lines 402 and 403 meet the two requirements, and it can be said that the two legs have settled stably to the seabed. Then, the actually achieved preload value is determined as the minimum value of lines 402 and 403, which are load values 412 and 413 respectively. Then, in the next preloading step, the preloading is repeated for the other two legs by applying a preload value 420 to the legs. As shown by lines 404 and 405, the measured preload decreases slowly. However, when the decrease in the leg load value is less than a predetermined threshold and the gradient is less than the gradient limit, the minimum achieved value is determined as the actually achieved preload values 414 and 415.

[0044] In the case of determining the actually achieved preload value, the operating margin of each leg can be determined. This is shown for the four legs 302-1, 302-2, 302-3, 302-4 of the four-leg platform unit in Figure 7 The actually achieved preload values 412, 414, 413, 415 are the uppermost lines for each leg. A safety factor is applied to the actually achieved preload value, resulting in the preload values with coefficient 412f, 413f, 414f, 415f. After preloading and after raising the hull to its operating height, the total platform weight is distributed over the four legs, resulting in each leg having an installed load value 512, 513, 514, 515. This difference, or in this figure, the gap between the preload value with coefficient and the installed leg load is the operating margin available for operations such as crane operations on the platform unit. Such a chart can be calculated by the control unit and fed back to the jacking operator, in particular, to the jacking operator user interface, so that the jacking operator obtains reliable information about the leg operating margin.

[0045] Figure 8a 、 8b In Figure 8aA crane operating envelope is shown, with the outreach plotted on the horizontal axis and the main lift load plotted on the vertical axis in the figure. In this graph, the maximum crane safe working load is plotted as line 601. This gives the maximum safe working load of the crane as if the crane were on a static basis, thus not considering the dynamic basis of the crane on the platform unit. Additionally, in this figure, the base safe working load is plotted as line 602. This is actually the operating margin identified using the preload value actually implemented. In this example, it can be seen that part of the base safe working line 602 is below the crane safe working line 601, thus reducing the actual safe crane operating envelope. Therefore, the maximum safe working load of the crane is determined by part 602a of the base safe working load and by part 601a of the crane safe working load. The actual working load of the crane is represented by point 603. During operation, the point 603 of the actual crane working load moves on this graph. Advantageously, line 602 is calculated in real time using actual crane data and actual measured outrigger loads. Thus, when the point 603 moves, line 602 can also move. Figure 8b Another representation of the crane operating envelope is shown, which has the profile of the jack-up platform unit 300, where the outriggers 302 and the crane 303 are around one outrigger. The crane operating envelope is here represented by the inner boundary 605 and the outer boundary 606 showing the minimum outreach for the lift load. Considering the preload value actually implemented and the operating outrigger load margin, the outer boundary 606 gives the maximum outreach for the lift load. In this example, it can be seen that part of the outer boundary 606, namely part 606a, is truncated. This corresponds to Figure 8a part 602a of the

[0046] which limits the maximum crane safe working load. Thus, the crane operator knows that moving the lift load outside the outer boundary is unsafe for the base and the platform unit. Additionally, these boundaries are calculated in real time and presented to the crane operator in real time at the crane operator interface. Thus, by combining and integrating the preload value actually implemented, the actual measured outrigger loads, and the crane operating envelope, a dynamic and preferably real-time crane operating envelope is obtained, allowing for a safer and more stable crane operation. Figures 4 to 8a In Figures 4 to 8a 、8b, examples of cranes are given, but all of these apply equally to booms and boom operations, where the booms mentioned for the crane can be read. Additionally, in Figure 3As explained, the method is equally applicable to active preloading or any combination thereof. The present application provides a method for determining the actually achieved preload value by monitoring the outrigger load characteristics during preloading. The method further includes determining the actual crane or jib operating envelope considering the actually achieved preloading. The method further includes considering other data such as environmental loads or crane or jib movements.

[0047] For the purposes of clear and concise description, features are described herein as part of the same or separate embodiments, however, it should be understood that the scope of the present application may include embodiments having combinations of all or some of the described features. In view of this paragraph, it will be apparent to the person skilled in the art that variations of the submitted claims may be combined with other features described in the submitted application, in particular with features disclosed in the dependent claims. It is understood that the illustrated embodiments have the same or similar components, except where they are described as different.

[0048] In the claims, any reference signs placed in parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of other features or steps than those listed in a claim. Further, the words "a" and "an" shall not be construed as limited to "only one", but rather are used to mean "at least one", and do not exclude a plurality. The fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Many variations will be apparent to the person skilled in the art. It is understood that all variations are included within the scope of the present application as defined by the following claims.

Claims

1. A method for determining a crane or jib operating envelope of a crane or jib mounted on a jack-up platform unit, the method comprising: Applying a preload to at least one leg of the jack-up platform unit; During a predetermined time interval, monitoring at least one characteristic of the leg, such as leg load value and / or leg penetration value; During the time interval, monitoring the leg characteristic and / or the gradient of the leg characteristic; Evaluating whether the leg characteristic is stable during the time interval; Repeating the above steps until the leg characteristic is stable during the time interval, whereby the leg characteristic remains within a predetermined threshold and the gradient of the leg characteristic remains within a predetermined limit; wherein the actually achieved preload value is the leg load value associated with the stable leg characteristic thus obtained; Determining the actual crane or jib operating envelope by calculating the leg load capacity of each leg based on the actually achieved preload value and converting the calculated leg load capacity into a crane or jib operating capacity.

2. The method according to claim 1, further determining the crane or jib operating capacity according to at least crane or jib movement and / or crane or jib load and / or environmental load.

3. The method according to any one of the preceding claims, wherein, Evaluating whether the leg characteristic is stable includes: evaluating the difference between the leg characteristic value and a predetermined threshold and / or evaluating the gradient of the leg characteristic with respect to a predetermined limit.

4. The method according to claim 1, wherein When the leg characteristic is the leg load value, evaluating whether the leg characteristic is stable includes: evaluating whether the decrease in the leg load value on the leg remains below a predetermined threshold, and evaluating whether the gradient of the leg load value on the leg is less than a predetermined limit.

5. The method according to claim 1, wherein When the leg characteristic is the leg penetration value, evaluating whether the leg characteristic is stable includes: evaluating whether the increase in the leg penetration value remains below a predetermined threshold, and evaluating whether the gradient of the leg penetration value of the leg is less than a predetermined limit.

6. The method according to claim 1 or 2, further comprising: Providing an alarm signal when the monitored leg characteristic value of the leg is evaluated as unstable due to the leg characteristic difference and / or the gradient of the leg characteristic being greater than the corresponding predetermined threshold.

7. The method according to claim 1 or 2, wherein Using actual crane or jib parameters, determining the actual crane or jib operating envelope in real time, the actual crane or jib parameters being such as lifting load and / or crane outreach and / or slewing angle and / or jib angle, and / or jib outreach.

8. The method according to claim 1, further comprising: Providing a control unit configured to receive the monitored values of the leg characteristics of the leg during a predetermined time interval and configured to monitor whether the leg characteristics are stable during the time interval.

9. The method according to claim 8, wherein, The control unit is configured to provide an alarm signal when the leg characteristics of the leg are evaluated as unstable.

10. The method according to claim 8 or 9, wherein, The control unit is configured to determine the actual crane or jib operating envelope by the following steps: for each leg, based on the implemented preload value, calculate the leg load capacity, and convert the calculated leg load capacity into a crane or jib operating capacity according to crane or jib parameters, the crane or jib parameters being such as lifting load and / or crane outreach and / or slewing angle and / or jib angle and / or jib outreach.

11. A system for determining the actual crane operating envelope of a crane on a jack-up platform unit, comprising: A jack-up system arranged to move associated legs relative to the hull of the jack-up platform unit and to apply loads on the legs; A control unit configured to receive the monitored leg characteristic values of the legs during preloading, wherein the control unit is further configured to monitor whether the leg characteristic values remain stable during a predetermined time interval, wherein the control unit is further configured to perform any one of the steps of the method according to any one of claims 1-10.

12. The system according to claim 11, further comprising a crane operator display and / or a jib operator display, the crane operator display being arranged to receive actual crane operating envelope data from the control unit, and the jib operator display being arranged to receive actual jib operating envelope data from the control unit.

13. The system according to claim 11, wherein, When the leg characteristic difference and / or the gradient of the leg characteristic is greater than a corresponding predetermined threshold, the leg characteristic is considered unstable.

14. A computer program product including software executed on one or more processing engines, performing the method according to any one of claims 1 to 10.

15. A non-transitory signal storage medium storing the computer program product according to claim 14.

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