CN111398662A - Current sensor for power transmission line - Google Patents
Current sensor for power transmission line Download PDFInfo
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- CN111398662A CN111398662A CN202010393419.3A CN202010393419A CN111398662A CN 111398662 A CN111398662 A CN 111398662A CN 202010393419 A CN202010393419 A CN 202010393419A CN 111398662 A CN111398662 A CN 111398662A
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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
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
Abstract
The invention discloses a current sensor of a power transmission line, which comprises: the output signal of the Rogowski coil module is a differential voltage signal of the current to be measured; the integrator module is used for converting the differential voltage signal into a voltage signal of the current to be measured; the DC blocking amplification module filters the voltage signal of the integrator module to remove DC, amplifies the voltage signal and outputs a power frequency signal and a high-frequency current signal; the high-pass filtering module filters power frequency and harmonic waves thereof in the high-frequency current signal and outputs the high-frequency current signal with large and small amplitude values; and monitoring and measuring power frequency current, high-frequency lightning current and high-frequency partial discharge current of the power transmission and distribution line in real time. The invention has the advantages that the fault can be detected only by detecting the currents, and the safe operation of the line can be effectively monitored in real time.
Description
Technical Field
The invention relates to a current sensor, in particular to a current sensor of a power transmission line.
Background
The complexity of the transmission and distribution network is complex, and the normal power frequency current transported in the power grid needs to be monitored and protected. Lightning strike can generate high-frequency lightning current; trees are laid down on the line, and high-frequency partial discharge current can be generated. The high-frequency currents belong to fault currents, and only when the fault currents are detected, corresponding faults can be detected, and safe operation of the line can be effectively monitored in real time.
The Rogowski coil is formed by uniformly winding a wire on a non-ferromagnetic structure with uniform size, electromotive force is induced by a winding coil, an output signal of the Rogowski coil is a differential voltage signal of a current to be measured, the differential voltage signal can be restored into the signal to be measured only by an integrator, and the Rogowski coil has the characteristics of high bandwidth and difficulty in saturation, overcomes various defects of a traditional electromagnetic current transformer, and is very suitable for measuring the current of a power transmission and distribution system.
Disclosure of Invention
The invention aims to provide a current sensor for a power transmission line, which can effectively monitor the safety of the line.
In order to solve the above technical problems, the present invention provides a current sensor for a power transmission line, comprising
The Rogowski coil module: the output signal is a differential voltage signal of the measured current;
an integrator module: converting the differential voltage signal into a voltage signal of the measured current;
a blocking amplification module: filtering the voltage signal of the integrator module to remove direct current, amplifying and outputting a power frequency signal and a high-frequency current signal;
a high-pass filtering module: filtering power frequency and harmonic thereof in the high-frequency current signal, and outputting a high-frequency current signal with a large amplitude;
the module monitors and measures power frequency current, high-frequency lightning current and high-frequency partial discharge current of the power transmission and distribution line in real time, and can detect faults only by detecting the currents, so that the safe operation of the line is effectively monitored in real time.
And the high-frequency current signal with small amplitude output by the high-pass filtering module is output by the high-gain amplifying module.
The Rogowski coil module is a high-frequency Rogowski coil module, and the bandwidth of the Rogowski coil module is at least more than 2 MHz.
The signal output by the integrator module passes through a blocking circuit formed by a capacitance resistor and reaches the in-phase end of the in-phase amplifier, and the output signal of the blocking amplification module is adjusted by an adjustable resistor to calibrate the output precision.
The high-pass filtering module comprises a fourth-order high-pass filter and a third-order high-pass filter, the fourth-order high-pass filter filters low-frequency signals to output high-frequency current signals with large amplitude, and the third-order high-pass filter filters low-frequency signals to output high-frequency current signals with small amplitude.
The invention has the following advantages:
1) the power frequency current and the high frequency current are separately output, so that the analysis of the power frequency and the high frequency is simplified, effective technical support is provided for detecting the effective current and the fault current, and great convenience is provided for signal processing; the power frequency output can always monitor the normal current in the circuit;
2) the high-frequency current output part filters a power frequency signal, great convenience is provided for high-frequency analysis, and the power frequency content in the traveling wave is very low, so that the filtering of the power frequency does not bring great influence on the analysis of the original waveform, and the waveform is difficult to intercept due to the existence of the power frequency, so that the traveling wave signal can be well captured by the filtering of the power frequency;
3) the traveling wave has great variation in size, the large one reaches hundreds of kiloamperes, the small one reaches several amperes, and the output of two ranges can separate the large and small faults, so that the faults can be analyzed carefully;
4) the sensor needs to be matched with a high-frequency Rogowski coil, so that the inherent frequency of the Rogowski coil is improved, the whole acquisition frequency band is improved, and the high frequency can not be achieved by a common current sensor.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic block diagram of the circuit of the present invention;
FIG. 2 is a circuit diagram of the present invention;
description of the figures
P1 — integrator block; p2-dc blocking amplification module;
p3 — fourth order filter; p4 — third order filter;
p5-high gain non-inverting amplifier.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 1 shows a schematic block circuit diagram of an embodiment of the present invention, and fig. 2 shows a circuit diagram of an embodiment of the present invention. As shown in fig. 1 and 2, the present invention provides a current sensor for a transmission line, wherein the three outputs, i.e., the upper, middle and lower outputs shown in fig. 2, respectively correspond to a power frequency output, a high-frequency large-range output and a high-frequency small-range output; the high-gain DC-DC converter comprises a Rogowski coil module, an integrator module P1, a DC blocking amplification module P2, a fourth-order high-pass filter P3, a third-order high-pass filter P4 and a high-gain in-phase amplifier P5.
The rogowski coil module is a high-frequency rogowski coil, the bandwidth of the rogowski coil module at least reaches more than 2 MHz, the frequency can be very high due to the hollow characteristic, and the high frequency can not be reached by a common current sensor.
The integrator module P1 converts the differential voltage signal used by the high-frequency rogowski coil into a voltage signal reflecting the primary current, and is disposed between the high-frequency rogowski coil and the blocking and amplifying module. As shown in fig. 2, two output terminals of the high-frequency rogowski coil are respectively connected with a non-inverting input terminal and an inverting input terminal of the operational amplifier U1A, R1 and C1 jointly determine an integration time, and R2 is a direct current gain limiting resistor to limit a direct current gain caused by an offset voltage of the operational amplifier.
The blocking amplification module P2 filters the voltage signal obtained by the integrator module to remove direct current, amplifies the voltage signal, and adjusts the adjustable resistance to calibrate the output precision; which is located between the integrator block and the high-pass filter block. After the signal is output by the integrator module, the signal passes through a DC blocking circuit consisting of a capacitor and a resistor and reaches the in-phase end of the in-phase amplifier. The dc blocking process is required because the output signal of the integrating circuit in the previous stage is not located at the center point due to the dc gain caused by the offset voltage of the integrating circuit in the previous stage. And the high impedance input of the in-phase amplifier also avoids the crosstalk among all paths. The output signals are adjusted through adjustable resistors RX1, RX2 and RX3, and the output accuracy is calibrated. Wherein: c2 and R3 form a power frequency channel for blocking, C3 and R7 form a high-frequency large-range gear for blocking, C8 and R14 form a high-frequency small-range gear for blocking, and RX1, RX2 and RX3 are respectively responsible for adjusting the amplification factor of three-way output.
The fourth order high pass filter P3 is located on the high frequency current wide range channel, which filters out the power frequency and its harmonics, leaving a pure high frequency current signal for analysis. The high-frequency current with large amplitude is directly output after filtering the signal output by the blocking amplification module. The capacitors C4, C5, C6 and C7 and the resistors R8, R9, R10 and R11 jointly determine the knee frequency, the knee frequency of 1KHZ is set, corresponding values are obtained according to a coefficient table of the Chebyshev filter, and the balance between the Q value and the frequency attenuation gradient is realized.
The third-order high-pass filter P4 is located on a high-frequency current small-range channel, and is used for filtering power frequency and harmonic waves thereof, and leaving a pure high-frequency current signal for analysis. The signal output by the blocking amplification module is filtered and then output to the next-stage high-gain amplification module. The capacitors C9, C10, C11 and the resistors R15, RC16, R18 jointly determine the knee frequency, and the knee frequency is set to 1KHZ, so that the corresponding value is obtained according to the coefficient table of the chebyshev filter.
The high-gain non-inverting amplifier P5 is located on the high-frequency current small-scale channel. In order to measure a fine high-frequency current signal, the signal needs to be amplified and output, so that the signal is convenient to analyze. The high-gain amplification module amplifies the tiny voltage signals filtered by the third-order filter, and the amplification result is directly output. Wherein: the (1+ R19/R17) is the amplification factor, the amplification factor is set to be 20 times in the embodiment, the C12 is a high-frequency noise suppression capacitor, the C12 capacitor suppresses disturbance of the ultrahigh frequency interference signal, such as power supply high-frequency ripple, and obtains relatively small noise output, and the capacitor smoothes the output waveform.
The amplifiers shown in fig. 2 are all supplied with plus and minus 5V.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A transmission line current sensor is characterized in that: comprises that
The Rogowski coil module: the output signal is a differential voltage signal of the measured current;
an integrator module: converting the differential voltage signal into a voltage signal of the measured current;
a blocking amplification module: filtering the voltage signal of the integrator module to remove direct current, amplifying and outputting a power frequency signal and a high-frequency current signal;
a high-pass filtering module: and filtering power frequency and harmonic waves thereof in the high-frequency current signal, and outputting the high-frequency current signal with large and small amplitude.
2. The transmission line current sensor of claim 1, wherein: and the high-frequency current signal with small amplitude output by the high-pass filtering module is output by the high-gain amplifying module.
3. The transmission line current sensor of claim 1, wherein: the Rogowski coil module is a high-frequency Rogowski coil module, and the bandwidth of the Rogowski coil module is at least more than 2 MHz.
4. The transmission line current sensor of claim 1, wherein: the signal output by the integrator module passes through a blocking circuit formed by a capacitance resistor and reaches the in-phase end of the in-phase amplifier, and the output signal of the blocking amplification module is adjusted by an adjustable resistor to calibrate the output precision.
5. The transmission line current sensor of claim 1, wherein: the high-pass filtering module comprises a fourth-order high-pass filter and a third-order high-pass filter, the fourth-order high-pass filter filters low-frequency signals to output high-frequency current signals with large amplitude, and the third-order high-pass filter filters low-frequency signals to output high-frequency current signals with small amplitude.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010393419.3A CN111398662A (en) | 2020-05-11 | 2020-05-11 | Current sensor for power transmission line |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010393419.3A CN111398662A (en) | 2020-05-11 | 2020-05-11 | Current sensor for power transmission line |
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| Publication Number | Publication Date |
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| CN111398662A true CN111398662A (en) | 2020-07-10 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010393419.3A Pending CN111398662A (en) | 2020-05-11 | 2020-05-11 | Current sensor for power transmission line |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098402A (en) * | 2021-03-11 | 2021-07-09 | 广芯微电子（广州）股份有限公司 | Low-power-consumption band-pass amplifying circuit with self-calibration center frequency |
| CN113325265A (en) * | 2021-05-12 | 2021-08-31 | 武汉三相电力科技有限公司 | Device for detecting mixed traveling wave in power transmission line |
| CN114089135A (en) * | 2021-11-19 | 2022-02-25 | 南京征途信息技术有限公司 | Partial discharge sensor for variable distribution high-frequency current and method thereof |
-
2020
- 2020-05-11 CN CN202010393419.3A patent/CN111398662A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098402A (en) * | 2021-03-11 | 2021-07-09 | 广芯微电子（广州）股份有限公司 | Low-power-consumption band-pass amplifying circuit with self-calibration center frequency |
| CN113325265A (en) * | 2021-05-12 | 2021-08-31 | 武汉三相电力科技有限公司 | Device for detecting mixed traveling wave in power transmission line |
| CN114089135A (en) * | 2021-11-19 | 2022-02-25 | 南京征途信息技术有限公司 | Partial discharge sensor for variable distribution high-frequency current and method thereof |
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