CN111830297B - Anti-interference method of electric energy meter under 0.5mT power frequency magnetic field - Google Patents
Anti-interference method of electric energy meter under 0.5mT power frequency magnetic field Download PDFInfo
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- CN111830297B CN111830297B CN202010504739.1A CN202010504739A CN111830297B CN 111830297 B CN111830297 B CN 111830297B CN 202010504739 A CN202010504739 A CN 202010504739A CN 111830297 B CN111830297 B CN 111830297B
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Abstract
The invention discloses an anti-interference method of an electric energy meter under a 0.5mT power frequency magnetic field, which 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 power frequency magnetic field state of the last statistical period according to the power sampled in the last statistical period, and entering the step 7 if the power frequency magnetic field state is judged to be in; 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.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to an anti-interference method of an electric energy meter under a 0.5mT power frequency magnetic field.
Background
With the rapid development of economy, the automation and intelligence of production and life are increasingly relied on, and the demand for electric power is not kept away. The scale of the power terminals as a ring of grid terminals is also continuously expanding. And an electric energy meter is a very important power terminal.
The new standard of single-phase intelligent electric energy meter technical Specification in 2013 of national network has no load requirement on a 0.5mT power frequency magnetic field: the electric energy meter is in a working state, the current circuit has no current, the electric energy meter is placed in the interference of a 0.5mT power frequency magnetic field, and the test output of the electric energy meter does not generate more than one pulse. In the design of high-precision equipment such as an electric energy meter, since the sampling of an electric energy signal is accurate to millivolt level, a small magnetic field fluctuation can also cause the measurement misalignment, so that the magnetic field must be studied deeply to shield the interference.
The existing magnetic field shielding mode mainly starts from the aspect of manganese copper sampling, and has two modes: 1) Changing the welding position of the sampling signal wire to make the induction voltages cancel each other; 2) Changing the winding mode of the sampling signal wires, wherein under the condition that the two signal wires are not wound tightly, gaps are formed between the wires, when the electric energy meter is in a magnetic field environment, the magnetic induction wires pass through the gaps between the two wires, induced voltage can appear on the wires, and the sampling signals are interfered; after the two wires are wound tightly, gaps between the wires can be ignored, the induced voltage is greatly reduced, and the error stability of the electric energy meter is improved. An anti-interference intelligent electric energy meter disclosed in Chinese patent with application number 201310008166.3 or a manganese-copper shunt disclosed in Chinese patent with application number 201810282319.6.
In the above manner, in the case of the electric power of more than 10w, the influence of the magnetic field induction is substantially negligible. The starting current of the single-phase electric energy meter is 0.4% Ib (according to the technical specification of the intelligent electric energy meter of the south China network, the Ib current is 5A, the reference voltage is 220V, and the starting power is 4.4 w). Under the condition of small current, the magnetic field induction risk exists, so that the situations of larger error deviation and the like are caused, and even under the condition that residents do not use electricity, the electric energy meter Mo Ming is also caused to walk due to the magneto-electric induction principle, thereby influencing normal use and injuring benefits of users.
Disclosure of Invention
The invention aims to solve the technical problem of providing an anti-interference method of an electric energy meter under a 0.5mT power frequency magnetic field, which can conveniently detect magnetic field induction and shield, and avoid metering errors.
The technical scheme adopted for solving the technical problems is as follows: a method for preventing interference of an electric energy meter under a 0.5mT power frequency magnetic field is characterized by comprising the following steps: the method comprises the following steps:
1) Initializing power-on, and after the electric energy meter is powered on, opening a power frequency magnetic field judgment shielding by default;
2) Sampling the output power of the metering part of the electric energy meter, if the power is larger than a first preset value, entering the step 3), otherwise, entering the step 4);
3) Performing a conventional metering function, returning to step 2);
4) Comparing the sampled power with a second preset value, wherein the second preset value is smaller than the first preset value, if the sampled power is continuously sampled for N times to be smaller than the second preset value, entering a step 5), otherwise, repeating the step; n is a preset fault tolerance value;
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, judging the sampling times in the last counting period after each counting period is finished, if the sampling times are smaller than N', not judging the power frequency magnetic field, repeating the step, otherwise, entering the step 6); n' is the preset minimum sampling times;
6) Judging the power frequency magnetic field state of the last statistical period according to the power sampled in the last statistical period, judging whether the ratio of the power smaller than a second preset value is larger than the preset ratio, if so, indicating that the power fluctuates in the last statistical period, preliminarily judging that the power is in the power frequency magnetic field state, and entering the step 7); if not, the power does not fluctuate in the last statistical period, and the step returns to the step 5);
7) And shielding the current pulse signal in the last statistical period when the electric energy meter is in the power frequency magnetic field state, and not counting the effective electric energy value.
Preferably, in step 5), one minute is taken as one statistical period.
Preferably, in order to ensure a normal metering of the effective electrical energy, in step 5) the sampled power is simultaneously compared in real time with a first preset value, and once it is greater than the first preset value, the process returns to step 3).
Preferably, in step 6), it is determined whether the ratio of the power smaller than the second preset value is greater than a preset ratio, that is, whether the number of powers smaller than the second preset value is greater than a certain value in the power values sampled in one statistical period, where the ratio is a ratio of the number of powers smaller than the preset value to the sampling number.
Preferably, in order to avoid erroneous judgment caused by power sampling only, a magneto-resistance sampling circuit is arranged in the electric energy meter, and whether the electric energy meter is in a power frequency magnetic field state is further confirmed by sampling the voltage of the magneto-resistance.
Preferably, the magneto-resistance sampling circuit comprises a first resistor and a second resistor, wherein the first resistor is a magneto-resistance, one end of the first resistor is grounded, the other end of the first resistor is connected with one end of the second resistor, and the other end of the second resistor is connected to a power supply.
Preferably, the accuracy of the power frequency magnetic field judgment is ensured, when the step 6) preliminarily judges that the power frequency magnetic field state is in the power frequency magnetic field state and enters the step 7), the voltage values at two ends of the first resistor are sampled, then whether the voltage values are larger than a voltage preset value is judged, whether the current magnetic field environment is further confirmed, if so, the current magnetic field environment is indicated to be in the power frequency magnetic field state, and the step 7) is entered; if not, the power frequency magnetic field state is not displayed, and the step 5 is returned.
Further, in step 7), the electric energy meter records related event records simultaneously, including the time of entering the power frequency magnetic field state, the time of exiting the power frequency magnetic field state and the number of rate pulses in the process of the power frequency magnetic field state.
Further, the electric energy meter transmits the relevant records to an electricity consumption information acquisition system through a communication channel, and the electricity consumption information acquisition system reads the power frequency magnetic field event monitored by the electric energy meter through the communication channel, positions the fault electric energy meter and eliminates the fault.
The communication channel is a carrier wave, RS485, infrared or wireless module.
Compared with the prior art, the invention has the advantages that: judging whether the sampling power is in a power frequency magnetic field state or not by judging the sampling power, shielding pulse signals generated in the power frequency magnetic field state, and not counting effective electric energy values, so that normal use is prevented from being influenced, and benefits of users are injured; the electromagnetic field environment monitoring and data transmission for users can be realized, and the electricity consumption condition of the electric energy meter can be timely, quickly and accurately fed back; meanwhile, the accuracy of judging the state of the power frequency magnetic field is further ensured through a magneto-resistance sampling circuit; the abnormal state of the user site can be timely and quickly obtained and timely processed; the system has complete power frequency event record and can trace electric quantity data according to rate pulses.
Drawings
FIG. 1 is a block diagram of a magnetic field monitoring system employed in the method of the present invention;
FIG. 2 is a graph of one minute sample data reference changes in the ambient power of a 0.5mT magnetic field;
FIG. 3 is a schematic diagram of a magneto-resistive sampling circuit employed in the method of the present invention;
fig. 4 is a flow chart of the method of the present invention.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
Referring to fig. 1, the invention is to protect a method for preventing interference under a power frequency magnetic field of 0.5mT of an electric energy meter, wherein a magnetic field monitoring system is formed by using the electric energy meter 1, a communication channel 2 and an electricity consumption information acquisition system 3, and all components of the magnetic field monitoring system are in the prior art, wherein the communication channel 2 mainly comprises: carrier wave, RS485, infrared, wireless modules, etc. In order to ensure the accuracy of magnetic field monitoring, a magneto resistor sampling circuit is further arranged in the electric energy meter 1 (on the main control circuit board), see fig. 3, and the magneto resistor sampling circuit comprises a first resistor RM1 and a second resistor 101, wherein the first resistor RM1 is a magneto resistor, one end of the first resistor RM1 is grounded, the other end of the first resistor RM1 is connected with one end of the second resistor 101, the other end of the second resistor 101 is connected to a power supply VCC, and voltages at two ends of the first resistor RM1 are sampled through an ADC. The existence of the power frequency magnetic field is judged through the power monitoring of the electric energy meter 1 and the voltage monitoring of the magneto resistor.
The principle of the invention is that through researching the 0.5mT power frequency magnetic field environment, under the condition of 220V reference voltage and no current, the influence of magnetic field induction signals can be directly reflected on the output power effective value data of the metering chip of the electric energy meter 1, the statistics is carried out according to one minute, the fluctuation condition of power can be seen in fig. 2, wherein the abscissa is time, and the ordinate is power.
According to the national south network technical specification, the starting power of the single-phase intelligent electric energy meter is 4.4W, and the internal anti-submarine setting of the conventional metering chip is 70% of the starting power in consideration of factors such as the precision of the metering chip, namely, less than 3W is not accumulated in the electric energy register of the metering chip. In the 0.5mT magnetic field environment, the power fluctuates, and part of energy is accumulated and counted into the electric energy register of the metering chip, and when the accumulated electric energy reaches a certain value, the phenomenon of pulse character-moving at the electric energy meter is caused.
The normal starting test shows that the power value represented by the electric energy meter is basically stable at about 4.4w and has larger difference with the power fluctuation under the magnetic field environment of 0.5mT, so that the electricity utilization environment of the electric energy meter can be identified.
The anti-interference method of the invention comprises the following steps:
1) After the electric energy meter 1 is electrified, the power frequency magnetic field judgment shielding is started by default, small signal current, power and pulse are shielded, current impact in the electrifying process is prevented, and the power frequency magnetic field judgment flow is entered prematurely;
2) Sampling the output power (such as 1 second for 1 time) of the metering part of the electric energy meter 1, if the power is larger than a first preset value, such as 10W, entering the step 3), otherwise, entering the step 4);
3) Perform conventional metering functions: storing the sampled power as effective power, and obtaining an effective electric energy value through accumulation; returning to step 2);
4) Comparing the sampled power with a second preset value, such as 3W, wherein the second preset value is smaller than the first preset value, if the sampled power is continuously sampled for N times to be smaller than the second preset value, entering the step 5), otherwise, repeating the step; n is a preset fault tolerance value and can be a natural number greater than or equal to 1;
5) The method comprises the steps of entering a power frequency magnetic field judging process, sampling voltage and current power data of the electric energy meter 1 every second, taking one minute as a statistical period, firstly judging the sampling times in the last statistical period after each statistical period is finished, if the sampling times are smaller than N', not judging the power frequency magnetic field, repeating the step, otherwise entering the step 6); n' is a preset minimum sampling number, which is a natural number not greater than 60, and in this embodiment, is preferably 20; this is because the timing of sampling is constant every minute when sampling is performed after power-up, and the time for entering the sampling is variable, and sampling may be performed by inserting from 58s, which is one minute, so that the sampling times in the statistics period are too small, errors are easily caused, statistical significance is lost, and statistics is not performed; in the step, the sampled power is simultaneously compared with a first preset value in real time, and once the sampled power is larger than the first preset value, the step returns to the step 3);
6) Judging the power frequency magnetic field state of the last statistical period according to the power sampled in the last statistical period, judging whether the ratio of the power smaller than a second preset value is larger than a preset ratio, namely, whether the number of the powers smaller than the second preset value is larger than a certain value in the power values sampled in one minute, wherein the ratio is the ratio of the number of the powers smaller than the preset value to the sampling times, if the ratio is preferably 80%, if the ratio is the ratio, the power is expressed to have fluctuation in the last minute, namely, the power is primarily judged to be in the power frequency magnetic field state, and then the step 7 is entered; if not, the power does not fluctuate in the last minute, and the step returns to the step 5);
7) Sampling voltage values at two ends of the first resistor RM1 through an ADC, judging whether the voltage value is larger than a voltage preset value, further confirming whether the current magnetic field environment exists or not, if so, indicating that the current magnetic field environment exists in a power frequency magnetic field state, and entering step 8); if not, the state is not in the power frequency magnetic field state, and the step 5) is returned;
8) Shielding the current pulse signal in the last statistical period under the power frequency magnetic field state of the electric energy meter 1, not counting the effective electric energy value, and simultaneously recording related event records, including state entering time and exiting time, and the rate pulse number in the process; the relevant records are transmitted to an electricity consumption information acquisition system 3 through a communication channel 2;
9) The electricity consumption information acquisition system 3 reads the power frequency magnetic field event monitored by the electric energy meter 1 through the communication channel 2, positions the fault electric energy meter 1, and removes the fault, namely, timely maintains and corrects the abnormality.
When the state of entering the power frequency magnetic field is determined, the electric energy meter 1 and the electricity acquisition system 3 realize data interaction through the communication channel 2, and abnormal events and alarm signals detected by the electric energy meter 1 on site can be transmitted to the electricity acquisition system 3 in real time.
In the above process, the default electric energy meter 1 is in the power frequency strong magnetic prevention state.
Claims (10)
1. A method for preventing interference of an electric energy meter under a 0.5mT power frequency magnetic field is characterized by comprising the following steps: the method comprises the following steps:
1) Initializing power-on, and after the electric energy meter (1) is powered on, opening a power frequency magnetic field judgment shielding by default;
2) Sampling the output power of the metering part of the electric energy meter (1), if the power is larger than a first preset value, entering the step 3), otherwise, entering the step 4);
3) Performing a conventional metering function, returning to step 2);
4) Comparing the sampled power with a second preset value, wherein the second preset value is smaller than the first preset value, if the sampled power is continuously sampled for N times to be smaller than the second preset value, entering a step 5), otherwise, repeating the step; n is a preset fault tolerance value;
5) Entering a power frequency magnetic field judging process, sampling voltage and current power data of the electric energy meter (1) every second, setting a statistical period, firstly judging the sampling times in the last statistical period after each statistical period is finished, if the sampling times are smaller than N', not judging the power frequency magnetic field, repeating the step, otherwise, entering the step 6); n' is the preset minimum sampling times;
6) Judging the power frequency magnetic field state of the last statistical period according to the power sampled in the last statistical period, judging whether the ratio of the power smaller than a second preset value is larger than the preset ratio, if so, indicating that the power fluctuates in the last statistical period, preliminarily judging that the power is in the power frequency magnetic field state, and entering the step 7); if not, the power does not fluctuate in the last statistical period, and the step returns to the step 5);
7) And shielding the current pulse signal in the last statistical period when the electric energy meter (1) is in the power frequency magnetic field state, and not counting the effective electric energy value.
2. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 1, wherein the method is characterized by comprising the following steps: in step 5), one minute is taken as one statistical period.
3. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 1, wherein the method is characterized by comprising the following steps: in step 5), the sampled power is simultaneously compared in real time with a first preset value, and once it is greater than the first preset value, the process returns to step 3).
4. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 1, wherein the method is characterized by comprising the following steps: in step 6), it is determined whether the ratio of the power smaller than the second preset value is greater than a preset ratio, that is, whether the number of powers smaller than the second preset value is greater than a certain value in the power values sampled in one statistical period, where the ratio is a ratio of the number of powers smaller than the preset value to the sampling number.
5. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 1, wherein the method is characterized by comprising the following steps: a magneto-resistance sampling circuit is arranged in the electric energy meter (1), and whether the electric energy meter is in a power frequency magnetic field state is further confirmed by sampling the voltage of the magneto-resistance.
6. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 5, wherein the method is characterized by comprising the following steps: the magneto-resistance sampling circuit comprises a first resistor (RM 1) and a second resistor (101), wherein the first resistor (RM 1) is a magneto-resistance, one end of the first resistor (RM 1) is grounded, the other end of the first resistor is connected with one end of the second resistor (101), and the other end of the second resistor (101) is connected to a power supply (VCC).
7. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 5, wherein the method is characterized by comprising the following steps: when the step 6) preliminarily judges that the power frequency magnetic field state is in the power frequency magnetic field state and enters the step 7), sampling the voltage values at two ends of the first resistor (RM 1), judging whether the voltage value is larger than a voltage preset value or not, further confirming whether the current magnetic field environment is present or not, if so, indicating that the current magnetic field state is in the power frequency magnetic field state, and entering the step 7); if not, the power frequency magnetic field state is not displayed, and the step 5 is returned.
8. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 1, wherein the method is characterized by comprising the following steps: in the step 7), the electric energy meter (1) records related event records simultaneously, wherein the event records comprise the entering time and the exiting time of the power frequency magnetic field state and the rate pulse number in the process of the power frequency magnetic field state.
9. The method for preventing interference under the power frequency magnetic field of 0.5mT of the electric energy meter according to claim 8, wherein the method is characterized by comprising the following steps: the electric energy meter (1) transmits relevant records to the electricity consumption information acquisition system (3) through the communication channel (2), and the electricity consumption information acquisition system (3) reads the power frequency magnetic field event monitored by the electric energy meter (1) through the communication channel (2), positions the fault electric energy meter (1) and eliminates faults.
10. The method for preventing interference of the electric energy meter under the power frequency magnetic field of 0.5mT according to claim 9, wherein the method is characterized by comprising the following steps: the communication channel (2) is a carrier wave, RS485 or wireless module.
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| CN102830255A (en) * | 2012-08-23 | 2012-12-19 | 王金泽 | Smart electricity meter with function of monitoring and protecting power failure |
| CN103698564A (en) * | 2013-12-26 | 2014-04-02 | 华立仪表集团股份有限公司 | Method for preventing power frequency magnetic field startup of PCBs (Printed Circuit Boards) of electricity meter |
| CN109001997A (en) * | 2018-07-13 | 2018-12-14 | 安徽云图信息技术有限公司 | A kind of anti-tampering environment information acquisition system |
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