Maintenance support device and maintenance support method

Abstract

To determine a measurement method and an inspection period for a plant, taking an error in an amount of deterioration into consideration.SOLUTION: A maintenance assisting device according to the present invention includes: a malfunction distribution function creation unit that creates a failure distribution function indicating a relation between a malfunction probability of the plant and time, based on a deterioration function indicating a relation between an amount of deterioration of the plant and time and based on an excess portion exceeding a predetermined allowable amount of deterioration in a sum of a probability distribution of an error between a measured value of the amount of deterioration and a real value of the amount of deterioration; and an inspection period calculation unit that calculates, as an inspection period for the plant, a time corresponding to a predetermined allowable malfunction probability in the malfunction distribution function.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a maintenance support device and a maintenance support method. [Background technology]

[0002] Large-scale plants such as chemical plants, oil plants, and power plants are composed of numerous pieces of mechanical equipment, each of which is subject to periodic inspections. Appropriately determining the periodic inspection interval (frequency) is important from the perspective of stable plant operation and cost reduction. If the interval is extremely short, the inspection costs will increase, but the probability of a malfunction occurring before the next inspection will decrease. On the other hand, if the interval is extremely long, the inspection costs will decrease, but the probability of a malfunction occurring will increase. Furthermore, in this case, malfunctions often occur suddenly, and, combined with the size and complexity of the plant, the restoration costs and opportunity losses due to plant shutdowns will increase by orders of magnitude.

[0003] Recently, technology for using computers to create plant maintenance plans has become widespread. The plant inspection plan optimization device described in Patent Document 1 expresses the variability in plant operation as a probability distribution, and estimates the amount of deterioration taking into account the variability in plant operation in combination with the probability distribution of the deterioration state of the plant at the time of the previous inspection, thereby optimizing the plant inspection plan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-77296 Summary of the Invention [Problem to be solved by the invention]

[0005] Measured values ​​of deterioration amounts always contain errors. However, the plant inspection plan optimization device of Patent Document 1 does not take into account the error between the true value and the measured value of the deterioration amount. Therefore, when there are multiple methods for measuring the deterioration amount (options for which deterioration amount to measure) and the errors for each method are different, a separate measure is required to select the measurement method. Therefore, an object of the present invention is to determine the measurement method and inspection interval of a plant by taking into account the error in the deterioration amount. [Means for solving the problem]

[0006] The maintenance support device of the present invention comprises: a failure distribution function creating unit that creates a failure distribution function that indicates the relationship between a deterioration amount of a plant and time, based on a deterioration function that indicates the relationship between a deterioration amount of the plant and time, and based on an excess portion that exceeds a predetermined allowable deterioration amount in the sum of a probability distribution of an error between a measured value of the deterioration amount and a true value of the deterioration amount and the deterioration amount indicated by the deterioration function; and an inspection cycle calculation unit that calculates a time corresponding to a predetermined allowable failure probability in the failure distribution function as an inspection cycle for the plant. a cost calculation unit that calculates an average cost for each method of measuring the deterioration amount when the inspection cycle is extended, using the inspection cycle, a first cost spent to perform a normal inspection of the plant if the plant is not broken during the inspection cycle, a second cost spent to restore the plant if the plant is broken during the inspection cycle and a third cost as an opportunity loss due to the shutdown of the plant, and a fourth cost for obtaining a deterioration amount of the plant, and divides the sum of the first cost, the second cost, the third cost, and the fourth cost by an average value of time until the plant is inspected; and a maintenance method determination unit that determines the measurement method that reduces the average cost to a level that satisfies a predetermined standard. The present invention is characterized by comprising: Other means will be described in the detailed description of the invention. [Effects of the Invention]

[0007] According to the present invention, it is possible to determine the measurement method and inspection interval of a plant taking into consideration errors in the amount of deterioration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating a configuration of a maintenance support device. [Figure 2] FIG. 10 is a diagram illustrating the amount of deterioration over time. [Figure 3] FIG. 10 is a diagram illustrating an error probability distribution. [Figure 4] FIG. 10 is a diagram illustrating the relationship between a degradation function and an error probability distribution. [Figure 5] FIG. 10 is a diagram illustrating a failure distribution function. [Figure 6]FIG. 10 is a diagram illustrating an inspection cycle. [Figure 7] FIG. 10 is a diagram illustrating the relationship between a degradation function and an error probability distribution. [Figure 8] FIG. 10 is a diagram illustrating a failure distribution function. [Figure 9] FIG. 10 is a diagram illustrating an inspection cycle. [Figure 10] 10 is a flowchart of a measurement method and inspection period determination process. [Figure 11] 10 is a flowchart of a target error calculation process procedure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings, etc. In this embodiment, first, a combination of a deterioration amount measurement method and an inspection interval that minimizes costs is determined. There are many candidates for the deterioration amount measurement method, but the greater the variation (e.g., variance) in the deterioration amount, the greater the cost. Therefore, in this embodiment, the maximum variation that allows inspection to be performed at a cost lower than the target cost is calculated.

[0010] The types and quantities of equipment that make up a plant vary. In some cases, the types and quantities reach tens of thousands, while in other cases, the plant is made up of a single piece of equipment. In the former case, if a specific key piece of equipment stops, the entire plant may stop. In this embodiment, the term "plant" is a broad concept that includes both a collection of equipment and a single piece of equipment.

[0011] (Configuration of maintenance support device) Figure 1 is a diagram illustrating the configuration of a maintenance support device. The maintenance support device 1 is a general-purpose computer, and includes a central control unit 11, an input device 12 such as a mouse or keyboard, an output device 13 such as a display, a main memory device 14, and an auxiliary memory device 15. These are interconnected by a bus. The auxiliary memory device 15 stores a time-series degradation amount 31, an error probability distribution 32, an allowable degradation amount 33, an allowable failure probability 34, a maintenance cost 35, a measurement cost 36, and a target cost 37 (details will be described later).

[0012] The failure distribution function creation unit 21, inspection cycle calculation unit 22, cost calculation unit 23, maintenance method determination unit 24, and target error calculation unit 25 in the main memory device 14 are programs. The central control unit 11 reads these programs from the auxiliary memory device 15 and loads them into the main memory device 14, thereby realizing the functions of each program (described in detail later). The auxiliary memory device 15 may be configured independent of the maintenance support device 1.

[0013] (Time series deterioration amount) FIG. 2 is a diagram for explaining the time-series deterioration amount 31. The time-series deterioration amount 31 is a time-series representation of the deterioration amount of a certain plant obtained from past tests, etc. The time-series deterioration amount 31 exists for each measurement method. The time on the horizontal axis is the elapsed time since the start of service of that part of the plant or the last maintenance. A specific example of the deterioration amount on the vertical axis will be described immediately below.

[0014] When measurement method 1 is "wall thickness measurement using an ultrasonic measuring instrument," the amount of deterioration is the measured wall thickness of a pipe minus the reference wall thickness (the increase due to the adhesion of impurities, etc.). The reference wall thickness is, for example, the wall thickness of the pipe immediately after it was put into service or immediately after the previous maintenance.

[0015] When measurement method 2 is "frequency measurement using a vibration measuring instrument," the amount of deterioration is the value obtained by subtracting the reference frequency from the measured frequency of a pump (the increase due to wear of the rotating shaft). The reference frequency is, for example, the frequency immediately after the pump was put into service or immediately after the previous maintenance.

[0016] When measurement method 3 is "temperature measurement using a thermometer," the deterioration amount is the measured temperature of a container minus the reference temperature (the increase due to a decline in cooling function). The reference temperature is, for example, the temperature immediately after the container was put into service or immediately after the last maintenance.

[0017] The amount of deterioration is not limited to an increase. A decrease can also be considered as the amount of deterioration. For example, if measurement method 4 is "pressure measurement using a pressure gauge," the amount of deterioration is the value obtained by subtracting the measured pressure from the reference pressure in a certain container (the decrease due to a deterioration in sealing function). The reference pressure is, for example, the pressure immediately after the container was put into service or immediately after the previous maintenance.

[0018] Hereinafter, for the sake of convenience, in the examples of measurement methods 1 to 3, the "value obtained by subtracting the reference value from the measured value of XX at a certain XX" will be referred to as the "measured value of the amount of deterioration."

[0019] The many time-series "●" marks in Figure 2 indicate the amount of degradation at each time. The degradation function 41 shows the relationship between time and the amount of degradation. The degradation function 41 is a regression curve that minimizes the sum of the squares of the distances from the ● marks. The degradation function 41 is usually an upward-sloping curve that passes through the origin.

[0020] (True and measured values) The measured value includes an error. The error is a value obtained by subtracting the true value of the degradation amount from the measured value of the degradation amount. If the measured value is larger than the true value, the error is a positive value, and if the measured value is smaller than the true value, the error is a negative value. The true value is a measurement value obtained by a measurement method that measures the degradation amount with higher accuracy than a certain measurement method. Alternatively, the true value may be the degradation amount output by the degradation function 41 as a result of inputting a certain time into the degradation function 41 (an estimated value by the degradation function 41).

[0021] (Error probability distribution) Fig. 3 is a diagram illustrating the error probability distribution 32. To the left of the black arrow in Fig. 3 are the time-series degradation amount 31 and degradation function 41 in Fig. 2. In the following, as an example, the value obtained by subtracting the true value (the degradation value at that time on the degradation function 41) from the measured value of the degradation amount at each time (the degradation amount indicated by ●) is defined as the "error." If we ignore whether the error is positive or negative, the length of each dashed line in Fig. 3 is the error.

[0022] To the right of the black arrow in FIG. 3 is the error probability distribution 32. The error probability distribution 32 is a probability distribution of errors. An error probability distribution 32 exists for each measurement method. In many cases, each error probability distribution 32 can be approximated by a normal distribution defined by a mean and a variance. The error probability distribution 32 is affected by the measurement method, the accuracy of the measuring instrument, the proficiency of the operator operating the measuring instrument, and the like. Of course, the error probability distribution 32 may also be affected by the cumulative operating time of the plant, and the like. However, the error probability distribution 32 in this embodiment is not affected by the cumulative operating time, and the like.

[0023] (Deterioration function and error probability distribution) 4 is a diagram illustrating the relationship between a degradation function and an error probability distribution. Error probability distributions 32a, 32b, and 32c are superimposed horizontally at each time point (three times in the figure) of a degradation function 41. The unit of the error probability distribution (the vertical axis on the right side of FIG. 3) is the unit of the degradation amount, so the error probability distribution at that time point can be added to or subtracted from the degradation amount at each time point on the degradation function 41. As mentioned above, the mean and variance of error probability distribution 32 are the same regardless of the position of the horizontal axis. The allowable deterioration amount 33 (dotted line) is the amount of deterioration beyond which the plant will break down, and is set in advance by the specifications of the plant manufacturer, etc.

[0024] In the error probability distributions 32a, 32b, and 32c, excess portions 39 that exceed the allowable degradation amount 33 are shaded. The area of ​​this shaded portion (excess portion 39) is defined as the failure probability at that time. At the time of error probability distribution 32a, the failure probability is almost "0." At the time of error probability distribution 32b, the failure probability is a value slightly below "0.5." At the time of error probability distribution 32c, the failure probability is a value slightly above "0.5." In other words, the failure probability is the excess portion 39 that exceeds the predetermined allowable degradation amount out of the sum of the error probability distribution and the degradation amount indicated by the degradation function.

[0025] (Probability distribution of errors and probability distribution of deterioration amount) The error probability distribution is different from the probability distribution of the deterioration amount. The mean and variance of the error probability distribution are smaller than those of the deterioration amount, respectively, by the amount that the true value of the deterioration amount is subtracted from the measured value of the deterioration amount. The probability distribution of the deterioration amount is significantly affected not only by errors caused by differences in measurement methods and measurement proficiency, but also by operational instability caused by plant deterioration. If the error is not clear, evaluating the probability distribution of the deterioration amount ultimately amounts to evaluating the operational instability of the plant.

[0026] On the other hand, evaluating the probability distribution of the error directly evaluates only the error resulting from differences in measurement methods, differences in the level of measurement proficiency, etc. In other words, if the deterioration function 41 oscillates over time when viewed microscopically, the oscillations are all considered to be the result of instability in the plant operation and are then ignored, and the measurement method is determined mainly by evaluating the error, which is a feature of this embodiment.

[0027] (Failure distribution function) FIG. 5 is a diagram explaining the failure distribution function. The failure distribution function 51 shows the relationship between time and failure probability. The horizontal axis of the failure distribution function 51 is time, and the vertical axis is the failure probability (area of ​​the shaded portion) in FIG. 4. In other words, the height of the rectangle below the failure distribution function 51 is the failure probability at that time in FIG. 4. The failure distribution function 51 is usually an upward-sloping curve that passes through the origin and asymptotically approaches a failure probability of 1.0.

[0028] (Allowable failure probability) The user of the plant calculates an expected value E of the opportunity loss when the plant stops based on past values such as the production capacity of the plant, the unit price of products, etc., the recovery time at the time of stoppage, and the recovery cost of the plant. On the other hand, the user determines an upper limit U of the allowable opportunity loss based on the projected settlement, the insured amount with damage insurance, etc. The result P (0 < P < 1) obtained by dividing the upper limit U by the expected value E is the allowable failure probability. The above-mentioned allowable deterioration amount 33 is set by the manufacturer of the plant based on a technical perspective. In contrast, the allowable failure probability is set by the user of the plant based on a business perspective. Incidentally, here the expected value E is a concept different from "Ce" in Equation 1 described later. However, for the convenience of calculation, the two may be regarded as the same.

[0029] (Inspection period) FIG. 6 is a diagram for explaining the inspection period. In FIG. 6, the same failure distribution function 51 and the allowable failure probability 34 (dashed line) as in FIG. 5 are shown. The time between the time corresponding to the intersection point 53 of the failure distribution function 51 and the allowable failure probability 34 and the origin is the inspection period 52 (Tn). An example where the user does not set the allowable failure probability 34 will be described later.

[0030] Even if the deterioration function 41 is the same, if the variance of the error probability distribution 32 changes, the position and shape of the failure distribution function 51 will change. This will be explained in FIGS. 7 to 8.

[0031] FIG. 7 is also a diagram for explaining the relationship between the deterioration function and the error probability distribution. However, the variances of the error probability distributions 32d, 32e, and 32f in FIG. 7 are smaller than the variances of the error probability distributions 32a, 32b, and 32c (error probability distribution 32) in FIG. 4. The allowable deterioration amount 33 in FIG. 7 is the same as the allowable deterioration amount 33 in FIG. 4. Furthermore, as described above, even in FIG. 7, regardless of the position of the horizontal axis, the shape of the error probability distribution 32 is the same. Then, the failure probability in FIG. 7 (the excess part 39 which is the area of the shaded part) is smaller than the failure probability in FIG. 4 (the excess part 39 which is the area of the shaded part).

[0032] FIG. 8 is also a diagram for explaining the failure distribution function. However, the failure distribution function 51b in FIG. 8 has a smaller failure probability at the same time (located further down the diagram) than the failure distribution function 51 in FIG. 5 (dashed line 51 in FIG. 8). This is because the failure probability is smaller in FIG. 7. Ultimately, the failure distribution function 51 includes "variance" as a parameter in addition to the variables of time and failure probability, and the value of the variance determines the position and shape of the failure distribution functions 51 and 51b.

[0033] FIG. 9 is also a diagram illustrating the inspection period. The tolerable failure probability 34 in FIG. 9 is the same as the tolerable failure probability 34 in FIG. 6. Because the failure distribution function 51b has shifted downward compared to the failure distribution function 51 in FIG. 6 (the dashed line 51 in FIG. 9), the intersection 53b between the failure distribution function 51b and the tolerable failure probability 34 moves to the right compared to the intersection 53 in FIG. 6. As a result, the inspection period 52b is longer than the inspection period 52 in FIG. 6.

[0034] (cost) Maintenance cost 35 (Figure 1) consists of normal inspection cost Cm and breakdown cost Ce. Normal inspection cost Cm is the cost of performing a normal inspection when no plant failure has occurred at time Tn. Breakdown cost Ce is the sum of the cost of restoring the plant when a plant failure has occurred at time Tn and the cost (opportunity loss) associated with shutting down the plant. Measurement cost 36 (Figure 1) is also referred to as measurement cost Ca. Measurement cost Ca is the cost of measuring the amount of deterioration. Normal inspection cost Cm, breakdown cost Ce, and measurement cost Ca are set for each measurement method.

[0035] The average cost C(Tn) when the inspection interval is extended is calculated by the following formula 1. "F(Tn)" is the failure distribution function 51 described above.

number

[0036] The first term in the numerator on the right side of Equation 1 is the normal inspection cost Cm multiplied by the probability "1-F(Tn)" that no failure has occurred at time Tn. The second term in the numerator on the right side of Equation 1 is the failure cost Ce multiplied by the probability "F(Tn)" that a failure has occurred at time Tn. The third term in the numerator on the right side of Equation 1 is the measurement cost Ca mentioned above. The denominator on the right side of Equation 1 is the average time until inspection, which is simulated here by the integral value of "1-F(t)" from "0" to "Tn".

[0037] (Measurement method and inspection period determination procedure) FIG. 10 is a flowchart of the measurement method and inspection period determination process. In step S101, the failure distribution function creating unit 21 of the maintenance support device 1 creates the deterioration function 41. Specifically, the failure distribution function creating unit 21 creates the deterioration function 41 by the method described with reference to FIG.

[0038] In step S102, the failure distribution function creating unit 21 calculates an error. Specifically, the failure distribution function creating unit 21 calculates the error described in the left diagram of FIG. In step S103, the failure distribution function creation unit 21 creates an error probability distribution. Specifically, the failure distribution function creation unit 21 uses the error calculated in step S102 to create the error probability distribution 32 described on the right side of FIG. 3.

[0039] In step S104, the failure distribution function creation unit 21 creates the failure distribution function 51. Specifically, the failure distribution function creation unit 21 creates the failure distribution function 51 using the given allowable degradation amount 33, the degradation function 41 created in step S101, and the error probability distribution 32 created in step S103.

[0040] 4, the failure distribution function 21 adds (or subtracts) the error probability distribution to any point on the deterioration function 41, and creates a failure distribution function 51 based on an excess portion 39 (shaded portion) of the addition result that exceeds the allowable deterioration amount 33. That is, in steps S101 to S104, the failure distribution function creation unit 21 creates the failure distribution function based on the deterioration function that indicates the relationship between the deterioration amount of the plant and time, and also based on an excess portion 39 that exceeds a predetermined allowable deterioration amount of the sum of the deterioration amount indicated by the deterioration function and the probability distribution of the error between the measured value of the deterioration amount and the true value of the deterioration amount.

[0041] In step S105, the inspection cycle calculation unit 22 of the maintenance support device 1 calculates the inspection cycle. Specifically, the inspection cycle calculation unit 22 calculates the inspection cycle 52 (FIG. 6) using the given tolerable failure probability 34 and the failure distribution function 51 created in step S104. The inspection cycle calculated here is referred to as "Tn."

[0042] In step S106, the cost calculation unit 23 of the maintenance support device 1 calculates the average cost. Specifically, the cost calculation unit 23 calculates the average cost C(Tn) by substituting "Tn" calculated in step S105 into the right side of Formula 1. Note that the regular inspection cost Cm, the breakdown cost Ce, and the measurement cost Ca in Formula 1 are given.

[0043] Steps S101 to S106 are repeated for all measurement methods. When the repeated processing is completed, the cost calculation unit 23 temporarily holds the average costs C(Tn) for all measurement methods.

[0044] In step S107, the maintenance method determination unit 24 of the maintenance support device 1 displays the measurement method and inspection interval. Specifically, the maintenance method determination unit 24 determines the measurement method and its inspection interval Tn that have the smallest average cost C(Tn), and displays them on the output device 13. The maintenance method determination unit 24 may determine a measurement method and its inspection interval Tn that reduces the average cost C(Tn) to a degree that satisfies a predetermined standard, even if it is not the smallest. Thereafter, the measurement method and inspection interval determination processing procedure ends.

[0045] (Modification of measurement method and inspection period determination procedure) The following is a change to the measurement method and inspection period determination process procedure when the user has not set the allowable failure probability 34 in advance. In step S105, the inspection cycle calculation unit 22 randomly generates candidates for the tolerable failure probability 34. Steps S105 and S106 are performed for each of the randomly generated candidates. In step S107, the maintenance method determination unit 24 displays on the output device 13 the measurement method with the smallest average cost C(Tn) and its inspection cycle Tn, and further displays the allowable failure probability 34 corresponding to that smallest average cost.

[0046] (Target error calculation procedure) FIG. 11 is a flowchart of the target error calculation process. In step S201, the target error calculation unit 25 of the maintenance support device 1 receives a target value of the average cost. Specifically, the target error calculation unit 25 receives the target value C of the average cost C(Tn) input by the user via the input device 12. The target error calculation unit 25 may obtain a target value that has already been stored as the target cost 37 in the auxiliary storage device 15.

[0047] In step S202, the target error calculation unit 25 accepts an initial value of the error variance input by the user via the input device 12. The error variance is affected by the measurement method, the accuracy of the measuring instrument, the uniformity of the proficiency of the workers who operate the measuring instrument, etc. In many cases, the user inputs an initial value corresponding to the uniformity of the current proficiency, etc. The target error calculation unit 25 may automatically generate the initial value without accepting an input from the user.

[0048] In step S203, the failure distribution function creating unit 21 of the maintenance support device 1 creates the deterioration function 41. Specifically, the failure distribution function creating unit 21 creates the deterioration function 41 by the method described with reference to FIG.

[0049] In step S204, the failure distribution function creating unit 21 creates an error probability distribution. Specifically, the failure distribution function creating unit 21 uses the initial value of the error variance received in step S202 and a predetermined error average to create the error probability distribution 32 described on the right side of Fig. 3. The "predetermined error average" here may be based on, for example, past examples (the actual results of the time-series deterioration amount 31).

[0050] In step S205, the failure distribution function creation unit 21 creates the failure distribution function 51. Specifically, the failure distribution function creation unit 21 creates the failure distribution function 51 using the given allowable degradation amount 33, the degradation function 41 created in step S203, and the error probability distribution 32 created in step S204.

[0051] As described above, the excess portion 39 exceeding the allowable degradation amount 33 is determined from the allowable degradation amount 33 and the error probability distribution 32 (see FIG. 4 etc.). In other words, when the failure distribution function creating unit 21 creates the failure distribution function 51 using the given allowable degradation amount 33, the degradation function 41 created in step S203, and the error probability distribution 32 created in step S204, this means that the failure distribution function creating unit 21 creates the failure distribution function 51 based on the degradation function 41 as well as based on the excess portion 39 exceeding the predetermined allowable degradation amount 32.

[0052] In step S206, the inspection cycle calculation unit 22 of the maintenance support device 1 calculates the inspection cycle. Specifically, the inspection cycle calculation unit 22 calculates the inspection cycle 52 (FIG. 6) using the given tolerable failure probability 34 and the failure distribution function 51 created in step S205. The inspection cycle calculated here is referred to as "Tn."

[0053] In step S207, the cost calculation unit 23 of the maintenance support device 1 calculates the average cost. Specifically, the cost calculation unit 23 calculates the average cost C(Tn) by substituting "Tn" calculated in step S206 into the right side of Formula 1. Note that the regular inspection cost Cm, the breakdown cost Ce, and the measurement cost Ca in Formula 1 are given.

[0054] In step S208, the target error calculation unit 25 of the maintenance support device 1 determines whether the average cost is smaller than the target value. Specifically, first, the target error calculation unit 25 compares the average cost C(Tn) calculated in step S207 with the target value Co received in step S201. Second, if the average cost C(Tn) is smaller than the target value C0 (step S208 "YES"), the target error calculation unit 25 retains the initial value of the variance and proceeds to step S210; otherwise (step S208 "NO"), the target error calculation unit 25 proceeds to step S209.

[0055] In step S209, the target error calculation unit 25 reviews the error variance. Specifically, the target error calculation unit 25 holds the result of subtracting a predetermined step size from the initial value of the variance accepted in step S202 as the reviewed variance, and returns to step S203.

[0056] In steps S203 to S208 after returning, the revised variance is used instead of the initial value. After steps S203 to S209 are repeated multiple times, when the process passes through "YES" in step S208, the target error calculation unit 25 of the maintenance support device 1 holds the latest (smallest) of the revised variances. In other words, the target error calculation unit 22 calculates the variance of the error probability distribution that makes the cost when the inspection cycle is extended smaller than the accepted target value.

[0057] In step S210, the target error calculation unit 25 displays the target value of the error variance. Specifically, the target error calculation unit 25 displays the temporarily stored initial value of the variance or the revised variance on the output device 13. Thereafter, the target error calculation process procedure ends.

[0058] (Effects of this embodiment) The maintenance support device of this embodiment has the following advantages. (1) The maintenance support device can calculate the inspection period of the plant corresponding to the tolerable failure probability of the plant. (2) The maintenance support device can determine a method for measuring the deterioration of the plant that minimizes the cost when the inspection interval is extended. (3) The maintenance support device can calculate the variance of the probability distribution of the error according to the target value of the cost.

[0059] (4) The maintenance support device can define the error for each measurement method using the true value of the deterioration amount. (5) The maintenance support device can set the amount of deterioration that will lead to a breakdown of the plant as the allowable deterioration amount, which is set by the plant manufacturer or the like. (6) The maintenance support device can calculate the tolerable failure probability based on the upper limit of loss that the plant user can tolerate and the expected amount of loss.

[0060] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0061] Furthermore, the above-mentioned configurations, functions, processing units, processing means, etc. may be partly or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-mentioned configurations, functions, etc. may also be implemented in software, with a processor interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD. In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0062] 1 Maintenance support equipment 11 Central control unit 12 Input Devices 13 Output Devices 14 Main memory 15 Auxiliary storage 21 Failure distribution function creation section 22 Inspection period calculation section 23 Cost Calculation Department 24 Maintenance method determination department 25 Target error calculation section 31 Time series deterioration 32 Error Probability Distribution 33 Allowable Deterioration 34 Acceptable failure probability 35 Maintenance Costs 36 Measurement Costs 37 Target Cost 39 Excess portion 41 Degradation Function 51 Failure distribution function

Claims

1. a failure distribution function creating unit that creates a failure distribution function that indicates the relationship between a deterioration amount of the plant and time, based on a deterioration function that indicates the relationship between time and a deterioration amount of the plant, and based on an excess portion that exceeds a predetermined allowable deterioration amount out of a sum of a probability distribution of an error between a measured value of the deterioration amount and a true value of the deterioration amount and the deterioration amount indicated by the deterioration function; an inspection cycle calculation unit that calculates a time corresponding to a predetermined allowable failure probability in the failure distribution function as an inspection cycle for the plant; a cost calculation unit that calculates, for each method of measuring the deterioration amount, an average cost obtained by dividing the sum of the first cost, the second cost, the third cost, and the fourth cost by an average value of time until an inspection of the plant when the inspection period is extended, using the inspection period, a first cost spent to perform a normal inspection of the plant when the plant is not faulty during the inspection period, a second cost spent to restore the plant when the plant is faulty during the inspection period and a third cost as an opportunity loss due to the shutdown of the plant, and a fourth cost for obtaining a deterioration amount of the plant; a maintenance method determination unit that determines the measurement method that reduces the average cost to a level that satisfies a predetermined standard; A maintenance support device comprising:

2. receiving a target value for the average cost; a target error calculation unit that calculates the variance of a probability distribution of the error that makes the average cost smaller than the received target value; 2. The maintenance support device according to claim 1, wherein:

3. The true value is The degradation amount is a measurement value obtained by another measurement method that measures the degradation amount with higher accuracy than the certain measurement method, or is an amount of degradation output by the degradation function.

3. The maintenance support device according to claim 2, wherein:

4. The predetermined allowable deterioration amount is The deterioration amount is such that the plant will fail; 4. The maintenance support device according to claim 3, wherein:

5. The predetermined tolerable failure probability is: A value obtained by dividing the upper limit of loss that a user of the plant can tolerate in the event that the plant is shut down by the expected amount of loss in the event that the plant is shut down; 5. The maintenance support device according to claim 4, wherein:

6. The failure distribution function creation unit of the maintenance support device creating a failure distribution function that indicates the relationship between a deterioration amount of the plant and time, and based on an excess portion that exceeds a predetermined allowable deterioration amount out of the sum of a probability distribution of an error between the measured value of the deterioration amount and the true value of the deterioration amount and the deterioration amount indicated by the deterioration function; The inspection cycle calculation unit of the maintenance support device calculating a time corresponding to a predetermined allowable failure probability in the failure distribution function as an inspection period for the plant; The cost calculation unit of the maintenance support device using the inspection cycle, a first cost spent to perform a normal inspection of the plant when the plant is not out of order during the inspection cycle, a second cost spent to restore the plant when the plant is out of order during the inspection cycle and a third cost as an opportunity loss due to the shutdown of the plant, and a fourth cost for acquiring the deterioration amount of the plant, an average cost obtained by dividing the sum of the first cost, the second cost, the third cost, and the fourth cost by an average value of the time until the plant is inspected when the inspection cycle is extended, for each method of measuring the deterioration amount; The maintenance method determination unit of the maintenance support device determining the measurement method that reduces the average cost to a level that satisfies a predetermined standard; A maintenance support method for a maintenance support device.

Images