CN116223903B - Anti-interference circuit and method for three-phase three-wire electric energy meter under alternating current magnetic field - Google Patents
Anti-interference circuit and method for three-phase three-wire electric energy meter under alternating current magnetic field Download PDFInfo
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- CN116223903B CN116223903B CN202310498946.4A CN202310498946A CN116223903B CN 116223903 B CN116223903 B CN 116223903B CN 202310498946 A CN202310498946 A CN 202310498946A CN 116223903 B CN116223903 B CN 116223903B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters
- G01R22/06—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods
- G01R22/061—Details of electronic electricity meters
- G01R22/066—Arrangements for avoiding or indicating fraudulent use
Abstract
The invention discloses an anti-interference circuit and method under an alternating magnetic field of a three-phase three-wire electric energy meter, and belongs to the technical field of electric energy metering. The current sampling loop of the electric energy meter comprises a sampling element part, a signal conversion and filtering circuit part and a metering part, wherein the sampling element part comprises an A-phase sampling element and a C-phase sampling element, and the signal conversion and filtering circuit part comprises an A-phase conversion and filtering circuit and a C-phase conversion and filtering circuit. The signal conversion and filtering circuit part also comprises a B-phase signal conversion and filtering circuit, wherein the input end of the B-phase signal conversion and filtering circuit is suspended, and the output end of the B-phase signal conversion and filtering circuit is connected with the B-phase input end of the measured part. The invention collects the induction current generated by the alternating magnetic field through the B-phase signal conversion and filtering circuit, and then calculates the compensation value by utilizing the induction current, thereby eliminating the interference of the alternating magnetic field environment on the power metering, and simultaneously having the advantages of simplicity, reliability, easy realization and the like.
Description
Technical Field
The invention relates to the technical field of electric energy metering, in particular to an anti-interference circuit under an alternating magnetic field of a three-phase three-wire electric energy meter, and also relates to an anti-interference method.
Background
At present, the working requirements of the electric energy meter in the 0.5mt power frequency alternating current magnetic field environment are defined in the technical specifications of the domestic electric energy meter. For example, the part of 4.7.11 external influence in technical Specification of D-level three-phase multifunctional electric energy meter of southern electric network has no-load working condition requirement on a 0.5mT power frequency magnetic field: the electric energy meter is in a working state, a current circuit is free of current, the electric energy meter is placed in the interference of a power frequency magnetic field of 0.5mT, and more than one pulse is not generated by the test output of the electric energy meter in 20 times of creep time. However, the sampling precision of the electric energy signal of the high-precision three-phase electric energy meter is millivolt level, the tiny magnetic field fluctuation can possibly introduce electric energy metering errors, and the environment of the alternating current magnetic field of the electric energy meter is complex, so that corresponding anti-interference measures must be adopted.
Aiming at a three-phase three-wire electric energy meter, the Chinese patent application with publication number of CN 111830297A discloses an anti-interference method of the electric energy meter under a 0.5mT power frequency magnetic field, and the method sequentially comprises the following steps: 1) Powering up and initializing; 2) Sampling the output power of the electric energy meter, if the power is larger than a first preset value, entering the step 3), otherwise, entering the step 4); performing a conventional metering function, returning to step 2); 4) Comparing the sampled power with a second preset value, and if the sampled power is continuously sampled for N times to be smaller than the second preset value, entering a step 5); 5) Entering a power frequency magnetic field judging process, sampling voltage and current power data of the electric energy meter every second, setting a counting period, and entering a step 6 after each counting period is finished; 6) Judging the working magnetic field state of the last statistical period according to the power sampled in the last statistical period, and entering the step 7 if judging that the working magnetic field state is in the working magnetic field state; 7) And shielding the current pulse signal when the electric energy meter is in the power frequency magnetic field state in the last statistical period. However, the above-mentioned needs to meet certain magnetic field conditions in practical application conditions, and under the condition of high power consumption of users, the electric energy metering error introduced by the ac magnetic field cannot be avoided. On the other hand, the field electricity utilization environment magnetic field is changeable and complex, the situation misjudgment is easy to occur on the judgment conditions, and if misjudgment occurs in the low-power electricity utilization environment of a user, the actual electric energy of the user is accumulated and removed, so that metering errors are caused. Meanwhile, the scheme is only aimed at a power frequency magnetic field of 0.5mt, and errors introduced by a strong alternating current magnetic field environment cannot be avoided.
Disclosure of Invention
The invention provides an anti-interference circuit and method under an alternating magnetic field of a three-phase three-wire electric energy meter, and aims to: interference under different alternating current magnetic fields is dealt with, and meanwhile the influence of anti-interference measures on metering precision is avoided.
The technical scheme of the invention is as follows:
the anti-interference circuit of the three-phase three-wire electric energy meter under the alternating current magnetic field comprises a sampling element part, a signal conversion and filtering circuit part and a metering part, wherein the sampling element part comprises an A-phase sampling element and a C-phase sampling element, and the signal conversion and filtering circuit part comprises an A-phase conversion and filtering circuit and a C-phase conversion and filtering circuit; the output end of the phase A sampling element is connected with the input end of the phase A phase conversion and filtering circuit, and the output end of the phase A phase conversion and filtering circuit is connected with the phase A input end of the metering part; the output end of the C-phase sampling element is connected with the input end of the C-phase converting and filtering circuit, the output end of the C-phase converting and filtering circuit is connected with the C-phase input end of the metering part, the signal converting and filtering circuit part also comprises a B-phase converting and filtering circuit, the input end of the B-phase converting and filtering circuit is suspended, and the output end of the B-phase converting and filtering circuit is connected with the B-phase input end of the metering part.
As the further improvement of the anti-interference circuit under the alternating-current magnetic field of the three-phase three-wire electric energy meter: the sampling element is connected with the signal conversion and filtering circuit and the signal conversion and filtering circuit is connected with the metering element through twisted pair wires.
As the further improvement of the anti-interference circuit under the alternating-current magnetic field of the three-phase three-wire electric energy meter: the B-phase signal converting and filtering circuit is located in the middle of the a-phase signal converting and filtering circuit and the C-phase signal converting and filtering circuit.
As the further improvement of the anti-interference circuit under the alternating-current magnetic field of the three-phase three-wire electric energy meter: the B-phase signal conversion and filtering circuit is identical to the layout structure of the a-phase signal conversion and filtering circuit and the C-phase signal conversion and filtering circuit.
The invention also provides a method based on the anti-interference circuit under the alternating-current magnetic field of the three-phase three-wire electric energy meter, which comprises the following steps: when calculating power, calculating an initial calculation value P of the power through voltage and current acquired by an electric energy meter 0 Then according to the induction current obtained from the B phase input end of the metering partAnd the voltage value acquired by the electric energy meter to calculate the compensation power P 1 Will P 0 And P 1 The sum is used as the final calculated value of the power.
As a further improvement of the method: compensating powerWhereinFor the voltage between phase A and phase B +.>Is the voltage between the C phase and the B phase.
Compared with the prior art, the invention has the following beneficial effects: (1) The invention collects the induction current generated by the alternating magnetic field through the B-phase signal conversion and filtering circuit with the suspended input end, and then calculates the compensation value by utilizing the induction current, thereby eliminating the interference of the alternating magnetic field environment on the power measurement; (2) The invention is simple and reliable, is easy to realize, does not introduce new metering errors, and has good stability and high reliability; (3) The invention adopts the twisted pair for connection, and compared with the traditional mode shown in fig. 2, the effective induction area of the connecting wire in the alternating magnetic field can be made to approach zero, and the metering error of the connecting part under the effect of magnetic field interference is avoided.
Drawings
FIG. 1 is a schematic diagram of a current sampling loop of the present invention;
fig. 2 is a schematic diagram of a conventional current sampling loop.
In the figure:
1. a sampling element portion; 2. a signal conversion and filtering circuit section; 3. a metering section; 4. b phase signal conversion and filtering circuit.
Ai+, AI-are the a-phase current sampling signals (i.e. a-phase current) Positive and negative terminals of (a);
CI+ and CI-are C-phase current sampling signals (i.e., C-phase current) Positive and negative terminals of (a);
UAI+ and UAI-are A phase current sampling signals respectivelyAnd the magnetic field generates A-phase induction current in A-phase part of the signal conversion and filtering circuit>The sum is converted into a voltage signal (for representing +.>Size of (d) positive and negative terminals;
UBI+、UBI-induced current signals acquired for phase B respectively (i.eSize of (d) positive and negative terminals;
UCI+ and UCI-are C-phase current sampling signals respectivelyAnd C-phase induced current generated by the magnetic field in the C-phase part of the signal conversion and filtering circuit +.>The sum is converted into a voltage signal (for representing +.>Size of (d) and negative ends.
Detailed Description
The technical scheme of the invention is described in detail below with reference to the accompanying drawings:
for a three-phase three-wire electric energy meter, only the current of the A phase and the current of the C phase and the voltage between the A phase and the B phase are detected in normal meteringVoltage between C and B phases->。
As shown in fig. 2, a current sampling circuit of a conventional three-phase three-wire electric energy meter comprises a sampling element part 1, a signal conversion and filtering circuit part 2 and a metering part 3. The sampling element section 1 includes an a-phase sampling element and a C-phase sampling element, and the signal converting and filtering circuit section 2 includes an a-phase signal converting and filtering circuit and a C-phase signal converting and filtering circuit. The output end of the phase A sampling element is connected with the input end of the phase A phase conversion and filtering circuit, and the output end of the phase A phase conversion and filtering circuit is connected with the phase A input end of the metering part 3; the output end of the C-phase sampling element is connected with the input end of the C-phase converting and filtering circuit, and the output end of the C-phase converting and filtering circuit is connected with the C-phase input end of the metering part 3.
Under the influence of no alternating-current magnetic field, the electric energy metering formula is as follows:. Wherein->For the voltage between phase A and phase B +.>For the voltage between C and B phases, +.>For phase A current, +.>Is the C phase current.
However, if induced current of A phase and C phase is introduced in the AC magnetic field environment, the induced current of A phase is expressed asThe induced current of phase C is noted +.>. Therefore, the power value measured by the three-phase three-wire electric energy meter in the alternating-current magnetic field environment is actually: />。
To solve the above problems, as shown in fig. 2, the present embodiment adds a B-phase signal converting and filtering circuit 4 to the signal converting and filtering circuit portion 2, the input terminal of the B-phase signal converting and filtering circuit 4 is suspended, and the output terminal is connected to the B-phase input terminal of the measured portion 3.
Preferably, the B-phase signal converting and filtering circuit 4 is located in the middle of the a-phase signal converting and filtering circuit and the C-phase signal converting and filtering circuit.
Preferably, the B-phase signal converting and filtering circuit 4 is identical to the layout structure of the a-phase signal converting and filtering circuit and the C-phase signal converting and filtering circuit.
Since the a phase (including the resistors AR1 and AR2 used for signal conversion, the resistors AR3 and AR4 of the signal filter circuit, and the capacitors AC1, AC2 and AC3 of the signal filter circuit), the B phase (including the resistors BR1 and BR2 used for signal conversion, the resistors BR3 and BR4 of the signal filter circuit, and the capacitors BC1, BC2 and BC3 of the signal filter circuit), and the C phase (including the resistors CR1 and CR2 used for signal conversion, the resistors CR3 and CR4 of the signal filter circuit, and the capacitors CC1, CC2 and CC3 of the signal filter circuit) adopt the same layout structure, the three-phase induced current signals introduced by the signal conversion and the filter circuit are the same, namely:. Meanwhile, since the B-phase signal converting and filtering circuit 4 has no input, the signal received by the B-phase input terminal of the metering section 3 contains only the induced current +.>。
Meanwhile, the sampling element is connected with the signal conversion and filtering circuit and the signal conversion and filtering circuit is connected with the metering element through twisted pair, so that the effective induction area of the connecting part in the alternating magnetic field is as close to zero as possible, and the interference of the alternating magnetic field introduced from the connecting part is reduced.
After improvement, when calculating power, the initial calculated value P of the power is calculated by the voltage and the current acquired by the electric energy meter 0 (procedure as described above) and then based on the induced current obtained at the B-phase input of metering section 3And the voltage value acquired by the electric energy meter to calculate the compensation power: />。
Will P 0 And P 1 The sum is taken as the final calculated value of the power:。
therefore, the compensation power is calculated by using the induced current, and then the original measured power value is compensated and corrected, so that the obtained power value is consistent with the power value under the influence of the AC magnetic field, and the metering error introduced by the electric energy meter under the AC magnetic field environment can be completely avoided.
Claims (2)
1. The anti-interference circuit of the three-phase three-wire electric energy meter under the alternating current magnetic field comprises a sampling element part (1), a signal conversion and filtering circuit part (2) and a metering part (3), wherein the sampling element part (1) comprises an A-phase sampling element and a C-phase sampling element, and the signal conversion and filtering circuit part (2) comprises an A-phase signal conversion and filtering circuit and a C-phase signal conversion and filtering circuit; the output end of the phase A sampling element is connected with the input end of the phase A phase conversion and filtering circuit, and the output end of the phase A phase conversion and filtering circuit is connected with the phase A input end of the metering part (3); the output end of the C-phase sampling element is connected with the input end of the C-phase conversion and filtering circuit, and the output end of the C-phase conversion and filtering circuit is connected with the C-phase input end of the metering part (3), and the C-phase sampling element is characterized in that: the signal conversion and filtering circuit part (2) further comprises a B-phase signal conversion and filtering circuit (4), wherein the input end of the B-phase signal conversion and filtering circuit (4) is suspended, and the output end of the B-phase signal conversion and filtering circuit is connected with the B-phase input end of the measured part (3);
the phase B conversion and filtering circuit (4) is positioned in the middle of the phase A conversion and filtering circuit and the phase C conversion and filtering circuit;
the phase B signal converting and filtering circuit (4) is identical to the phase A signal converting and filtering circuit and the phase C signal converting and filtering circuit in the layout and layout structure, so that the three-phase induction current signals introduced by the signal converting and filtering circuit in the alternating magnetic field environment are identical,the method comprises the steps of carrying out a first treatment on the surface of the Meanwhile, since the B-phase signal conversion and filtering circuit (4) has no input, the B-phase input of the metering part (3)The received signal contains only the induced current +.>Is marked as->；Induced currents of the A phase, the B phase and the C phase respectively;
when calculating power, the initial calculation value of the power is calculated through the voltage and the current acquired by the electric energy meter；Wherein->For the voltage between phase A and phase B +.>For the voltage between C and B phases, +.>For phase A current, +.>Is C phase current;
then based on the induction current obtained from the B phase input end of the metering part (3)And the voltage value acquired by the electric energy meter to calculate the compensation power +.>Will->And->The sum is taken as the final calculated value of the power;
compensating power。
2. The anti-interference circuit of the three-phase three-wire electric energy meter under the alternating magnetic field is characterized in that: the sampling element is connected with the signal conversion and filtering circuit and the signal conversion and filtering circuit is connected with the metering part through twisted pair wires.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310498946.4A CN116223903B (en) | 2023-05-06 | 2023-05-06 | Anti-interference circuit and method for three-phase three-wire electric energy meter under alternating current magnetic field |
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| CN202310498946.4A CN116223903B (en) | 2023-05-06 | 2023-05-06 | Anti-interference circuit and method for three-phase three-wire electric energy meter under alternating current magnetic field |
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| CN116223903B true CN116223903B (en) | 2023-09-19 |
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