Patent Number: 
Section: claims

1. A monitoring target selecting device which is configured to output a measurement parameter to an abnormality sign monitoring device that is configured to detect an abnormality sign of a plant on the basis of a correlation value representing a correlation between a plurality of the measurement parameters of the plant, the abnormality sign indicating that an operation state of the plant has a possibility to be abnormal, comprising:a classification unit configured to acquire a plurality of measurement parameters measured in the plant, classify a change behavior of measured value over a time for each of the plurality of measurement parameters in a first period, and classify a change behavior of a measured value over a time for each of the plurality of measurement parameters in a second period which is a period after the first period; anda selection unit configured to,when the behavior of the measurement parameter in the first period is the same as the behavior of the measurement parameter in the second period, select this measurement parameter as a measurement parameter to be output to the abnormality sign monitoring device on the basis of a result of comparing a behavior of the measurement parameter in the first period and a behavior of the measurement parameter in the second period, andwhen a difference between the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period exists, determine whether the difference is normal or abnormal on the basis of information stored in a storage unit in advance, and select this measurement parameter as the measurement parameter to be output to the abnormality sign monitoring device in case that the difference is determined to be normal,wherein the classification unit is configured to classify the measurement parameter, on the basis of an inclination value of a measured value over a time, into a first behavior whose inclination value is equal to or greater than a classification threshold value, a second behavior whose absolute value of the inclination value is less than the classification threshold value, and a third behavior whose absolute value of the inclination value is equal to or greater than the classification threshold value when the inclination value is a negative value. 2. The monitoring target selecting device according to claim 1,wherein, when the classification results of the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the same, the selection unit selects the measurement parameter to be output to the abnormality sign monitoring device. 3. The monitoring target selecting device according to claim 1,wherein, when a ratio or difference between mean values of the measurement parameter in each period is within a range of a first predetermined value in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the second behavior, the selection unit selects the measurement parameter to be output to the abnormality sign monitoring device. 4. The monitoring target selecting device according to claim 1,wherein, when a ratio or difference between respective inclination values is within a range of a second predetermined value in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the first behavior, the selection unit selects the measurement parameter to be output to the abnormality sign monitoring device. 5. The monitoring target selecting device according to claim 1,wherein, when respective inclination values are negative values and a ratio or difference between respective inclination values is within a range of a second predetermined value in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the third behavior, the selection unit selects the measurement parameter to be output to the abnormality sign monitoring device. 6. The monitoring target selecting device according to claim 1, further comprising:a storage unit configured to store the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period for each measurement parameter,wherein the selection unit refers to information stored in the storage unit, and selects the measurement parameter to be output to the abnormality sign monitoring device when the behavior of the measurement parameter in the second period is normal:when the behavior of the measurement parameter in the first period is different from the behavior of the measurement parameter in the second period;when a ratio or difference between mean values of the measurement parameter in each period is outside the range of a first predetermined value in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the second behavior;when a ratio between respective inclination values is outside a predetermined range in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the first behavior; orwhen respective inclination values are negative values and a ratio or difference between respective inclination values is outside the range of a second predetermined value in case that the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period are the third behavior. 7. A monitoring target selecting method of a monitoring target selecting device which is configured to output a measurement parameter to an abnormality diagnosis abnormality sign monitoring device that is configured to detect an abnormality sign of a plant on the basis of a correlation value representing a correlation between a plurality of the measurement parameters of the plant, the abnormality sign indicating that an operation state of the plant has a possibility to be abnormal, the method comprising:a step of acquiring, by a classification unit, a plurality of measurement parameters measured in the plant and classifying a change behavior of a measured value over a time for each of the plurality of measurement parameters in a first period;a step of classifying, by the classification unit, a change behavior of a measured value over a time for each of the plurality of measurement parameters in a second period which is a period after the first period; anda step of, when the behavior of the measurement parameter in the first period is the same as the behavior of the measurement parameter in the second period, selecting this measurement parameter to be output to the abnormality sign monitoring device on the basis of a result of comparing a behavior of the measurement parameter in the first period and a behavior of the measurement parameter in the second period, and when a difference between the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period exists, determining whether the difference is normal or abnormal on the basis of information stored in a storage unit in advance, and selecting this measurement parameter as the measurement parameter to be output to the abnormality sign monitoring device in case that the difference is determined to be normal, by the selection unit,wherein in steps of classifying the behaviors of the measurement parameters in the first and second period, classifying the measurement parameter, on the basis of an inclination value of a measured value over a time, into a first behavior whose inclination value is equal to or greater than a classification threshold value, a second behavior whose absolute value of the inclination value is less than the classification threshold value, and a third behavior whose absolute value of the inclination value is equal to or greater than the classification threshold value when the inclination value is a negative value, by the classification unit. 8. A non-transitory computer readable medium that stores a program causes a computer of a monitoring target selecting device which is configured to output a measurement parameter to an abnormality sign monitoring device that is configured to detect an abnormality sign of a plant on the basis of a correlation value representing a correlation between a plurality of the measurement parameters of the plant, the abnormality sign indicating that an operation state of the plant has a possibility to be abnormal, to executea procedure of acquiring a plurality of measurement parameters measured in the plant and classifying a change behavior of a measured value over a time for each of the plurality of measurement parameters in a first period;a procedure of classifying a change behavior of a measured value over a time for each of the plurality of measurement parameters in a second period which is a period after the first period; anda procedure of, when the behavior of the measurement parameter in the first period is the same as the behavior of the measurement parameter in the second period, selecting this measurement parameter to be output to the abnormality sign monitoring device on the basis of a result of comparing a behavior of the measurement parameter in the first period and a behavior of the measurement parameter in the second period, and when a difference between the behavior of the measurement parameter in the first period and the behavior of the measurement parameter in the second period exists, determining whether the difference is normal or abnormal on the basis of information stored in a storage unit in advance, and selecting this measurement parameter as the measurement parameter to be output to the abnormality sign monitoring device in case that the difference is determined to be normal, by the selection unit,wherein the classification unit is configured to classify the measurement parameter, on the basis of an inclination value of a measured value over a time, into a first behavior whose inclination value is equal to or greater than a classification threshold value, a second behavior whose absolute value of the inclination value is less than the classification threshold value, and a third behavior whose absolute value of the inclination value is equal to or greater than the classification threshold value when the inclination value is a negative value.