CN112067949A - Alternating current precision power distribution monitoring system - Google Patents
Alternating current precision power distribution monitoring system Download PDFInfo
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- CN112067949A CN112067949A CN202011131437.0A CN202011131437A CN112067949A CN 112067949 A CN112067949 A CN 112067949A CN 202011131437 A CN202011131437 A CN 202011131437A CN 112067949 A CN112067949 A CN 112067949A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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Abstract
The invention provides an alternating current precision power distribution monitoring system, which can realize the purpose of synchronous sampling by arranging a frequency measuring circuit to monitor the frequency of a power grid in real time, tracking the frequency change of the power grid, and adjusting the sampling period according to the frequency change before each sampling; compared with the method for converting sine waves into square waves by the existing comparator, the method for converting sine waves into square waves by adopting the adder can solve the technical problem that small signals in the prior art are difficult to convert sine waves into square waves, improve the conversion efficiency and reduce the distortion of square wave signals.
Description
Technical Field
The invention relates to the field of power distribution monitoring, in particular to an alternating current precision power distribution monitoring system.
Background
The power distribution monitoring system collects data of current, voltage, active power, reactive power, power factors, frequency, harmonic waves and the like of the power distribution transformer and provides data reference for load prediction, line loss analysis, fault judgment, economic operation and the like. The traditional method for measuring the power grid frequency achieves synchronous sampling by adopting a phase-locked loop method, but with the continuous increase of nonlinear loads in a power distribution network, the harmonic content in the power grid is higher and higher, and the method adopting the phase-locked loop is not suitable for measuring the power grid frequency. Because the invention provides the alternating current precision power distribution monitoring system for solving the problem that frequency measurement cannot be synchronously sampled in the prior art, the frequency change of a power grid is tracked in real time, and the sampling interval is adjusted according to the frequency change of the power grid, so that synchronous sampling is realized.
Disclosure of Invention
In view of this, the invention provides an ac precision power distribution monitoring system, which tracks the frequency change of the power grid in real time and adjusts the sampling interval according to the frequency change of the power grid, thereby realizing synchronous sampling.
The technical scheme of the invention is realized as follows: the invention provides an alternating current precision power distribution monitoring system which comprises a transformer conversion circuit, a frequency measurement circuit and a processor, wherein the frequency measurement circuit comprises resistors R1-R3, a resistor R18, a resistor R19, a potentiometer RP3 and a first operational amplifier;
the input end of the transformer conversion circuit inputs three-phase alternating-current voltage or current, and the output end of the transformer conversion circuit is electrically connected with the non-inverting input end of the first operational amplifier through a resistor R18;
one end of a potentiometer RP3 is electrically connected with a positive electrode of a power supply, the other end of the potentiometer RP3 is electrically connected with a negative electrode of the power supply, a sliding end of a potentiometer RP3 is electrically connected with one end of a resistor R2 and one end of a resistor R1 through a resistor R3 respectively, the other end of the resistor R2 is grounded, the other end of the resistor R1 is electrically connected with an inverted input end of a first operational amplifier, an output end of the operational amplifier is electrically connected with one end of the resistor R19 and a timer integrated in the processor respectively, and the other end of the resistor R19 is electrically connected with the power supply.
On the basis of the above technical solution, preferably, the mobile terminal further includes an anti-aliasing filter;
the output end of the transformer conversion circuit is electrically connected with one end of a resistor R18 through an anti-aliasing filter, and the other end of the resistor R18 is electrically connected with the non-inverting input end of the first operational amplifier.
Further preferably, the anti-aliasing filter comprises: a second order RC low-pass filter and a voltage follower;
the output end of the transformer conversion circuit is electrically connected with the input end of the second-order RC low-pass filter, and the output end of the second-order RC low-pass filter is electrically connected with one end of the resistor R18 through the voltage follower.
Further preferably, the device further comprises a voltage measuring circuit and a current measuring circuit;
the output end of the transformer conversion circuit is electrically connected with the input end of the voltage measurement circuit and the input end of the current measurement circuit through the anti-aliasing filter respectively, and the output end of the voltage measurement circuit and the output end of the current measurement circuit are electrically connected with the A/D sampling pins of the processor in a one-to-one correspondence mode.
Further preferably, the voltage measuring circuit comprises an amplifying circuit and a sine wave to square wave circuit;
the output end of the transformer conversion circuit is electrically connected with the input end of the amplifying circuit through the anti-aliasing filter, and the output end of the amplifying circuit is electrically connected with an A/D sampling pin of the processor through the sine wave-to-square wave circuit.
Further preferably, the amplifying circuit includes: resistors R9-R11 and a second operational amplifier;
one end of the resistor R9 is electrically connected with the power supply, the other end of the resistor R9 is electrically connected with one end of the resistor R10 and the non-inverting input end of the second operational amplifier, and the other end of the resistor R10 is grounded;
the output end of the transformer conversion circuit is electrically connected with the inverting input end of the second operational amplifier through the anti-aliasing filter, the resistor R11 is connected between the inverting input end of the second operational amplifier and the output end of the second operational amplifier in parallel, and the output end of the second operational amplifier is electrically connected with the A/D sampling pin of the processor through the sine wave-to-square wave circuit.
Further preferably, the sine wave to square wave circuit includes: an adder and a voltage stabilizing circuit;
the output end of the amplifying circuit is electrically connected with the first input end of the adder and the input end of the voltage stabilizing circuit respectively, the output end of the voltage stabilizing circuit is electrically connected with the second input end of the adder, and the output end of the adder is electrically connected with the A/D sampling pin of the processor.
Further preferably, the voltage regulator circuit includes: resistors R12-R14, a diode D3, a diode D4 and a third operational amplifier;
the output end of the amplifying circuit is electrically connected with the cathode of the diode D3, one end of the resistor R14 and the inverting input end of the third operational amplifier through a resistor R12, the non-inverting input end of the third operational amplifier is grounded, the other end of the resistor R14 is electrically connected with the second input end of the adder through a resistor R13, the anode of the diode D3 is electrically connected with the cathode of the diode D4 and the output end of the third operational amplifier, and the anode of the diode D4 is electrically connected with the other end of the resistor R14.
Further preferably, the adder includes: a resistor R15, a resistor R16 and a fourth operational amplifier;
the output end of the amplifying circuit is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R15, the other end of the resistor R14 is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R13, the non-inverting input end of the fourth operational amplifier is grounded, a resistor R16 is connected between the inverting input end and the output end of the fourth operational amplifier in parallel, and the output end of the fourth operational amplifier is electrically connected with an A/D sampling pin of the processor.
Compared with the prior art, the alternating current precision power distribution monitoring system has the following beneficial effects:
(1) the frequency measurement circuit is arranged to monitor the power grid frequency in real time, track the change of the power grid frequency and adjust the sampling period according to the change of the frequency before each sampling, so that the aim of synchronous sampling can be fulfilled;
(2) the anti-aliasing filter is arranged in the frequency measurement circuit, so that the anti-aliasing filter can be used for filtering high-frequency signal components in the output signal of the transformer conversion circuit, and can pass the frequency of a useful signal with very small attenuation, inhibit out-of-band frequency signals and prevent the signals from generating frequency spectrum aliasing and high-frequency interference phenomena;
(3) the voltage measuring circuit is internally provided with an adder for carrying out amplitude limiting on the alternating current signal output by the amplifying circuit, so that the output signal becomes an approximate square wave signal, and compared with the method for realizing the conversion from the sine wave to the square wave by adopting the adder, the method for realizing the conversion from the sine wave to the square wave by adopting the adder can solve the technical problem that the conversion from the sine wave to the square wave is difficult to realize by small signals in the prior art, improve the conversion efficiency and reduce the distortion of the square wave signal;
(4) the voltage stabilizing circuit is arranged on the second input end of the adder to condition the sine wave output by the amplifying circuit, so that the voltage of the second input end of the adder is stabilized at a certain fixed value, the technical problem that in the prior art, the voltage of the input end of the adder is subjected to any small change or peak noise near a threshold voltage to cause the jump of the output voltage of the adder is solved, and the anti-interference capability of the adder is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a block diagram of an AC precision power distribution monitoring system according to the present invention;
FIG. 2 is a detailed block diagram of an AC precision power distribution monitoring system according to the present invention;
FIG. 3 is a circuit diagram of a frequency measurement circuit in an AC precision power distribution monitoring system according to the present invention;
fig. 4 is a circuit diagram of an anti-aliasing filter, an amplifying circuit, an adder and a voltage stabilizing circuit in the ac precision power distribution monitoring system according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1, an ac precision power distribution monitoring system according to the present invention includes a transformer conversion circuit, a frequency measurement circuit, a voltage measurement circuit, a current measurement circuit, and a processor.
And the transformer conversion circuit inputs three-phase alternating-current voltage or three-phase alternating-current and performs voltage division, isolation and current-voltage conversion on the three-phase alternating-current voltage or the three-phase alternating-current. In this embodiment, the transformer conversion circuit may include a voltage transformer conversion circuit and a current transformer conversion circuit, and the two circuits have the same structure but different types of transformers; the output of the voltage transformer conversion circuit is electrically connected with the input of the voltage measurement circuit, and the output of the current transformer conversion circuit is electrically connected with the input of the current measurement circuit. Preferably, the circuit structure of the voltage transformer conversion circuit is as shown in fig. 4, and the voltage transformer conversion circuit includes a voltage dividing resistor R4, a voltage transformer T1, a clamp protection circuit, and a current-voltage conversion circuit composed of an operational amplifier LM324, where a three-phase alternating voltage is divided by a voltage dividing resistor R4 to obtain a weak current signal, the current signal is isolated by the voltage transformer T1, limited by the clamp protection circuit, and then output to the current-voltage conversion circuit for current-voltage conversion, where the capacitor C4 and the potentiometer RP2 are used to compensate displacement; the potentiometer RP1 and the resistor R8 are used to adjust the output voltage of the operational amplifier LM 324.
And the frequency measuring circuit is used for detecting the power grid frequency. The common measurement method based on the Fourier transform is used for detecting the power grid parameters, when the power distribution network runs normally, the power grid frequency fluctuates continuously at 50Hz, and the actual period changes continuously, so if the measurement method based on the Fourier transform is used for detecting the harmonic waves, in the sampling process, when the sampling frequency is not integral multiple of the signal frequency, the measurement method using the Fourier transform can generate a frequency leakage phenomenon and a barrier effect, so that the measured frequency, phase and amplitude are inaccurate, and the requirement of system synchronism can not be met. If there is a sampling synchronization bias, spectral leakage degrades the accuracy of harmonic analysis. One of the main causes of synchronization errors is the drift of the signal frequency, and many methods assume that the signal frequency is unchanged, obviously limited, and is not in accordance with engineering practice. The second reason for the synchronization error is the limited resolution of the sampling timer, but as the word length and operating frequency of the MCU increase, the influence of this factor will decrease, however, if sampling at equal intervals is used, the accumulated error will be quite large. The hardware approach for reducing sampling synchronization deviation is called as a hardware synchronization method, and is usually a phase-locked loop (PLL) method, which has a relatively complex circuit, a relatively high cost, and is greatly influenced by factors such as devices and environments. In an alternating current sampling system, generally, an electric quantity value of N points is sampled in a cycle, and data processing is performed on the electric quantity value, but the frequency of a power grid has certain fluctuation, so that a sampling interval needs to be continuously adjusted according to the frequency of the power grid, and synchronous sampling can be realized. In this embodiment, the frequency measurement circuit monitors the power grid frequency in real time, tracks the change of the power grid frequency, and adjusts the sampling period according to the change of the frequency before each sampling, thereby achieving the purpose of synchronous sampling.
Preferably, as shown in fig. 3, the frequency measuring circuit includes resistors R1-R3, resistor R18, resistor R19, potentiometer RP3, and a first operational amplifier; the input end of the transformer conversion circuit inputs three-phase alternating-current voltage or current, and the output end of the transformer conversion circuit is electrically connected with the non-inverting input end of the first operational amplifier through a resistor R18; one end of a potentiometer RP3 is electrically connected with a positive electrode of a power supply, the other end of the potentiometer RP3 is electrically connected with a negative electrode of the power supply, a sliding end of a potentiometer RP3 is electrically connected with one end of a resistor R2 and one end of a resistor R1 through a resistor R3 respectively, the other end of the resistor R2 is grounded, the other end of the resistor R1 is electrically connected with an inverted input end of a first operational amplifier, an output end of the operational amplifier is electrically connected with one end of the resistor R19 and a timer integrated in the processor respectively, and the other end of the resistor R19 is electrically connected with the power supply.
The resistor R1, the resistor R18 and the first operational amplifier form a differential amplifier, an input analog signal is converted into a digital signal and is input to an input pin of a timer integrated in the processor, the period and the frequency of a periodic wave are calculated by detecting the time of two pulse intervals, and after the period of the periodic wave is obtained, the A/D sampling interval time is set, so that the alternating current sampling for tracking the frequency change is realized; the frequency measurement circuit is realized by adopting an operational amplifier, and the operational amplifier has a zero drift phenomenon. Therefore, in this embodiment, the zero adjustment circuit is configured by the resistor R2, the resistor R3, the potentiometer RP3 and the 5V power supply, and is used to eliminate the zero drift phenomenon of the operational amplifier, and the offset adjustment range of the zero adjustment circuit is ± 5 mV.
And the anti-aliasing filter is used for filtering high-frequency signal components in the output signal of the transformer conversion circuit, allowing the frequency of a useful signal to pass through with small attenuation, inhibiting out-of-band frequency signals and preventing the signals from generating frequency spectrum aliasing and high-frequency interference phenomena. The output end of the transformer conversion circuit is electrically connected with one end of a resistor R18 through an anti-aliasing filter, and the other end of the resistor R18 is electrically connected with the non-inverting input end of the first operational amplifier. Preferably, as shown in fig. 2, the anti-aliasing filter comprises a second-order RC low-pass filter and a voltage follower; the output end of the transformer conversion circuit is electrically connected with the input end of the second-order RC low-pass filter, and the output end of the second-order RC low-pass filter is electrically connected with one end of the resistor R18 through the voltage follower. Wherein the cut-off frequency of the second-order RC low-pass filter is 800Hz at most.
The voltage measuring circuit is used for detecting the magnitude of three-phase voltage in the power grid; the current measuring circuit is used for detecting the magnitude of three-phase current in the power grid. The output end of the transformer conversion circuit is electrically connected with the input end of the voltage measurement circuit and the input end of the current measurement circuit through the anti-aliasing filter respectively, and the output end of the voltage measurement circuit and the output end of the current measurement circuit are electrically connected with the A/D sampling pins of the processor in a one-to-one correspondence mode. In this embodiment, the circuit structures of the voltage measuring circuit and the current measuring circuit are the same, and therefore, only the structure of the voltage measuring circuit will be described here. Preferably, as shown in fig. 2, the voltage measuring circuit includes an amplifying circuit and a sine wave to square wave circuit.
The amplifying circuit is arranged in the embodiment to perform voltage lifting on the output signal of the anti-aliasing filter because the secondary side output of the voltage transformer is an alternating current signal and has positive and negative characteristics, and the maximum range of the pin voltage of the A/D sampling part of the processor is generally 0-3V or 0-5V. In this embodiment, the output terminal of the transformer conversion circuit is electrically connected to the input terminal of the amplifying circuit through the anti-aliasing filter, and the output terminal of the amplifying circuit is electrically connected to the a/D sampling pin of the processor through the sine wave to square wave circuit. Preferably, as shown in fig. 4, the amplifying circuit includes: resistors R9-R11 and a second operational amplifier; specifically, one end of the resistor R9 is electrically connected to the power supply, the other end of the resistor R9 is electrically connected to one end of the resistor R10 and the non-inverting input terminal of the second operational amplifier, and the other end of the resistor R10 is grounded; the output end of the transformer conversion circuit is electrically connected with the inverting input end of the second operational amplifier through the anti-aliasing filter, the resistor R11 is connected between the inverting input end of the second operational amplifier and the output end of the second operational amplifier in parallel, and the output end of the second operational amplifier is electrically connected with the A/D sampling pin of the processor through the sine wave-to-square wave circuit.
In the sine-to-square wave circuit, since the output signal of the amplifying circuit is a sine wave, it is inconvenient to capture the signal, and in order to capture the signal by the a/D pin of the processor, it needs to be converted into a square wave signal. In this embodiment, the sine wave to square wave circuit includes: adder and voltage regulator circuit.
Because the voltage of the second input end of the adder is slightly changed or peak noise is generated near the threshold voltage, the output voltage of the adder jumps, and the interference resistance of the adder is poor, so that in order to solve the above problem, the voltage stabilizing circuit is arranged in the embodiment to condition the sine wave output by the amplifying circuit, so that the voltage of the second input end of the adder is stabilized at a certain fixed value. The input end of the voltage stabilizing circuit is electrically connected with the output end of the amplifying circuit, and the output end of the voltage stabilizing circuit is electrically connected with the second input end of the adder. Preferably, as shown in fig. 4, the voltage stabilizing circuit includes: resistors R12-R14, a diode D3, a diode D4 and a third operational amplifier; specifically, the output end of the amplifying circuit is electrically connected to the cathode of the diode D3, one end of the resistor R14, and the inverting input end of the third operational amplifier through a resistor R12, the non-inverting input end of the third operational amplifier is grounded, the other end of the resistor R14 is electrically connected to the second input end of the adder through a resistor R13, the anode of the diode D3 is electrically connected to the cathode of the diode D4 and the output end of the third operational amplifier, and the anode of the diode D4 is electrically connected to the other end of the resistor R14. The diode D3 and the diode D4 form a clamping circuit, and clamp the voltages of the diode D3 and the diode D4 at a certain fixed value; the resistors R12-R14 are used for removing the coupled signals in the signals.
And the adder is used for carrying out amplitude limiting on the alternating current signal output by the amplifying circuit so that the output signal becomes an approximate square wave signal. In this embodiment, the first input terminal of the adder is electrically connected to the output terminal of the amplifying circuit, the second input terminal of the adder is electrically connected to the output terminal of the voltage stabilizing circuit, and the output terminal of the adder is electrically connected to the a/D sampling pin of the processor. Preferably, as shown in fig. 4, the adder includes: a resistor R15, a resistor R16 and a fourth operational amplifier; the output end of the amplifying circuit is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R15, the other end of the resistor R14 is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R13, the non-inverting input end of the fourth operational amplifier is grounded, a resistor R16 is connected between the inverting input end and the output end of the fourth operational amplifier in parallel, and the output end of the fourth operational amplifier is electrically connected with an A/D sampling pin of the processor. The adder of the embodiment is an inverting adder, the input impedance of the adder is low, and input signals easily flow into the adder without influencing a post-stage circuit; the resistor R15 and the resistor R16 are used for filtering; the gain of the fourth operational amplifier is high enough, and the amplitude of the input signal is large enough, so that the instantaneous value of the input signal multiplied by the gain is larger than the amplitude which can be output by the operational amplifier, the output is about to be limited, and the output signal is approximate to a square wave.
The working principle of the embodiment is as follows: three-phase alternating voltage or three-phase alternating current is converted into a weak voltage signal through a transformer conversion circuit, the voltage signal is filtered through an anti-aliasing filter, the filtered signal is divided into two paths, one path is input to a frequency measurement circuit for zero crossing point triggering, and a trigger pulse is sent to a timer pin of a processor, the processor calculates the period and the frequency of a periodic wave according to the time of the interval of two adjacent pulses, and after the period of the periodic wave is obtained, the A/D sampling interval time is set, so that alternating current sampling for tracking frequency change is realized;
the other path is input to a voltage measuring circuit and a current measuring circuit, the voltage measuring circuit and the current measuring circuit perform voltage detection on an anti-aliasing filter output signal, and since the three-phase alternating current voltage and the three-phase alternating current detection principle are the same, only the working principle of the voltage measuring circuit is described here: and after the output signal of the anti-aliasing filter is subjected to voltage lifting through the amplifying circuit, a sine wave signal is output, the sine wave signal is converted into a square wave signal after amplitude limiting through the adder, the square wave signal is input to an A/D sampling pin of the processor, and the A/D sampling pin of the processor samples according to the adjusted sampling interval.
The beneficial effect of this embodiment does: the frequency measurement circuit is arranged to monitor the power grid frequency in real time, track the change of the power grid frequency and adjust the sampling period according to the change of the frequency before each sampling, so that the aim of synchronous sampling can be fulfilled;
the anti-aliasing filter is arranged in the frequency measurement circuit, so that the anti-aliasing filter can be used for filtering high-frequency signal components in the output signal of the transformer conversion circuit, and can pass the frequency of a useful signal with very small attenuation, inhibit out-of-band frequency signals and prevent the signals from generating frequency spectrum aliasing and high-frequency interference phenomena;
the voltage measuring circuit is internally provided with an adder for carrying out amplitude limiting on the alternating current signal output by the amplifying circuit, so that the output signal becomes an approximate square wave signal, and compared with the method for realizing the conversion from the sine wave to the square wave by adopting the adder, the method for realizing the conversion from the sine wave to the square wave by adopting the adder can solve the technical problem that the conversion from the sine wave to the square wave is difficult to realize by small signals in the prior art, improve the conversion efficiency and reduce the distortion of the square wave signal;
the voltage stabilizing circuit is arranged on the second input end of the adder to condition the sine wave output by the amplifying circuit, so that the voltage of the second input end of the adder is stabilized at a certain fixed value, the technical problem that in the prior art, the voltage of the input end of the adder is subjected to any small change or peak noise near a threshold voltage to cause the jump of the output voltage of the adder is solved, and the anti-interference capability of the adder is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. The utility model provides an exchange accurate distribution monitoring system, its includes mutual-inductor converting circuit, frequency measurement circuit and treater, its characterized in that: the frequency measurement circuit comprises resistors R1-R3, a resistor R18, a resistor R19, a potentiometer RP3 and a first operational amplifier;
the input end of the transformer conversion circuit inputs three-phase alternating-current voltage or current, and the output end of the transformer conversion circuit is electrically connected with the non-inverting input end of the first operational amplifier through a resistor R18;
one end of the potentiometer RP3 is electrically connected with the positive electrode of a power supply, the other end of the potentiometer RP3 is electrically connected with the negative electrode of the power supply, the sliding end of the potentiometer RP3 is electrically connected with one end of a resistor R2 and one end of a resistor R1 through a resistor R3 respectively, the other end of the resistor R2 is grounded, the other end of the resistor R1 is electrically connected with the inverting input end of a first operational amplifier, the output end of the operational amplifier is electrically connected with one end of the resistor R19 and a timer integrated in the processor respectively, and the other end of the resistor R19 is electrically connected with the power supply.
2. An ac precision power distribution monitoring system as claimed in claim 1 wherein: said further comprising an anti-aliasing filter;
the output end of the transformer conversion circuit is electrically connected with one end of a resistor R18 through an anti-aliasing filter, and the other end of the resistor R18 is electrically connected with the non-inverting input end of the first operational amplifier.
3. An ac precision power distribution monitoring system as claimed in claim 2 wherein: the anti-aliasing filter comprises: a second order RC low-pass filter and a voltage follower;
the output end of the transformer conversion circuit is electrically connected with the input end of the second-order RC low-pass filter, and the output end of the second-order RC low-pass filter is electrically connected with one end of the resistor R18 through the voltage follower.
4. An ac precision power distribution monitoring system as claimed in claim 2 wherein: the device also comprises a voltage measuring circuit and a current measuring circuit;
the output end of the transformer conversion circuit is electrically connected with the input end of the voltage measurement circuit and the input end of the current measurement circuit through the anti-aliasing filter respectively, and the output end of the voltage measurement circuit and the output end of the current measurement circuit are electrically connected with the A/D sampling pins of the processor in a one-to-one correspondence mode.
5. An ac precision power distribution monitoring system according to claim 4 wherein: the voltage measuring circuit comprises an amplifying circuit and a sine wave to square wave circuit;
the output end of the transformer conversion circuit is electrically connected with the input end of the amplifying circuit through the anti-aliasing filter, and the output end of the amplifying circuit is electrically connected with an A/D sampling pin of the processor through the sine wave-to-square wave circuit.
6. An ac precision power distribution monitoring system according to claim 5 wherein: the amplification circuit includes: resistors R9-R11 and a second operational amplifier;
one end of the resistor R9 is electrically connected with the power supply, the other end of the resistor R9 is electrically connected with one end of the resistor R10 and the non-inverting input end of the second operational amplifier, and the other end of the resistor R10 is grounded;
the output end of the transformer conversion circuit is electrically connected with the inverting input end of the second operational amplifier through the anti-aliasing filter, the resistor R11 is connected between the inverting input end of the second operational amplifier and the output end of the second operational amplifier in parallel, and the output end of the second operational amplifier is electrically connected with the A/D sampling pin of the processor through the sine wave-to-square wave circuit.
7. An ac precision power distribution monitoring system according to claim 5 wherein: the sine wave-to-square wave circuit comprises: an adder and a voltage stabilizing circuit;
the output end of the amplifying circuit is electrically connected with the first input end of the adder and the input end of the voltage stabilizing circuit respectively, the output end of the voltage stabilizing circuit is electrically connected with the second input end of the adder, and the output end of the adder is electrically connected with the A/D sampling pin of the processor.
8. An ac precision power distribution monitoring system according to claim 7 wherein: the voltage stabilizing circuit comprises: resistors R12-R14, a diode D3, a diode D4 and a third operational amplifier;
the output end of the amplifying circuit is electrically connected with the cathode of the diode D3, one end of the resistor R14 and the inverting input end of the third operational amplifier through the resistor R12 respectively, the non-inverting input end of the third operational amplifier is grounded, the other end of the resistor R14 is electrically connected with the second input end of the adder through the resistor R13, the anode of the diode D3 is electrically connected with the cathode of the diode D4 and the output end of the third operational amplifier respectively, and the anode of the diode D4 is electrically connected with the other end of the resistor R14.
9. An ac precision power distribution monitoring system according to claim 8 wherein: the adder includes: a resistor R15, a resistor R16 and a fourth operational amplifier;
the output end of the amplifying circuit is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R15, the other end of the resistor R14 is electrically connected with the inverting input end of the fourth operational amplifier through a resistor R13, the non-inverting input end of the fourth operational amplifier is grounded, a resistor R16 is connected between the inverting input end and the output end of the fourth operational amplifier in parallel, and the output end of the fourth operational amplifier is electrically connected with an A/D sampling pin of the processor.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113030658A (en) * | 2021-03-03 | 2021-06-25 | 珠海南自电气系统工程有限公司 | Stray current integrated monitoring system |
| CN116359588A (en) * | 2023-05-31 | 2023-06-30 | 北京智芯微电子科技有限公司 | Sampling adjustment method and device based on frequency following and intelligent switch |
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2020
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113030658A (en) * | 2021-03-03 | 2021-06-25 | 珠海南自电气系统工程有限公司 | Stray current integrated monitoring system |
| CN113030658B (en) * | 2021-03-03 | 2023-09-15 | 珠海南自电气系统工程有限公司 | Stray current comprehensive monitoring system |
| CN116359588A (en) * | 2023-05-31 | 2023-06-30 | 北京智芯微电子科技有限公司 | Sampling adjustment method and device based on frequency following and intelligent switch |
| CN116359588B (en) * | 2023-05-31 | 2023-08-25 | 北京智芯微电子科技有限公司 | Sampling adjustment method and device based on frequency following and intelligent switch |
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