Line disturbance monitor
First Claim
1. A disturbance monitor for monitoring at least one operating parameter of a power line comprising:
- input means connectable to the power line for providing at least one analog signal representative of the time varying value of the parameter;
A/D conversion means connected to said input means for sampling the analog signal at predetermined intervals and producing at each sample time a digital sample word representing the value of the sampled parameter at the sample time;
disturbance sensing means connected to receive digital sample words from said A/D conversion means, said disturbance sensing means storing reference parameter values for the power line and to detect deviations from the reference parameter values by the received digital sample words and derive in response to such deviations data indicative of a disturbance on the line;
storage means including at least one storage zone having a plurality of storage locations of which a predetermined number are assigned to pre-disturbance operation, and the remainder are assigned to post-disturbance operation, said predetermined number of storage locations being arranged for sequential addressing in a loop to store sequentially generated sample words with the most recently generated sample word replacing the oldest stored sample word, and said remainder of said storage locations arranged to store sample words sequentially addressed;
control means including a main digital processing unit connected to receive sample words from said A/D conversion means and programmed to cause the sample words to be written into the pre-disturbance storage locations as the sample words are generated, and said control means being responsive to said disturbance sensing means to cause subsequently generated sample words to be written into the post-disturbance locations;
data flag generating means responsive to at least one predetermined operating condition and inserting data flags representing the predetermined condition into said storage means between successively generated sample words; and
said control means, after said post-disturbance locations have been filled, reading the sample words and the data flags from the storage means in chronological order of storage and preparing said sample words for display of the corresponding signals in analog form, the data represented by the flags being chronologically related to said corresponding signals.
1 Assignment
0 Petitions
Accused Products
Abstract
A monitor (FIG. 1) of disturbances of normal voltage/current parameters of a power line 12 consists of input A/D conversion means 18 by which the actual parameters are sampled and digitized and applied to a store 36 controlled by a main microprocessor 30. A real time clock also provides time markers which are stored as flags with the sample data. The store has a plurality of locations which are addressed in a loop whereby newly digitized sample data replaces that stored previously. A secondary microprocessor 54 also receives the digitized measured parameter data which it compares with stored nominal parameter data to detect a disturbance, the detection causing the store to store subsequent sample data sequentially in different locations. Thereafter the main processor reads the data from the store to provide samples stored prior to, and subsequent to, the disturbance and the real time relationship between them. The data read from the store is reproduced on a dot-matrix printer 62 in graphical form related to the real time markers and the information relating to the disturbance printed alphanumerically to a higher degree of accuracy than the printer resolution permits. The data may be stored on a removable floppy disc 112 for reproduction on a high resolution plotter and external event inputs 104 may be provided to cater for a limited number of bistable condition changes considered as disturbances.
33 Citations
17 Claims
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1. A disturbance monitor for monitoring at least one operating parameter of a power line comprising:
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input means connectable to the power line for providing at least one analog signal representative of the time varying value of the parameter; A/D conversion means connected to said input means for sampling the analog signal at predetermined intervals and producing at each sample time a digital sample word representing the value of the sampled parameter at the sample time; disturbance sensing means connected to receive digital sample words from said A/D conversion means, said disturbance sensing means storing reference parameter values for the power line and to detect deviations from the reference parameter values by the received digital sample words and derive in response to such deviations data indicative of a disturbance on the line; storage means including at least one storage zone having a plurality of storage locations of which a predetermined number are assigned to pre-disturbance operation, and the remainder are assigned to post-disturbance operation, said predetermined number of storage locations being arranged for sequential addressing in a loop to store sequentially generated sample words with the most recently generated sample word replacing the oldest stored sample word, and said remainder of said storage locations arranged to store sample words sequentially addressed; control means including a main digital processing unit connected to receive sample words from said A/D conversion means and programmed to cause the sample words to be written into the pre-disturbance storage locations as the sample words are generated, and said control means being responsive to said disturbance sensing means to cause subsequently generated sample words to be written into the post-disturbance locations; data flag generating means responsive to at least one predetermined operating condition and inserting data flags representing the predetermined condition into said storage means between successively generated sample words; and said control means, after said post-disturbance locations have been filled, reading the sample words and the data flags from the storage means in chronological order of storage and preparing said sample words for display of the corresponding signals in analog form, the data represented by the flags being chronologically related to said corresponding signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of monitoring a power line for deviation of an operating parameter from a reference, said method comprising:
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deriving from the power line an analog signal representative of the parameter; digitizing the signal by sampling to form a succession of sample words which represent values of the parameter at the times of sampling; storing a predetermined number of the sample words and a predetermined number of sample times in locations of a store arranged in a loop such that each generated sample word replaces the oldest stored word; comparing a function of the sample words which represents the function of the operating parameter with a function which represents the reference and, in response to a deviation therefrom indicative of a line disturbance, storing a succeeding predetermined number of generated sample words in different locations in the store; subsequently reading the stored sample words from the store in chronological order of storage; and displaying representations of the sample values, as a function of position with respect to one axis of the display, against sample times as a function of position with respect to the other axis of the display relative to the time at which the disturbance is detected. - View Dependent Claims (15, 16, 17)
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Specification