CN112526201A - Double-path synchronous sampling and measuring method - Google Patents
Double-path synchronous sampling and measuring method Download PDFInfo
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- CN112526201A CN112526201A CN202011269563.2A CN202011269563A CN112526201A CN 112526201 A CN112526201 A CN 112526201A CN 202011269563 A CN202011269563 A CN 202011269563A CN 112526201 A CN112526201 A CN 112526201A
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- 230000001360 synchronised effect Effects 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000005259 measurement Methods 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 238000004891 communication Methods 0.000 claims description 14
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- 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
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- 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
- G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/06—Arrangements for measuring electric power or power factor by measuring current and voltage
Abstract
The invention discloses a double-path synchronous sampling and measuring method, which comprises the following steps: the voltage and current signals of the circuit with 16 channels are changed into alternating current input signals through a voltage transformer and a current transformer, the alternating current input signals are filtered by adopting a low-pass filter circuit, the filtered signals are synchronously sampled and held by a sampling/holding circuit to be changed into discrete signals, the sampling/holding circuit adopts a synchronous sampling and time-sharing conversion method, namely, a circuit consisting of two 8-channel synchronous sampling and synchronous holding A/D converters is adopted, a low-zero-drift amplifying circuit is adopted in the first stage of the circuit, a low-pass filter follower is adopted in the second stage of the circuit, the phase difference of each channel point is calculated through conversion at each sampling point, and 2-path A/D sampling is synchronized again by adopting a frequency measurement and tracking phase-locking method. The invention improves the anti-interference capability of input signals, improves the output impedance, and reduces the angular difference caused by the influence of resistance and capacitance on the phase of each channel, thereby realizing the improvement of measurement precision and speed.
Description
Technical Field
The invention relates to a double-path synchronous sampling and measuring method, and belongs to the technical field of double-path synchronous measurement.
Background
The measurement accuracy and measurement speed are directly related to the linear accuracy (accuracy of specific difference) and the phase accuracy (accuracy of angular difference) of the multifunction table. The alternating current sampling is equivalent to replacing a smooth sinusoidal curve with a step curve, and the theoretical error of the alternating current sampling mainly has two terms: one is the error produced by substituting temporally continuous data with temporally discrete data approximations, which mainly depends on the conversion speed of the a/D and the processing speed of the CPU; another term is the quantization error produced by quantizing successive voltages and currents, which depends mainly on the number of bits of the a/D converter. The existing sampling circuit has large error and low measurement speed.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: a two-way synchronous sampling and measuring method is provided to solve the technical problems in the prior art.
The technical scheme adopted by the invention is as follows: a two-way synchronous sampling measurement method comprises the following steps: voltage and current signals of circuits of 16 channels are converted into alternating current input signals with amplitude values of-5V to + 5V through a voltage transformer and a current transformer, then the alternating current input signals are filtered by a low-pass filter circuit, the filtered signals are synchronously sampled and held by a sample/hold circuit to be converted into discrete signals, the sample/hold circuit adopts a synchronous sampling and time-sharing conversion method, namely, a circuit formed by two 8-channel synchronous sampling and synchronous holding A/D converters is adopted, a low-zero-drift amplification circuit is adopted at the first stage of the circuit, a low-pass filter follower is adopted at the second stage of the circuit, the A/D converter is required to respectively perform A/D conversion on multiple channels at each sampling point, the phase difference of each channel point is calculated, and 2-channel A/D sampling is synchronized again by adopting a frequency measurement and tracking phase-locking method.
Preferably, the voltage and current signals of the circuit with 16 channels adopt a multifunctional standard table capable of collecting 2 channels and 16 channels, each channel comprises 4U channels and 4I channels, and the multifunctional standard table samples 2 channels and 16 channels of analog signals and calculates various voltages, currents and powers.
Preferably, the first path 8 of the analog large signal is a voltage range of 0-456V, the voltage is divided and sampled by a high-precision resistor, the output end of the analog large signal is connected with an amplifier OP2177 to increase output impedance, and the analog large signal is switched into an AD (analog to digital) signal and sampled at the same time; the current range is 0-20A, the current is converted into a small current signal (0-20 mA) through a current transformer, the small current signal is converted into a voltage signal through a sampling resistor, a gear is switched by adopting an analog switch, and finally the voltage signal is sent into an AD (analog to digital) for sampling at the same time.
Preferably, the second path 8 of the analog small signal is a differential signal with a voltage range of 0-10V, the anti-interference capability of the signal is improved by adopting differential input, the output impedance is improved by using an amplifier OP2177, the signal is sent to an instrument amplifier with gain to be processed, the high-frequency clutter signal in the environment is filtered out, and finally the signal is sent to AD for simultaneous sampling.
Preferably, the signals processed by the first path of 8 channels and the second path of 8 channels are sent to an AD sampler, the AD sampler adopts a CPLD and a DSP to cooperatively control 2 blocks of AD, so as to realize sampling synchronization, and the error of the synchronous phase is less than 0.1 us.
Preferably, the AD sampler processes signals and then sends the sampling data to a CPLD cache through a high-speed serial bus to achieve a buffer storage amount, the DSP reads the sampling data at one time, the occupancy rate of the DSP is reduced, the 16-channel sampling data collected by the DSP calculates voltage, current, power and harmonic waves at the same time, ensures that the data of each cycle participate in calculation, and realizes seamless sampling and calculation functions. The data accuracy of the instrument is improved, and the real-time performance is also improved.
Preferably, the data calculated by the DSP is sent to the ARM through a parallel bus, and the ARM collects the calculated data and realizes the functions of digital display, graphic display, statistics and analysis according to the requirements of customers.
Preferably, the multifunctional standard meter is provided with a network port communication interface and a serial port communication interface.
Preferably, the network port communication interface adopts an RJ45 interface, 10/100M self-adaptation, the serial port communication interface adopts RS232/RS485, and configuration parameters can be read and compared through a protocol to check whether parameter setting is correct or not.
The invention has the beneficial effects that: compared with the prior art, the invention adopts the design ideas of synchronous sampling and time-sharing conversion, can save cost, only adopts two 8-channel synchronous sampling and synchronous holding A/D converters, adopts a low-zero-drift amplifying circuit in the first stage of the circuit, improves the anti-interference capability of an input signal, adopts a low-pass filter follower in the second stage of the circuit to improve output impedance, reduces the influence of current in the circuit, and simultaneously reduces the angular difference caused by the phase of each channel influenced by resistance capacitance.
Drawings
FIG. 1 is a block diagram of a two-way synchronous sampling measurement system.
Fig. 2 is a schematic diagram of a system for detecting access to a reference table.
Detailed Description
The invention is further described with reference to the accompanying drawings and specific embodiments.
Example 1: as shown in fig. 1-2, a two-way synchronous sampling measurement method includes a two-way synchronous sampling measurement system, as shown in fig. 1, the two-way synchronous sampling measurement system (multifunctional standard meter) includes two 16 channels, a sampling board, a connection board and a main board (ARM), each 8 channels (including 4U channel and 4I channel) is connected to one sampling board, the sampling board is connected to the connection board, the connection board is connected to the main board, the connection board is further connected to a liquid crystal conversion board, a front panel and a power board, the power board is connected to a power terminal, the main board is connected to a communication interface, the method includes: voltage and current signals of circuits of 16 channels are converted into alternating current input signals with amplitude values of-5V to + 5V through a voltage transformer and a current transformer, then the alternating current input signals are filtered by a low-pass filter circuit, the filtered signals are synchronously sampled and held by a sample/hold circuit to be converted into discrete signals, the sample/hold circuit adopts a synchronous sampling and time-sharing conversion method, namely, a circuit formed by two 8-channel synchronous sampling and synchronous holding A/D converters is adopted, a low-zero-drift amplification circuit is adopted at the first stage of the circuit, a low-pass filter follower is adopted at the second stage of the circuit, the A/D converter is required to respectively perform A/D conversion on multiple channels at each sampling point, the phase difference of each channel point is calculated, and 2-channel A/D sampling is synchronized again by adopting a frequency measurement and tracking phase-locking method.
The multifunctional standard meter is matched with three-phase power to design a multichannel accuracy testing system so as to simulate the actual working condition on site and improve the detection efficiency, the multifunctional standard meter adopts a double high-speed processor and a large-scale logic array structure, an ADI 400MHz DSP is combined with a CPLD to be responsible for sampling and calculation, and an ARM is responsible for display and communication.
Preferably, the voltage and current signals of the circuit with 16 channels adopt a multifunctional standard table capable of collecting 2 channels and 16 channels, each channel comprises 4U channels and 4I channels, and the multifunctional standard table samples 2 channels and 16 channels of analog signals and calculates various voltages, currents and powers.
Preferably, the first path 8 of the analog large signal is a voltage range of 0-456V, the voltage is divided and sampled by a high-precision resistor, the output end of the analog large signal is connected with an amplifier OP2177 to increase output impedance, and the analog large signal is switched into an AD (analog to digital) signal and sampled at the same time; the current range is 0-20A, the current is converted into a small current signal (0-20 mA) through a current transformer, the small current signal is converted into a voltage signal through a sampling resistor, a gear is switched by adopting an analog switch, and finally the voltage signal is sent to AD (analog to digital) for sampling; the second path 8 of the channel is a small analog signal, the voltage range is 0-10V, differential input is adopted, the anti-interference capability of the signal is improved, the output impedance is improved by using an amplifier OP2177, the signal is sent to an instrument amplifier with gain to be processed, a high-frequency clutter signal in the environment is filtered out, and finally the signal is sent to AD for simultaneous sampling; 2, adopting a high-precision low-temperature drift device for the 16-path simulation channel to ensure that the variation of the adopted signal along with time and temperature is less than 10 ppm; the influence of the environment on the signals is eliminated by adding the band-pass filter, and the adoption precision of the instrument is guaranteed to reach five ten-thousandths.
Preferably, the signals processed by the first path of 8 channels and the second path of 8 channels are sent to an AD sampler, the AD sampler adopts a CPLD and a DSP to cooperatively control 2 blocks of AD, so as to realize sampling synchronization, and the error of the synchronous phase is less than 0.1 us.
Preferably, the AD sampler processes signals and then sends the sampling data to a CPLD cache through a high-speed serial bus to achieve a buffer storage amount, the DSP reads the sampling data at one time, the occupancy rate of the DSP is reduced, the 16-channel sampling data collected by the DSP calculates voltage, current, power and harmonic waves at the same time, ensures that the data of each cycle participate in calculation, and realizes seamless sampling and calculation functions. The data accuracy of the instrument is improved, and the real-time performance is also improved.
Preferably, the data calculated by the DSP is sent to the ARM through a parallel bus, and the ARM collects the calculated data and realizes the functions of digital display, graphic display, statistics and analysis according to the requirements of customers.
Preferably, the multifunctional standard meter is provided with a network port communication interface and a serial port communication interface, so that the multifunctional standard meter can conveniently communicate with various instruments and meters. The network port communication interface adopts RJ45 interface, 10/100M self-adaptation, and the serial port communication interface adopts RS232/RS485, and its configuration parameter reading is compared through the stipulation, looks over whether parameter setting is correct.
The manner in which the multi-purpose watch accesses the test system is shown in figure 2. Extracting current and voltage signals of the high-voltage side injection switch as reference signals; and current and voltage signals at PT and CT sides are acquired simultaneously, and high-precision testing of specific difference and angular difference is performed on the signals and reference signals. The method reduces the precision requirement of the primary signal power source, can obtain a high-precision test result as long as the source output is kept stable, and can realize automatic test.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present invention, and therefore, the scope of the present invention should be determined by the scope of the claims.
Claims (9)
1. A double-path synchronous sampling measurement method is characterized in that: the method comprises the following steps: voltage and current signals of circuits of 16 channels are converted into alternating current input signals with amplitude values of-5V to + 5V through a voltage transformer and a current transformer, then the alternating current input signals are filtered by a low-pass filter circuit, the filtered signals are synchronously sampled and held by a sample/hold circuit to be converted into discrete signals, the sample/hold circuit adopts a synchronous sampling and time-sharing conversion method, namely, a circuit formed by two 8-channel synchronous sampling and synchronous holding A/D converters is adopted, a low-zero-drift amplification circuit is adopted at the first stage of the circuit, a low-pass filter follower is adopted at the second stage of the circuit, the A/D converter is required to respectively perform A/D conversion on multiple channels at each sampling point, the phase difference of each channel point is calculated, and 2-channel A/D sampling is synchronized again by adopting a frequency measurement and tracking phase-locking method.
2. A two-way synchronous sampling measurement method according to claim 1, characterized in that: the voltage and current signals of the circuit with 16 channels adopt a multifunctional standard table capable of collecting 2 channels and 16 channels, each channel comprises a 4U channel and a 4I channel, the multifunctional standard table samples 2 channels of analog signals of the 16 channels, and various voltages, currents and powers are calculated.
3. A two-way synchronous sampling measurement method according to claim 2, characterized in that: the first 8-channel is an analog large signal, the voltage range is 0-456V, the analog large signal is subjected to voltage division sampling through a resistor, the output end of the analog large signal is connected with an amplifier OP2177 to follow, a gear is switched by an analog switch, and the analog large signal is sent into an AD (analog to digital) circuit and is sampled at the same time; the current range is 0-20A, the current is converted into a small current signal through a current transformer, the small current signal is 0-20mA, the small current signal is converted into a voltage signal through a sampling resistor, a gear is switched by adopting an analog switch, and finally the voltage signal is sent into an AD (analog-to-digital) circuit for sampling at the same time.
4. A two-way synchronous sampling measurement method according to claim 2, characterized in that: the second path 8 is analog small signal with voltage range of 0-10V, which is output by amplifier OP2177 by differential input, sent to instrument amplifier with gain to process signal, and finally sent to AD for sampling.
5. A two-way synchronous sampling measurement method according to claim 2, characterized in that: and the signals processed by the first path of 8 channels and the second path of 8 channels are sent to an AD sampler, and the AD sampler controls 2 AD blocks by adopting the cooperation of a CPLD and a DSP.
6. A two-way synchronous sampling measurement method according to claim 4, characterized in that: the AD sampler processes signals and then sends sampling data to a CPLD cache through a high-speed serial bus to achieve the cache amount, the DSP reads out the sampling data at one time, and the 16 channels of sampling data collected by the DSP calculate voltage, current, power and harmonic waves at the same time.
7. A two-way synchronous sampling measurement method according to claim 1, characterized in that: and the data calculated by the DSP is sent to the ARM through a parallel bus, and the ARM collects the calculated data and realizes the functions of digital display, graphic display, statistics and analysis according to the requirements of customers.
8. A two-way synchronous sampling measurement method according to claim 2, characterized in that: the multifunctional standard meter is provided with a network port communication interface and a serial port communication interface.
9. A two-way synchronous sampling measurement method according to claim 7, characterized in that: the network port communication interface adopts RJ45 interface, 10/100M self-adaptation, and the serial port communication interface adopts RS232/RS485, reads its configuration parameter through the stipulation and compares, checks whether parameter setting is correct.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116593769A (en) * | 2023-07-17 | 2023-08-15 | 烟台东方威思顿电气有限公司 | High-precision electric energy calculation method with wide dynamic range |
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