Method for determining main dimensions of offshore wind farm construction vessel

Abstract

The application discloses a kind of offshore wind power construction ship main scale determination method, comprising the following steps: step one, determine several main sea areas that ship will carry out offshore wind power construction in future;Step two, collect the environmental conditions of main sea area;Environmental conditions include water depth and sea wave conditions;Step three, according to the past ship main scale selection experience, and comprehensively consider economic factors, preliminarily determine several groups of ship main scale;Step four, determine the operable determination criterion of ship;Step five, the operable window proportion of ship in different sea areas of different main scale is calculated by calculating software of body dynamics;Step six, by calculating the continuous construction proportion of ship of different main scale and estimating the cost of ship, determine the best ship main scale.The application can provide reliable basis for ship construction in different sea areas, improve the adaptability of ship in different sea areas in offshore wind power construction.

Description

Technical Field

[0001] This invention relates to a method for determining the main dimensions of an offshore wind power construction vessel. Background Technology

[0002] With the development of offshore wind power in my country, near-shore resources have been gradually developed, and the construction of offshore wind farms is increasingly moving towards deep-sea areas. Due to the greater depth and more severe wave conditions in deep-sea areas, the safety and quality of offshore wind power construction are adversely affected, posing significant challenges to the construction of offshore wind power projects.

[0003] Offshore wind power construction relies heavily on various types of floating vessels. The suitability of floating vessels for offshore wind power construction depends not only on the environmental characteristics of the construction area but also on the performance of the floating vessels themselves, with the vessel's main dimensions being the key determinant of its performance. These main dimensions include length, beam, depth, and draft; vessels with different main dimensions exhibit varying performance characteristics. For example, narrow and long vessels offer better speed but poorer stability, while wide and broad vessels offer excellent stability but lower speed. Therefore, in future offshore wind power construction, the rational selection of vessel main dimensions is crucial for improving construction efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for determining the main dimensions of offshore wind power construction vessels. This method provides a reliable basis for construction vessels to operate in different sea areas and can improve the adaptability of vessels in offshore wind power construction in different sea areas.

[0005] The objective of this invention is achieved as follows: a method for determining the main dimensions of an offshore wind power construction vessel, comprising the following steps:

[0006] Step 1: Identify several key sea areas where the vessel will conduct offshore wind power construction in the future;

[0007] Step 2: Collect environmental conditions for the main sea areas. Environmental conditions include water depth and wave conditions. Among them, wave conditions are wave data for 3 hours after wind swell separation. Wave conditions include wind wave significant wave height, wind wave average period, main swell significant wave height, main swell average period, secondary swell significant wave height, and secondary swell average period.

[0008] Step 3: Based on past experience in selecting ship main dimensions and taking into account economic factors, several sets of ship main dimensions are initially determined. Each set of ship main dimensions includes length, beam, depth and draft.

[0009] Step 4: Determine the criteria for determining the workability of the vessel;

[0010] Step 5: Calculate the proportion of operational windows for ships of different main dimensions in different sea areas using floating body dynamics calculation software;

[0011] Step six: Determine the optimal main dimensions of the ship by calculating the proportion of continuous construction for ships of different main dimensions and estimating the cost of the ship.

[0012] The method for determining the main dimensions of offshore wind power construction vessels mentioned above involves collecting environmental conditions of major sea areas over a past period through meteorological and hydrological websites during step two.

[0013] The above-mentioned method for determining the main dimensions of offshore wind power construction vessels involves, in step three, first proposing a set of main vessel dimensions based on experience, and then obtaining the remaining sets of main vessel dimensions by stretching them to a certain extent.

[0014] In the above-mentioned method for determining the main dimensions of offshore wind power construction vessels, in step four, the criteria for determining the workability of the vessel are determined based on the main construction processes performed by the vessel.

[0015] The above-mentioned method for determining the main dimensions of offshore wind power construction vessels, in step five, when calculating the proportion of the vessel's operational window, firstly, the six-degree-of-freedom motion response of the vessel under different 3-hour sea wave conditions is calculated using floating body dynamics calculation software, and then the calculated six-degree-of-freedom motion response is compared with the vessel's operational criterion; if the six-degree-of-freedom motion response of the vessel under a certain 3-hour sea wave condition is not greater than the vessel's operational criterion, then the vessel is operational under that 3-hour sea wave condition, otherwise it is not operational; the proportion of the vessel's operational window in a certain sea area is calculated according to the following formula (1):

[0016]

[0017] In formula (1), n ​​is the total number of 3 hours that the vessel can operate in the sea area within a certain period; N is the total number of 3 hours within that period.

[0018] The above-mentioned method for determining the main dimensions of offshore wind power construction vessels, wherein, in step six, the continuous construction ratio is calculated according to the following formula (2):

[0019]

[0020] Before defining continuous construction in formula (2), discontinuous construction is defined. Discontinuous construction means that if a ship can work during a certain 3-hour period, but cannot work during the preceding and following 3-hour periods, then the ship is in discontinuous construction during that 3-hour period; otherwise, it is in continuous construction. If there are m discontinuous construction periods in the total number of 3-hour periods n that the ship can work during a period, then the number of 3-hour periods of continuous construction is nm.

[0021] When estimating the cost of a ship, the total cost of the ship is proportional to the amount of steel used in the ship, and the amount of steel used in the ship is proportional to the main dimensions of the ship.

[0022] The method for determining the main dimensions of offshore wind power construction vessels of the present invention has the following characteristics:

[0023] 1) At present, domestic hydrological standards do not pay enough attention to the identification of multi-peak spectra. The statistical methods used actually mix the multi-peak spectra of swell and wind waves into a single-peak spectrum. However, the floating vessels commonly used in offshore wind power construction are very sensitive to wave cycles. Therefore, this invention uses wave data after wind swell separation, which can more accurately describe wave conditions and thus make a more reliable selection of the main dimensions of the vessel.

[0024] 2) Currently, the selection of the main dimensions of construction vessels in China is determined solely based on a specific wave environment condition (a given set of wave heights and periods), without considering the impact of wave randomness (changes in wave height and period over time) on vessel motion, nor the differences in wave conditions across different construction areas. Therefore, the selected main dimensions of construction vessels have poor adaptability. This invention considers 3-hour wave data from the past two years for the construction area and takes into account the influence of different construction areas, which is beneficial for improving the adaptability of engineering vessels and enhancing construction efficiency.

[0025] 3) Seakeeping is not the only factor to consider when selecting the main dimensions of a construction vessel. Since offshore wind power construction is a continuous process, the proportion of continuous operational windows for the vessel should also be considered. Furthermore, cost should also be taken into account when selecting the main dimensions of the construction vessel. Previously, the main dimensions of construction vessels were determined solely based on seakeeping, which could not meet the needs of actual construction. This invention comprehensively considers the seakeeping of the construction vessel, the proportion of continuous operational windows, and the vessel's cost to select the main dimensions of the construction vessel, thus meeting the needs of actual construction. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method for determining the main dimensions of offshore wind power construction vessels according to the present invention. Detailed Implementation

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] Please see Figure 1 The method for determining the main dimensions of offshore wind power construction vessels of the present invention includes the following steps:

[0029] Step 1: Determine several major sea areas where the vessel will carry out offshore wind power construction in the future. Since the wave environment conditions vary greatly in different sea areas, and the vessel for offshore wind power construction will not only carry out construction operations in a specific sea area, but will need to carry out construction operations in different sea areas according to the construction requirements of different offshore wind farms, it is necessary to consider multiple sea areas where the vessel will carry out construction in the future.

[0030] Step 2: Collect environmental conditions of major sea areas; collect environmental conditions of major sea areas over a period of time through open-source or commercial meteorological and hydrological websites; environmental conditions include water depth and wave conditions, of which wave conditions are wave data for 3 hours after wind swell and wave separation, and wave conditions include wind wave significant wave height, wind wave average period, main swell significant wave height, main swell average period, secondary swell significant wave height, and secondary swell average period.

[0031] Step 3: Based on past experience in selecting ship main dimensions and taking into account economic factors, several sets of ship main dimensions are initially determined. Each set of ship main dimensions includes ship length, ship width, molded depth, and draft. First, a set of ship main dimensions is drafted based on experience. The remaining sets of ship main dimensions are then derived by stretching the original set of ship main dimensions by a certain proportion.

[0032] Step 4: Determine the criteria for determining the workability of the vessel;

[0033] Step 5: Calculate the proportion of workable windows for ships of different main dimensions in different construction sea areas using floating body dynamics calculation software;

[0034] The criteria for determining the workability of a vessel are determined based on the main construction processes carried out by the vessel. When calculating the proportion of the workability window for a vessel, the six-degree-of-freedom motion response of the vessel under different 3-hour sea wave conditions is first calculated using floating body dynamics calculation software. Then, the calculated six-degree-of-freedom motion response is compared with the vessel's workability criteria. If the six-degree-of-freedom motion response of the vessel under a certain 3-hour sea wave condition is not greater than the vessel's workability criteria, then the vessel is workable under that 3-hour sea wave condition; otherwise, it is not workable. The proportion of the workability window for a vessel in a certain sea area is calculated according to the following formula (1):

[0035]

[0036] In formula (1), n ​​is the total number of 3-hours that the vessel can operate in the sea area within a certain period; N is the total number of 3-hours within that period.

[0037] Step 6: Determine the optimal main dimensions of the ship by calculating the proportion of continuous construction for ships of different main dimensions and estimating the cost of the ship.

[0038] The proportion of continuous construction on ships is calculated according to the following formula (2):

[0039]

[0040] Before defining continuous construction in formula (2), discontinuous construction is defined. Discontinuous construction means that if a ship can work during a certain 3-hour period, but cannot work during the preceding and following 3-hour periods, then the ship is in discontinuous construction during that 3-hour period; otherwise, it is in continuous construction. If there are m discontinuous construction periods in the total number of 3-hour periods n that the ship can work during a period, then the number of 3-hour periods of continuous construction is nm.

[0041] When estimating the cost of a ship, the total cost of the ship is proportional to the amount of steel used in the ship, and the amount of steel used in the ship is proportional to the main dimensions of the ship. This allows us to estimate the cost of ships with different main dimensions. By combining the continuous construction ratio of ships with different main dimensions and the cost of the ships, the optimal main dimensions of the ship can be determined.

[0042] The following example of determining the main dimensions of a crane vessel will be used to illustrate the method for determining the main dimensions of offshore wind power construction vessels according to the present invention.

[0043] Step 1: Based on my country's future offshore wind farm planning, three main sea areas were identified where the crane vessel will conduct offshore wind power construction. The latitude and longitude coordinates of these three sea areas are shown in Table 1 below:

[0044] Table 1

[0045] Latitude (°) Longitude (°) Sea Area 1 21.0 111.6 Sea Area 2 22.4 116.4 Sea Area 3 22.4 117.2

[0046] Step two: The average water depth of the three sea areas mentioned above, as well as the 3-hour wave data of wind waves and swells for 2018 and 2019, were obtained through commercial hydro-meteorological data websites. Since there are eight sets of 3-hour wave data in 24 hours, there are a total of 5,840 sets of 3-hour wave data in two years.

[0047] The average water depth of sea area 1 is 20m. The 3-hour wave data for 2018 to 2019 are shown in Table 2 below:

[0048] Table 2

[0049]

[0050] The average water depth of sea area 2 is 28m. The 3-hour wave data for 2018 to 2019 are shown in Table 3 below:

[0051] Table 3

[0052]

[0053]

[0054] The average water depth of sea area 3 is 25m. The 3-hour wave data for 2018 to 2019 are shown in Table 4 below:

[0055] Table 4

[0056]

[0057]

[0058] Step 3: The "Huaxi 5000" is a large, fully azimuth-rotating crane vessel that has been used in multiple offshore wind power projects in China. It boasts excellent performance and its technology is currently at a leading level in China. Therefore, based on the main dimensions of this crane vessel (length 180m, beam 46m, depth 17m, draft 11.5m), a certain proportion of stretching was performed to determine the main dimensions of four crane vessels, including the "Huaxi 5000," as shown in Table 5 below:

[0059] Table 5

[0060]

[0061] Step four: Determine the workability criteria for crane vessel construction. Based on research into the construction technology of monopile and jacket foundations on large crane vessels, it is believed that when the crane vessel is large, it has full-rotation lifting capability. Therefore, the main construction process will be to have the crane vessel and transport barge berth side by side, with the crane on the crane vessel rotating 90 degrees to the side to retrieve the monopile or jacket from the transport barge, and then hooking it up for lifting. Therefore, there are two main workability criteria in the entire construction process:

[0062] Standard 1, Roll: The roll angle of the crane vessel during the entire lifting process shall not exceed 5°;

[0063] Criterion 2, Pitch: When the crane vessel lifts a load from a transport barge, the pitch angle shall not exceed 0.6°;

[0064] When using floating hydrodynamic calculation software to calculate hydrodynamics, the calculation model is obtained by stretching the geometric model of the "Huaxi 5000" large azimuth crane ship; in the seakeeping calculation, it is considered that the ship's center of gravity is all 2m above the waterline; if the ship's six-degree-of-freedom motion response under a certain 3-hour sea wave condition is not greater than the ship's workability judgment criterion, then the ship is considered workable under that 3-hour sea wave condition, and is recorded as 1; otherwise, it is not workable, and is recorded as 0; the theoretical workable window ratio is the ratio of the total number of 3-hour workable hours of the ship to the total number of 3-hour workable hours from 2018 to 2019 (5840 groups).

[0065] Taking the four main dimensions of the ship as an example to see whether they meet Criterion 1 (roll) under the environmental conditions of sea area 1, see Table 6 below:

[0066] Table 6

[0067]

[0068]

[0069] The proportion of the theoretically operable window for ships of principal dimension 1 is shown in Table 7 below:

[0070] Table 7

[0071]

[0072] The proportion of the theoretically operable window for ships in principal dimension 2 is shown in Table 8 below:

[0073] Table 8

[0074]

[0075] The proportion of the theoretically operable window for ships with a main dimension of 3 is shown in Table 9 below:

[0076] Table 9

[0077]

[0078]

[0079] The theoretically operable window proportions for ships with a principal dimension of 4 are shown in Table 10 below:

[0080] Table 10

[0081]

[0082] Step 5: Determine the optimal main dimensions of the vessel based on the calculated continuous construction ratio and the estimated vessel cost. The vessel's workable window ratio is calculated as the ratio of the total number of 3-hour workable periods (the total number of "1"s) to the total number of 3-hour workable periods over a given time. However, actual construction is a continuous process, and the longer the vessel can work continuously, the more conducive it is to construction. Therefore, the proportion of continuous construction within the total number of 3-hour workable periods should also be calculated. Discontinuous construction is defined as a situation where, within all 3-hour workable periods, the vessel cannot work for the preceding and following 3 hours. The number of 3-hour workable periods minus the number of discontinuous construction periods equals the number of 3-hour workable periods.

[0083] Vessels of main dimensional 1 had seven instances of continuous 3-hour construction work on 2018.XX; vessels of main dimensional 2 had six instances of continuous 3-hour construction work on 2018.XX; vessels of main dimensional 3 had three instances of continuous 3-hour construction work on 2018.XX; and vessels of main dimensional 4 had zero instances of continuous 3-hour construction work on 2018.XX. (See Table 11 below.)

[0084] Table 11

[0085]

[0086] The ratio of the total number of 3 hours of continuous operation (nm) of the four main sizes of vessels between 2018 and 2019 to the total number of 3 hours (N, 5840 groups) between 2018 and 2019 is the proportion of continuous construction by the four main sizes of vessels.

[0087] The proportion of continuous construction on ships with main dimension 1 is shown in Table 12 below:

[0088] Table 12

[0089]

[0090] The proportion of continuous construction on ships with a main dimension of 2 is shown in Table 13 below:

[0091] Table 13

[0092]

[0093]

[0094] The proportion of continuous construction on ships with a main dimension of 3 is shown in Table 14 below:

[0095] Table 14

[0096]

[0097] The proportion of continuous construction on ships with a main dimension of 4 is shown in Table 15 below:

[0098] Table 15

[0099]

[0100] The selection of a ship's main dimensions should also consider its economic efficiency. Generally speaking, the ship's cost P is related to the amount of steel used W. h It is directly proportional to the amount of steel used in shipbuilding, W. h It is also directly proportional to the main dimensions; the amount of steel used in a ship, W h Calculate using the following formula:

[0101] P = a·W h

[0102] W h =k·(L·B·H)

[0103] In the formula, P is the cost of the ship; a is the cost coefficient; W h Let L be the amount of steel used in the ship (t); k be the steel coefficient; L be the length of the ship (m); B be the beam of the ship (m); and H be the depth of the ship (m). The cost of the main dimension 4 ("Huaxi 5000") is 1.3 billion yuan. The costs of the other three ships are shown in Table 16 below:

[0104] Table 16

[0105]

[0106] The proportion and cost of continuous construction for ships of the four main dimensions are compared in Table 17 below:

[0107] Table 17

[0108]

[0109] Based on construction experience, construction efficiency is higher when the continuous construction ratio is greater than 80%. Therefore, as can be seen from Table 17, ships with main dimensions 3 and 4 do not meet the requirements. Considering the cost of the ship, the main dimension 2 was finally determined as the main dimension of the ship.

[0110] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A method for determining the main dimensions of an offshore wind power construction vessel, characterized in that, Includes the following steps: Step 1: Identify several key sea areas where the vessel will conduct offshore wind power construction in the future; Step 2: Collect environmental conditions of major sea areas; collect environmental conditions of major sea areas over a period of time through meteorological and hydrological websites; environmental conditions include water depth and wave conditions, of which wave conditions are wave data for 3 hours after wind swell and wave separation; wave conditions include wind wave significant wave height, wind wave average period, main swell significant wave height, main swell average period, secondary swell significant wave height, and secondary swell average period. Step 3: Based on past experience in selecting ship main dimensions and taking into account economic factors, several sets of ship main dimensions are initially determined. Each set of ship main dimensions includes ship length, ship width, molded depth, and draft. First, a set of ship main dimensions is drafted based on experience. The remaining sets of ship main dimensions are then derived by stretching the original set of ship main dimensions by a certain proportion. Step four, determine the workability criteria for the vessel; the workability criteria for the vessel are determined based on the main construction processes to be carried out on the vessel; Step 5: Calculate the proportion of operational windows for ships of different main dimensions in different sea areas using floating body dynamics calculation software; When calculating the proportion of a ship's operational window, the six-degree-of-freedom motion response of the ship under different 3-hour sea wave conditions is first calculated using floating body dynamics software. Then, the calculated six-degree-of-freedom motion response is compared with the ship's operational criterion. If the ship's six-degree-of-freedom motion response under a certain 3-hour sea wave condition is not greater than the ship's operational criterion, it means that the ship is operational under that 3-hour sea wave condition; otherwise, it is not operational. The proportion of a vessel's operational window in a certain sea area can be calculated using the following formula (1): In formula (1), n ​​is the total number of 3-hours that the vessel can operate in the sea area within a certain period; N is the total number of 3-hours within that period. Step 6: Determine the optimal main dimensions of the ship by calculating the proportion of continuous construction for ships of different main dimensions and estimating the cost of the ship. The continuous construction ratio is calculated according to the following formula (2): Before defining continuous construction in formula (2), discontinuous construction is defined. Discontinuous construction means that if a ship can work during a certain 3-hour period, but cannot work during the preceding and following 3-hour periods, then the ship is in discontinuous construction during that 3-hour period; otherwise, it is in continuous construction. If there are m discontinuous construction periods in the total number of 3-hour periods n that the ship can work during a period, then the number of 3-hour periods of continuous construction is nm. When estimating the cost of a ship, the total cost of the ship is proportional to the amount of steel used in the ship, and the amount of steel used in the ship is proportional to the main dimensions of the ship.

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