CN108957140B - Loop impedance measurement system and method with wide dynamic range - Google Patents

Loop impedance measurement system and method with wide dynamic range Download PDF

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Publication number
CN108957140B
CN108957140B CN201810719705.7A CN201810719705A CN108957140B CN 108957140 B CN108957140 B CN 108957140B CN 201810719705 A CN201810719705 A CN 201810719705A CN 108957140 B CN108957140 B CN 108957140B
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signal
injection
current
frequency
unit
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CN108957140A (en
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王斌武
殷小东
姜春阳
刘俊杰
雷民
周峰
熊博
刘浩
刘俭
汪根荣
袁建平
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
State Grid Tianjin Electric Power Co Ltd
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
State Grid Tianjin Electric Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/14—Measuring resistance by measuring current or voltage obtained from a reference source
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

The invention discloses a loop impedance measuring system and method with a wide dynamic range, and belongs to the field of current transformer detection. A loop impedance measuring system with wide dynamic range comprises a signal injection unit 101, a current signal detection unit 102, a high-frequency signal detection unit 103, a signal processing and control unit 104, an injection coupling circuit and a detection coupling circuit; the signal processing and control unit 104 generates a high-frequency digital signal, and the high-frequency digital signal is injected into a secondary circuit of the current transformer through the DA1, the signal injection unit 101 and the injection coupling circuit; the gear positions of the control signal injection unit 101, the current signal detection unit 102, and the high-frequency signal detection unit 103; the signal processing and control unit 104 processes and controls the high frequency digital signal. The impedance measurement method has wider application range of accurate impedance measurement in a wide dynamic range, and also provides a reliable data base for deeper fault state analysis of CT winding faults, insulation abnormity, CT transformation ratio replacement and the like.

Description

Loop impedance measurement system and method with wide dynamic range
Technical Field
The present invention relates to the field of current transformer detection, and more particularly to a wide dynamic range loop impedance measurement system and method.
Background
The technical methods for analyzing the fault state of the secondary circuit of the metering current transformer and identifying the electricity stealing state are various, the fault states of a secondary open circuit, a secondary bypass, a primary bypass, a secondary series semiconductor and the like of the current transformer can be generally analyzed, and the most effective method in the technical methods is to analyze by using the high-frequency equivalent impedance of the secondary circuit as a characteristic quantity. High frequency equivalent impedance calculations are typically performed by injecting a high frequency signal and then measuring the return signal.
The secondary circuit of the metering current transformer has large impedance difference and wide impedance range of different special variable metering current transformers due to different transformation ratios, process difference and the like of the current transformers, and the high-frequency equivalent impedance is about different from 0.1 ohm to 100k ohm. The existing device and system for analyzing the loop fault state and the electricity stealing state by using the secondary loop impedance as the characteristic quantity cannot realize the measurement of such a wide impedance range, so that the fault state analysis recognition rate is not high.
Disclosure of Invention
The invention aims to effectively solve the problems of large difference of high-frequency equivalent impedance and wide dynamic range of secondary circuits of different special variable metering current transformers, not only can greatly improve the identification rate of failure state analysis of the secondary circuits, but also provides a data basis for deeper failure state analysis of CT winding failure, insulation abnormality, CT transformation ratio replacement and the like through accurate impedance measurement in a wide dynamic range, and provides a loop impedance measuring system and method in a wide dynamic range.
A wide dynamic range loop impedance measurement system comprising: a signal injection unit 101, a current signal detection unit 102, a high frequency signal detection unit 103, a signal processing and control unit 104, an injection coupling circuit, and a detection coupling circuit;
the signal injection unit 101 adjusts the injected sinusoidal voltage signal
Figure GDA0003632161800000021
The amplitude of (d);
the current signal detection unit 102 detects a current signal injected into the coupling circuit
Figure GDA0003632161800000022
Through AD2 to signal processing and control unit 104;
the high-frequency signal detecting unit 103 detects and detects the coupling circuit
Figure GDA0003632161800000023
For sampling the resistance R2Voltage signals at two ends pass through the AD1 to the signal processing and control unit 104;
the injection coupling circuit and the detection coupling circuit are in a coupling mode of a signal from a measuring system to a secondary circuit of the current transformer;
the signal processing and control unit 104 generates a high-frequency digital signal, and the high-frequency digital signal is injected into a secondary circuit of the current transformer through the DA1, the signal injection unit 101 and the injection coupling circuit; the gear positions of the control signal injection unit 101, the current signal detection unit 102, and the high-frequency signal detection unit 103;
the signal processing and control unit 104 processes and controls the high frequency digital signal, including: (1) when the high-frequency equivalent impedance of the metering secondary circuit is small, the signal injection unit 101 switches the gear injection
Figure GDA0003632161800000024
Sine injected for signal injection unitVoltage signal, current signal detection unit 102 switches gear detection
Figure GDA0003632161800000025
To the injection voltage
Figure GDA0003632161800000026
The generated current; if it is detected
Figure GDA0003632161800000027
And (3) if the impedance is larger than 1/10 of the full range of AD2, calculating the impedance by adopting an injection current detection method, injecting the impedance of a secondary loop of the current transformer, and ending the process.
Wherein
Figure GDA0003632161800000028
Figure GDA0003632161800000029
Then the impedance of the secondary loop is measured
Figure GDA00036321618000000210
Wherein n is0For coil T1 turns, R0For injecting a sampling resistor, Z, into the front-end circuit1cA high frequency equivalent impedance of constant frequency of coil T1;
Figure GDA00036321618000000211
for measuring the injection voltage when the secondary circuit is open
Figure GDA00036321618000000212
The generated current; looping step (1) if the detected signal is less than 1/10 of the full range of the AD, and if the signal injection unit and the current signal detection unit are switched to the maximum gear, the detected signal is less than 1/10 of the full range of the AD, and entering step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the signal injection unit switches the gear injection signal
Figure GDA00036321618000000213
The high-frequency signal detection unit switches gears and detects voltage signals
Figure GDA00036321618000000214
If a voltage signal is detected
Figure GDA00036321618000000215
If the measured value is more than 1/10 of the full range of AD1, calculating impedance by adopting an injection return method, and ending the process;
wherein
Figure GDA0003632161800000031
Measuring impedance of secondary circuit
Figure GDA0003632161800000032
Then
Figure GDA0003632161800000033
Wherein R is2In order to detect the sampling resistance of the front-end circuit,
Figure GDA0003632161800000034
to inject the voltage into the metering secondary loop,
Figure GDA0003632161800000035
is composed of
Figure GDA0003632161800000036
The current generated by the power supply is used,
Figure GDA0003632161800000037
for sampling the resistance R2The voltage across the two terminals is such that,
if the detected signal is less than 1/10 of the full scale of AD, loop step (2), if the signal injection unit and the high frequency signal detection unit switch to the maximum gear, calculate the impedance according to the formula (6), and the process ends.
Optionally, the injection coupling circuit and the detection coupling circuit,
wherein
Figure GDA0003632161800000038
Due to the fact that
Figure GDA0003632161800000039
Then
Figure GDA00036321618000000310
Wherein
Figure GDA00036321618000000311
Due to the fact that
Figure GDA00036321618000000312
Then
Figure GDA00036321618000000313
Figure GDA00036321618000000314
n2For the number of turns of the coil T2,
Figure GDA00036321618000000315
is the voltage across T1 and,
Figure GDA00036321618000000316
a front-end current is detected for coupling to the signal.
Optionally, the signal injection unit has a plurality of signal amplification stages; the current signal detection unit is provided with a plurality of signal amplification gears; the high-frequency signal detection unit is provided with a plurality of signal amplification gears.
Optionally, the high frequency digital signal frequency range is 1kHz to 100 kHz.
Optionally, the coupling mode is a magnetic coupling mode.
A loop impedance measuring method with wide dynamic range comprises,
step one, the signal processing and control unit 104 controls the signal injection unit 101 to switch the gear injection signal
Figure GDA0003632161800000041
And generates high-frequency digital signals which are injected into the injection coupling circuit and the secondary circuit of the current transformer through the DA1 and the signal injection unit 101;
step two, coupling the high-frequency digital signal to a secondary circuit of the current transformer by the injection coupling circuit and the detection coupling circuit;
step three, the current signal detection unit 102 detects that the current signal injected into the coupling circuit passes through the AD2 to reach the signal processing and control unit;
step four, the high-frequency signal detection unit 103 detects and detects the voltage signal of the coupling circuit and transmits the voltage signal to the signal processing and control unit through the AD 1;
step five, (1) when the high-frequency equivalent impedance of the metering secondary circuit is small, the signal injection unit 101 switches the gear injection
Figure GDA0003632161800000042
Figure GDA0003632161800000043
The current signal detecting unit 102 switches the gear detection for the sinusoidal voltage signal injected by the signal injecting unit
Figure GDA0003632161800000044
To the injection voltage
Figure GDA0003632161800000045
The generated current; if it is detected
Figure GDA0003632161800000046
If the impedance is larger than 1/10 of the full range AD2, calculating the impedance by adopting an injection current detection method, injecting the impedance of a secondary circuit of the current transformer, and ending the process;
wherein
Figure GDA0003632161800000047
Figure GDA0003632161800000048
Then the impedance of the secondary loop is measured
Figure GDA0003632161800000049
Wherein n is0For coil T1 turns, R0For injecting a sampling resistor, Z, into the front-end circuit1cA high frequency equivalent impedance at a constant frequency of coil T1;
Figure GDA00036321618000000410
for measuring the injection voltage when the secondary circuit is open
Figure GDA00036321618000000411
The generated current ends the process; looping step (1) if the detected signal is less than 1/10 of the full range of the AD, and if the signal injection unit and the current signal detection unit are switched to the maximum gear, the detected signal is less than 1/10 of the full range of the AD, and entering step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the signal injection unit switches the gear injection signal
Figure GDA00036321618000000412
The high-frequency signal detection unit switches gears and detects voltage signals
Figure GDA0003632161800000051
If a voltage signal is detected
Figure GDA0003632161800000052
1/10 of the full range of AD1 is larger, the impedance is calculated by adopting an injection return method, and the process is ended;
wherein
Figure GDA0003632161800000053
Measuring impedance of secondary circuit
Figure GDA0003632161800000054
Then
Figure GDA0003632161800000055
Wherein R is2In order to detect the sampling resistance of the front-end circuit,
Figure GDA0003632161800000056
to inject the voltage into the metering secondary loop,
Figure GDA0003632161800000057
is composed of
Figure GDA0003632161800000058
The current is produced by the power generation device,
Figure GDA0003632161800000059
for sampling the resistance R2The voltage across the two terminals is such that,
if the detected signal is less than 1/10 full scale of AD, loop step (2), if the signal injection unit and the high frequency signal detection unit switch to the maximum gear, according to the formula
Figure GDA00036321618000000510
And calculating the impedance, and ending the process.
Optionally, the injection coupling circuit and the detection coupling circuit,
wherein
Figure GDA00036321618000000511
Due to the fact that
Figure GDA00036321618000000512
Then the
Figure GDA00036321618000000513
Wherein
Figure GDA00036321618000000514
Due to the fact that
Figure GDA00036321618000000515
Then the
Figure GDA00036321618000000516
Figure GDA00036321618000000517
n2For the number of turns of the coil T2,
Figure GDA00036321618000000518
is the voltage across T1 and,
Figure GDA00036321618000000519
a front-end current is detected for coupling to the signal.
Optionally, the signal injection unit has a plurality of signal amplification stages; the current signal detection unit is provided with a plurality of signal amplification gears; the high-frequency signal detection unit is provided with a plurality of signal amplification gears.
Optionally, the high frequency digital signal frequency range is 1kHz to 100 kHz.
Optionally, the coupling mode is a magnetic coupling mode.
The high-frequency equivalent impedance range which can be accurately measured by the invention is 0.1 ohm to 100k ohm, and the dynamic range of the measured high-frequency equivalent impedance is 106. The impedance measurement with the accurate wide dynamic range has wider application range, and provides reliable data base for deeper fault state analysis of CT winding faults, insulation abnormity, CT transformation ratio replacement and the like.
Drawings
FIG. 1 is a block diagram of a wide dynamic range loop impedance measurement system of the present invention;
FIG. 2 is a flow chart of a method for measuring loop impedance with a wide dynamic range according to the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
FIG. 1 is a block diagram of a wide dynamic range loop impedance measurement system according to the present invention.
The invention provides a loop impedance measurement system with wide dynamic range, as shown in fig. 1, comprising: a signal injection unit 101, a current signal detection unit 102, a high-frequency signal detection unit 103, a signal processing and control unit 104, an injection coupling circuit, and a detection coupling circuit;
the signal injection unit 101 adjusts the injected sinusoidal voltage signal
Figure GDA0003632161800000061
The amplitude of (d);
the current signal detection unit 102 detects a current signal injected into the coupling circuit
Figure GDA0003632161800000062
Through AD2 to signal processing and control unit 104;
the high-frequency signal detecting unit 103 detects and detects the coupling circuit
Figure GDA0003632161800000071
For sampling the resistance R2Voltage signals at two ends pass through the AD1 to the signal processing and control unit 104;
the signal injection unit 101 has a plurality of signal amplification stages; the current signal detection unit 102 has a plurality of signal amplification stages; the high frequency signal detection unit 103 has a plurality of signal amplification stages.
The injection coupling circuit and the detection coupling circuit are in a coupling mode of a signal from a measuring system to a secondary circuit of the current transformer; the coupling mode is a magnetic coupling mode; injection coupling circuit and detection coupling circuit, wherein the number of turns of coil T1 is n0The number of turns of the coil T2 is n2；
Wherein
Figure GDA0003632161800000072
Due to the fact that
Figure GDA0003632161800000073
Then
Figure GDA0003632161800000074
Wherein
Figure GDA0003632161800000075
Due to the fact that
Figure GDA0003632161800000076
Then
Figure GDA0003632161800000077
Wherein R is0For injecting into the front-end circuit sampling resistor, R2For detecting the sampling resistance of the front-end circuit, Z1cA high frequency equivalent impedance of constant frequency of coil T1;
Figure GDA0003632161800000078
a sinusoidal voltage signal injected for the signal injection unit,
Figure GDA0003632161800000079
to the injection voltage
Figure GDA00036321618000000710
The current generated is used as a current source,
Figure GDA00036321618000000711
for measuring the injection voltage when the secondary circuit is open
Figure GDA00036321618000000712
The current generated is used as a current source,
Figure GDA00036321618000000713
Figure GDA00036321618000000714
is the voltage across T1 and,
Figure GDA00036321618000000715
to inject the voltage into the metering secondary loop,
Figure GDA00036321618000000716
is composed of
Figure GDA00036321618000000717
The current generated by the power supply is used,
Figure GDA00036321618000000718
for coupling to the signal detection front-end current,
Figure GDA00036321618000000719
for sampling the resistance R2The voltage across the terminals.
The signal processing and control unit 104 generates a high-frequency digital signal, and the high-frequency digital signal is injected into a secondary circuit of the current transformer through the DA1, the signal injection unit 101 and the injection coupling circuit; the gear positions of the control signal injection unit 101, the current signal detection unit 102, and the high-frequency signal detection unit 103; the high frequency digital signal frequency range is 1kHz-100 kHz.
The signal processing and control unit 104 processes and controls the high frequency digital signal, including:
(1) when the high-frequency equivalent impedance of the metering secondary circuit is small, the signal injection unit 101 switches the gear injection
Figure GDA0003632161800000081
The current signal detecting unit 102 switches the shift position and detects
Figure GDA0003632161800000082
If it is detected
Figure GDA0003632161800000083
1/10 of full scale of AD2, calculating impedance by injection current detection method,
impedance injected into secondary circuit of current transformer
Figure GDA0003632161800000084
Is provided with
Figure GDA0003632161800000085
Then the impedance of the secondary loop is measured
Figure GDA0003632161800000086
Wherein
Figure GDA0003632161800000087
Is a constant; ending the process; looping step (1) if the detected signal is less than 1/10 of the full range of AD, and if the signal injection unit and the current signal detection unit switch to the maximum gear, the detected signal1/10 less than the full range of AD, go to step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the signal injection unit switches the gear injection signal
Figure GDA0003632161800000088
The high-frequency signal detection unit switches gears and detects voltage signals
Figure GDA0003632161800000089
If a voltage signal is detected
Figure GDA00036321618000000810
1/10 of the full range of AD1 is larger, and the impedance is calculated by adopting an injection return method;
wherein
Figure GDA00036321618000000811
Measuring impedance of secondary circuit
Figure GDA00036321618000000812
Then
Figure GDA00036321618000000813
Wherein R is0，R2，n0，n2A constant value; ending the process; if the detected signal is less than 1/10 full scale of AD, loop step (2), if the signal injection unit and the high frequency signal detection unit switch to the maximum gear, according to the formula
Figure GDA0003632161800000091
And calculating the impedance, and ending the process.
FIG. 2 is a flow chart of a method for measuring loop impedance with a wide dynamic range according to the present invention.
A loop impedance measurement method with a wide dynamic range, as shown in fig. 2, includes,
step one, the signal processing and control unit 104 controls the signal injectionIn-cell 101 shift level injection signal
Figure GDA0003632161800000092
And generates a high-frequency digital signal which is injected into the injection coupling circuit and the secondary circuit of the current transformer through the DA1 and the signal injection unit 101, wherein the frequency range of the high-frequency digital signal is 1kHz-100 kHz.
Step two, coupling the high-frequency digital signal to a secondary circuit of the current transformer by the injection coupling circuit and the detection coupling circuit; optionally, the coupling mode is a magnetic coupling mode; injection coupling circuit and detection coupling circuit, wherein the number of turns of coil T1 is n0The number of turns of the coil T2 is n2
Wherein
Figure GDA0003632161800000093
Due to the fact that
Figure GDA0003632161800000094
Then
Figure GDA0003632161800000095
Wherein
Figure GDA0003632161800000096
Due to the fact that
Figure GDA0003632161800000097
Then
Figure GDA0003632161800000098
Wherein R is0For injecting into the front-end circuit sampling resistor, R2For detecting the sampling resistance of the front-end circuit, Z1cA high frequency equivalent impedance of constant frequency of coil T1;
Figure GDA0003632161800000099
positive for signal injection unit injectionThe string voltage signal is a signal of the string voltage,
Figure GDA00036321618000000910
to injection voltage
Figure GDA00036321618000000911
The current generated is used as a current source,
Figure GDA00036321618000000912
for measuring the injection voltage when the secondary circuit is open
Figure GDA00036321618000000913
The current generated is used as a current source,
Figure GDA00036321618000000914
Figure GDA00036321618000000915
is the voltage across T1 and,
Figure GDA00036321618000000916
to inject the voltage into the metering secondary loop,
Figure GDA00036321618000000917
is composed of
Figure GDA00036321618000000918
The current generated by the power supply is used,
Figure GDA00036321618000000919
for coupling to the signal detection front-end current,
Figure GDA0003632161800000101
for sampling the resistance R2The voltage across the terminals.
Step three, the current signal detection unit 102 detects that the current signal injected into the coupling circuit passes through the AD2 to reach the signal processing and control unit;
step four, the high-frequency signal detection unit 103 detects and detects the voltage signal of the coupling circuit and transmits the voltage signal to the signal processing and control unit through the AD 1;
the signal injection unit is provided with a plurality of signal amplification gears; the current signal detection unit is provided with a plurality of signal amplification gears; the high-frequency signal detection unit is provided with a plurality of signal amplification gears.
Step five, (1) when the high-frequency equivalent impedance of the metering secondary circuit is smaller, the current signal detection unit 102 is controlled to switch gears, and the current signal is detected
Figure GDA0003632161800000102
If the detected current signal
Figure GDA0003632161800000103
1/10 which is larger than the full range of AD2, calculates the impedance by adopting an injection current detection method, injects a high-frequency voltage signal from a coil T1, and detects a current signal generated by a coil T1;
impedance of injection loop
Figure GDA0003632161800000104
Is provided with
Figure GDA0003632161800000105
Then the impedance of the secondary loop is measured
Figure GDA0003632161800000106
Wherein
Figure GDA0003632161800000107
Is a constant;
ending the process; looping step (1) if the detected signal is less than 1/10 of the full range of the AD, and if the signal injection unit and the current signal detection unit are switched to the maximum gear, the detected signal is less than 1/10 of the full range of the AD, and entering step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the high-frequency signal detection unit is controlled to switch gears to detect a voltage signal
Figure GDA0003632161800000108
If a voltage signal is detected
Figure GDA0003632161800000109
1/10 of full range which is larger than AD1, adopting an injection return method to calculate impedance, injecting a high-frequency voltage signal from a coil T1, and detecting a high-frequency signal coupled to a coil T2;
wherein
Figure GDA00036321618000001010
Measuring impedance of secondary circuit
Figure GDA00036321618000001011
Then
Figure GDA0003632161800000111
Wherein R is0，R2，n0，n2A constant value; ending the process; if the detected signal is less than 1/10 full scale of AD, loop step (2), if the signal injection unit and the high frequency signal detection unit switch to the maximum gear, according to the formula
Figure GDA0003632161800000112
And calculating the impedance, and ending the process.
The high-frequency equivalent impedance range which can be accurately measured by the invention is 0.1 ohm to 100k ohm, and the dynamic range of the measured high-frequency equivalent impedance is 106. The impedance measurement with the accurate wide dynamic range has wider application range, and provides reliable data base for deeper fault state analysis of CT winding fault, insulation abnormity, CT transformation ratio replacement and the like.

Claims (9)

1. A wide dynamic range loop impedance measurement system, characterized by: the device comprises a signal injection unit (101), a current signal detection unit (102), a high-frequency signal detection unit (103), a signal processing and control unit (104), an injection coupling circuit and a detection coupling circuit;
the signal injection unit (101) adjusts the injected sinusoidal voltage signal
Figure FDA0003632161790000011
The amplitude of (d);
a current signal detection unit (102) detects a current signal injected into the coupling circuit
Figure FDA0003632161790000012
Through AD2 to a signal processing and control unit (104);
the high-frequency signal detection unit (103) detects and detects the coupling circuit
Figure FDA0003632161790000013
For sampling the resistance R2Voltage signals at two ends pass through the AD1 to a signal processing and control unit (104);
the injection coupling circuit and the detection coupling circuit are in a coupling mode of a signal from a measuring system to a secondary circuit of the current transformer;
the signal processing and control unit (104) generates a high-frequency digital signal, and the high-frequency digital signal is injected into a secondary circuit of the current transformer through the DA1, the signal injection unit (101) and the injection coupling circuit; the gear positions of a control signal injection unit (101), a current signal detection unit (102) and a high-frequency signal detection unit (103);
a signal processing and control unit (104) processes and controls the high frequency digital signals, the processing and control comprising:
(1) when the high-frequency equivalent impedance of the metering secondary circuit is small, the signal injection unit (101) switches gear injection
Figure FDA0003632161790000014
The current signal detection unit (102) switches the gear detection for the sinusoidal voltage signal injected by the signal injection unit
Figure FDA0003632161790000015
To the injection voltage
Figure FDA0003632161790000016
The generated current; if it is detected
Figure FDA0003632161790000017
If the current is larger than 1/10 of the full range AD2, calculating impedance by adopting an injection current detection method, calculating the impedance of a secondary circuit of the current transformer, and ending the process;
wherein
Figure FDA0003632161790000018
Figure FDA0003632161790000019
Then the impedance of the secondary loop is measured
Figure FDA00036321617900000110
Wherein n is0For coil T1 turns, R0For injecting a sampling resistor, Z, into the front-end circuit1cA high frequency equivalent impedance at a constant frequency of coil T1;
Figure FDA0003632161790000021
for measuring the injection voltage when the secondary circuit is open
Figure FDA0003632161790000022
The generated current; looping step (1) if the detected signal is less than 1/10 of the full scale of the AD2, and if the signal injection unit and the current signal detection unit switch to the maximum gear, the detected signal is less than 1/10 of the full scale of the AD2, and entering step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the signal injection unit switches the gear injection signal
Figure FDA0003632161790000023
The high-frequency signal detection unit switches gears and detects voltage signals
Figure FDA0003632161790000024
If a voltage signal is detected
Figure FDA0003632161790000025
If the measured value is more than 1/10 of the full range of AD1, calculating impedance by adopting an injection return method, and ending the process;
wherein
Figure FDA0003632161790000026
Measuring impedance of secondary circuit
Figure FDA0003632161790000027
Then
Figure FDA0003632161790000028
Wherein R is2In order to detect the sampling resistance of the front-end circuit,
Figure FDA0003632161790000029
to inject the voltage into the metering secondary loop,
Figure FDA00036321617900000210
is composed of
Figure FDA00036321617900000211
The current is produced by the power generation device,
Figure FDA00036321617900000212
for sampling the resistance R2Voltage across, n2Is coil T2 turns;
and (3) if the detected signal is less than 1/10 of the full scale of the AD1, circulating the step (2), and if the signal injection unit and the high-frequency signal detection unit are switched to the maximum gear, calculating the impedance according to the formula (6), and ending the process.
2. The system of claim 1, wherein: the injection coupling circuit and the detection coupling circuit,
wherein
Figure FDA00036321617900000213
Figure FDA00036321617900000214
Then
Figure FDA00036321617900000215
Wherein
Figure FDA00036321617900000216
Figure FDA00036321617900000217
Then
Figure FDA00036321617900000218
Figure FDA0003632161790000031
n2For the number of turns of the coil T2,
Figure FDA0003632161790000032
is the voltage across T1 and,
Figure FDA0003632161790000033
a front-end current is detected for coupling to the signal.
3. The system of claim 1, wherein: the signal injection unit is provided with a plurality of signal amplification gears; the current signal detection unit is provided with a plurality of signal amplification gears; the high-frequency signal detection unit is provided with a plurality of signal amplification gears.
4. The system of claim 1, wherein: the high frequency digital signal frequency range is 1kHz-100 kHz.
5. The system of claim 1, wherein: the coupling mode is a magnetic coupling mode.
6. A loop impedance measurement method with wide dynamic range is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
step one, a signal processing and control unit (104) controls a signal injection unit (101) to switch gear injection signals
Figure FDA0003632161790000034
And generating high-frequency digital signals which are injected into the injection coupling circuit and the secondary circuit of the current transformer through the DA1 and the signal injection unit (101);
step two, coupling the high-frequency digital signal to a secondary circuit of the current transformer by the injection coupling circuit and the detection coupling circuit;
step three, the current signal detection unit (102) detects a current signal injected into the coupling circuit, and the current signal passes through the AD2 to the signal processing and control unit (104);
step four, the high-frequency signal detection unit (103) detects and detects the voltage signal of the coupling circuit and transmits the voltage signal to the signal processing and control unit (104) through the AD 1;
step five, (1) when the high-frequency equivalent impedance of the metering secondary circuit is small, the signal injection unit (101) switches gear injection
Figure FDA0003632161790000035
Sinusoidal voltage signal, current injected for signal injection unit (101)Signal detection unit (102) shift position detection
Figure FDA0003632161790000036
To injection voltage
Figure FDA0003632161790000037
The generated current; if it is detected
Figure FDA0003632161790000038
1/10 of the full range is larger than AD2, impedance is calculated by adopting an injection current detection method, impedance of a secondary circuit of the current transformer is calculated, and the process is finished;
wherein
Figure FDA0003632161790000039
Figure FDA00036321617900000310
Then the impedance of the secondary loop is measured
Figure FDA00036321617900000311
Wherein n is0For coil T1 turns, R0For injecting a sampling resistor, Z, into the front-end circuit1cA high frequency equivalent impedance of constant frequency of coil T1;
Figure FDA0003632161790000041
for measuring the injection voltage when the secondary circuit is open
Figure FDA0003632161790000042
The generated current ends the process; looping step (1) if the detected signal is less than 1/10 of the full scale of the AD2, and if the signal injection unit and the current signal detection unit switch to the maximum gear, the detected signal is less than 1/10 of the full scale of the AD2, and entering step (2);
(2) when the high-frequency equivalent impedance of the metering secondary circuit is larger, the signal injection unit switches the gear injection signal
Figure FDA0003632161790000043
The high-frequency signal detection unit switches gears and detects voltage signals
Figure FDA0003632161790000044
If a voltage signal is detected
Figure FDA0003632161790000045
If the measured value is more than 1/10 of the full range of AD1, calculating impedance by adopting an injection return method, and ending the process;
wherein
Figure FDA0003632161790000046
Measuring impedance of secondary circuit
Figure FDA0003632161790000047
Then
Figure FDA0003632161790000048
Wherein R is2In order to detect the sampling resistance of the front-end circuit,
Figure FDA0003632161790000049
in order to inject the voltage to the metering secondary loop,
Figure FDA00036321617900000410
is composed of
Figure FDA00036321617900000411
The current generated by the power supply is used,
Figure FDA00036321617900000412
for sampling the resistance R2At both endsVoltage, n2Is coil T2 turns;
looping step (2) if the detected signal is less than 1/10 of full scale of AD1, if the signal injection unit and the high frequency signal detection unit are switched to the maximum gear according to the formula
Figure FDA00036321617900000413
And calculating the impedance, and ending the process.
7. The method of claim 6, wherein: the injection coupling circuit and the detection coupling circuit,
wherein
Figure FDA00036321617900000414
Figure FDA00036321617900000415
Then
Figure FDA00036321617900000416
Wherein
Figure FDA00036321617900000417
Figure FDA0003632161790000051
Then
Figure FDA0003632161790000052
Figure FDA0003632161790000053
n2For the number of turns of the coil T2,
Figure FDA0003632161790000054
is the voltage across T1 and,
Figure FDA0003632161790000055
a front-end current is detected for coupling to the signal.
8. The method of claim 6, wherein: the signal injection unit is provided with a plurality of signal amplification gears; the current signal detection unit is provided with a plurality of signal amplification gears; the high-frequency signal detection unit is provided with a plurality of signal amplification gears.
9. The method of claim 6, wherein: the high frequency digital signal frequency range is 1kHz-100 kHz.
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