JP2015045329A - Method and system for monitoring load and stress of floating body facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system for monitoring the load and stress of a floating body facility enabling monitoring at many structural weak points only by measuring limited indicators related on the whole behavior such as floating body movement of the floating body facility.SOLUTION: A method for monitoring the load and stress of a floating body facility corresponding to this invention estimates in real time the loads and stresses of plural monitoring portions 15a, 15b, 15c of a floating body facility 10 on the basis of measurement of indicators related on the whole behavior of the floating body facility 10 containing floating body movement in operation of the floating body facility 10 and/or weather/hydrographic conditions.

Description

  The present invention relates to a load / stress monitoring method for a floating facility and a load / stress monitoring system for a floating facility that can monitor structural weak points.

General structure maintenance is performed based on the concept of periodic inspection and periodic maintenance. However, certain residual reliability is not necessarily ensured in the construction of periodic inspections and periodic maintenance. In order to prevent damage, the inspection and maintenance interval is set on the safe side, and unnecessary surplus safety is generated.
In a floating offshore wind power generation facility or the like, it is required to monitor the residual reliability accurately and remotely in order to make the frequency of inspection and maintenance necessary and sufficient.
For example, a structural weak point of a floating offshore power generation facility includes a tower opening. In the tower opening, there are examples in which fatigue cracks occur or the entire collapse starts from the buckling of the part.
There is a demand for a technique for constantly monitoring stress history and the like for these weak points on the structure, but no practical technique has been developed yet.

  In Patent Document 1, since periodic maintenance of wind power generation facilities has been operated by setting a maintenance period of a certain period in consideration of a sufficient safety factor, there was a tendency to perform maintenance at a maintenance interval shorter than necessary. Paying attention to this, whether or not the actual operation status has reached the amount of operation that requires maintenance based on the operation results of the wind power generation equipment acquired by the operating state monitoring means and the preset maintenance conditions of the wind power generation equipment It is described that it is determined.

  In Patent Document 2, load time-series data acting on an evaluation target part of a wind turbine is obtained, stress time-series data is obtained from the load time-series data, and stress based on the stress time-series data is given over the evaluation target part compensation operation period. In this case, it is described that a fracture toughness value required at least for the evaluation target part to maintain a predetermined strength is obtained and a required fracture toughness value serving as an index is determined based on the fracture toughness value.

  In Patent Document 3, a plurality of strain gauges and accelerometers for measuring stress are arranged at a plurality of positions of a support structure that supports a liquefied gas tank structured as a part of a hull, and these strain gauges and accelerometers are used. It is described that stress is calculated based on an electrical signal and the remaining life is evaluated.

  In Patent Document 4, the stress of the hull is detected by the stress detecting means, the detection information of the stress detecting means is accumulated by the accumulating means, and the state of the ship at the time of navigation is derived by the ship state deriving means. It is described that the soundness of the hull structure is estimated and evaluated based on the stress information and the ship state information.

JP 2006-342766 A International Publication No. 2010/038305 JP 2005-3554 A JP 2002-326598 A

In Patent Document 1, the amount of power generation, the number of rotations of the windmill, the actual operation time, and the like are measured as the operation results of the wind power generation facility (paragraph number (0009)). Then, the set values of the operation time and the number of rotations of the windmill as the maintenance conditions are compared with the operation values as the operation results and the actual values of the number of rotations of the windmill (paragraph number (0014)).
Therefore, in patent document 1, it does not measure the floating body movement of a floating body facility or the whole behavior of a floating body facility, and does not monitor a structural weak point location.

  Patent document 2 calculates | requires the appropriate value of the evaluation parameter | index relevant to the durability of a member by simulation, and does not measure the floating body movement of the actual floating body facility, or the whole behavior of a floating body facility.

  The method using a strain gauge as in Patent Document 3 is suitable for measuring stress at a structural weak spot, but in a floating facility, there are many structural weak spots, It is not sufficient to measure only the weak point, and it is not practical to measure the floating body movement of the floating facility and the whole behavior of the floating facility. In addition, there is a problem of the life of the strain gauge, and long-term reliability cannot be ensured in a floating facility that cannot be entered regularly.

The ship state deriving means in Patent Document 4 includes a wind direction detecting means for detecting the wind direction, a direction measuring means for measuring the bow direction of the hull, an inclination detecting means for detecting rolling and pitching of the hull, and an up and down direction for detecting the vertical acceleration of the bow. It consists of acceleration detection means. That is, by using the means constituting the ship state deriving means, it is possible to estimate the floating body motion during the operation of the hull.
However, in Patent Document 4, the stress detected by the stress detection means is corrected based on the information from the ship state deriving means, so that the stress at the location where the stress detection means is not installed is estimated. The state derivation means does not measure the floating body motion during operation of the hull (paragraph number (0033)).

  The present invention does not exhaustively measure structural weak points that exist in many floating facilities, but only measures limited indicators related to the overall behavior of floating facilities, including floating body motion. An object of the present invention is to provide a load / stress monitoring method for a floating facility and a load / stress monitoring system for a floating facility that can monitor a number of structural weak spots.

  In the load / stress monitoring method for a floating facility corresponding to the present invention as set forth in claim 1, based on the measurement of an index related to the overall behavior of the floating facility including floating body motion and / or weather / sea conditions during operation of the floating facility. The load or stress of a plurality of monitoring parts of the floating facility is estimated in real time. According to the first aspect of the present invention, the structural weak points existing in a large number of floating facilities can be covered only by measuring limited indicators related to the overall behavior including floating body movements and weather / sea conditions. It is not possible to measure in a realistic and instant manner, but it is possible to perform monitoring on a monitoring site, that is, on a number of structural weak spots in real time.

  According to a second aspect of the present invention, in the load / stress monitoring method for a floating facility according to the first aspect, an index relating to the overall behavior is obtained by measuring with a measuring means provided in the floating facility. According to the second aspect of the present invention, it is possible to directly measure a limited index related to the entire behavior including the floating body motion of the floating body facility and the weather / sea conditions by the measuring means provided in the floating body facility.

  According to the third aspect of the present invention, in the load / stress monitoring method for a floating facility according to the first or second aspect, the remaining fatigue life of a plurality of monitoring parts is determined based on a history of estimated values of the load or stress. It is characterized by evaluating. According to the third aspect of the present invention, it is possible to evaluate, for each part, the remaining life at a number of weak points from a time-series estimated value of load / stress.

  According to a fourth aspect of the present invention, in the load / stress monitoring method for a floating facility according to the third aspect, the time for inspection and maintenance is determined based on the monitoring part having the least fatigue remaining life among the plurality of monitoring parts. It is characterized by doing. According to the present invention described in claim 4, it is possible to rationally determine the maintenance inspection time without setting unnecessary surplus safety.

  The present invention according to claim 5 is the load / stress monitoring method for a floating facility according to claim 3 or claim 4, wherein the load or stress and / or fatigue is determined from a time-series tendency of the estimated value of the load or stress. It is characterized by predicting future changes in remaining life. According to the fifth aspect of the present invention, the future prediction of the load / stress and the remaining fatigue life can be accurately performed before the dangerous state is entered.

  According to a sixth aspect of the present invention, in the load / stress monitoring method for a floating facility according to any one of the third to fifth aspects, the estimated value of the load or stress and / or the evaluation value of the remaining fatigue life is used. It is characterized by issuing an alarm. According to the sixth aspect of the present invention, a dangerous state can be notified by an alarm, and future safety can be reliably ensured.

  According to a seventh aspect of the present invention, in the load / stress monitoring method for a floating facility according to any one of the third to sixth aspects, the estimated value of the load or stress and / or the evaluation value of the remaining fatigue life is used. It is characterized by controlling the operation of the floating facility. According to the seventh aspect of the present invention, it is possible to change the driving condition to avoid the danger before entering the dangerous state.

  The present invention according to claim 8 is the load / stress monitoring method for a floating facility according to any one of claims 1 to 7, wherein the estimated value of the load at a plurality of monitoring sites is calculated from the floating body motion to the inertia of the floating facility. It is characterized by calculating force and / or mooring force and obtaining external force including wave force so as to satisfy the mechanical condition. According to the present invention described in claim 8, a reasonable load can be easily estimated by assuming the calculated inertial force and / or the mooring force and the external force that satisfies the end condition.

  According to a ninth aspect of the present invention, in the load / stress monitoring method for a floating facility according to any one of the first to eighth aspects, the estimated stress values of the plurality of monitoring parts are obtained by structural analysis for each monitoring part. It is characterized by using a conversion factor from the obtained load to stress. According to the ninth aspect of the present invention, the stress can be reasonably estimated for each weak spot, that is, for each monitoring site.

According to a tenth aspect of the present invention, in the load / stress monitoring method for a floating facility according to the first or second aspect, the estimated values of the loads of the plurality of monitoring sites are obtained based on the following formula (1): It is characterized by that.
Formula (1): {F _i } = [A _ij ] {x _j } + [B _ij ] {x _j ′} + [C _ij ] {x _j ′ ′}
However, {F _i } is a load, {x _j } is displacement, {x _j ′} is velocity, {x _j ′} is acceleration, [A _ij ], [B _ij ], and [C _ij ] are motion − The load correlation matrix, i is the type of load, and j is 6 degrees of freedom of floating body motion. According to the tenth aspect of the present invention, the load can be easily estimated using a predetermined calculation formula.

  The present invention according to claim 11 is the load / stress monitoring method for a floating facility according to claim 10, wherein a motion-load correlation matrix is used to determine a response function of a floating body motion and a load response function having six degrees of freedom. Step 2 for preparing the first and second derivatives of the floating body response function, the load response function, the displacement response function based on the floating body response function, and the prepared first and second derivatives Is obtained by Step 3 for identifying the value of the motion-load correlation matrix. According to the eleventh aspect of the present invention, a motion-load correlation matrix for obtaining an estimated value of a load that varies depending on the monitoring site can be easily obtained.

  The present invention according to claim 12 is the load / stress monitoring method for a floating facility according to claim 11, wherein the value of the motion-load correlation matrix obtained in step 3 and the time series data of actual floating body motion are used. The method further comprises step 4 of calculating time-series data of loads generated in each cross section of the plurality of monitoring sites. According to the present invention as set forth in claim 12, it is possible to calculate load time-series data and know the tendency of the load generated in the floating facility.

  The invention according to claim 13 is the load / stress monitoring method for a floating facility according to claim 11 or claim 12, wherein the response function of the floating body motion and the response function of the load are obtained by a water tank test or numerical calculation. Features. According to the present invention as set forth in claim 13, the response function necessary for the calculation can be easily determined in advance.

The present invention according to claim 14 is the load / stress monitoring method for a floating facility according to claim 1, claim 2, or claim 10 to claim 13, wherein the estimated values of stress at a plurality of monitoring sites Is obtained based on the following formula (2).
Formula (2): {σ _k } = [D _ki ] {f _i }
However, {σ _k } is a stress, {f _i } is a unit load, [D _ki ] is a load-stress correlation matrix, k is a monitoring site, and i is a load type. According to the present invention as set forth in claim 14, the stress can be easily estimated using a predetermined calculation formula.

  The present invention according to claim 15 is the load / stress monitoring method for a floating facility according to claim 14, wherein a finite element model including a load-stress correlation matrix and a monitoring portion of the floating facility is created, and the unit is defined as a model boundary. It is characterized in that it is obtained by Step 5 in which a load is applied and Step 6 in which a stress at a monitoring site when a unit load is loaded is calculated and a value of a load-stress correlation matrix is identified. According to the present invention of the fifteenth aspect, a load-stress correlation matrix that obtains an estimated value of stress that varies depending on the monitoring site can be easily obtained.

  The present invention according to claim 16 is the load / stress monitoring method for a floating facility according to claim 15, wherein the value of the load-stress correlation matrix obtained in step 6 and the time series data of the load calculated in step 4 are obtained. And step 7 for calculating time series data of stress generated in the monitoring region when the estimated load acts as a cross-sectional force. According to the present invention of the sixteenth aspect, it is possible to calculate the time series data of the stress and know the tendency of the stress generated in the floating facility.

  The present invention according to claim 17 is the load / stress monitoring method for a floating facility according to claim 16, wherein the fatigue damage degree is calculated based on the time-series data of the stress obtained in step 7, and the cumulative number of monitoring parts is calculated. The fatigue damage level is calculated, and the fatigue life expectancy is evaluated by the difference between the current value and the allowable value of the cumulative fatigue damage level. According to the present invention as set forth in claim 17, it is possible to evaluate the remaining life at each of a number of weak points for each part from the estimated values of load and stress in time series, and to predict the danger before entering a dangerous state. It becomes possible.

  In the load / stress monitoring system for a floating facility corresponding to the present invention as set forth in claim 18, the floating body motion during the operation of the floating facility and / or an index relating to the overall behavior of the floating facility including weather / sea conditions is measured. Measuring means, load / stress estimation means for estimating loads or stresses of a plurality of monitoring parts in the floating facility based on the measurement values of the measurement means, and output means for outputting the estimation results of the load / stress estimation means It is characterized by that. According to the present invention as set forth in claim 18, it is possible to cover structural weak points existing in a large number of floating facilities only by measuring a limited index related to the overall behavior including floating body movements and weather / sea conditions. It is possible to perform monitoring by estimating loads or stresses on a monitoring site, that is, a large number of structural weak points, instead of performing measurement in an objective and instant manner.

  According to a nineteenth aspect of the present invention, in the load / stress monitoring system for a floating facility according to the eighteenth aspect, the system further comprises a history recording means for recording a history of an estimated value of the load or stress. According to the 19th aspect of the present invention, it is possible to predict a number of weak spots in the future from the time-series estimated values of the load / stress recorded in the history recording means.

  The present invention according to claim 20 is the load / stress monitoring system for a floating facility according to claim 19, wherein the fatigue of a plurality of monitoring sites is based on the history of the estimated values of the load or stress recorded by the history recording means. It further comprises fatigue remaining life evaluation means for evaluating the remaining life. According to the 20th aspect of the present invention, it is possible to evaluate the remaining lifetimes at a number of weak points from the recorded time-series estimated values of loads and stresses.

  According to a twenty-first aspect of the present invention, in the load / stress monitoring system for a floating facility according to the twenty-first aspect, the fatigue life expectancy evaluation means performs an inspection based on a monitoring part having the smallest fatigue life remaining among the monitoring parts. It is characterized by judging the time of maintenance. According to the twenty-first aspect of the present invention, it is possible to rationally determine the maintenance inspection time without setting unnecessary surplus safety.

  The present invention according to claim 22 is the load / stress monitoring system for a floating facility according to claim 20 or claim 21, wherein the load / stress estimation means and / or fatigue life evaluation means is an estimated value of load or stress. Future changes in load or stress and / or remaining fatigue life are predicted from the time series trends of According to the twenty-second aspect of the present invention, it is possible to accurately cope with the risk before entering a dangerous state by performing future prediction of the load / stress and the fatigue life remaining.

  According to a twenty-third aspect of the present invention, in the load / stress monitoring system for a floating facility according to any one of the twenty-second to twenty-second aspects, an estimated value of the load or stress and / or a remaining fatigue life by the load / stress estimating means It further comprises alarm means for giving an alarm based on the evaluation value of fatigue life remaining by the evaluation means. According to the twenty-third aspect of the present invention, a dangerous state can be notified by an alarm, and future safety can be reliably ensured.

  According to a twenty-fourth aspect of the present invention, in the load / stress monitoring system for a floating facility according to any one of the twenty-second to twenty-third aspects, an estimated value of the load or stress and / or a remaining fatigue life by the load / stress estimating means An operation control means for controlling the operation of the floating facility is further provided based on the evaluation value of the fatigue life remaining by the evaluation means. According to the twenty-fourth aspect of the present invention, it is possible to change to operating conditions that avoid danger before entering the dangerous state.

  The present invention described in claim 25 is the load / stress monitoring system for a floating facility according to any one of claims 20 to 24, wherein the load / stress estimation means and / or the fatigue life expectancy evaluation means and the output means are: It is provided in a place separated from the floating facilities. According to the present invention described in claim 25, for example, a plurality of floating facilities installed offshore can be monitored on land.

  According to the load / stress monitoring method for a floating facility of the present invention, it is only necessary to measure a limited index related to the overall behavior including the floating body motion and weather / sea conditions of the floating facility. Rather than comprehensively and instantly measuring weak points, it is possible to perform monitoring on a monitoring site, that is, a large number of structural weak points in real time.

  In addition, when the indicator related to the overall behavior is obtained by measuring with the measuring means provided in the floating facility, the limit relating to the overall behavior including the floating body motion of the floating facility and the weather / sea conditions is measured by the measuring means provided in the floating facility. The measured index can be directly measured.

  In addition, when evaluating the fatigue life expectancy of multiple monitoring parts based on the history of estimated load / stress values, the remaining life at many weak spots can be calculated for each part from the time-series estimated values of load / stress. Can be evaluated.

  In addition, when judging the inspection and maintenance timing based on the monitoring portion with the least fatigue remaining life among multiple monitoring portions, rationalize the maintenance and inspection timing without setting unnecessary surplus safety. Can be judged.

  In addition, when predicting future changes in load / stress and / or fatigue life expectancy from time-series trends in estimated values of load / stress, it is dangerous to predict future changes in load / stress and fatigue life expectancy. It can be dealt with accurately before entering the state.

  Further, when an alarm is issued based on an estimated value of load / stress and / or an evaluation value of fatigue life expectancy, a dangerous state can be notified by the alarm, and future safety can be reliably ensured.

  In addition, when controlling the operation of a floating facility based on the estimated value of load / stress and / or evaluation value of fatigue life expectancy, it is possible to change the operating condition to avoid danger before entering the dangerous state. It becomes.

  In addition, when estimating the load of multiple monitoring parts by calculating the inertial force and / or mooring force of the floating facility from the floating body motion and assuming external force including wave force to satisfy the mechanical condition, By assuming the calculated inertial force and / or the mooring force and the external force that satisfies the end condition, a reasonable load can be easily estimated.

  In addition, when using the load-to-stress conversion coefficient obtained by structural analysis for each monitoring site to estimate the stress at multiple monitoring sites, the stress can be rationalized for each weak spot, that is, for each monitoring site. Can be estimated.

Moreover, when the estimated value of the load of several monitoring site | parts is calculated | required based on following Numerical formula (1), a load can be estimated simply using the defined calculation formula.
Formula (1): {F _i } = [A _ij ] {x _j } + [B _ij ] {x _j ′} + [C _ij ] {x _j ′ ′}
However, {F _i } is a load, {x _j } is displacement, {x _j ′} is velocity, {x _j ′} is acceleration, [A _ij ], [B _ij ], and [C _ij ] are motion − The load correlation matrix, i is the type of load, and j is 6 degrees of freedom of floating body motion.

  Further, a step 1 for obtaining a 6-DOF floating body motion response function and a load response function as a motion-load correlation matrix, a step 2 for preparing first and second derivatives of the floating body motion response function, and a load , The displacement response function based on the response function of the floating body motion, and the prepared first-order derivative and second-order derivative are substituted into Equation (1) to identify the value of the motion-load correlation matrix by step 3 In the case of obtaining, a motion-load correlation matrix that obtains an estimated value of a load that varies depending on the monitoring site can be easily obtained.

  Further, the method further includes step 4 of calculating time series data of loads generated in each cross section of the plurality of monitoring sites using the value of the motion-load correlation matrix obtained in step 3 and the time series data of actual floating body motion. In this case, the tendency of the load generated in the floating facility can be known.

  Moreover, when the response function of the floating body motion and the response function of the load are obtained by a water tank test or numerical calculation, a response function necessary for the calculation can be easily obtained in advance.

Moreover, when the estimated value of the stress of a plurality of monitoring parts is obtained based on the following mathematical formula (2), the stress can be simply estimated using a predetermined calculation formula.
Formula (2): {σ _k } = [D _ki ] {f _i }
However, {σ _k } is a stress, {f _i } is a unit load, [D _ki ] is a load-stress correlation matrix, k is a monitoring site, and i is a load type.

  In addition, the load-stress correlation matrix is used to create a finite element model including the monitoring part of the floating facility, and to apply the unit load to the model boundary, and to calculate the stress at the monitoring part at the time of loading the unit load. In the case of obtaining in step 6 for identifying the value of the stress correlation matrix, a load-stress correlation matrix for obtaining an estimated value of stress that differs depending on the monitoring site can be easily obtained.

  Also, using the value of the load-stress correlation matrix obtained in step 6 and the time series data of the load calculated in step 4, the time series data of the stress generated in the monitoring site when the estimated load acts as the sectional force. When step 7 is calculated, it is possible to calculate time series data of stress and know the tendency of stress generated in the floating facility.

  In addition, the fatigue damage level is calculated based on the time series data of the stress obtained in Step 7, the cumulative fatigue damage level of the monitoring site is calculated, and the fatigue surplus is calculated by the difference between the current value of the cumulative fatigue damage level and the allowable value. When evaluating the lifetime, it is possible to evaluate the remaining lifetime at a number of weak spots for each site from the estimated values of load and stress in time series, and to predict the danger before entering a dangerous state.

  According to the load / stress monitoring system for a floating facility of the present invention, it is only necessary to measure a limited index related to the overall behavior including the floating body motion and weather / sea conditions of the floating facility. Rather than comprehensively and instantly measuring weak points, it is possible to estimate and monitor loads / stresses at a monitoring site, that is, a number of structural weak points.

  In addition, in the case of further comprising a history recording means for recording the history of estimated values of load / stress, from the estimated values of load / stress time series recorded in the history recording means, Predictions can be made.

  In addition, based on the history of the estimated load / stress value recorded by the history recording means, if further equipped with fatigue remaining life evaluation means for evaluating the fatigue remaining life of a plurality of monitoring sites, From the estimated value of the time series of stress, the remaining life at many weak spots can be evaluated.

  In addition, when the fatigue life expectancy evaluation means determines the time for inspection and maintenance based on the monitoring part with the least fatigue remaining life among the monitoring parts, maintenance is performed without setting unnecessary surplus safety. The timing of inspection can be reasonably judged.

  If the load / stress estimation means and / or fatigue life expectancy evaluation means predicts future changes in load / stress and / or fatigue life expectancy from the time-series trend of the estimated values of load / stress,・ By predicting the future of stress and fatigue life, it is possible to deal with it accurately before entering a hazardous state.

  In addition, in the case where alarm means for giving a warning based on the estimated value of the load / stress by the load / stress estimation means and / or the evaluation value of the remaining fatigue life by the fatigue life expectancy evaluation means is further provided, It is possible to notify, and future safety can be surely ensured.

  In addition, when further provided with an operation control means for controlling the operation of the floating facility based on the estimated value of the load / stress by the load / stress estimation means and / or the evaluation value of the fatigue remaining life by the fatigue remaining life evaluation means Before entering a dangerous state, it becomes possible to change to an operating condition that avoids the danger.

  Further, when the load / stress estimation means and / or the fatigue life expectancy evaluation means and the output means are provided at a location separated from the floating facility, for example, a plurality of floating facilities installed offshore can be monitored on land.

The figure which shows the basic concept of the load and stress monitoring method by this embodiment The block diagram which shows the load and stress monitoring system by this embodiment The graph which shows an example of the prediction method from the time series tendency of the estimated value of the stress by this embodiment

The load / stress monitoring method according to the embodiment of the present invention will be described below.
FIG. 1 is a diagram showing a basic concept of a load / stress monitoring method according to this embodiment.
As shown in FIG. 1 (a), the measurement object is the floating body movement during the operation of the floating body facility and / or the overall behavior of the floating body facility including the weather / sea conditions. Based on the measurement of the index related to the overall behavior, the load of a plurality of monitoring parts of the floating facility is estimated in real time, and the stress is estimated in real time based on the estimated load.
In other words, it is not only comprehensive and instant measurement of structural weaknesses that exist in floating facilities, but only by measuring indicators related to the overall behavior including the fluctuations of the floating facilities and the weather and sea conditions. That is, it is possible to monitor a large number of structural weak points in real time.

Since comprehensive and instant measurement of structural weak points is not required, a large number of measurement means are not required, and the durability of a large number of measurement means, for example, when strain gauges are used instantly There is no need to consider the reliability and reliability.
In addition, by estimating the load and stress at the monitoring site in real time and monitoring a large number of structural weak spots in real time, an indicator of the overall behavior of the floating facility including floating body motion and / or weather / sea conditions The impact on the load and stress can be known from moment to moment, which can contribute to the comparison with the design limit value of the load and stress and the confirmation of the safety factor. In addition, changes in load and stress can be known from time to time, and future prediction of load and stress can be easily made from the tendency. Furthermore, inspection maintenance can be managed accurately by accumulating momentary changes in load and stress.

FIG. 1B shows the relationship between the parameters.
The floating facility is a dynamic system to which various external forces are loaded as shown in FIG.
As shown in FIG. 1B, the floating body motion is generated by the external force, but the motion is generated as a result in which the inertial force and the mooring force generated thereby are balanced. In addition, bending, twisting, and shearing loads are generated as integral values of external force, inertial force, and mooring force.
However, it is practically impossible to grasp the whole image of the external force and the inertial force because many parameters such as the applied force position and the direction of the force are required.

FIG. 1C shows the concept of load estimation.
Focusing on the motion that is aggregated to 6 degrees of freedom (swing of the floating facility), the bending, torsion, shearing and axial load are estimated from the motion. This six-degree-of-freedom motion is pitching, rolling, yawing, heaving, swaging, and surging.
Specifically, the method for estimating the bending, torsional and shearing load first calculates the inertial force and the mooring force from the motion of 6 degrees of freedom, and calculates the load due to the inertial force and the mooring force. Since the mechanical conditions are not satisfied as they are, external forces such as wave forces are estimated (assumed) so as to satisfy the mechanical conditions. Thereby, a reasonable load can be easily estimated.
In addition, when a unit load of bending, twisting, and shear load of the whole structure is applied, the stress generated at the weak point (monitoring point) on the structure is obtained by structural analysis.
When selecting structural weak points (monitoring points), refer to past cases of damage at similar land facilities and other cases of floating structures, and consider the actual structure of the floating facilities. .

FIG. 2 is a block diagram showing a load / stress monitoring system according to the present embodiment.
In the present embodiment, an offshore wind power generation facility is shown as the floating facility 10.
A floating facility (offshore wind power generation facility) 10 includes a lower structure 11, a tower 12, a nacelle 13, and a rotor 14, and the lower structure 11 is a floating structure having buoyancy, and is a floating structure moored with a mooring line. Is an offshore wind power generation facility. However, it may be a floating facility other than the offshore wind power generation facility.

  The load / stress monitoring system according to the present embodiment includes a measuring unit 21 that measures an index relating to the entire behavior of the floating body facility 10 including the floating body motion and / or weather / sea conditions during operation of the floating body facility 10, and the measuring unit 21. Load / stress estimation means 31 for estimating the load / stress of the plurality of monitoring parts 15a, 15b, 15c in the floating facility 10 based on the measured values of the floating body 10, and output means 32 for outputting the estimation result of the load / stress estimation means 31; It has.

The measuring means 21 is provided in the floating facility 10.
The measuring means 21 includes, for example, a gyro sensor that measures pitching, rolling, and yawing of the floating facility 10, and an accelerometer that measures heaving, swaging, and surging. That is, the floating body motion during operation of the floating body facility 10 is a motion (floating body) that is measured by a gyro sensor and an accelerometer and is aggregated in six degrees of freedom of pitching, rolling, yawing, heaving, swaying, and surging. Facility upset).
The weather / sea conditions are measured by a measuring means 21 such as an anemometer, anemometer, and wave height meter. The overall behavior of the floating facility 10 may be governed by an index that affects the behavior of the floating facility 10 due to wind direction, wind speed, wave height, and the like, in addition to the fluctuation of the floating facility due to six degrees of freedom. Therefore, it is possible to estimate in real time the loads and stresses of the plurality of monitoring parts 15a, 15b, and 15c of the floating facility 10 by measuring the indicators related to the overall behavior of the floating facility 10 including the weather and sea conditions. .
The monitoring part 15a is, for example, an opening of the tower 12, the monitoring part 15b is, for example, an intersection of internal reinforcement members of the tower 12, and the monitoring part 15c is, for example, an end part of the internal reinforcement member of the lower structure 11.

According to the load / stress monitoring system according to the present embodiment, the load / stress on the monitoring sites 15a, 15b, 15c, that is, a number of structural weak points, can be measured only by measuring the fluctuation of the floating facility 10, weather, sea conditions, and the like. It is possible to estimate and monitor without comprehensive and instant measurement.
In addition, the measurement result of the indicator related to the overall behavior of the floating facility 10 during the operation of the floating facility 10 or the measurement result of the indicator related to the overall behavior of the floating facility 10 including the weather and sea conditions is used independently, respectively. 15b, 15c can be estimated in real time, or a combination of both can be used. By combining and using the measurement result of the index related to the whole behavior due to the floating body motion and the measurement result of the index related to the whole behavior including the weather and sea conditions, the load / stress can be estimated more accurately.

The load / stress monitoring system according to the present embodiment includes a history recording unit 33 for recording a history of estimated values of loads / stresses, and a plurality of monitoring based on the history of estimated values of loads / stresses recorded by the history recording unit 33. The fatigue remaining life evaluation means 34 for evaluating the fatigue remaining life of the parts 15a, 15b, 15c, the estimated value of load / stress by the load / stress estimation means 31 and / or the evaluation value of the fatigue remaining life by the fatigue remaining life evaluation means 34 The operation of the floating facility 10 is controlled on the basis of the estimated value of the load / stress by the alarm means 35 for performing an alarm based on the load / stress estimation means 31 and / or the estimated value of the remaining fatigue life by the fatigue remaining life evaluation means 34. Operation control means 22 is further provided.
The operation control means 22 is provided in the floating facility 10.

By providing the history recording means 33, it is possible to predict a number of weak spots in the future from the time-series estimated values of loads and stresses recorded in the history recording means 33.
In the history recording unit 33, in addition to the time-series estimated values of the load / stress, it is also possible to record the history of the measurement results of the indicators related to the floating body motion and the overall behavior measured by the measuring unit 21. For example, it is possible to predict a typhoon from the records and current values of the floating body motion, wind direction, wind speed, wave height, etc. of the floating facility 10, and to predict future load / stress time-series estimated values more accurately.
Further, by providing the fatigue remaining life evaluation means 34, the remaining life in the monitoring portions 15a, 15b, and 15c can be evaluated for each portion from the recorded time-series estimated values of the load / stress.
Further, by providing the alarm means 35, it is possible to notify a dangerous state by an alarm, and it is possible to ensure future safety.
In addition, by providing the operation control means 22, it is possible to change to an operation condition that avoids danger before entering the dangerous state.

The load / stress estimation means 31, the output means 32, the history recording means 33, the fatigue remaining life evaluation means 34, and the alarm means 35 are preferably provided in a place separated from the floating facility 10, for example, a plurality of floating bodies installed offshore. The facility 10 can be monitored on land. Information can be transmitted and received between the separated locations and the plurality of floating facilities 10 using wireless communication or submarine cables.
The fatigue life assessment means 34 preferably determines the time of inspection and maintenance based on the monitoring parts 15a, 15b, 15c having the smallest fatigue life remaining out of the monitoring parts 15a, 15b, 15c, and an unnecessary surplus. It is possible to reasonably determine the timing of maintenance and inspection without setting safety.
Further, it is preferable that the load / stress estimation means 31 and / or the remaining fatigue life evaluation means 34 predict a future change in the load / stress and / or remaining fatigue life from the time series tendency of the estimated value of the load / stress. By predicting the load / stress and fatigue life expectancy in the future, it is possible to deal with it accurately before entering a hazardous state.

  In the maintenance inspection, since it is rare that a person is resident in the floating facility 10, the maintenance inspection person, equipment, replacement parts, etc. are usually transported from a nearby port by ship to perform the maintenance inspection. In particular, when a typhoon is approaching, it is not possible to leave a ship for maintenance and inspection, so it is important to make a future prediction of the fatigue life expectancy and conduct an early inspection. For this reason, it is preferable to use global-scale weather information in addition to the prediction of the typhoon from the records and current values of the floating body movement, wind direction, wind speed, wave height, etc. of the floating body facility 10.

FIG. 3 shows an example of a prediction method based on the time series tendency of the stress estimated value according to the present embodiment. In FIG. 3, the horizontal axis represents time, the vertical axis represents stress, and the estimated value (section A) up to the present is represented by a solid line. A one-dot broken line B in FIG. 3 is a prediction based on the section A, and indicates that an allowable value is reached at the estimated time C. Such graph display can be performed by the output means 32.
In the state shown in FIG. 3, an alarm is issued by the alarm means 35 a predetermined time before the estimated time C. Further, before reaching the estimated time C, the operation control means 22 controls, for example, the direction of the nacelle 13 and / or the blade angle of the rotor 14 so that the stress does not exceed the allowable value.

  In the load / stress monitoring method according to the present embodiment, the fatigue / lifetime of the monitoring parts 15a, 15b, 15c is evaluated based on the history of the estimated values of the load / stress, thereby estimating the time series of the load / stress. From the value, the remaining lifetime at a number of weak spots can be evaluated for each part.

  Further, in the load / stress monitoring method according to the present embodiment, the timing of inspection and maintenance is determined based on the monitoring parts 15a, 15b, 15c having the least fatigue remaining life among the plurality of monitoring parts 15a, 15b, 15c. Therefore, it is possible to reasonably determine the maintenance inspection timing without setting unnecessary surplus safety.

  Further, in the load / stress monitoring method according to the present embodiment, by predicting future changes in the load / stress and / or fatigue life expectancy from the time-series trend of the estimated value of load / stress, before entering a dangerous state. Can be dealt with accurately.

  Further, in the load / stress monitoring method according to the present embodiment, an alarm is issued based on the estimated value of load / stress and / or the evaluation of the remaining fatigue life, so that a dangerous state can be notified by the alarm and future safety can be improved. It can be surely secured.

  Further, in the load / stress monitoring method according to the present embodiment, by controlling the operation of the floating facility 10 based on the estimated value of load / stress and / or the evaluation of the remaining fatigue life, the risk can be reduced before entering the dangerous state. It is possible to change to operating conditions to avoid.

  Further, in the load / stress monitoring method according to the present embodiment, the estimated values of the loads of the plurality of monitoring portions 15a, 15b, and 15c are calculated by calculating the inertial force and / or mooring force of the floating facility 10 from the floating body motion, A reasonable load can be estimated by obtaining an external force including a wave force so as to satisfy the condition.

  Further, in the load / stress monitoring method according to the present embodiment, the estimated stress values of the plurality of monitoring parts 15a, 15b, 15c are the conversion coefficients from the load to the stress obtained by the structural analysis for each of the monitoring parts 15a, 15b, 15c. Can be used to reasonably estimate the stress for each weak spot, that is, for each of the monitoring sites 15a, 15b, and 15c.

The load (cross-sectional force) generated in the plurality of monitoring parts 15a, 15b, and 15c of the floating facility 10 can also be obtained from the following formula (1) based on the time series data of the measured floating body motion.
Formula (1): {F _i } = [A _ij ] {x _j } + [B _ij ] {x _j ′} + [C _ij ] {x _j ′ ′}
However, {F _i } is a load, {x _j } is displacement, {x _j ′} is velocity, {x _j ′} is acceleration, [A _ij ], [B _ij ], and [C _ij ] are motion − The load correlation matrix, i is the type of load, and j is 6 degrees of freedom of floating body motion. By using the calculation formula thus defined, the load can be easily estimated.
As described above, the types of loads include bending, twisting, shearing, and axial force, and the six degrees of freedom of floating body motion are pitching, rolling, yawing, heaving, swaging, and surging.

Using the mathematical formula (1) as a basic formula, basically, an operation of identifying the motion-load correlation matrices [A _ij ], [B _ij ], [C _ij ] in the mathematical formula (1) is performed. Moreover, the numerical value of each matrix changes for every cross section of the monitoring site | part 15a, 15b, 15c to which attention is paid.
The procedure for _{obtaining the} motion-load correlation matrix [A _ij ], [B _ij ], [C _ij ] is as follows.
As Step 1, a response function of floating body motion and a load function of 6 degrees of freedom are obtained by a water tank test or numerical calculation. By using a water tank test or numerical calculation, a response function necessary for the calculation can be easily obtained in advance without using the actual floating facility 10.
As step 2, first and second derivative of the response function of floating body motion obtained in step 1 are prepared.
As Step 3, the response function of the load obtained in Step 1, the response function of the displacement based on the response function of the floating body motion, and the prepared first-order derivative and second-order derivative are respectively represented by {F _i } in Equation (1). _{, {x j}, {x} j '}, is substituted into _{x j''}, exercise by using the least square method - load correlation matrix _{[a ij], [B ij} ], the value of _{[C ij]} Is identified. As described above, the motion-load correlation matrices [A _ij ], [B _ij ], and [C _ij ] for obtaining different estimated values of loads depending on the monitoring parts 15a, 15b, and 15c can be easily obtained.
In addition, in the identification of each matrix, when sufficient approximation is obtained, it may be limited to the motion related to the target load. (For example, the moment about the Y axis may be limited to surging and pitching.) Also, in identifying the values of the motion-load correlation matrices [A _ij ], [B _ij ], [C _ij ]. In addition to the least square method, various approximation methods including a complement method can be used.

Further, as step 4, using the values of the motion-load correlation matrix [A _ij ], [B _ij ], [C _ij ] obtained in step 3 and time series data of actual floating body motion, a plurality of monitoring sites It is also possible to calculate time-series data of loads generated in the respective cross sections 15a, 15b, and 15c, and in this case, it is possible to know a tendency of loads generated in the floating facility 10.
The actual time series data of the floating body movement is obtained by measuring using a gyro sensor or an accelerometer as a measuring means provided in the floating body facility 10.

Moreover, the stress which arises in the some monitoring site | part 15a, 15b, 15c of the floating body facility 10 can also be calculated | required from the following Numerical formula (2) by implementing an elastic finite element analysis.
Formula (2): {σ _k } = [D _ki ] {f _i }
However, {σ _k } is a stress, {f _i } is a unit load, [D _ki ] is a load-stress correlation matrix, k is a monitoring site, and i is a load type. By using the calculation formula defined in this way, the stress can be easily estimated.

An operation of identifying the load-stress correlation matrix [D _ki ] in the formula (2) is basically performed using the formula (2) as a basic formula. Moreover, the numerical value of each matrix changes for every cross section of monitoring site | part 15a, 15b, 15c which evaluates stress.
The procedure for _{obtaining the} load-stress correlation matrix [D _ki ] is as follows.
As step 5, a finite element model including the monitoring parts 15a, 15b and 15c of the floating facility 10 (the monitoring parts 15a, 15b and 15c for evaluating the local stress are fine meshes) is created, and a unit load is applied to the model boundary.
As step 6, the stress in the monitoring parts 15a, 15b, 15c when the unit load is loaded is calculated, and the value of the load-stress correlation matrix [D _ki ] is identified. In this way, the load-stress correlation matrix [D _ki ] that obtains the estimated stress values that differ depending on the monitoring sites 15a, 15b, and 15c can be easily obtained.

Further, as step 7, using the value of the load-stress correlation matrix [D _ki ] obtained in step 6 and the time series data of the load calculated in step 4, monitoring when the estimated load acts as a cross-sectional force It is also possible to calculate the time series data of the stress generated in the parts 15a, 15b and 15c. In this case, the time series data of the stress can be calculated and the tendency of the stress generated in the floating facility 10 can be known.

Further, time-series data of the obtained stress to calculate the fatigue damage degree d _i based on at step 7, as represented by the following formula (3), monitoring site 15a, 15b, 15c cumulative fatigue damage of the D can be calculated.
Formula (3): D = Σd _i
The fatigue life expectancy can be evaluated by the difference between the current value of the cumulative fatigue damage degree D and the allowable value. That is, it is possible to evaluate the remaining life at a number of weak spots for each part from time-series estimated values of load and stress, and to predict the danger before entering a dangerous state.
Note that (several hours such a day) when the monitoring time is limited, and appropriately correct the d _i obtained during monitoring time is substituted into equation (3).

  Note that the load estimation method using Equation (1), the stress estimation method using Equation (2), and the cumulative fatigue damage degree D estimation method using Equation (3) are different from each other. Any combination of the estimation methods can be used.

  The load / stress monitoring method and the load / stress monitoring system for a floating facility according to the present invention can be used, for example, in an offshore wind power generation facility.

10 Floating facilities (offshore wind power generation facilities)
DESCRIPTION OF SYMBOLS 11 Substructure 12 Tower 13 Nacelle 14 Rotor 15a, 15b, 15c Monitoring part 21 Measuring means 22 Operation control means 31 Load / stress estimation means 32 Output means 33 History recording means 34 Fatigue remaining life evaluation means 35 Alarm means

Claims (25)

  Estimating loads or stresses of a plurality of monitoring parts of the floating facility in real time based on measurement of indices related to the overall behavior of the floating facility including floating body motion and / or weather / sea conditions during operation of the floating facility A load / stress monitoring method for floating facilities.   The load / stress monitoring method for a floating facility according to claim 1, wherein the index relating to the floating body motion and / or the overall behavior is obtained by measuring with a measuring unit provided in the floating facility.   The load / stress monitoring method for a floating facility according to claim 1 or 2, wherein a fatigue life expectancy of a plurality of the monitoring parts is evaluated based on a history of estimated values of the load or the stress.   4. The load / stress monitoring method for a floating facility according to claim 3, wherein the inspection / maintenance time is determined based on the monitoring part having the least remaining fatigue life among the plurality of monitoring parts.   The floating body according to claim 3 or 4, wherein a future change of the load or the stress and / or the fatigue life is predicted from a time series tendency of the estimated value of the load or the stress. Facility load / stress monitoring method.   6. The load / stress monitoring of a floating facility according to claim 3, wherein an alarm is issued based on the estimated value of the load or the stress and / or the evaluation value of the fatigue life expectancy. Method.   The floating facility according to any one of claims 3 to 6, wherein operation of the floating facility is controlled based on the estimated value of the load or the stress and / or an evaluation value of the fatigue life expectancy. Load / stress monitoring method.   The estimated value of the load of the plurality of monitoring parts is obtained by calculating an inertial force of the floating facility from the floating body motion and / or the overall behavior, and assuming an external force including a wave force so as to satisfy a mechanical condition. The load / stress monitoring method for a floating facility according to any one of claims 1 to 7. The estimated value of the stress of the plurality of monitoring parts uses a conversion coefficient from load to stress obtained by structural analysis for each of the monitoring parts. Load / stress monitoring method for floating body facilities. The load / stress monitoring method for a floating facility according to claim 1 or 2, wherein the estimated values of the loads of the plurality of monitoring parts are obtained based on the following mathematical formula (1).
Formula (1): {F _i } = [A _ij ] {x _j } + [B _ij ] {x _j ′} + [C _ij ] {x _j ′ ′}
However, {F _i } is a load, {x _j } is displacement, {x _j ′} is velocity, {x _j ′} is acceleration, [A _ij ], [B _ij ], and [C _ij ] are motion − The load correlation matrix, i is the type of load, and j is 6 degrees of freedom of floating body motion. The motion-load correlation matrix is
Determining a response function of the floating body motion and a response function of the load with six degrees of freedom; and
Preparing a first and second derivative of the response function of the floating body motion;
Substituting the response function of the load, the response function of the displacement based on the response function of the floating body motion, and the prepared first-order derivative and the second-order derivative into Equation (1), The load / stress monitoring method for a floating facility according to claim 10, wherein the value is obtained by step 3 of identifying a value.   Step 4 of calculating the time series data of the load generated in each cross section of the plurality of monitoring sites using the value of the motion-load correlation matrix obtained in Step 3 and the time series data of the actual floating body motion. The load / stress monitoring method for a floating facility according to claim 11, further comprising:   The load / stress monitoring method for a floating facility according to claim 11 or 12, wherein the response function of the floating body motion and the response function of the load are obtained by a water tank test or numerical calculation. 14. The estimated value of the stress of the plurality of monitoring parts is obtained based on the following mathematical formula (2), wherein the estimated value of the stress is any one of claims 1, 2, or 10 to 13. Load / stress monitoring method for floating facilities.
Formula (2): {σ _k } = [D _ki ] {f _i }
However, {σ _k } is a stress, {f _i } is a unit load, [D _ki ] is a load-stress correlation matrix, k is a monitoring site, and i is a load type. The load-stress correlation matrix is
Creating a finite element model including the monitoring site of the floating facility and applying a unit load to the model boundary; and
15. The load / stress monitoring of a floating facility according to claim 14, wherein the stress at the monitoring part at the time of loading the unit load is calculated and obtained in step 6 of identifying a value of the load-stress correlation matrix. Method.   Using the value of the load-stress correlation matrix obtained in step 6 and the time-series data of the load calculated in step 4, the estimated load generated in the monitoring site when acting as a cross-sectional force 16. The load / stress monitoring method for a floating facility according to claim 15, further comprising step 7 of calculating time series data of stress.   The fatigue damage level is calculated based on the time series data of the stress obtained in step 7, the cumulative fatigue damage level of the monitoring site is calculated, and the difference between the current value and the allowable value of the cumulative fatigue damage level is calculated. 17. The method for monitoring the load / stress of a floating facility according to claim 16, wherein the remaining fatigue life is evaluated.   Measuring means for measuring an index relating to the overall behavior of the floating facility including floating body motion and / or weather / sea conditions during operation of the floating facility, and a plurality of monitoring in the floating facility based on the measurement value of the measuring means A load / stress monitoring system for a floating facility, comprising: load / stress estimation means for estimating a load or stress of a part; and output means for outputting an estimation result of the load / stress estimation means.   19. The load / stress monitoring system for a floating facility according to claim 18, further comprising history recording means for recording a history of the estimated value of the load or the stress.   Further comprising fatigue remaining life evaluating means for evaluating fatigue remaining lives of a plurality of the monitoring parts based on the history of the estimated value of the load or stress recorded by the history recording means. The load / stress monitoring system for a floating facility according to claim 19.   21. The load of a floating facility according to claim 20, wherein the fatigue life expectancy evaluation means determines a time for inspection and maintenance based on the monitoring part having the smallest fatigue remaining life among the monitoring parts.・ Stress monitoring system.   The load / stress estimation means and / or the fatigue remaining life evaluation means predict a future change of the load or stress and / or the fatigue remaining life from a time series tendency of the estimated value of the load or the stress. The load / stress monitoring system for a floating facility according to claim 20 or 21, characterized in that:   The apparatus further comprises alarm means for issuing an alarm based on the estimated value of the load or stress by the load / stress estimating means and / or the evaluation value of the fatigue life expectancy by the fatigue remaining life evaluation means. The load / stress monitoring system for a floating facility according to any one of claims 20 to 22.   Operation control means for controlling the operation of the floating facility based on the estimated value of the load or stress by the load / stress estimation means and / or the evaluation value of the fatigue life expectancy by the fatigue remaining life evaluation means The load / stress monitoring system for a floating facility according to any one of claims 20 to 23, wherein the system is provided.   The floating body according to any one of claims 20 to 24, wherein the load / stress estimation means and / or the fatigue remaining life evaluation means and the output means are provided at a location separated from the floating body facility. Facility load / stress monitoring system.