System and method to characterize and identify operating modes of electric loads

Abstract

A system characterizes and identifies one of a plurality of different operating modes of a number of electric loads. The system includes a processor; a voltage sensor providing a voltage signal for one of the electric loads to the processor; a current sensor providing a current signal for the one electric load to the processor; and a routine executed by the processor and structured to characterize the different operating modes using steady state and voltage-current trajectory features determined from the voltage and current signals, and to identify a particular one of the different operating modes based on a plurality of operating mode membership functions of the steady state and voltage-current trajectory features.

What is claimed is: 
     
         1 . A system to characterize and identify one of a plurality of different operating modes of a number of electric loads, said system comprising:
 a processor;   a sensor providing a voltage signal for one of said electric loads to said processor;   a current sensor providing a current signal for said one of said electric loads to said processor; and   a routine executed by said processor and structured to characterize said different operating modes using steady state and voltage-current trajectory features determined from said voltage and current signals, and to identify a particular one of said different operating modes based on a plurality of operating mode membership functions of said steady state and voltage-current trajectory features.   
     
     
         2 . The system of  claim 1  wherein said different operating modes comprise a no load mode, a parasitic mode, an active mode, and a standby mode. 
     
     
         3 . The system of  claim 2  wherein said routine identifies the active mode if a first one of said membership functions of real power of the voltage and current signals is greater than or equal to a predetermined value and otherwise, if area of a voltage-current trajectory plot of the voltage and current signals is negative, determines a first value of a second one of said membership functions of the area for the parasitic mode and a second value of a third one of said membership functions of the area for the active mode, and otherwise, if the area is positive, determines a third value of a fourth one of said membership functions of the area for the parasitic mode and a fourth value of a fifth one of said membership functions of the area for the active mode. 
     
     
         4 . The system of  claim 2  wherein said routine calculates a probability of one of said different operating modes from at least one of:
 (1) a first product of a first one of said membership functions of real power of the voltage and current signals times a second one of said membership functions of total harmonic distortion greater than the seventh harmonic for the no load mode, 
 (2) a second product of a third one of said membership functions of the real power times a fourth one of said membership functions of area of a voltage-current trajectory plot of the voltage and current signals for the parasitic mode, and 
 (3) a third product of a fifth one of said membership functions of total harmonic distortion greater than the seventh harmonic times a sixth one of said membership functions of the area times a seventh one of said membership functions of the real power for the active mode. 
 
     
     
         5 . The system of  claim 4  wherein said routine identifies the no load mode in the event that the first one of said membership functions is greater than a first predetermined value, and the first, second and third products are all less than a second smaller predetermined value. 
     
     
         6 . The system of  claim 4  wherein a probability difference is equal to one minus a second largest one of said first, second and third products divided by the largest one of said first, second and third products; and wherein if the probability difference is less than a predetermined value, and if the second product is the largest one of said first, second and third products and the third product is the second largest one of said first, second and third products, then said routine identifies the active mode. 
     
     
         7 . The system of  claim 4  wherein after said routine identifies said active mode corresponding to a first value of the real power, if a subsequent second value of the real power is less than half of the first value, then said routine identifies said standby mode. 
     
     
         8 . The system of  claim 1  wherein said steady state and voltage-current trajectory features comprise total harmonic distortion greater than the seventh harmonic, average power of the voltage and current signals, and area of a voltage-current trajectory plot of the voltage and current signals. 
     
     
         9 . The system of  claim 8  wherein a plurality of said membership functions are employed for each of said steady state and voltage-current trajectory features. 
     
     
         10 . The system of  claim 1  wherein said processor, for each line cycle of said voltage and current signals, inputs and stores a line cycle of data from said voltage and current signals, calculates total harmonic distortion greater than the seventh harmonic, average power of the voltage and current signals, and area of a voltage-current trajectory plot of the voltage and current signals from the stored line cycle of data, and displays the identified particular one of said different operating modes. 
     
     
         11 . A method to characterize and identify one of a plurality of different operating modes of a number of electric loads, said method comprising:
 providing a voltage signal for one of said electric loads to a processor;   providing a current signal for said one of said electric loads to said processor; and   characterizing by said processor said different operating modes using steady state and voltage-current trajectory features determined from said voltage and current signals, and identifying a particular one of said different operating modes based on a plurality of operating mode membership functions of said steady state and voltage-current trajectory features.   
     
     
         12 . The method of  claim 11  further comprising:
 said different operating modes comprising a no load mode, a parasitic mode, an active mode, and a standby mode. 
 
     
     
         13 . The method of  claim 12  further comprising:
 identifying the active mode if a first one of said membership functions of real power of the voltage and current signals is greater than or equal to a predetermined value; 
 otherwise, if area of a voltage-current trajectory plot of the voltage and current signals is negative, determining a first value of a second one of said membership functions of the area for the parasitic mode and a second value of a third one of said membership functions of the area for the active mode; and 
 otherwise, if the area is positive, determining a third value of a fourth one of said membership functions of the area for the parasitic mode and a fourth value of a fifth one of said membership functions of the area for the active mode. 
 
     
     
         14 . The method of  claim 1  further comprising:
 calculating a probability of one of said different operating modes from at least one of: 
 (1) a first product of a first one of said membership functions of real power of the voltage and current signals times a second one of said membership functions of total harmonic distortion greater than the seventh harmonic for the no load mode, 
 (2) a second product of a third one of said membership functions of the real power times a fourth one of said membership functions of area of a voltage-current trajectory plot of the voltage and current signals for the parasitic mode, and 
 (3) a third product of a fifth one of said membership functions of total harmonic distortion greater than the seventh harmonic times a sixth one of said membership functions of the area times a seventh one of said membership functions of the real power for the active mode. 
 
     
     
         15 . The method of  claim 14  further comprising:
 identifying the no load mode in the event that the first one of said membership functions is greater than a first predetermined value, and the first, second and third products are all less than a smaller second predetermined value. 
 
     
     
         16 . The method of  claim 14  further comprising:
 employing a probability difference equal to one minus a second largest one of said first, second and third products divided by the largest one of said first, second and third products; and 
 if the probability difference is less than a predetermined value, and if the second product is the largest one of said first, second and third products and the third product is the second largest one of said first, second and third products, then identifying the active mode. 
 
     
     
         17 . The method of  claim 14  further comprising:
 after identifying said active mode corresponding to a first value of the real power, if a subsequent second value of the real power is less than half of the first value, then identifying said standby mode. 
 
     
     
         18 . The method of  claim 11  further comprising:
 said steady state and voltage-current trajectory comprising total harmonic distortion greater than the seventh harmonic, average power of the voltage and current signals, and area of a voltage-current trajectory plot of the voltage and current signals. 
 
     
     
         19 . The method of  claim 18  further comprising:
 employing a plurality of said membership functions for each of said steady state and voltage-current trajectory features. 
 
     
     
         20 . The method of  claim 11  further comprising:
 for each line cycle of said voltage and current signals:
 inputting and storing a line cycle of data from said voltage and current signals, 
 calculating total harmonic distortion greater than the seventh harmonic, average power of the voltage and current signals, and area of a voltage-current trajectory plot of the voltage and current signals from the stored line cycle of data, and 
 displaying the identified particular one of said different operating modes.