Sub-harmonic detection and control system
First Claim
1. A sub-harmonic detection and control system comprising:
- a sub-harmonic detection module connected to an input signal, said sub-harmonic detection module operable to detect a presence of at least two distinct types of sub-harmonic content in the input signal,a logical signal processor electrically connected to the sub-harmonic detection module, said logical signal processor operable to independently determine at least two distinct types of adverse phenomena associated with said at least two distinct types of sub-harmonic content, respectively, wherein said logical signal processor generates at least two output signals representative of said determinations, anda system controller electrically connected to the logical signal processor, said system controller responsive to said at least two output signals to eliminate effects of said two distinct types of adverse phenomena.
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Abstract
A distribution series capacitor control system is provided with a sub-harmonic detection module connected to an input signal and operable to detect the presence of at least two distinct types of sub-harmonic content in the input signal. A logical signal processor is electrically connected to the sub-harmonic detection module, and operates to independently determine the existence of self-excitation during induction motor starting and ferroresonant phenomena based upon the at least two distinct types of sub-harmonic content, respectively. A system controller is electrically connected to the logical signal processor and operates to eliminate effects of self-excitation during induction motor starting and ferroresonant phenomena on the system.
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Citations
22 Claims
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1. A sub-harmonic detection and control system comprising:
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a sub-harmonic detection module connected to an input signal, said sub-harmonic detection module operable to detect a presence of at least two distinct types of sub-harmonic content in the input signal, a logical signal processor electrically connected to the sub-harmonic detection module, said logical signal processor operable to independently determine at least two distinct types of adverse phenomena associated with said at least two distinct types of sub-harmonic content, respectively, wherein said logical signal processor generates at least two output signals representative of said determinations, and a system controller electrically connected to the logical signal processor, said system controller responsive to said at least two output signals to eliminate effects of said two distinct types of adverse phenomena. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sub-harmonic detection and control system for use with an electrical distribution system having a bank of series-connected capacitors, comprising:
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a sub-harmonic detection module including at least one input that receives an input signal, at least one filter electrically connected to the at least one input that isolates a sub-harmonic component of the input signal, a first comparator electrically connected to the at least one filter for generating a first output signal when a voltage of the sub-harmonic component exceeds a first threshold value, a second comparator electrically connected to the at least one filter for generating a second output signal when the voltage of the sub-harmonic component exceeds a second threshold value, and first and second outputs electrically connected to the first and second comparators, respectively, a logical signal processor electrically connected to said first and second outputs, said logical signal processor receives said first and second output signals, wherein said logical signal processor, upon receipt of said first output signal, acts to determine a presence of a first distinct event associated with said first output signal, and wherein said logical signal processor, upon receipt of said second output signal, acts to determine a presence of a second distinct event associated with said second output signal, a system controller electrically connected to the logical signal processor, wherein said system controller is operable, in response to a determination of said first distinct event, to insert a damping resistor in parallel with said bank of series-connected capacitors, and wherein said system controller is further operable, upon receipt of a determination of said second distinct event, to bypass said bank of series-connected capacitors.
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8. A method for detecting and controlling sub-harmonic signal content in an electrical distribution system comprising the steps of:
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detecting the presence of at least two distinct types of sub-harmonic content in an input signal, determining the presence of at least two distinct types of adverse phenomena associated with said at least two distinct types of sub-harmonic content, and controlling the electrical distribution system to eliminate effects of said at least two distinct types of adverse phenomena. - View Dependent Claims (9, 10, 11, 20)
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12. A method for detecting and controlling sub-harmonic signal content in a distribution capacitor control system having a bank of series-connected capacitors, comprising the steps of:
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isolating a sub-harmonic content of an input signal, comparing a voltage value of the sub-harmonic content to first and second distinct threshold voltages, generating a first output signal indicative of whether the voltage value of the sub-harmonic content exceeds the first threshold voltage, generating a second output signal indicative of whether the voltage value of the sub-harmonic content exceeds the second threshold voltage, processing the first and second output signals to determine the existence of first and second sub-harmonic phenomena, upon determining the existence of the first sub-harmonic phenomenon, controlling the system to eliminate the first sub-harmonic phenomenon, and upon determining the existence of the second sub-harmonic phenomenon, controlling the system to eliminate the second sub-harmonic phenomenon. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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21. A computer readable medium incorporating instructions for determining ferroresonance and self-excitation events, the instructions comprising:
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starting a timer to begin a sequence having a first portion and a second portion, counting a number of first pulses representative of a first sub-harmonic content received during the first or second portions, counting a number of second pulses representative of a second sub-harmonic content received during the first or second portions, counting a number of second pulses representative of a second sub-harmonic content received during the first or second portions, generating a ferroresonance event signal when more than one second pulse is counted during the first or second portions, counting the number of successive sequences in which at least one first pulse is counted, and generating a self-excitation event signal when the number of successive sequences in which at least one first pulse is counted is at least 3.
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22. A computer readable medium incorporating instructions for controlling a system to eliminate a first sub-harmonic phenomenon, the instructions comprising:
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receiving an output signal indicating a first sub-harmonic event, inserting a damping resistor in parallel electronic relationship to a bank of series-connected capacitors, bypassing the bank of series connected capacitors when the sub-harmonic event persists approximately three seconds following the insertion of the damping resistor, and isolating the damping resistor approximately five second following the insertion of the damping resistor when the sub-harmonic event discontinues within approximately three seconds following the insertion of the damping resistor.
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Specification