WO2013166005A1 - Systèmes d'acquisition de données de système électrique - Google Patents

Systèmes d'acquisition de données de système électrique Download PDF

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Publication number
WO2013166005A1
WO2013166005A1 PCT/US2013/038848 US2013038848W WO2013166005A1 WO 2013166005 A1 WO2013166005 A1 WO 2013166005A1 US 2013038848 W US2013038848 W US 2013038848W WO 2013166005 A1 WO2013166005 A1 WO 2013166005A1
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WIPO (PCT)
Prior art keywords
signal
signals
response
clock
filter
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PCT/US2013/038848
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English (en)
Inventor
Anthony J. RANSON
Richard T. Dickens
Adriano MCAVOY
Original Assignee
Mehta Tech, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from US13/484,096 external-priority patent/US20130285719A1/en
Application filed by Mehta Tech, Inc. filed Critical Mehta Tech, Inc.
Publication of WO2013166005A1 publication Critical patent/WO2013166005A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
    • G01R19/2509—Details concerning sampling, digitizing or waveform capturing

Definitions

  • Embodiments relate to power system data acquisition systems and, in particular, to event recording in power systems.
  • a phasor measurement unit PMU must maintain a total vector error (TVE) in a phasor measurement below a specified maximum.
  • TVE total vector error
  • synchronization, delays in processing, or the like can increase a likelihood of exceeding the TVE maximum. For example, in a 60 Hz power system, a time error of +/- 26 s, without an magnitude errors, can result in a TVE exceeding the specified maximum amount.
  • FIG. 1 is a block diagram illustrating a power system data acquisition system according to an embodiment.
  • FIG. 2 is a block diagram illustrating a module of a power system data acquisition system according to an embodiment.
  • FIG. 3 is a block diagram illustrating a digital filter according to an embodiment.
  • FIG. 4 is a block diagram illustrating a digital filter according to another embodiment.
  • FIG. 5 is a block diagram illustrating a power system data acquisition system according to another embodiment.
  • FIG. 6 is a block diagram illustrating a clock signal generator according to an embodiment.
  • FIG. 7 is a block diagram illustrating an example of a clock signal analyzer of FIG. 6.
  • FIG. 1 is a block diagram illustrating a power system data acquisition system according to an embodiment.
  • a data acquisition system 10 is coupled to a power system 12.
  • the power system 12 can include voltage transformers 14, current transformers 16, or other custom sensors 18. Circuit breakers, power generators, transformers, temperature sensors, or other components can be part of the power system 12.
  • the system 10 includes interfaces 20 for such power system components.
  • Two interfaces 20 are illustrated as coupled to the power system 12, however, any number of interfaces can be present.
  • the interfaces 20 can include isolation circuitry, step- down transformers, input protection, transducers, or other circuitry to condition a signal associated with component of the power system 12 to prepare for digitization.
  • An interface 20 can be coupled to one or more power system component.
  • the system 10 can include one or more modules 22. Each module 22 can be coupled to one or more interfaces 20.
  • a module 22 can be configured to digitize the signal from the interface 20 and filter the digitized signal. In particular, the module 22 can be configured to generate a time-shifted, digitized signal.
  • the system 10 includes two modules 22; however, any number of modules 22 can be present.
  • only one module 22 is illustrated as being coupled to interfaces 20; however, each module 22 can be coupled to any number of interfaces 20.
  • the modules 22 are coupled to a communication medium 24.
  • the communication medium 24 can be a network, backplane, bus, or the like.
  • a controller 26 can be coupled to the communication medium 24 and be configured to communicate with the modules 22. The controller 26 can be configured to communicate through an interface 28 to other systems outside of the data acquisition system 10.
  • a time shift can be introduced into the digitized signal that can be a non-integer multiple of a sample period used for digitization.
  • the signal from the interface can be scaled to allow for full use of a range of the digitized signal.
  • signal processing can be performed substantially independently for each signal associated with each interface 20. In other words, measurement of different, contemporaneous events with different propagation delays and ranges can be substantially synchronized and digitized with improved accuracy.
  • FIG. 2 is a block diagram illustrating a module of a power system data acquisition system according to an embodiment.
  • the module 50 is configured to receive input signals 52.
  • the input signals 52 can be signals from the interfaces 20 described above.
  • Digitizers 54 are configured to digitize the input signals 52. Although only two digitizers are illustrated, any number of digitizers can be present. In addition, each input signal 52 can, but need not be associated with a dedicated digitizer 54.
  • a multi-channel digitizer 56 can include a multiplexer front-end that can selectively route input signals 52 to one or more digitizers 54. However, substantially independent digitized signals 58 can be generated corresponding to the input signals 52.
  • Each digitized signal 58 can be filtered by a corresponding digital filter 60.
  • a controller 64 can be configured to store the filtered signals 62 in a memory 66, transmit the signals over a communication interface 68.
  • a calibration time for an associated input can be stored in the memory 66.
  • a digitizer 54 can be coupled to an interface 20 to receive an input signal 52 from that interface 20.
  • Another digitizer 54 can be coupled to a different interface 20.
  • a calibration time for each signal path can be established so that substantially contemporaneous events in the power system 12 result in substantially
  • contemporaneous digitized signals 62 after the respective calibration times are applied.
  • the calibration times for the various inputs can be used to align the digitized signals in time to an external reference signal.
  • a sample clock can be substantially synchronized with a global positioning system (GPS) clock, Inter-range Instrumentation Group (IRIG) signal, a related reference signal, or the like. That is, not only can differences in the relative delay times between when events associated with different inputs occur and when the events are digitized be substantially eliminated, but the differences in delay times relative to the reference clock can be substantially eliminated as well.
  • the calibration times can, but need not accommodate for the entire difference in delay between an event and a reference signal.
  • the calibration times can accommodate a difference in delay between events and an internal reference signal. Subsequent processing can accommodate a difference between the internal and external reference signals.
  • the filter 60 can be configured to implement the calibration time and/or scale the digitized signal 58.
  • the filter 60 is configured to scale the digitized signal 58 to allow use of a full range of the digitized signal.
  • the controller 64 is coupled to the communication interface 68.
  • communication interface 68 can be an interface suitable to couple the module 50 to the communication medium 24 described above.
  • digitizers 54 have been described as receiving the input signals 52, other circuitry can be present between a digitizer 54 and the interface to the module 50 for the input signals 52.
  • input protection, attenuators, amplifiers, filters, or the like can be present.
  • FIG. 3 is a block diagram illustrating a digital filter according to an embodiment.
  • a finite impulse response (FIR) filter 90 is an example of the digital filter 60.
  • the filter 90 has coefficients 92 ao through a ⁇ .
  • the coefficients 92 can implement a FIR filter to filter an input signal 94 to generate an output signal 96.
  • initial coefficients are determined for a desired filter shape.
  • the coefficients can be integer coefficients.
  • the coefficients can be scaled up such that a largest coefficient has a magnitude greater than or equal to one half of a maximum magnitude of a coefficient. For example, using an 8 bit signed integer for coefficients, an initial coefficient set can be 43, 16, and 2.
  • the coefficients can be scaled up by multiplying the coefficients by a constant, logically left shifting the coefficients, or the like. Using logically left shifting as an example, left shifting the coefficients by one bit results in coefficients of 86, 32, and 4. For an 8 bit signed integer, a maximum magnitude is 127 and one half is approximately 64. Thus, logically shifting the coefficients results in at least one coefficient, namely 86, being greater then 64, or one half of the maximum magnitude.
  • the initial coefficients can be stored in the memory 66 and shifted by the controller 64.
  • the shifted coefficients can be stored in the memory 66.
  • the stored coefficients can be selected such that the initial coefficients have at least one coefficient that is greater than one half of a maximum magnitude.
  • the coefficients can represent other types of numbers.
  • the coefficients can represent fractional fixed point numbers within a range.
  • An example of a range is from - 1 to +1 .
  • integers and fixed point numbers have been described, the coefficients can also be represented by floating point numbers as desired.
  • the coefficients can be scaled down according to a desired range of sensed values. For example, during a calibration a range of sensed values, when digitized, could correspond to a range greater than the full range available using the scaled up coefficients described above.
  • the coefficients can be scaled down to appropriately scale the filtered signal 96. That is, with the coefficients scaled up as described above, a given input signal range may result in overflows. Accordingly, the coefficients can be scaled down so that a particular range of sensed values is fully contained within the range of the filtered signal 96.
  • the memory 66 can be configured to store a maximum sensed value.
  • the controller 64 is configured to scale the filter coefficients such that when the maximum sensed value is filtered by the digital filter, an output of the digital filter is less than a maximum output magnitude of the digital filter.
  • a raw scale factor can be stored.
  • the raw scale factor can be a value such that when the scaled up coefficients are multiplied by or divided by the raw scale factor, the resulting coefficients are the coefficients that result in a desired scaling for a desired input range.
  • each digitized signal 58 can be independently scaled as desired.
  • a given module can be configurable to receive different types of signals having different ranges.
  • FIG. 4 is a block diagram illustrating a digital filter according to another embodiment.
  • filter coefficients can be calculated for a digital filter in response to a calibration time.
  • the calibration time can be used to shift a sampled signal in time relative to a sample clock.
  • Filter 100 includes coefficients 102 bo through bN+M -
  • the memory 66 can be configured to store a calibration time that is a fraction of a sample period.
  • Coefficients 102 can be generated from filter coefficients 92 to generate a time-shifted output.
  • the time shifting can be created by appropriately creating the coefficients 102 to maintain the filtering of the digital filter 90, but introducing a time shift.
  • M additional stages can be used as in the filter 100.
  • a factor a can represent a fraction of a sample period.
  • the coefficients 102 can be calculated with equations 1 -3.
  • bo a 0 (1 -a) (1 )
  • coefficients 102 can be calculated for filter 100 that effectively shift the filtered signal in time by a fraction of a sample period. Although two filter coefficients have been used as an example for coefficients 92, any number N+1 coefficients can be used to generate N+2 coefficients 102 for shifting in time by a fraction of the sample period.
  • a delay of a non-integer multiple of the sample period can be introduced. That is, the delay can be greater than one sample period, but still have a granularity that is less than a sample period. For example, a delay can be 3.5 times the sample period.
  • additional delay stages can be introduced.
  • the controller 64 can be configured to calculate the coefficients 102 in response to the coefficients 92 and the calibration time. That is, the coefficients of the filter 90 can be stored in the memory 66.
  • the controller 64 can receive a calibration time, for example, after installation in the field.
  • the controller 64 can be configured to generate coefficients 104 for the digital filter 100 in response to the calibration time and the coefficients 92.
  • the controller 64 can be configured to calculate the coefficients 102 in a variety of ways.
  • the controller 64 is programmed with equations to calculate each of the coefficients 102 in response to the coefficients 92 and a calibration time. Using the example of equations 1 -3 above, the controller 64 can be configured to convert the calibration time into a. The controller 64 can then calculate the coefficients 102.
  • the memory 66 is configured to store coefficients of an interpolation filter.
  • coefficients of an interpolation filter are represented by equations 4 and 5:
  • Co (1 -a) (4)
  • the coefficients c 0 and Ci can be convolved with the coefficients 92 a 0 through aN- That is, the controller 64 is configured to calculate coefficients of the interpolation filter in response to a calibration time. The controller 64 is configured to then convolve the recently calculated interpolation filter coefficients with the initial filter coefficients to generate the coefficients 102 of the filter 100.
  • the filter 100 can be created that can scale and time shift an input signal.
  • input signals 52 can be substantially synchronized and normalized in a data acquisition system 10.
  • N+1 coefficients 92 or N+M+1 coefficients 102 a digital filter can be used that does not use only unit delay functions.
  • a N+1 -th order filter of FIG. 3 can be implemented with less than N+1 coefficients.
  • linear interpolation has been described as a technique to obtain a filtered value between two samples
  • other interpolation techniques can be used.
  • a cubic interpolation technique can be used.
  • coefficients Co through C3 can be created for a cubic interpolation filter and convolved with coefficients 92.
  • equations can be created to calculate the coefficients bo through bN+3 in response to a calibration time.
  • the filter that implements the interpolation can be a linear phase filter, a non-linear phase filter can be used.
  • the filter that implements the interpolation can, but need not be an all pass filter.
  • FIG. 5 is a block diagram illustrating a power system data acquisition system according to another embodiment.
  • the system 120 includes a clock module 122 configured to receive a clock signal 124.
  • the clock module 122 is configured to generate a synchronization signal in response to the clock signal 124.
  • the clock module 122 is coupled to the communication medium 24 and can transmit the synchronization signal through the communication medium 24.
  • the modules 22 are configured to receive the synchronization signal.
  • the modules 22 are configured to generate a time-shifted, digitized signal. That is, the modules 22 can create digitized signals representing aspects of the power system 12 that can be calibrated in time internal to a single module 22. Multiple modules can be synchronized to the synchronization signal. As a result, the digitized signals can be synchronized both across modules 22 and to an external reference, such as the clock signal 124.
  • FIG. 6 is a block diagram illustrating a clock signal generator according to an embodiment.
  • the clock signals 143 and 145 can be generated by a global positioning system (GPS) clock 142.
  • the clock signal 143 can be a one-pulse-per-second (1 PPS) signal from a GPS clock receiver.
  • the clock signals 145 can be N clock signals, such as Inter-range Instrumentation Group (IRIG) signals.
  • IRIG Inter-range Instrumentation Group
  • the IRIG signals can include IRIG-B signals in different formats.
  • the N clock signals can be a pulse width modulated IRIG-B signal, an amplitude modulated IRIG-B signal, and a Manchester modulated IRIG-B signal. Accordingly, each clock signal 145 will have a reference marker that occurs at 1 PPS.
  • a signal conditioner 149 is configured to first condition the clock signals 143 and 145.
  • the signal conditioner 149 is configured process the clock signals 143 and 145 to remove glitches or other transients that are shorter in time than a threshold.
  • the signal conditioner 149 can have an initial threshold of about 2 microseconds to deglitch the clock signals 143 and 145. This threshold can be set as desired, for example, dependent on the modulation scheme, bit period, or the like.
  • the clock signals 143 and 145 can be filtered to attempt to remove glitches.
  • the signal conditioner 149 is also configured to demodulate and/or decode the clock signals 146.
  • the signal conditioner 149 can decode a pulse width modulated IRIG-B signal, demodulate an amplitude modulated IRIG-B signal, and decode a Manchester modulated IRIG-B signal.
  • the clock signals 145 can be transformed into respective time code frames 146.
  • the clock signal analyzer 148 is configured to receive the time code frames 146 and the conditioned 1 PPS signal 144. The clock signal analyzer 148 is configured to analyze these signals to determine a quality of the clock signals represented by the time code frames 146 and conditioned 1 PPS signal 144. The clock signal analyzer 148 can generate status signals 150 related to the time code frames 146.
  • a clock signal selector 152 is configured to receive status signal 150 from the clock signal analyzer 148. The status signals 150 can represent whether an associated time code frames 146 is missing, stable, or the like. Using the status signals 150, the clock signal selector 152 is configured to select a time code frame 146 as an output clock signal 154. In an embodiment, multiple clock signals can be generated from a single clock signal source as output clock signals 154.
  • a reference clock signal can be selected from among multiple such signals.
  • the selected clock signal can change in response to changes in stability, period, phase, or the like of the input clock signals.
  • a more stable clock signal can be generated and, consequently, more accurate measurements.
  • the clock module 140 can synchronize to signals from a GPS clock 142; however, if the signals from the GPS clock 142 are lost, an accuracy of the output clock signals 154 can be substantially maintained. As a result, phasor measurements will have a greater likelihood of remaining within specified ranges for total vector errors.
  • the functionality described can be implemented in a programmable logic device.
  • a field programmable gate array FPGA
  • other devices can be used, such as an application specific integrated circuit, a digital signal processor, discrete components, a general purpose processor, or the like.
  • each clock source can generate corresponding clock signals, such as IRIG signals. Accordingly, the clock signal analyzer 148 can select from among the multiple clock signals from multiple sources for use as the clock signal 154.
  • FIG. 7 is a block diagram illustrating an example of a clock signal analyzer of FIG. 6.
  • the reference signal extractor 162 is configured to receive the time code frames 146.
  • reference markers indicate divisions between time code frames. Within IRIG-B signals, the reference markers occur at a 1 PPS rate.
  • the reference signal extractor 162 is configured to extract these periodic pulse signals from the time code frames 146.
  • the clock signal analyzer 148 can extract 1 PPS signals from the time code frames 146 that are substantially aligned to the reference markers within the respective time code frames 146.
  • a 1 PPS signal can be extracted from each clock signal 146. For example, once converted into time code frames, position identifiers within the time code frames can be identified to extract the 1 PPS signal. In particular, a frame reference marker can be extracted. Accordingly, in this example, four 1 PPS signals are available, a 1 PPS 144 from the GPS clock 142, and three reference markers 166 from the IRIG-B time code frames 146.
  • IRIG-A signals can be used to generate a 10 pulse-per-second signals as reference signals. Subsequent period and phase monitoring can be adjusted accordingly. Furthermore, any number of IRIG signals can be used.
  • a period and phase monitor 164 is configured to monitor the periods of the reference signals 166.
  • the clock signal analyzer 148 is configured to determine if a 1 PPS signal is out of range.
  • the clock signal analyzer 148 can be configured to store a number of local oscillator 147 cycles that substantially corresponds to one second.
  • the connections of the local oscillator 147 have only been illustrated in particular locations; however, the local oscillator 147 signal can be distributed as needed.
  • the period and phase monitor 164 is configured to count a number of local oscillator 147 cycles for each period of the reference signals 166. For example, a counter that is clocked by the local oscillator 147 can run for each reference signal 166. The reference signal 166 can latch the value and reset the associated counter.
  • the number of local oscillator 147 cycles for a period of each reference signal 166 can be compared against the stored number corresponding to one second.
  • the reference signal 166 and the corresponding clock signal can be identified as missing. That is, if the period of the reference signal 166 is not within a range of the stored number, the reference signal 166 can be identified as missing.
  • Other criteria can be used to determine if a reference signal 166 is missing. For example, a number of periods of the reference signal 166 that are out of range can be used to determine if the reference signal 166 is missing.
  • the number of periods that the reference signal 166 can be out of range before being characterized as missing is zero. That is, if the reference signal 166 period is out of range once, then it is characterized as missing. However, in another embodiment, a number of consecutive periods where the reference signal 166 period is out of range exceeds a threshold, then the reference signal 166 can be characterized as missing. Accordingly, glitches, transients, or the like can be suppressed.
  • Another threshold number of periods can be used to determine if a reference signal 166 is present, or not missing. For example, to characterize a reference signals as not missing, the reference signal 166 must be in range for 8 consecutive periods. Although 8 consecutive periods has been used as an example, other thresholds can be used.
  • a phase of the reference signal 166 can be measured by the period and phase monitor 164.
  • an edge of the 1 PPS 144 signal such as a rising edge, can be used to reset counters associated with the reference signals 166. These counters can be clocked by the local oscillator 147.
  • An edge of the reference signal 166 can be used to latch the count of a counter. Accordingly, the latched value represents the phase difference between the 1 PPS signal 144 and the reference signals 166.
  • a single 1 PPS signal 168 can be selected.
  • a 1 PPS signal from a reference signal 166 that has the most stable periods, stable phase, or the like can be used as the selected 1 PPS signal 168.
  • the phase difference between a reference signal 166 and the 1 PPS signal 144 can be used if the 1 PPS signal 144 is missing. For example, at a time when the 1 PPS signal 144 is present, the phases of the reference signals 166 can be measured. The phase of the selected 1 PPS signal 168 can be adjusted by the measured phase when the 1 PPS signal 144 is missing.
  • a local oscillator monitor 170 can be configured to monitor the local oscillator 147. The local oscillator monitor 170 is configured to receive the local oscillator 147 signal and the selected 1 PPS signal 168.
  • the local oscillator monitor 170 is configured to count cycles of the local oscillator 147 between events of the 1 PPS signal 168.
  • the 1 PPS signal 168 was selected by the period and phase monitor 164 as the best 1 PPS signal. Accordingly, a value of counter that is clocked by the local oscillator 147 and latched by the 1 PPS signal 168 will represent a frequency of the local oscillator 147.
  • the output of the counter that counts the local oscillator 147 cycles can be low pass filtered.
  • the filtered value can be output as the local oscillator frequency 172. Since the local oscillator frequency 172 was low pass filtered over multiple 1 second periods, the resulting value is a relatively stable representation of the number of local oscillator 147 cycles in a 1 PPS period.
  • a 1 PPS signal generator 174 is configured to generate 1 PPS signals 176 and 180.
  • the period and pulse-width of the 1 PPS signals 176 and 180 can be set in terms of local oscillator 147 cycles.
  • 1 PPS signal generator 174 is configured to synchronize the 1 PPS signals 176 and 180 with the selected 1 PPS signal 168.
  • the 1 PPS signal generator 174 can be configured to measure a phase delay from the selected 1 PPS signal 168 to the 1 PPS signal 180.
  • the rising edge of the selected 1 PPS signal 168 can clear a counter that is clocked by the local oscillator 147.
  • the rising edge of the 1 PPS signal 180 latches the count. If the 1 PPS signal 168 is missing the latch is cleared.
  • the 1 PPS signal generator 174 is configured to synchronize the 1 PPS signal 180 to the selected 1 PPS signal 168 by substantially continuously reducing the measured phase error in small steps.
  • the 1 PPS signal 180 is unsynchronized or "free running."
  • the low-pass filtered local oscillator frequency 172 can be used to generate the 1 PPS signal 180. As a result, the 1 PPS signal 180 can continue running with effectively little drift.
  • the sample clock generator 178 is configured to generate a sample clock signal 182.
  • the sample clock signal 182 can be generated in response to the local oscillator frequency 172 and a 1 PPS signal 180. For example, for a given sample clock 182 frequency, a dividing factor and a remainder can be loaded in the sample clock generator 178. That is, the local oscillator frequency 172 can be divided by the sample clock 182 frequency to generate the dividing factor and the remainder.
  • a number of cycles of the remainder can be deleted from local oscillator 147 signal when generating the sample clock 182.
  • the frequency 172 of the local oscillator 147 can be divided by the remainder.
  • the result is a period after which a cycle of the local oscillator 147 signal is deleted. Accordingly, the deleted cycles can be spread across the 1 PPS period.
  • the local oscillator 147 signal with deleted cycles can be divided by the dividing factor.
  • the rising-edge of the sample clock signal 182 can be synchronized to the an edge of the 1 PPS signal 180. The result is the desired sample clock signal 182 at the desired frequency and synchronized with the 1 PPS signal 180.
  • An internal clock signal generator 184 can be configured to generate an internal clock signal 186, such as an internal IRIG signal.
  • the internal clock signal 186 can be used by the clock signal selector 152 as a clock signal 154 if the other clock signals from the GPS clock 142 are not present.
  • the internal clock signal generator 184 can use data from the IRIG time code frames 146 to create an IRIG-B stream which has its reference mark synchronized to the 1 PPS Out signal.
  • signals from GPS Clock 142 can conditioned, processed, measured, and finally used to generate a stable 1 PPS signal.
  • This 1 PPS signal can be used to generate IRIG-B signals, whether from an external source or internally generated, that are substantially synchronized in phase and frequency with the 1 PPS signal.
  • sample clock signals can be generated that are substantially synchronized in phase and frequency with the 1 PPS signal.
  • an internal 1 PPS signal can maintain synchronization with a degree of stability. Accordingly, if such external clock sources are lost, a time during which the total vector errors of measurements remain below a specified maximum can be increased. That is the data acquisition system can be more tolerant of input clock signal faults and remain within specified operating requirements.
  • An embodiment can include a computer readable medium storing computer readable code that, when executed on an appropriately configured computer, causes the computer to perform one or more of the operations described above.
  • computer readable medium storing computer readable code that, when executed on an appropriately configured computer, causes the computer to perform one or more of the operations described above.
  • Certain exemplary embodiments include apparatuses, comprising a controller configured to receive a plurality of clock signals, obtain a plurality of reference signals from the clock signals, select one of the clock signals in response to the reference signals, and generate an output clock signal in response to the selected clock signal.
  • the clock signals comprise a plurality of Inter-range Instrumentation Group (IRIG) signals.
  • the controller is further configured to extract periodic pulse signals from the clock signals and generate the output clock signal in response to the periodic pulse signals.
  • the controller is further configured to compare phases of the periodic pulse signals and generate the output clock signal in response to the periodic pulse signals.
  • the controller is further configured to count cycles of an internal oscillator in response to the periodic pulse signals. In certain forms of such apparatuses the controller is further configured to filter the counted cycles. In certain forms of such apparatuses the controller is figurer configured to generate the output clock in response to the filtered, counted cycles if no clock signal is selected. In certain forms of such apparatuses the controller is further configured to adjust a phase of a generated periodic pulse signal in response to a selected periodic pulse signal.
  • Certain exemplary embodiments include methods comprising receiving a plurality of clock signals; obtaining a plurality of reference signals from the clock signals; selecting one of the clock signals in response to the reference signals; and
  • the clock signals comprise a plurality of Inter-range
  • Instrumentation Group signals.
  • Certain forms of such methods further comprise: extracting periodic pulse signals from the clock signals; and generating the output clock signal in response to the periodic pulse signals.
  • Certain forms of such methods further comprise: comparing phases of the periodic pulse signals; and generating the output clock signal in response to the periodic pulse signals.
  • Certain forms of such methods further comprise counting cycles of an internal oscillator in response to the periodic pulse signals.
  • Certain forms of such methods further comprise filtering the counted cycles.
  • Certain forms of such methods further comprise generating the output clock in response to the filtered, counted cycles if no clock signal is selected.
  • Certain forms of such methods further comprise adjusting a phase of a generated periodic pulse signal in response to a selected periodic pulse signal.
  • Certain exemplary embodiments include a computer readable medium storing code that, when executed on a computer, causes the computer to: receive a plurality of clock signals; obtain a plurality of reference signals from the clock signals; select one of the clock signals in response to the reference signals; and generate an output clock signal in response to the selected clock signal.
  • the clock signals comprise a plurality of Inter-range Instrumentation Group (IRIG) signals.
  • the computer readable medium includes code that, when executed on the computer, causes the computer to: extract periodic pulse signals from the clock signals; and generate the output clock signal in response to the periodic pulse signals.
  • the computer readable medium stores code that, when executed on the computer, causes the computer to: compare phases of the periodic pulse signals; and generate the output clock signal in response to the periodic pulse signals. In certain forms the computer readable medium further stores code that, when executed on the computer, causes the computer to count cycles of an internal oscillator in response to the periodic pulse signals. In certain forms the computer readable medium further stores code that, when executed on the computer, causes the computer to filter the counted cycles. In certain forms the computer readable medium further stores code that, when executed on the computer, causes the computer to generate the output clock in response to the filtered, counted cycles if no clock signal is selected.
  • the computer readable medium further stores code that, when executed on the computer, causes the computer to adjust a phase of a generated periodic pulse signal in response to a selected periodic pulse signal.
  • Certain exemplary embodiments include apparatuses, comprising: a digitizer configured to digitize a signal; a memory configured to store a calibration time; and a controller configured to: calculate filter coefficients for a digital filter in response to the calibration time; and filter the digitized signal with the digital filter.
  • the controller is configured to filter the digitized signal such that the digitized signal is shifted in time by a non-integer multiple of a sample period of the digitized signal.
  • the controller is further configured to offset the filtered signal by a time offset associated with the calibration time and the time offset is greater than one sample period of the digitized signal.
  • the memory is configured to store a plurality of initial filter coefficients; and the controller is configured to combine the initial filter coefficients and the calibration time to generate the filter coefficients for the digital filter.
  • the memory is configured to store a plurality of initial filter coefficients; and the controller is configured to combine the initial filter coefficients and the calibration time to generate the filter coefficients for the digital filter.
  • the memory is configured to store a plurality of filter coefficients of the digital filter; and the controller is configured to scale the filter coefficients such that a magnitude of a largest coefficient is greater than or equal to one-half of a maximum magnitude of a coefficient.
  • the memory is configured to store a maximum sensed value; and the controller is configured to scale the filter coefficients such that when the maximum sensed value is filtered by the digital filter, an output of the digital filter is less than a maximum output magnitude of the digital filter.
  • Certain exemplary embodiments include methods, comprising: storing a calibration time; digitizing a signal; calculating filter coefficients for a digital filter in response to the calibration time; and filtering the digitized signal with the digital filter.
  • Certain forms include filtering the digitized signal with the digital filter comprises filtering the digitized signal such that the digitized signal is shifted in time by a non-integer multiple of a sample period of the digitized signal.
  • filtering the digitized signal with the digital filter comprises offsetting the filtered signal by a time offset associated with the calibration time and the time offset is greater than one sample period of the digitized signal.
  • Certain forms further comprise storing a plurality of initial filter coefficients; and combining initial filter coefficients and the calibration time to generate the filter coefficients for the digital filter. Certain forms further comprise storing a plurality of initial filter coefficients; and combining the initial filter coefficients and the calibration time to generate the filter coefficients for the digital filter. Certain forms further comprise storing a plurality of filter coefficients of the digital filter; and scaling the filter coefficients such that a magnitude of a largest coefficient is greater than or equal to one-half of a maximum magnitude of a coefficient. Certain forms further comprise storing a maximum sensed value; and scaling the filter coefficients such that when the maximum sensed value is filtered by the digital filter, an output of the digital filter is less than a maximum output magnitude of the digital filter.
  • Certain exemplary embodiments include systems comprising: an interface configured to condition a signal associated with a power system; a clock module configured to generate a synchronization signal; and a module coupled to the interface and configured to: digitize the signal from the interface; filter the digitized signal; and generate a time-shifted, digitized signal in response to the filtering and the
  • the module comprises a memory configured to store a calibration time associated with the interface and the module is further configured to generate coefficients for a digital filter in response to the calibration time. In certain forms the module is configured to shift the digitized signal by a non-integer multiple of a sample period when filtering the digitized signal.
  • the interface is one of a plurality of interfaces, each interface configured to condition a corresponding signal associated with the power system; and the module is coupled to at least two of the interfaces and configured to: digitize the signals from the interfaces; filter the digitized signals; and generate time-shifted, digitized signals in response to the filtering and the synchronization signal. In certain forms the module is one of a plurality of modules; and each module is configured to receive the synchronization signal.
  • the interface includes isolation circuitry coupled to a voltage transformer. In certain forms the interface includes isolation circuitry coupled to a current

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

L'invention porte sur un système qui comporte une interface configurée pour mettre en forme un signal associé à un système électrique; un module d'horloge configuré pour générer un signal de synchronisation; un module couplé à l'interface et configuré pour numériser le signal provenant de l'interface, pour filtrer le signal numérisé et pour générer un signal numérisé temporellement décalé en réponse au filtrage et au signal de synchronisation.
PCT/US2013/038848 2012-04-30 2013-04-30 Systèmes d'acquisition de données de système électrique WO2013166005A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US201261640242P 2012-04-30 2012-04-30
US61/640,242 2012-04-30
US13/484,096 US20130285719A1 (en) 2012-04-30 2012-05-30 Power system data acquisition systems
US13/484,091 US8866517B2 (en) 2012-04-30 2012-05-30 Power system data acquisition systems
US13/484,096 2012-05-30
US13/484,091 2012-05-30

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CN115083137A (zh) * 2022-07-19 2022-09-20 珠海格力电器股份有限公司 红外补偿的处理系统

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US20070188206A1 (en) * 2006-02-16 2007-08-16 Hynix Semiconductor Inc. Delay locked loop with a function for implementing locking operation periodically during power down mode and locking operation method of the same
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US20070188206A1 (en) * 2006-02-16 2007-08-16 Hynix Semiconductor Inc. Delay locked loop with a function for implementing locking operation periodically during power down mode and locking operation method of the same
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CN113391544A (zh) * 2021-05-11 2021-09-14 国网浙江省电力有限公司湖州供电公司 一种基于北斗gps的对时系统校验装置及方法
CN115083137A (zh) * 2022-07-19 2022-09-20 珠海格力电器股份有限公司 红外补偿的处理系统
CN115083137B (zh) * 2022-07-19 2023-08-11 珠海格力电器股份有限公司 红外补偿的处理系统

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