Operational monitoring for a converter

Abstract

Monitoring a converter ( 1 ) includes detecting whether a value of an input variable ( 2 ) for the converter ( 1 ) assumes a first prescribed input reference value ( 41 ) and checking whether an output variable ( 3 ) from the converter ( 1 ) likewise assumes a corresponding, second prescribed output reference value ( 61 ). This means that the operation of the converter is tested only at occasional instants, specifically only using individual, prescribed values. The fact that only prescribed values ( 41, 61 ) are compared with instantaneous values of the input and output variables ( 2, 3 ) means that the invention can be implemented using very simple means. The method is particularly suitable for monitoring the operation of a converter ( 1 ) in a control or protective device for an electrical switchgear assembly. In this context, when a malfunction in the converter ( 1 ) is detected, all protective functions which are dependent on the converter ( 1 ) are preferably turned off.

1. A monitoring apparatus for monitoring the operation of a converter having means for monitoring an input variable and at least one output variable, characterized in that the monitoring apparatus has
 an input detector for detecting an input reference value for an input variable for the converter,  
 an output detector for detecting an output reference value for an output variable, and  
 an evaluation unit for comparing results from the input detector and from the output detector and for producing a corresponding status signal which conveys correct operation or a malfunction in the converter.  
 
     
     
       2. The monitoring apparatus as claimed in  claim 1 , characterized in that the prescribed reference values correspond to a value zero for a voltage or for a current. 
     
     
       3. The monitoring apparatus as claimed in  claim 1 , characterized in that the converter is a digital/analog converter, the output detector is an analog detector, and the input detector and the evaluation unit are produced in one digital unit. 
     
     
       4. The monitoring apparatus as claimed in  claim 1 , characterized in that the converter is an analog/digital converter, the input detector is an analog detector, and the output detector and the evaluation unit are produced in one digital unit. 
     
     
       5. A method for monitoring the operation of a converter, characterized by
 determination of whether an input variable for the converter lies within a first prescribed tolerance range about an input reference value,  
 determination of whether an output variable from the converter lies within a second prescribed tolerance range about an output reference value, and,  
 if both the input variable and the output variable lie within the respective prescribed tolerance range for the respective reference value, the converter being established to be operating correctly, and otherwise the converter being established to be malfunctioning.  
 
     
     
       6. The method as claimed in  claim 5 , characterized in that the input reference value or the output reference value corresponds to a value zero for a voltage or for a current. 
     
     
       7. The method as claimed in  claim 5 , characterized in that, once it has been ascertained that the converter is malfunctioning, the output variable is marked as invalid. 
     
     
       8. The method as claimed in  claim 5 , characterized in that, once it has been ascertained that the converter is malfunctioning, protective functions of a protective device for an electrical switchgear assembly which are dependent on the converter are turned off. 
     
     
       9. The method as claimed in  claim 5 , characterized in that determination of whether both the input variable and the output variable lie within the respective prescribed tolerance range takes place on the basis of values of the input variable and values of the output variable which have been determined after having been shifted relative to one another by a delay time for the converter. 
     
     
       10. The method as claimed in  claim 5 , characterized in that the output variable is compared with the output reference value depending on whether the input variable for the converter lies within the first prescribed tolerance range for the input reference value. 
     
     
       11. A monitoring apparatus, comprising:
   a detector system configured to:      compare an input variable of a monitored device with an input reference value and generate a first flag indicative of the result of the comparison; and        compare an output variable of the monitored device with an output reference value and generate a second flag indicative of the result of the comparison; and          an evaluation unit configured to determine the status of the monitored device based on the generated first and second flags.     
     
     
       12. The apparatus of  claim 11 , wherein the monitored device comprises a converter that is configured to receive analog input variables and to output digital output variables. 
     
     
       13. The apparatus of  claim 11 , wherein the monitored device comprises a converter configured to receive digital input variables and to output analog output variables. 
     
     
       14. The apparatus of  claim 11 , wherein the detector system comprises:
   an input detector configured to compare the input variable and the input reference value; and        an output detector configured to compare the output variable and the output reference value.     
     
     
       15. The apparatus of  claim 14 , wherein the input detector is further configured to perform the comparison on a periodic basis. 
     
     
       16. The apparatus of  claim 14 , wherein the output detector is further configured to perform the comparison on a periodic basis. 
     
     
       17. The apparatus of  claim 14 , wherein the input and output reference values are prescribed, and wherein the input and output variables are measurements representative of time- varying electrical voltage or current values.   
     
     
       18. The apparatus of  claim 17 , wherein the input and output reference values are zero. 
     
     
       19. The apparatus of  claim 14 , wherein the output detector is further configured to compare the output variable and the output reference value only if the comparison of the input variable and the input reference value indicates that the input variable is sufficiently matched to the input reference value. 
     
     
       20. The apparatus of  claim 11 , wherein the monitored device comprises a converter including a plurality of cascaded converter sections, each configured to produce an output variable, and wherein the detector system is further configured to compare each of the output variables with associated output reference values and to generate corresponding flags indicative of the results of the comparisons. 
     
     
       21. A computer readable medium including instructions which when executed by a microprocessor causes the microprocessor to perform monitoring of a converter, comprising the steps of:
   Comparing an input variable for the converter with an input reference value;        Comparing an output variable from the converter with an output reference value; and        Determining a converter status based on the comparison of the input variable with the input reference value and based on the comparison of the output variable with the output reference value.     
     
     
       22. The computer readable medium of  claim 21 , wherein the converter receives analog input variables and outputs digital output variables. 
     
     
       23. The computer readable medium of  claim 21 , wherein the converter receives digital input variables and outputs analog output variables. 
     
     
       24. The computer readable medium of  claim 21 , wherein the comparison of the input variable with the input reference value is performed on a periodic basis. 
     
     
       25. The computer readable medium of  claim 21 , wherein the comparison of the output variable with the output reference values is performed on a periodic basis. 
     
     
       26. The computer readable medium of  claim 21 , wherein the input and output reference values are prescribed, and wherein the input and output variables are measurement representative of time- varying electrical voltage or current values.   
     
     
       27. The computer readable medium of  claim 26 , wherein the input and the output reference values are zero. 
     
     
       28. The computer readable medium of  claim 21 , wherein said comparing on output variable from the converter with an output reference value occurs only if said comparing an input variable for the converter with an input reference value indicates that the input variable is sufficiently matched to the input reference value. 
     
     
       29. The computer readable medium of  claim 21 , wherein the converter comprises a plurality of cascaded converter sections, each producing an output variable, and wherein the method further comprises comparing each of the output variables with associated output reference values and generating corresponding flags indicative of the results of the comparisons. 
     
     
       30. A device for monitoring a converter, comprising:
   input detector means for comparing an input variable for the converter with an input reference value;        output detector means for comparing an output variable from the converter with an output reference value; and        evaluation means for determining a converter status based on the comparison of the input variable with the input reference value and based on the comparison of the output variable with the output reference value.     
     
     
       31. The device of  claim 30 , wherein the converter receives analog input variables and outputs digital output variables. 
     
     
       32. The device of  claim 30 , wherein the converter receives digital input variables and outputs analog output variables. 
     
     
       33. The device of  claim 30 , wherein the input detector means is configured to compare an input variable with an input reference value on a periodic basis. 
     
     
       34. The device of  claim 30 , wherein the output detector means is configured to compare an output variable with an output reference values on a periodic basis. 
     
     
       35. The device of  claim 30 , wherein the input and output reference values are prescribed, and wherein the input and output variables are measurements representative of time- varying electrical voltage or current values.   
     
     
       36. The device of  claim 35 , wherein the input and output reference values are zero. 
     
     
       37. The device of  claim 30 , wherein the output detector means is configured to compare the output variable and the output reference value only if the comparison of the input variable and the input reference value indicates that the input variable is sufficiently matched to the input reference value. 
     
     
       38. The device of  claim 30 , wherein the converter comprises a plurality of cascaded converter sections, each producing and output variable, and wherein the device further comprises means for comparing each of the output variables with associated output reference values and generating corresponding flags indicative of the results of the comparisons. 
     
     
       39. A system, comprising:
   a converter;        a detector configured to compare converter variables with associated reference values, the detector comprising:      an input detector configured to compare an input variable with an input reference value; and        an output detector configured to compare an output variable with an output reference value, and          an evaluation circuit operatively coupled to the detector and configured to determine the status of the converter based on the comparisons.     
     
     
       40. The system of  claim 39 , wherein the input detector is further configured to perform the comparison on a periodic basis. 
     
     
       41. The system of  claim 39 , wherein the output detector is further configured to perform the comparison on a periodic basis. 
     
     
       42. The system of  claim 39 , wherein the output detector is further configured to compare the output variable with the output reference value only if the comparison of the input variable with the input reference value indicates that the input variable is sufficiently matched to the input reference value. 
     
     
       43. A monitoring apparatus for monitoring the operation of a converter, comprising:
   an input detector configured to determine whether an input variable for the converter lies within a range of an input reference value;        an output detector configured to determine whether an output variable lies within a range of an output reference value; and        an evaluation unit configured to compare results from the input detector and from the output detector and to produce a status signal indicating a status of the converter.     
     
     
       44. The monitoring apparatus of  claim 43 , wherein the input and output reference values correspond to a value zero for a voltage or for a current. 
     
     
       45. The monitoring apparatus of  claim 43 , wherein the converter is a digital/analog converter, the output detector is an analog detector, and the input detector and the evaluation unit are disposed in one digital unit. 
     
     
       46. The monitoring apparatus of  claim 43 , wherein the converter is an analog/digital converter, the input detector is an analog detector, and the output detector and the evaluation unit are disposed in one digital unit. 
     
     
       47. A method for monitoring the operation of a converter, comprising:
   determining whether an input variable for the converter lies within a first prescribed tolerance range about an input reference value;        determining whether an output variable from the converter lies within a second prescribed tolerance range about an output reference value; and        determining a status of the converter based on whether the input variable and the output variable lie within the respective prescribed tolerance range for the respective reference value.     
     
     
       48. The method of  claim 47 , wherein either the input reference value or the output reference value corresponds to a value zero for a voltage or for a current. 
     
     
       49. The method of  claim 47 , wherein when the status indicates that the converter is malfunctioning, the output variable is determined to be invalid. 
     
     
       50. The method of  claim 47 , wherein when the status indicates that the converter is malfunctioning, protective functions dependent on the converter are turned off. 
     
     
       51. The method of  claim 47 , wherein the determinations of whether the input variable and the output variable lie within the respective prescribed tolerance range is based on values of the input variable and values of the output variable which have been determined after having been shifted relative to one another by a delay time. 
     
     
       52. The method of  claim 47 , wherein the output variable is compared with the output reference value depending on whether the input variable for the converter lies within the first prescribed tolerance range.