Equipment replacement planning device, equipment replacement planning system, equipment replacement planning method, and equipment replacement planning program

Abstract

To provide a facility replacement planning device which can accelerate processing of laying out a replacement plan of a facility.SOLUTION: A facility replacement planning device 2A lays out replacement plans of a plurality of facilities in a planned period. The facility replacement planning device 2A comprises: a risk calculation unit 11 which calculates a risk being an expectation value of a cost generated due to a failure of the facility for each of the plurality of facilities; a replacement candidate extraction unit 12 which extracts a facility other than an excluded facility among the plurality of facilities as a candidate of the replacement target by deciding the facility to be excluded from the replacement target in the planned period from the plurality of facilities with calculation that incorporates the upper limit value of the values of accumulating a reduction amount of the risk for each of the plurality of facilities from the start year of the planned period to the end year of the planned period; and a replacement facility decision unit 13 which decides the facility being the replacement target in a year from the candidates for each year of the planned period.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an equipment replacement plan determination device, an equipment replacement plan determination system, an equipment replacement plan determination method, and an equipment replacement plan determination program for formulating a replacement plan for a plurality of pieces of equipment.

Background Art

[0002] In a power transmission and distribution system that performs power transmission and distribution, a replacement plan for a plurality of pieces of equipment managed and operated in the power transmission and distribution system is formulated. By appropriately formulating the replacement plan, the power transmission and distribution system can continue stable power transmission and distribution, and at the same time, it can reduce the increase in the maintenance cost of the power transmission and distribution system due to excessive replacement of equipment. Conventionally, in the power field or other fields, technologies for formulating replacement plans have been developed.

[0003] Patent Document 1 discloses a management business support system that quantitatively diagnoses the soundness of equipment and predicts the time when the equipment can guarantee its function for a plurality of pieces of equipment managed and operated in a water supply and sewerage facility, and evaluates a risk level, which is a judgment index for the priority of replacing the equipment. The management business support system according to Patent Document 1 extracts the equipment to be replaced annually based on the risk level of each piece of equipment and the budget constraints for each year. By formulating a replacement plan using the management business support system according to Patent Document 1, it is possible to level the cost required for replacing equipment annually and replace the equipment considering the risk level of each piece of equipment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The management support system described in Patent Document 1 performs the process up to the extraction of equipment without narrowing down the equipment to be replaced, so the processing load increases as the number of equipment to be managed and operated increases. According to the conventional technology described in Patent Document 1, there was a problem in that it was difficult to speed up the process of formulating equipment replacement plans.

[0006] This disclosure is made in view of the above, and aims to provide an equipment replacement plan formulation device that enables faster processing of equipment replacement plans. [Means for solving the problem]

[0007] To solve the aforementioned problems and achieve the objectives, the equipment replacement planning device according to this disclosure is an equipment replacement planning device that formulates replacement plans for multiple pieces of equipment over a planning period. The equipment replacement planning device according to this disclosure comprises: a risk calculation unit that calculates the risk, which is the expected value of the costs incurred due to the failure of each of the multiple pieces of equipment; a replacement candidate extraction unit that, for each year of the planning period, determines which pieces of equipment to be excluded from the replacement targets during the planning period from among the multiple pieces of equipment, and extracts the equipment other than the excluded pieces of equipment from among the multiple pieces of equipment as replacement target candidates; and a replacement equipment determination unit that, for each year of the planning period, determines which pieces of equipment to be replaced within the year from among the candidates. The risk calculation unit calculates risk based on a function where the risk increase rate (the rate at which risk increases) and the number of years elapsed since the start of the planning period are variables. The replacement candidate extraction unit sorts the multiple pieces of equipment in descending order of the calculated risk for the target year, which is one of the multiple years included in the planning period. It then adds the risk of each piece of equipment in the target year, starting with the piece of equipment with the greatest risk, to the cumulative value of the risk reduction amount for each piece of equipment from the start of the planning period to the year before the target year. It identifies one or more pieces of equipment that were subject to addition when the summation result exceeds the upper limit of the cumulative value of the risk reduction amount for each piece of equipment from the start of the planning period to the end of the planning period. It then finds the minimum risk increase rate for the identified one or more pieces of equipment and determines that the pieces of equipment whose risk increase rate is less than or equal to the minimum value will be excluded from the replacement targets for the planning period. [Effects of the Invention]

[0008] The equipment replacement planning device described herein has the effect of speeding up the process of formulating equipment replacement plans. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the configuration of the equipment replacement planning system according to Embodiment 1. [Figure 2] A diagram illustrating the overview of the processing performed by the equipment replacement planning device of the equipment replacement planning system according to Embodiment 1. [Figure 3]This figure shows an example of raw data acquired by the acquisition unit of the equipment replacement planning device according to Embodiment 1. [Figure 4] This diagram illustrates the process performed by the replacement candidate extraction unit of the equipment replacement planning device according to Embodiment 1. [Figure 5] This figure shows an example of the risk increase rate calculated by the replacement candidate extraction unit according to Embodiment 1. [Figure 6] A diagram illustrating the process performed by the equipment replacement determination unit of the equipment replacement planning device according to Embodiment 1. [Figure 7] This figure shows an example of a replacement plan created by the replacement plan creation unit of the equipment replacement plan formulation device according to Embodiment 1. [Figure 8] A flowchart showing the procedure of processing performed by the equipment replacement planning device according to Embodiment 1. [Figure 9] This figure shows an example of the display on the terminal device of the equipment replacement planning system according to Embodiment 1. [Figure 10] This figure shows an example configuration of an equipment replacement planning system according to a modified example of Embodiment 1. [Figure 11] This figure shows an example of the hardware configuration of the equipment replacement planning device according to Embodiment 1. [Figure 12] This figure shows an example of the hardware configuration of a terminal device according to Embodiment 1. [Modes for carrying out the invention]

[0010] The following describes in detail, with reference to the drawings, an equipment replacement plan formulation device, an equipment replacement plan formulation system, an equipment replacement plan formulation method, and an equipment replacement plan formulation program according to the embodiment.

[0011] Embodiment 1. FIG. 1 is a diagram showing a configuration example of an equipment replacement plan determination system 1A according to Embodiment 1. The equipment replacement plan determination system 1A determines replacement plans for a plurality of pieces of equipment during a planned period. In Embodiment 1, each of the plurality of pieces of equipment is equipment that constitutes a power transmission and distribution system and is equipment that is managed and operated in the power transmission and distribution system. The plurality of pieces of equipment in the power transmission and distribution system are, for example, transformers, towers, electric poles, and distribution cables.

[0012] The equipment replacement plan determination system 1A includes an equipment replacement plan determination device 2A and a terminal device 3. The equipment replacement plan determination device 2A determines replacement plans for a plurality of pieces of equipment during a planned period. The equipment replacement plan determination device 2A is constituted by, for example, one or more cloud servers. The cloud server is a server constructed in a cloud environment including computer resources provided in a cloud service home. Note that the equipment replacement plan determination device 2A may be a server other than a cloud server, for example, an on-premises server. The equipment replacement plan determination device 2A is managed by, for example, a power company that is a user of the equipment replacement plan determination system 1A.

[0013] The terminal device 3 is a terminal used in a power company that is a user of the equipment replacement plan determination system 1A. The terminal device 3 is used, for example, by a person who operates and manages the equipment provided in the power transmission and distribution system. The terminal device 3 can communicate with the equipment replacement plan determination device 2A via a network and transmits and receives information with the equipment replacement plan determination device 2A. The network is, for example, a WAN (Wide Area Network) such as the Internet, but may also be a LAN (Local Area Network). The number of terminal devices 3 constituting the equipment replacement plan determination system 1A is assumed to be arbitrary.

[0014] The equipment replacement plan determination device 2A includes an acquisition unit 10, a risk calculation unit 11, a replacement candidate extraction unit 12, a replacement equipment determination unit 13, and a replacement plan creation unit 14. The equipment replacement plan determination device 2A includes an original data storage unit 15, a risk definition storage unit 16, an intermediate data storage unit 17, a cumulative value upper limit definition storage unit 18, and a risk increase rate definition storage unit 19. The original data storage unit 15, the risk definition storage unit 16, the intermediate data storage unit 17, the cumulative value upper limit definition storage unit 18, and the risk increase rate definition storage unit 19 constitute storage units for storing data.

[0015] The acquisition unit 10 acquires original data from outside the equipment replacement plan determination device 2A. The original data is data used for calculating risks. A risk is the expected value of the cost incurred due to equipment failure. The cost incurred due to equipment failure is the cost required for recovery from the failure when the equipment fails. Details of the original data will be described later. The acquisition unit 10 outputs the acquired original data to the original data storage unit 15. The original data is stored in the original data storage unit 15. The equipment replacement plan determination device 2A collects the original data by storing the original data in the original data storage unit 15.

[0016] As an example of one mode in which the equipment replacement plan determination device 2A acquires original data, it can be mentioned that the original data is transmitted from the power transmission and distribution system to the equipment replacement plan determination device 2A, and the original data is automatically collected by the equipment replacement plan determination device 2A. Also, as another example, it can be mentioned that the acquisition unit 10 receives an input operation of the original data calculated manually or the original data recorded in a ledger or the like, and the original data is input to the equipment replacement plan determination device 2A by the input operation. The mode in which the equipment replacement plan determination device 2A acquires original data is assumed to be arbitrary.

[0017] The risk calculation unit 11 reads the original data from the original data storage unit 15. The risk calculation unit 11 calculates, for each of a plurality of pieces of equipment, the risk that is the expected value of the cost incurred due to the failure of the equipment. The risk calculation unit 11 outputs the calculation result of the risk to the replacement candidate extraction unit 12.

[0018] The replacement candidate extraction unit 12 extracts equipment that is a candidate for replacement from a group of equipment. The replacement candidate extraction unit 12 determines which equipment to exclude from replacement during the planning period from the group of equipment by performing a calculation that incorporates the value of the upper limit of the cumulative risk reduction amount, thereby extracting equipment other than the excluded equipment from the group of equipment as replacement candidates. The upper limit of the cumulative risk reduction amount is the upper limit of the cumulative value of the risk reduction amount for each of the group of equipment from the start year to the end year of the planning period. The replacement candidate extraction unit 12 outputs information indicating the equipment extracted as candidates to the replacement equipment determination unit 13.

[0019] The equipment replacement determination unit 13 determines, for each year of the planning period, the equipment to be replaced within that year from among the candidates. The equipment replacement determination unit 13 determines the equipment to be replaced from among the equipment extracted as candidates by the replacement candidate extraction unit 12. For each year of the planning period, the equipment replacement determination unit 13 outputs information indicating the equipment to be replaced to the replacement plan creation unit 14. In Embodiment 1, the year in the replacement plan is defined as January 1st to December 31st according to the calendar, but it is not limited to this. The division of the year in the replacement plan can be set arbitrarily.

[0020] The replacement plan creation unit 14 creates a replacement plan based on information from the replacement equipment determination unit 13. The replacement plan includes information indicating the equipment to be replaced and information indicating the year in which the equipment will be replaced. The replacement plan creation unit 14 outputs the created replacement plan. The equipment replacement plan formulation device 2A transmits the replacement plan to the terminal device 3.

[0021] Terminal device 3 includes a display unit 21 that displays information on a screen. When terminal device 3 receives a replacement plan, the display unit 21 displays the replacement plan. The display unit 21 functions as an output unit that outputs a replacement plan indicating the equipment to be replaced and the year in which the equipment will be replaced.

[0022] Next, an overview of the processing performed by the equipment replacement plan formulation device 2A will be described. Figure 2 is a diagram illustrating the overview of the processing performed by the equipment replacement plan formulation device 2A of the equipment replacement plan formulation system 1A according to Embodiment 1. Figure 2 shows an example of the trend of the total risk of multiple pieces of equipment over the planning period. The graph shown in the upper part of Figure 2 represents the trend of the total risk when there is no replacement plan. The graph shown in the lower part of Figure 2 represents the trend of the total risk when there is a replacement plan. Here, the planning period is 100 years, from 2022 to 2121. That is, the start year of the planning period is 2022, and the end year of the planning period is 2121.

[0023] The total risk in the initiation year is the same whether or not there is an exchange plan. Without an exchange plan, the total risk continues to increase every year from 2022 onwards. The dashed line in the upper part of Figure 2 represents the total risk in 2022. On the other hand, if there is an exchange plan, the total risk each year from 2023 onwards is leveled to be less than or equal to the total risk in 2022. In the lower part of Figure 2, the total risk in 2022 is represented by a solid line. The total risk used as the standard for leveling the total risk is called the total risk standard. In the example shown in Figure 2, the total risk standard is the total risk in 2022. In the upper part of Figure 2, the portion of the bar graph shown above the dashed line represents the risk that needs to be reduced by formulating an exchange plan.

[0024] The upper limit of the cumulative risk reduction over the calculation period is the difference between the total risk at the end of the calculation period and the total risk at the start of the calculation period, assuming there is no exchange plan. In the example shown in Figure 2, the upper limit of the cumulative risk reduction over the calculation period is the difference between the total risk in 2121 and the total risk in 2022, assuming there is no exchange plan.

[0025] Next, we will explain the details of the processing in each part of the equipment replacement planning device 2A. The raw data acquired by the acquisition unit 10 is data indicating the specifications of the equipment, or data from equipment inspection records, etc.

[0026] Figure 3 shows an example of raw data acquired by the acquisition unit 10 of the equipment replacement planning device 2A according to Embodiment 1. In Figure 3, "Transformer 1", "Transformer 2", ..., "Utility Pole 10,000,000" are examples of equipment. Here, each piece of equipment is represented by its type and its serial number. A serial number is assigned to each of the multiple pieces of equipment. In the example shown in Figure 3, the multiple pieces of equipment consist of 10 million pieces of equipment, from "Transformer 1" with serial number "1" to "Utility Pole 10,000,000" with serial number "10,000,000".

[0027] In Figure 3, the items "Expected Lifespan," "Voltage Class," "Operating Rate," and "Distance from Coast" are examples of equipment specifications. The specifications included in the raw data are those that affect the progression of equipment deterioration. The raw data may also include data for items other than those shown in Figure 3.

[0028] In the example shown in Figure 3, the item "Inspection Result (Inspection Item A)" represents the inspection record for a single inspection item, "Inspection Item A." The source data can include data for any number of inspection items. The inspection record primarily represents the results of inspecting the operating status of the equipment. Ranking is performed, for example, based on thresholds for qualitatively or quantitatively evaluating the operating status. The inspection results for "Inspection Item A" are ranked, for example, on a scale of 1 to 5. The inspection record data for "Inspection Item A" represents one of the five ranks. Note that the ranking of inspection results is not limited to a 5-level scale and is arbitrary. The inspection record data is not limited to being represented by ranks; it may also be represented by numerical values, etc.

[0029] The risk calculation unit 11 calculates the risk from the raw data based on a pre-set definition. The risk definition storage unit 16 stores information about the definition used in the process of calculating the risk from the raw data. Specifically, the risk definition storage unit 16 stores the parameters of the calculation formula used in the risk calculation unit 11 to calculate the risk. The calculation formula is, for example, "risk = A × polynomial{B × exp(C × elapsed years)}". Let x be any real number, then polynomial(x) = polynomial(x) = 1 + x + (x 2 ) / 2+(x 3 This is a function expressed as ) / 6. In the above formula, exp is an exponential function. The elapsed years are the number of years from the start year. The formula used to calculate the risk can be, for example, the formula shown in guidelines, etc. In addition, any formula set by the user may be used to calculate the risk.

[0030] In the above formula, A, B, and C each represent the risk increase rate. The risk calculation unit 11 calculates the risk based on a function in which the risk increase rate and the number of years elapsed since the start year are variables. Details of the risk increase rate will be described later. The risk calculation unit 11 reads information about the definition from the risk definition storage unit 16 and calculates the risk based on the definition.

[0031] The replacement candidate extraction unit 12 calculates the cumulative risk reduction limit and the risk increase rate. Based on the cumulative risk reduction limit and the risk increase rate, the replacement candidate extraction unit 12 determines which equipment to exclude from replacement during the planning period. The cumulative value limit definition storage unit 18 stores information about the definition used in the process of calculating the cumulative risk reduction limit. Specifically, the cumulative value limit definition storage unit 18 stores the parameters of the calculation formula used in the replacement candidate extraction unit 12 to calculate the cumulative risk reduction limit. The calculation formula is, for example, "cumulative risk reduction limit = XY". In this formula, X is the total risk in the final year if there is no replacement plan. Y is the total risk criterion. The replacement candidate extraction unit 12 obtains the values ​​of X and Y from the risk calculation unit 11.

[0032] The replacement candidate extraction unit 12 reads information about the definition from the cumulative value upper limit definition storage unit 18 and calculates the value of the cumulative risk reduction upper limit based on the definition. The replacement candidate extraction unit 12 outputs the calculated value of the cumulative risk reduction upper limit to the intermediate data storage unit 17. The value of the cumulative risk reduction upper limit is stored in the intermediate data storage unit 17. The replacement candidate extraction unit 12 also calculates the cumulative risk reduction amount for each year from the start year to the end year. Hereinafter, the cumulative risk reduction amount will be referred to as the cumulative risk reduction value. With one of the multiple years included in the calculation period as the target year, the cumulative risk reduction value is the difference obtained by subtracting the total risk standard from the total risk in the target year in the case where there is no replacement plan. The calculation formula used to calculate the cumulative risk reduction upper limit can be, for example, the calculation formula shown in guidelines, etc. In addition, any calculation formula set by the user may be used to calculate the cumulative risk reduction upper limit.

[0033] The risk increase rate definition storage unit 19 stores information about the definition used in the process of calculating the risk increase rate. Specifically, the risk increase rate definition storage unit 19 stores the parameters of the calculation formula used in the exchange candidate extraction unit 12 to calculate the risk increase rate. The calculation formula is, for example, "A=func1(original data)", "B=func2(original data)", and "C=func3(original data)". Each of func1, func2, and func3 represents a function that takes the original data as input and outputs a real number. In addition, for data that is represented by rank, such as inspection record data, the numerical value associated with each rank is input to the function.

[0034] The replacement candidate extraction unit 12 reads the original data from the original data storage unit 15. The replacement candidate extraction unit 12 reads information about the definition from the risk increase rate definition storage unit 19 and calculates the risk increase rate based on the definition. The replacement candidate extraction unit 12 outputs the calculated risk increase rate to the intermediate data storage unit 17. The risk increase rate is stored in the intermediate data storage unit 17. The risk calculation unit 11 reads the risk increase rate from the intermediate data storage unit 17 and calculates the risk by a calculation that incorporates the risk increase rate. The calculation formula used to calculate the risk increase rate can be, for example, a calculation formula shown in guidelines, etc. In addition, any calculation formula set by the user may be used to calculate the risk increase rate.

[0035] The replacement candidate extraction unit 12 determines which equipment to exclude from replacement during the planning period by performing the following process for each year included in the calculation period. The replacement candidate extraction unit 12 performs the same process for each year, treating each year included in the calculation period as a target year.

[0036] The replacement candidate extraction unit 12 sorts each of the multiple pieces of equipment in descending order of the risk calculated by the risk calculation unit 11 for the target year. Next, the replacement candidate extraction unit 12 adds the risk reduction amount for each of the multiple pieces of equipment to the cumulative risk reduction amount for each piece of equipment from the start year of the planning period to the year before the target year, in descending order of the calculated risk, and identifies one or more pieces of equipment that are subject to addition until the sum exceeds the upper limit of the cumulative risk reduction amount. Next, the replacement candidate extraction unit 12 finds the minimum risk increase rate for the identified one or more pieces of equipment. Next, the replacement candidate extraction unit 12 determines that the pieces of equipment whose risk increase rate is less than or equal to the minimum value will be excluded from the replacement targets for the planning period.

[0037] Figure 4 is a diagram illustrating the process performed by the replacement candidate extraction unit 12 of the equipment replacement plan formulation device 2A according to Embodiment 1. Figure 4 schematically shows how multiple pieces of equipment are sorted and how the risk reduction amount for each piece of equipment is added to the cumulative risk reduction amount. For the sake of simplifying the explanation of the process, Figure 4 assumes that the multiple pieces of equipment are four pieces of equipment: "Equipment 1", "Equipment 2", "Equipment 3", and "Equipment 4". Figure 4 uses the year 2024 as an example.

[0038] The replacement candidate extraction unit 12 obtains the calculated risk of each piece of equipment in 2024 from the risk calculation unit 11. In the example shown in Figure 4, of the four pieces of equipment, "Equipment 1" has the highest risk, and "Equipment 2 」、 The risk is lowest for "Equipment 3" and then for "Equipment 4". The replacement candidate extraction unit 12 sorts the four pieces of equipment in the order of "Equipment 1", "Equipment 2", "Equipment 3", and then "Equipment 4". The replacement candidate extraction unit 12 adds the risk for each piece of equipment, starting with "Equipment 1", to the cumulative risk reduction amount up to 2023, which is the year before the target year. Each time the replacement candidate extraction unit 12 adds the risk for each piece of equipment to the cumulative risk reduction amount up to 2023, it compares the result with the upper limit of the cumulative risk reduction amount for the calculation period.

[0039] The risk of "Equipment 1" in 2024 corresponds to the risk reduction amount if "Equipment 1" is replaced in 2024. The risk of "Equipment 2" in 2024 corresponds to the risk reduction amount if "Equipment 2" is replaced in 2024. In the example shown in Figure 4, the result of adding the risk reduction amount if "Equipment 1" is replaced in 2024 to the cumulative risk reduction amount up to 2023 is smaller than the upper limit of the cumulative risk reduction amount for the calculation period.

[0040] On the other hand, the sum of the risk reduction amount if "Equipment 1" is replaced in 2024 and the cumulative risk reduction amount up to 2023, plus the risk reduction amount if "Equipment 2" is replaced in 2024, is greater than the upper limit of the cumulative risk reduction amount during the calculation period. As a result, the replacement candidate extraction unit 12 identifies "Equipment 1" and "Equipment 2" as equipment that will be included in the addition until the sum of the cumulative risk reduction amount exceeds the upper limit.

[0041] Figure 5 shows an example of the risk increase rate calculated by the replacement candidate extraction unit 12 according to Embodiment 1. Figure 5 shows examples of the risk increase rates calculated for each of "Equipment 1", "Equipment 2", "Equipment 3", and "Equipment 4". Each of the risk increase rates A, B, and C is an arbitrary real number greater than zero.

[0042] The replacement candidate extraction unit 12 determines the minimum value A0 of the risk increase rate A, the minimum value B0 of the risk increase rate B, and the minimum value C0 of the risk increase rate C for the identified equipment, "Equipment 1" and "Equipment 2". In the example shown in Figure 5, A0=0.1, B0=0.1, and C0=0.3.

[0043] The replacement candidate extraction unit 12 compares the risk increase rate A for each of the equipment other than the identified equipment, namely "Equipment 3" and "Equipment 4," with the minimum value A0. The replacement candidate extraction unit 12 compares the risk increase rate B for each of "Equipment 3" and "Equipment 4" with the minimum value B0. The replacement candidate extraction unit 12 compares the risk increase rate C for each of "Equipment 3" and "Equipment 4" with the minimum value C0. The replacement candidate extraction unit 12 finds equipment that satisfies all of the following conditions: A ≤ A0, B ≤ B0, and C ≤ C0.

[0044] In the example shown in Figure 5, "Equipment 4" satisfies all of the conditions A ≤ A0, B ≤ B0, and C ≤ C0. "Equipment 4" is the equipment whose risk increase rates A, B, and C are less than or equal to the minimum values ​​A0, B0, and C0. The replacement candidate extraction unit 12 determines that "Equipment 4," whose risk increase rate is less than or equal to the minimum value, will be excluded from the equipment to be replaced during the planning period. As a result, the replacement candidate extraction unit 12 extracts "Equipment 1," "Equipment 2," and "Equipment 3," which are the equipment other than the excluded equipment, as candidates for replacement.

[0045] Equipment 4 has a lower risk in 2024 compared to Equipment 1 and Equipment 2. Also, Equipment 4 has a lower risk increase rate compared to Equipment 1 and Equipment 2. For these reasons, Equipment 4 will not be replaced before Equipment 1 and Equipment 2. Furthermore, if Equipment 1 and Equipment 2 are replaced after 2024, the cumulative risk reduction will exceed the upper limit of the cumulative risk reduction during the planning period. Therefore, Equipment 4 will not be considered for replacement during the calculation period, and the replacement candidate extraction unit 12 excludes Equipment 4 from the list of replacement candidates.

[0046] Equipment 3 has a lower risk in 2024 compared to Equipment 1 and Equipment 2. However, Equipment 3's risk increase rate B is greater than the minimum value B0, and its risk increase rate C is greater than the minimum value C0. Because Equipment 3's risk increase rates B and C are greater than the minimum values ​​B0 and C0, the risk of Equipment 3 may exceed the risk of Equipment 1 or Equipment 2 during the planning period until 2121. For this reason, Equipment 3 remains a candidate for replacement.

[0047] In the example shown in Figure 5, if both "Equipment 1" and "Equipment 2" are replaced in 2024, the cumulative risk reduction amount in 2024 will exceed the upper limit of the cumulative risk reduction amount for the planning period. Therefore, if both "Equipment 1" and "Equipment 2" are replaced in 2024, no equipment replacement will be necessary between 2025 and 2121.

[0048] The replacement candidate extraction unit 12 performs the same processing as when the target year is 2024 or later, and extracts equipment to be considered as candidates for replacement. The replacement candidate extraction unit 12 outputs information indicating the equipment extracted as candidates to the replacement equipment determination unit 13.

[0049] The replacement candidate extraction unit 12 extracts candidates for replacement by processing that incorporates the risk increase rate, thereby enabling the extraction of replacement candidates while considering the magnitude of future risks. Furthermore, by extracting candidates for replacement by processing that incorporates the cumulative risk reduction upper limit, the replacement candidate extraction unit 12 makes it possible to formulate a replacement plan that takes into account how much risk needs to be reduced from the total risk calculated for each year to eliminate the need for equipment replacement.

[0050] The equipment replacement determination unit 13 determines, for each year of the planning period, the equipment to be replaced within that year from among the candidates by performing the following process for each year included in the calculation period. The equipment replacement determination unit 13 sorts each of the candidate equipment to be replaced in descending order of the risk calculated by the risk calculation unit 11 for the target year.

[0051] Next, the equipment replacement determination unit 13 accumulates the risk reduction amount for each piece of equipment against the total risk standard, starting with the equipment with the highest calculated risk. The equipment replacement determination unit 13 identifies one or more pieces of equipment that have been included in the accumulation until the accumulated value of the risk reduction amount for each piece of equipment exceeds the total risk for the target year. The equipment replacement determination unit 13 determines that the identified one or more pieces of equipment will be replaced in the target year. The unit identifies one or more pieces of equipment that have been included in the accumulation until the result exceeds the upper limit, which is the upper limit of the accumulated risk reduction amount.

[0052] Figure 6 is a diagram illustrating the process performed by the equipment replacement determination unit 13 of the equipment replacement planning device 2A according to Embodiment 1. Figure 6 schematically shows how multiple pieces of equipment are sorted and how the risk reduction amount for each piece of equipment is accumulated against the total risk criterion. In Figure 6, as in Figure 4, the multiple pieces of equipment are assumed to be four pieces of equipment: "Equipment 1", "Equipment 2", "Equipment 3", and "Equipment 4". In Figure 6, the target year is 2024 as an example.

[0053] In the example shown in Figure 6, among the four pieces of equipment, "Equipment 1" has the highest risk, and "Equipment 2 」、The risk is lowest for "Equipment 3" and then for "Equipment 4". The equipment replacement determination unit 13 sorts the four pieces of equipment in the order of "Equipment 1", "Equipment 2", "Equipment 3", and "Equipment 4". In the example shown in Figure 6, "Equipment 4" is excluded from the replacement target by the replacement candidate extraction unit 12. For "Equipment 1", "Equipment 2", and "Equipment 3", which are candidates for replacement, the equipment replacement determination unit 13 accumulates the risk reduction amount for each piece of equipment, starting with "Equipment 1", against the total risk criterion. Each time the risk reduction amount for each piece of equipment is accumulated, the equipment replacement determination unit 13 compares the accumulated value with the total risk for the target year.

[0054] In the example shown in Figure 6, the risk reduction amount for "Equipment 1" is the risk reduction amount if "Equipment 1" is replaced in 2024. Furthermore, the difference between the total risk in 2024 and the total risk baseline represents the risk that needs to be reduced in 2024. In Figure 6, this difference is indicated by a double-headed arrow.

[0055] In the example shown in Figure 6, the cumulative value when the risk reduction amount for "Equipment 1" is accumulated against the total risk standard is greater than the total risk in 2024. This indicates that replacing "Equipment 1" in 2024 will reduce the risk by an amount greater than the difference between the total risk in 2024 and the total risk standard. As a result, the replacement equipment determination unit 13 stops the process of accumulating the risk reduction amount for each piece of equipment against the total risk standard and determines that "Equipment 1" is the piece of equipment to be replaced in 2024.

[0056] The equipment replacement determination unit 13 performs the same processing as when 2024 is the target year, even when the target year is 2024 or later, to determine the equipment to be replaced in the target year. For each year of the planning period, the equipment replacement determination unit 13 outputs information indicating the equipment to be replaced to the equipment replacement plan creation unit 14. The equipment replacement plan creation unit 14 creates a replacement plan based on the information from the equipment replacement determination unit 13.

[0057] Figure 7 shows an example of a replacement plan created by the replacement plan creation unit 14 of the equipment replacement plan formulation device 2A according to Embodiment 1. The example shown in Figure 7 shows an example of a replacement plan for each piece of equipment: "Transformer 1", "Transformer 2", ..., "Utility pole 10,000,000". As shown in Figure 7, the replacement plan creation unit 14 creates a replacement plan that summarizes the year in which each piece of equipment will be replaced. The replacement plan creation unit 14 outputs the created replacement plan. The equipment replacement plan formulation device 2A transmits the replacement plan to the terminal device 3.

[0058] Next, the procedure for processing performed by the equipment replacement planning device 2A will be described. Figure 8 is a flowchart showing the procedure for processing performed by the equipment replacement planning device 2A according to Embodiment 1. With the original data stored in the original data storage unit 15, the equipment replacement planning device 2A starts processing according to the procedure shown in Figure 8.

[0059] The replacement candidate extraction unit 12 retrieves the original data from the original data storage unit 15. The replacement candidate extraction unit 12 retrieves information about the definition used in the process of calculating the risk increase rate from the risk increase rate definition storage unit 19. In step S1, the replacement candidate extraction unit 12 calculates the risk increase rate. The equipment replacement plan formulation device 2A saves the calculated risk increase rate to the intermediate data storage unit 17.

[0060] The replacement candidate extraction unit 12 obtains information about the definition used in the process of calculating the upper limit of the cumulative risk reduction amount from the cumulative value upper limit definition storage unit 18. The risk calculation unit 11 calculates the total risk in the final year and the total risk standard in the case where there is no replacement plan. The replacement candidate extraction unit 12 obtains the total risk in the final year and the total risk standard in the case where there is no replacement plan from the risk calculation unit 11. In step S2, the replacement candidate extraction unit 12 calculates the upper limit of the cumulative risk reduction amount for the calculation period. The equipment replacement plan formulation device 2A saves the calculated upper limit, which is the upper limit of the cumulative risk reduction amount, to the intermediate data storage unit 17.

[0061] In step S3, the replacement candidate extraction unit 12 sets all equipment as candidates for replacement and sets the start year of the calculation period to the target year. In step S4, the risk calculation unit 11 calculates the risk for each equipment candidate for replacement in the target year. As will be described later, the process from step S4 to step S12 is repeated in the planning period, with the target year being advanced sequentially. In step S4, which is performed for the first time, that is, when the start year is set to the target year, all of the multiple pieces of equipment are candidates for replacement. The risk calculation unit 11 calculates the risk for each of the pieces of equipment in the target year. The risk calculation unit 11 outputs the risk calculation results to the replacement candidate extraction unit 12.

[0062] In step S5, the replacement candidate extraction unit 12 sorts the equipment candidates for replacement in descending order of the calculated risk. In step S6, the replacement candidate extraction unit 12 calculates the cumulative risk reduction value from the start year to the year prior to the target year. In step S6, which is performed first, i.e., when the start year is set to the target year, the replacement candidate extraction unit 12 calculates the cumulative risk reduction value by accumulating the risks for all equipment in the start year.

[0063] In step S7, the replacement candidate extraction unit 12 adds up the risk reduction amounts for each piece of equipment, starting with the equipment with the highest calculated risk, and identifies one or more pieces of equipment that are subject to addition by the time the sum exceeds the upper limit of the cumulative risk reduction amount. In step S8, the replacement candidate extraction unit 12 finds the minimum risk increase rate for the one or more pieces of equipment that have been identified.

[0064] In step S9, the replacement candidate extraction unit 12 determines which equipment among the candidates for replacement has a risk increase rate of less than or equal to the minimum value, and excludes it from the equipment to be replaced during the planning period. By determining which equipment to exclude from the equipment to be replaced during the planning period from among the multiple equipment candidates for replacement, the replacement candidate extraction unit 12 extracts equipment other than the excluded equipment from the multiple equipment as replacement candidates. The replacement candidate extraction unit 12 outputs information indicating the equipment extracted as candidates to the replacement equipment determination unit 13.

[0065] In step S10, the equipment replacement determination unit 13 determines the equipment to be replaced in the target year. In step S11, the replacement candidate extraction unit 12 determines whether the currently set target year is the end year of the calculation period. If the currently set target year is not the end year of the calculation period (step S11, No), in step S12, the replacement candidate extraction unit 12 sets the year following the currently set target year as the target year. After that, the equipment replacement plan formulation device 2A returns to step S4. In step S4, which is performed for the second time or later, the candidates for replacement are the equipment extracted by the replacement candidate extraction unit 12.

[0066] The equipment replacement planning device 2A sequentially advances the target year and repeats the process from step S4 to step S12 until the target year reaches the end year. If the currently set target year is the end year of the calculation period (step S11, Yes), the replacement equipment determination unit 13 outputs information indicating the equipment to be replaced to the replacement plan creation unit 14. The replacement plan creation unit 14 creates a replacement plan based on the information from the replacement equipment determination unit 13. With this, the equipment replacement planning device 2A completes the process according to the procedure shown in Figure 8.

[0067] According to the procedure shown in Figure 8, the equipment replacement determination unit 13 determines which equipment to replace each year from among the candidates for replacement narrowed down by the replacement candidate extraction unit 12. The equipment replacement plan formulation device 2A can reduce the processing load compared to determining which equipment to replace from among multiple pieces of equipment. Therefore, the equipment replacement plan formulation device 2A can speed up the process of formulating equipment replacement plans.

[0068] The equipment replacement planning device 2A transmits the replacement plan to the terminal device 3. The terminal device 3 displays the replacement plan on the display unit 21, which is the output unit. Users of the terminal device 3 can confirm the contents of the replacement plan from the display on the display unit 21. The output unit is not limited to the display unit 21; it may also be a printing unit that prints the replacement plan. The terminal device 3 may also output information other than the replacement plan through its output unit.

[0069] Figure 9 shows an example of the display on the terminal device 3 of the equipment replacement planning system 1A according to Embodiment 1. Figure 9 shows an example of displaying the trend of the total risk of multiple pieces of equipment over the planning period. The area shown in the upper part of Figure 9 is titled "Risk Trend". The bar graph in the area shown in the upper part of Figure 9 shows the trend of the total risk when there is no replacement plan. The area shown in the lower part of Figure 9 is titled "Risk Trend After Action". The bar graph in the area shown in the lower part of Figure 9 shows the trend of the total risk when there is a replacement plan. By comparing the two graphs, the user of the terminal device 3 can confirm that the total risk for each year is leveled out by the replacement plan.

[0070] The line graphs in the upper and lower sections of Figure 9 represent the trend of risk for each type of equipment. Users of terminal device 3 can check the trend of risk for each type of equipment from each line graph.

[0071] The equipment replacement planning system 1A may also accept various settings for the replacement plan from the terminal device 3. In this case, the user of the terminal device 3 inputs setting information, which is information about various settings, into the terminal device 3 by operating the terminal device 3. The terminal device 3 transmits the input setting information to the equipment replacement planning system 2A. The equipment replacement planning system 2A formulates a replacement plan according to the setting information received from the terminal device 3. The setting information includes, for example, information about the base year, which is the start year of the planning period, and information about the number of years in the planning period. The equipment replacement planning system 1A may also accept instructions for formulating a replacement plan from the terminal device 3. In this case, the equipment replacement planning system 2A formulates a replacement plan according to the instructions from the terminal device 3.

[0072] Next, a modified version of the equipment replacement planning system will be described. Figure 10 shows an example configuration of the equipment replacement planning system 1B according to a modified version of Embodiment 1. In the equipment replacement planning system 1A shown in Figure 1, raw data is collected in the raw data storage unit 15 inside the equipment replacement planning device 2A. In contrast, in the equipment replacement planning system 1B, the equipment replacement planning device 2B acquires raw data stored in the storage device 4 outside the equipment replacement planning device 2B. The equipment replacement planning system 1B comprises the equipment replacement planning device 2B, a terminal device 3, and a storage device 4.

[0073] The storage device 4 is composed of, for example, one or more cloud servers. A cloud server is a server built in a cloud environment. The storage device 4 may be a server other than a cloud server, for example, an on-premises server. The storage device 4 can communicate with the equipment replacement planning device 2B via a network. The storage device 4 transmits raw data to the equipment replacement planning device 2B. The acquisition unit 10 acquires the raw data transmitted from the storage device 4. In the equipment replacement planning system 1B, the raw data storage unit 15 shown in Figure 1 is omitted because the raw data is collected in the storage device 4. The acquisition unit 10 outputs the raw data to the risk calculation unit 11 and the replacement candidate extraction unit 12, respectively.

[0074] According to Embodiment 1, the equipment replacement planning devices 2A and 2B determine which equipment to exclude from replacement during the planning period and extract candidate equipment for replacement. The equipment replacement planning devices 2A and 2B can reduce the processing load compared to determining which equipment to replace from among multiple pieces of equipment. As a result, the equipment replacement planning systems 1A and 1B and the equipment replacement planning devices 2A and 2B have the effect of enabling faster processing for formulating equipment replacement plans.

[0075] The fields to which the equipment replacement planning systems 1A and 1B and the equipment replacement planning devices 2A and 2B can be applied are any fields where calculation formulas can be used for risk calculation, etc., and may include fields other than the power transmission and distribution sector. One example of a field other than the power transmission and distribution sector is the railway sector. The equipment replacement planning systems 1A and 1B and the equipment replacement planning devices 2A and 2B may be applied to fields other than the power transmission and distribution sector or the railway sector.

[0076] Next, the hardware configuration of the equipment replacement planning devices 2A and 2B will be described. Figure 11 is a diagram showing an example of the hardware configuration of the equipment replacement planning devices 2A and 2B according to Embodiment 1. The equipment replacement planning devices 2A and 2B are implemented by a computer system comprising a processing circuit 30 and a communication device 31. The processing circuit 30 comprises a processor 32 and a memory 33. The processing circuit 30 is a circuit in which the processor 32 executes software.

[0077] The processing units of the equipment replacement planning devices 2A and 2B, namely the acquisition unit 10, the risk calculation unit 11, the replacement candidate extraction unit 12, the replacement equipment determination unit 13, and the replacement plan creation unit 14, are implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 33.

[0078] In the processing circuit 30, the processor 32 reads and executes the equipment replacement planning program, which is stored in the memory 33, thereby realizing the functions of the processing units of the equipment replacement planning devices 2A and 2B. In other words, the processing circuit 30 is equipped with a memory 33 for storing the equipment replacement planning program, which will ultimately result in the processing of the equipment replacement planning devices 2A and 2B being executed. The equipment replacement planning program stored in the memory 33 can also be said to cause the computer to execute the procedures and methods of the equipment replacement planning devices 2A and 2B.

[0079] The processor 32 is a CPU (Central Processing Unit), processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor). The memory 33 includes, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Registered Trademark) (Electrically Erasable Programmable Read Only Memory), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, or DVDs (Digital Versatile Discs).

[0080] The equipment replacement plan formulation program stored in memory 33 may be provided in the form of being written to a storage medium such as a CD (Compact Disc)-ROM or DVD (Digital Versatile Disc)-ROM, or it may be provided via a communication line.

[0081] The communication device 31 communicates with external devices of the equipment replacement planning devices 2A and 2B. The communication device 31 of the equipment replacement planning device 2A communicates with the terminal device 3. The communication device 31 of the equipment replacement planning device 2B communicates with the terminal device 3 and with the storage device 4.

[0082] Next, the hardware configuration of the terminal device 3 will be described. Figure 12 is a diagram showing an example of the hardware configuration of the terminal device 3 according to Embodiment 1. The terminal device 3 is realized by a computer system comprising a processing circuit 40 and a communication device 41. The processing circuit 40 comprises a processor 42 and a memory 43. The processing circuit 40 and the communication device 41 are the same as the processing circuit 30 and communication device 31 shown in Figure 11. The processor 42 and memory 43 are the same as the processor 32 and memory 33 shown in Figure 11.

[0083] Terminal device 3 includes an input device 44 into which information is input by the operator and an output device 45 that outputs information. The input device 44 includes, for example, a keyboard, mouse, keypad, or touch panel. The display unit 21 of terminal device 3 is realized by a display device, which is the output device 45. The display device is, for example, an LCD (Liquid Crystal Display) or an organic EL (Electro-Luminescence) display. The output device 45 may also be a printer that outputs information by printing.

[0084] The configurations shown in the embodiments described above are examples of the content of this disclosure. The configurations of the embodiments can be combined with other known technologies. Some parts of the configurations of the embodiments can be omitted or modified without departing from the spirit of this disclosure. [Explanation of symbols]

[0085] 1A,1B Equipment replacement plan formulation system, 2A,2B Equipment replacement plan formulation device, 3 Terminal device, 4 Storage device, 10 Acquisition unit, 11 Risk calculation unit, 12 Replacement candidate extraction unit, 13 Replacement equipment determination unit, 14 Replacement plan creation unit, 15 Original data storage unit, 16 Risk definition storage unit, 17 Intermediate data storage unit, 18 Cumulative value upper limit definition storage unit, 19 Risk increase rate definition storage unit, 21 Display unit, 30,40 Processing circuit, 31,41 Communication device, 32,42 Processor, 33,43 Memory, 44 Input device, 45 Output device.

Claims

1. A device for formulating equipment replacement plans for multiple pieces of equipment during a planning period, For each of the aforementioned multiple pieces of equipment, a risk calculation unit calculates the risk, which is the expected value of the costs incurred due to the failure of the equipment. For each year of the aforementioned planning period, a replacement candidate extraction unit determines which equipment to be excluded from the equipment to be replaced during the planning period from among the multiple pieces of equipment, and extracts equipment other than the excluded equipment from the multiple pieces of equipment as candidates for replacement. For each year of the aforementioned planning period, a replacement equipment determination unit determines which equipment to be replaced within the year from among the candidates, Equipped with, The risk calculation unit calculates the risk based on a function in which the risk increase rate, which is the rate of increase of the risk, and the number of years elapsed since the start year of the planning period are variables. The replacement candidate extraction unit selects a target year which is one of several years included in the planning period. The calculated risks are sorted from one to the other, and the multiple pieces of equipment are sorted in descending order of risk. The cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the year prior to the target year is used to add the risk for each piece of equipment in the target year, starting with the piece of equipment with the greatest risk. One or more pieces of equipment that were subject to addition are identified when the sum exceeds the upper limit of the cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the end of the planning period. Determine the minimum risk increase rate for the one or more identified facilities. A device for formulating equipment replacement plans, characterized in that it determines, among the plurality of equipment, equipment whose risk increase rate is less than or equal to the minimum value, to be excluded from the equipment to be replaced during the planning period.

2. A system for formulating equipment replacement plans for multiple pieces of equipment during a planning period, For each of the aforementioned multiple pieces of equipment, a risk calculation unit calculates the risk, which is the expected value of the costs incurred due to the failure of the equipment. For each year of the aforementioned planning period, a replacement candidate extraction unit determines which equipment to be excluded from the equipment to be replaced during the planning period from among the multiple pieces of equipment, and extracts equipment other than the excluded equipment from the multiple pieces of equipment as candidates for replacement. For each year of the aforementioned planning period, a replacement equipment determination unit determines which equipment to be replaced within the year from among the candidates, An output unit that outputs the replacement plan indicating the equipment to be replaced and the year in which the equipment will be replaced, Equipped with, The risk calculation unit calculates the risk based on a function in which the risk increase rate, which is the rate of increase of the risk, and the number of years elapsed since the start year of the planning period are variables. The replacement candidate extraction unit selects a target year which is one of several years included in the planning period. The calculated risks are sorted from one to the other, and the multiple pieces of equipment are sorted in descending order of risk. The cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the year prior to the target year is used to add the risk for each piece of equipment in the target year, starting with the piece of equipment with the greatest risk. One or more pieces of equipment that were subject to addition are identified when the sum exceeds the upper limit of the cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the end of the planning period. Determine the minimum risk increase rate for the one or more identified facilities. A system for formulating equipment replacement plans, characterized in that it determines which of the aforementioned multiple pieces of equipment have a risk increase rate that is less than or equal to the minimum value, to be excluded from the equipment to be replaced during the planning period.

3. A method for formulating equipment replacement plans, which involves formulating replacement plans for multiple pieces of equipment during a planning period using an equipment replacement plan formulation device, The aforementioned equipment replacement plan formulation device, For each of the aforementioned multiple pieces of equipment, the step of calculating the risk, which is the expected value of the costs incurred due to the failure of said equipment, For each year of the aforementioned planning period, the steps include: determining which equipment to exclude from the equipment to be replaced during the planning period from among the multiple pieces of equipment, and extracting equipment other than the excluded equipment from the multiple pieces of equipment as candidates for replacement; For each year of the aforementioned planning period, the step is to determine which equipment to be replaced within the year from among the candidates, Includes, In the step of calculating the risk, the risk is calculated based on a function in which the risk increase rate (the rate at which the risk increases) and the number of years elapsed since the start year of the planning period are variables. In the step of extracting equipment other than the excluded equipment from the aforementioned multiple pieces of equipment as candidates for replacement, Regarding the target year, which is one of several years included in the aforementioned planning period, The calculated risks are sorted from one to the other, and the multiple pieces of equipment are sorted in descending order of risk. The cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the year prior to the target year is used to add the risk for each piece of equipment in the target year, starting with the piece of equipment with the greatest risk. One or more pieces of equipment that were subject to addition are identified when the sum exceeds the upper limit of the cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the end of the planning period. Determine the minimum risk increase rate for the one or more identified facilities. A method for formulating an equipment replacement plan, characterized in that, among the plurality of equipment, equipment whose risk increase rate is less than or equal to the minimum value is to be excluded from the equipment to be replaced during the planning period.

4. A program for formulating equipment replacement plans that causes a computer to formulate replacement plans for multiple pieces of equipment during the planning period, For each of the aforementioned multiple pieces of equipment, the step of calculating the risk, which is the expected value of the costs incurred due to the failure of said equipment, For each year of the aforementioned planning period, the steps include: determining which equipment to exclude from the equipment to be replaced during the planning period from among the multiple pieces of equipment, and extracting equipment other than the excluded equipment from the multiple pieces of equipment as candidates for replacement; For each year of the aforementioned planning period, the step is to determine which equipment to be replaced within the year from among the candidates, The computer is made to execute the above, In the step of calculating the risk, the risk is calculated based on a function in which the risk increase rate (the rate at which the risk increases) and the number of years elapsed since the start year of the planning period are variables. In the step of extracting equipment other than the excluded equipment from the aforementioned multiple pieces of equipment as candidates for replacement, Regarding the target year, which is one of several years included in the aforementioned planning period, The calculated risks are sorted from one to the other, and the multiple pieces of equipment are sorted in descending order of risk. The cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the year prior to the target year is used to add the risk for each piece of equipment in the target year, starting with the piece of equipment with the greatest risk. One or more pieces of equipment that were subject to addition are identified when the sum exceeds the upper limit of the cumulative value of the risk reduction amount for each of the multiple pieces of equipment from the start year to the end of the planning period. Determine the minimum risk increase rate for the one or more identified facilities. A program for formulating equipment replacement plans, characterized by determining which of the aforementioned multiple pieces of equipment have a risk increase rate that is less than or equal to the minimum value, to be excluded from the equipment to be replaced during the planning period.

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