CN114966518A - Method and device for testing influence of harmonic content and frequency fluctuation on metering error of intelligent electric meter - Google Patents
Method and device for testing influence of harmonic content and frequency fluctuation on metering error of intelligent electric meter Download PDFInfo
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Abstract
The invention discloses a method and a device for testing the influence of harmonic content and frequency fluctuation on the metering error of an intelligent ammeter, the method comprises the steps of firstly measuring to obtain the maximum initial inherent error of the electric energy meter to be tested under the condition of pure fundamental wave signal input, then respectively measuring to obtain the maximum metering error of the electric energy meter to be tested in a harmonic input experiment and a frequency fluctuation experiment, finally comprehensively calculating to obtain the maximum comprehensive error of the electric energy meter to be tested based on the maximum initial inherent error, the maximum metering error of the electric energy meter to be tested in the harmonic input experiment and the frequency fluctuation experiment, firstly, independently calculating the maximum metering error of the electric energy meter to be tested in the harmonic input experiment and the frequency fluctuation experiment, and then comprehensively calculating to obtain the maximum comprehensive error of the electric energy meter to be tested by adopting two maximum metering error results which are independently calculated, thereby effectively reducing the experiment workload, improving the experiment efficiency, and accurately analyzing the influence of the harmonic content and the frequency fluctuation on the metering error of the intelligent ammeter.
Description
Technical Field
The invention relates to the technical field of electric meter measurement, in particular to a method and a device for testing influences of harmonic content and frequency fluctuation on a measurement error of an intelligent electric meter.
Background
The intelligent electric meter is used as the most key and important power utilization information acquisition equipment of a power utilization information acquisition system, the power utilization is tightly connected with the intelligent power grid through a modern information transmission technology, and the intelligent electric meter is an important link for information interaction between a power supply party and the power utilization and an important basis for ensuring accurate measurement of electric energy of the intelligent power grid. In the face of huge power consumption and intelligent electric meter usage at present, the accuracy of electric meter metering is very important, and any tiny error can bring about huge economic loss. The development of power electronic technology and its wide application in industry, including the application of high-power rectifier in electrified railway and the application of arc furnace in steelmaking, will produce a large amount of harmonics, when the input signal contains the harmonics, the operating condition of each voltage, current transformer and electric energy metering chip in the smart electric meter will shift, thus make the electric energy meter that should measure correctly originally produce the error.
In addition, the running environment of the electric energy meter is complex and various, and the reasons for the electric energy meter to generate metering errors are also many, and the method can be roughly divided into two aspects, namely external factors and internal factors of the electric energy meter. The external factors include the working environment of the electric energy meter, such as temperature, humidity, air pressure and the like, and the characteristics of the externally input load, and the external factors may cause errors of the electric energy meter; the internal factors mainly comprise the component precision of the electric energy meter, an electric energy measurement algorithm and the like. The currently researched influence of the error of the electric energy meter is mainly concentrated on the research of the influence of the external environment, load distortion and the component precision of the intelligent electric meter on the intelligent electric meter, but the research on the testing device and method of the metering error of the intelligent electric meter under the dynamic load condition is still deficient, the current research on the influence of harmonic content and frequency fluctuation on the metering error of the intelligent electric meter is not carried out deeply, and the method and the device for testing the metering error under the steady state condition cannot meet the requirements.
Disclosure of Invention
The invention provides a method and a device for testing the influence of harmonic content and frequency fluctuation on the metering error of a smart meter, and aims to solve the technical problem that the influence of the harmonic content and the frequency fluctuation on the metering error of the smart meter cannot be measured in the prior art.
According to one aspect of the invention, a method for testing the influence of harmonic content and frequency fluctuation on the metering error of a smart meter is provided, which comprises the following steps:
inputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter, and measuring to obtain the maximum initial inherent error of the detected electric energy meter;
simultaneously inputting fundamental wave signals and different harmonic wave signals to the standard electric energy meter and the detected electric energy meter, and measuring to obtain a first maximum metering error of the detected electric energy meter;
only changing the frequency of the fundamental wave signal and measuring to obtain a second maximum metering error of the detected electric energy meter;
and calculating to obtain the maximum comprehensive error of the detected electric energy meter based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the detected electric energy meter.
Further, the process of inputting only the fundamental wave signal to the standard electric energy meter and the detected electric energy meter and measuring the maximum initial inherent error of the detected electric energy meter specifically includes:
setting experiment conditions, outputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter to carry out multiple experiments, measuring the electric energy values of the standard electric energy meter and the detected electric energy meter in each experiment, calculating to obtain the initial inherent error of the detected electric energy meter in a single experiment, and taking the maximum value from multiple initial inherent errors obtained from multiple experiment results as the maximum initial inherent error of the detected electric energy meter.
Further, the process of simultaneously inputting the fundamental wave signal and the different harmonic wave signals to the standard electric energy meter and the detected electric energy meter and measuring the first maximum metering error of the detected electric energy meter includes the following steps:
inputting a plurality of single harmonic signals based on different harmonic times and harmonic contents;
respectively synthesizing the fundamental wave signal and the single harmonic signals into a plurality of test signals one by one, and respectively outputting the test signals to the tested electric energy meter and the standard electric energy meter in a full-wave mode to test one by one;
recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a first metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
and taking the maximum value from a plurality of first metering error results obtained from multiple tests as the first maximum metering error of the detected electric energy meter in the harmonic experiment.
Further, the process of changing only the frequency of the fundamental wave signal and measuring the second maximum metering error of the detected electric energy meter includes the following steps:
setting a frequency fluctuation range and a fluctuation interval of the fundamental wave signal to generate a plurality of test signals with different frequency values;
respectively outputting a plurality of test signals with different frequency values to the tested electric energy meter and the standard electric energy meter for testing one by one;
recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a second metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
and taking the maximum value from a plurality of second metering error results obtained from the plurality of tests as the second maximum metering error of the detected electric energy meter in the frequency fluctuation experiment.
Further, the maximum comprehensive error of the detected electric energy meter is calculated by adopting the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electric energy meter to be tested, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
In addition, the invention also provides a device for testing the influence of harmonic content and frequency fluctuation on the metering error of the intelligent electric meter, which comprises a program-controlled power supply, a computer, a standard electric energy meter, an error calculator, a tested electric energy meter and a harmonic generator, wherein the computer is used for controlling the working states of the program-controlled power supply, the harmonic generator and the error calculator, the program-controlled power supply is used for outputting fundamental wave signals to the standard electric energy meter and the tested electric energy meter, the harmonic generator is used for outputting different harmonic signals to the standard electric energy meter and the tested electric energy meter, the error calculator is used for measuring the electric energy values of the tested electric energy meter and the standard electric energy meter in a pulse counting mode, the maximum initial inherent error of the tested electric energy meter is measured when only the fundamental wave signals are input to the standard electric energy meter and the tested electric energy meter, and the first maximum metering error of the tested electric energy meter is measured when the fundamental wave signals and different harmonic signals are simultaneously input to the standard electric energy meter and the tested electric energy meter And measuring to obtain a second maximum metering error of the detected electric energy meter when only the frequency of the fundamental wave signal is changed, and calculating to obtain a maximum comprehensive error of the detected electric energy meter based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the detected electric energy meter.
Further, the computer only controls the programmable power supply to output fundamental wave signals to the standard electric energy meter and the detected electric energy meter to carry out multiple experiments, the error calculator measures the electric energy values of the standard electric energy meter and the detected electric energy meter in each experiment, calculates initial inherent errors of the detected electric energy meter in a single experiment, and takes the maximum value of multiple initial inherent errors obtained from multiple experiment results as the maximum initial inherent error of the detected electric energy meter.
Further, the computer controls the harmonic generator to generate a plurality of single harmonic signals based on different harmonic times and harmonic content, and controls the program-controlled power supply to synchronously output the fundamental wave signals, so that the fundamental wave signals and the single harmonic signals are combined into a plurality of test signals one by one, the test signals are respectively output to the tested electric energy meter and the standard electric energy meter in a full-wave mode to be tested one by one, the error calculator records the electric energy values of the tested electric energy meter and the standard electric energy meter obtained in each test, calculates the first metering error of the tested electric energy meter in the test based on the electric energy values of the tested electric energy meter and the standard electric energy meter, and takes the maximum value from a plurality of first metering error results obtained in the tests as the first maximum metering error of the tested electric energy meter in the harmonic experiment.
Further, the computer controls the program-controlled power supply to output shock wave signals with different frequency values and respectively output the shock wave signals to the detected electric energy meter and the standard electric energy meter for one-by-one test, the error calculator records the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, calculates a second metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter, and takes a maximum value from a plurality of second metering error results obtained in multiple tests as a second maximum metering error of the detected electric energy meter in a frequency fluctuation experiment.
Further, the maximum comprehensive error of the detected electric energy meter is calculated by adopting the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electric energy meter to be tested, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
The invention has the following effects:
the method for testing the influence of harmonic content and frequency fluctuation on the metering error of the intelligent ammeter comprises the steps of firstly measuring to obtain the maximum initial inherent error of the tested ammeter under the condition of pure fundamental wave signal input, then the maximum metering errors of the detected electric energy meter in the harmonic input experiment and the frequency fluctuation experiment are respectively measured, finally the maximum comprehensive error of the detected electric energy meter is obtained through comprehensive calculation based on the maximum initial inherent error, the maximum metering errors in the harmonic input experiment and the frequency fluctuation experiment, the maximum comprehensive error of the electric energy meter to be detected is obtained by independently calculating the maximum metering error of the electric energy meter to be detected in a harmonic input experiment and a frequency fluctuation experiment respectively and then comprehensively calculating by adopting two independently calculated maximum metering error results, thereby effectively reducing the experiment workload, improving the experiment efficiency, and the influence of the harmonic content and the frequency fluctuation on the metering error of the intelligent electric meter can be accurately analyzed. More importantly, the method is obtained by analyzing the probability distribution situation of the electric energy metering error caused by harmonic wave change and frequency change in the actual work, the electric energy metering error caused by the harmonic wave change and the frequency change is in rectangular distribution in probability, so that the coefficient 1/3 in the evolution operation in the maximum comprehensive error calculation formula is determined, the influence of the harmonic wave change and the frequency change on the electric energy metering result in the actual work is analyzed to have the symmetry of positive and negative deviation, and in order to ensure the distribution symmetry of the rectangular interval of the maximum comprehensive error calculation result, the factor of 2 times is taken for the evolution operation result in the maximum comprehensive error calculation formula, so that the characteristic of wide confidence interval of the electric energy metering error in the actual work of the electric energy meter is met.
In addition, the device for testing the influence of the harmonic content and the frequency fluctuation on the metering error of the intelligent ammeter has the advantages.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
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 flow chart of a method for testing the influence of harmonic content and frequency fluctuation on the metering error of a smart meter according to a preferred embodiment of the invention.
Fig. 2 is a schematic view of a sub-flow of step S2 in fig. 1.
Fig. 3 is a sub-flowchart of step S3 in fig. 1.
Fig. 4 is a schematic block structure diagram of an apparatus for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter according to the preferred embodiment of the present invention.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.
As shown in fig. 1, a preferred embodiment of the present invention provides a method for testing the influence of harmonic content and frequency fluctuation on the metering error of a smart meter, which includes the following steps:
step S1: inputting fundamental wave signals to a standard electric energy meter and a detected electric energy meter, and measuring to obtain the maximum initial inherent error of the detected electric energy meter;
step S2: simultaneously inputting fundamental wave signals and different harmonic wave signals to the standard electric energy meter and the detected electric energy meter, and measuring to obtain a first maximum metering error of the detected electric energy meter;
step S3: only changing the frequency of the fundamental wave signal and measuring to obtain a second maximum metering error of the detected electric energy meter;
step S4: and calculating to obtain the maximum comprehensive error of the detected electric energy meter based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the detected electric energy meter.
It can be understood that, in the method for testing the influence of the harmonic content and the frequency fluctuation on the metering error of the smart meter in the embodiment, the maximum initial inherent error of the tested smart meter under the condition of pure fundamental wave signal input is firstly measured, then the maximum metering errors of the detected electric energy meter in the harmonic input experiment and the frequency fluctuation experiment are respectively measured, finally the maximum comprehensive error of the detected electric energy meter is obtained through comprehensive calculation based on the maximum initial inherent error, the maximum metering errors in the harmonic input experiment and the frequency fluctuation experiment, the maximum comprehensive error of the electric energy meter to be detected is obtained by independently calculating the maximum metering error of the electric energy meter to be detected in a harmonic input experiment and a frequency fluctuation experiment respectively and then comprehensively calculating by adopting two independently calculated maximum metering error results, thereby effectively reducing the experiment workload, improving the experiment efficiency, and the influence of the harmonic content and the frequency fluctuation on the metering error of the intelligent electric meter can be accurately analyzed.
It can be understood that step S1 specifically includes:
setting experiment conditions, outputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter to carry out multiple experiments, measuring the electric energy values of the standard electric energy meter and the detected electric energy meter in each experiment, calculating to obtain the initial inherent error of the detected electric energy meter in a single experiment, and taking the maximum value from multiple initial inherent errors obtained from multiple experiment results as the maximum initial inherent error of the detected electric energy meter.
Specifically, the environmental conditions such as temperature and humidity of an experiment are set, the voltage value, the current value and the frequency value of a fundamental wave signal are set, a pure sinusoidal voltage and current value standard electric energy meter and a detected electric energy meter are output, the electric energy values of the standard electric energy meter and the detected electric energy meter under the condition of pure fundamental wave input are obtained through testing, the initial inherent error of the detected electric energy meter in the experiment process is obtained through calculation, and then the maximum value is selected from a plurality of initial inherent errors obtained through multiple experiment results to serve as the maximum initial inherent error of the detected electric energy meter. The standard electric energy meter is used as an accuracy standard and is used for comparing with errors of the detected electric energy meter, and the accuracy grade of the standard electric energy meter is higher than that of the detected electric energy meter by at least one grade.
It is understood that, as shown in fig. 2, the step S2 includes the following steps:
step S21: inputting a plurality of single harmonic signals based on different harmonic times and harmonic contents;
step S22: respectively synthesizing the fundamental wave signal and the single harmonic signals into a plurality of test signals one by one, and respectively outputting the test signals to the tested electric energy meter and the standard electric energy meter in a full-wave mode to test one by one;
step S23: recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a first metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
step S24: and taking the maximum value from a plurality of first metering error results obtained from the multiple tests as the first maximum metering error of the detected electric energy meter in the harmonic experiment.
Specifically, the harmonic times and the harmonic content are controlled to input a plurality of single harmonic signals, the harmonic times are 2-15, a plurality of test signals are synthesized in a mode of superposing single harmonic signals by fundamental waves, the test signals are output in a full-wave mode to be tested one by one, the electric energy values of the tested electric energy meter and the standard electric energy meter obtained in each test are recorded, a first metering error of the tested electric energy meter in the test is obtained through calculation based on the electric energy values of the tested electric energy meter and the standard electric energy meter, the maximum value is taken from a plurality of first metering error results obtained through multiple tests and is used as the first maximum metering error of the tested electric energy meter in a harmonic experiment, and therefore the maximum metering error of the tested electric energy meter under the influences of different harmonic times and harmonic contents is obtained through measurement.
It is understood that, as shown in fig. 3, the step S3 includes the following steps:
step S31: setting a frequency fluctuation range and a fluctuation interval of the fundamental wave signal to generate a plurality of test signals with different frequency values;
step S32: respectively outputting a plurality of test signals with different frequency values to the tested electric energy meter and the standard electric energy meter for testing one by one;
step S33: recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a second metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
step S34: and taking the maximum value from a plurality of second metering error results obtained from the plurality of tests as the second maximum metering error of the detected electric energy meter in the frequency fluctuation experiment.
Specifically, the frequency fluctuation range and the fluctuation interval of the fundamental wave signal are set, then the fundamental wave signals with different frequency values are respectively output to the detected electric energy meter and the standard electric energy meter to be tested one by one, at the moment, no harmonic signal is input, the electric energy value of the detected electric energy meter and the electric energy value of the standard electric energy meter obtained in each test are recorded, the second metering error of the detected electric energy meter in the test is obtained through calculation based on the electric energy values of the detected electric energy meter and the standard electric energy meter, the maximum value is taken from a plurality of second metering error results obtained through multiple tests and is used as the second maximum metering error of the detected electric energy meter in the frequency fluctuation experiment, and therefore the maximum metering error of the detected electric energy meter under the influence of different fundamental wave frequencies is obtained through measurement.
It is understood that in steps S1 to S3, the formula for calculating the error based on the electric energy values of the detected electric energy meter and the standard electric energy meter is:
wherein e represents the initial inherent error/the first metering error/the second metering error, w' represents the electric energy value of the detected electric energy meter, and w represents the electric energy value of the standard electric energy meter.
It can be understood that the maximum comprehensive error of the detected electric energy meter is calculated in step S4 by specifically using the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electric energy meter to be tested, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
The method is obtained by analyzing the probability distribution situation of the electric energy metering error caused by harmonic wave change and frequency change in the actual work, the electric energy metering error caused by the harmonic wave change and the frequency change is in rectangular distribution in probability, so that a coefficient 1/3 in the evolution operation in the maximum comprehensive error calculation formula is determined, the influence of the harmonic wave change and the frequency change on the electric energy metering result in the actual work is analyzed to obtain the symmetry of positive and negative deviation, and in order to ensure the distribution symmetry of the rectangular interval of the maximum comprehensive error calculation result, the factor of 2 times is taken for the evolution operation result in the maximum comprehensive error calculation formula, so that the characteristic of wide confidence interval of the electric energy metering error in the actual work of the electric energy meter is met.
In addition, as shown in fig. 4, another embodiment of the present invention further provides an apparatus for testing the influence of harmonic content and frequency fluctuation on the metering error of a smart meter, preferably by using the method as described above, the apparatus includes a programmable power supply, a computer, a standard electric energy meter, an error calculator, a to-be-tested electric energy meter, and an error calculator, the computer is configured to control the operating states of the programmable power supply, the harmonic generator, and the error calculator, the programmable power supply is configured to output a fundamental wave signal to the standard electric energy meter and the to-be-tested electric energy meter, the harmonic generator is configured to output different harmonic signals to the standard electric energy meter and the to-be-tested electric energy meter, the error calculator is configured to measure the electric energy values of the to-be-tested electric energy meter and the standard electric energy meter by means of pulse counting, and measure the maximum initial inherent error, the maximum inherent error, of the to-be-tested electric energy meter, when only the fundamental wave signal is input to the standard electric energy meter and the to-be-tested electric energy meter, The method comprises the steps of measuring a first maximum metering error of the electric energy meter to be detected when a fundamental wave signal and different harmonic signals are simultaneously input into a standard electric energy meter and the electric energy meter to be detected, measuring a second maximum metering error of the electric energy meter to be detected when only the frequency of the fundamental wave signal is changed, and calculating to obtain a maximum comprehensive error of the electric energy meter to be detected based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the electric energy meter to be detected.
It can be understood that, the device for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter in the embodiment first measures the maximum initial inherent error of the tested smart meter under the condition of pure fundamental wave signal input, then the maximum metering errors of the detected electric energy meter in the harmonic input experiment and the frequency fluctuation experiment are respectively measured, finally the maximum comprehensive error of the detected electric energy meter is obtained through comprehensive calculation based on the maximum initial inherent error, the maximum metering errors in the harmonic input experiment and the frequency fluctuation experiment, the maximum comprehensive error of the electric energy meter to be detected is obtained by independently calculating the maximum metering error of the electric energy meter to be detected in a harmonic input experiment and a frequency fluctuation experiment respectively and then comprehensively calculating by adopting two independently calculated maximum metering error results, thereby effectively reducing the experiment workload, improving the experiment efficiency, and the influence of the harmonic content and the frequency fluctuation on the metering error of the intelligent electric meter can be accurately analyzed. More importantly, the method is obtained by analyzing the probability distribution situation of the electric energy metering error caused by harmonic wave change and frequency change in the actual work, the electric energy metering error caused by the harmonic wave change and the frequency change is in rectangular distribution in probability, so that the coefficient 1/3 in the evolution operation in the maximum comprehensive error calculation formula is determined, the influence of the harmonic wave change and the frequency change on the electric energy metering result in the actual work is analyzed to have the symmetry of positive and negative deviation, and in order to ensure the distribution symmetry of the rectangular interval of the maximum comprehensive error calculation result, the factor of 2 times is taken for the evolution operation result in the maximum comprehensive error calculation formula, so that the characteristic of wide confidence interval of the electric energy metering error in the actual work of the electric energy meter is met.
It can be understood that, when the computer controls the programmable power supply to output the fundamental wave signal to the standard electric energy meter and the detected electric energy meter only for multiple experiments, the error calculator measures the electric energy values of the standard electric energy meter and the detected electric energy meter in each experiment, calculates the initial intrinsic error of the detected electric energy meter in a single experiment, and takes the maximum value from multiple initial intrinsic errors obtained from multiple experiment results as the maximum initial intrinsic error of the detected electric energy meter.
The computer controls the harmonic generator to generate a plurality of single harmonic signals based on different harmonic times and harmonic content, and simultaneously controls the program-controlled power supply to synchronously output fundamental wave signals so as to combine the fundamental wave signals with the single harmonic signals one by one into a plurality of test signals, the test signals are respectively output to the tested electric energy meter and the standard electric energy meter to be tested one by one in a full-wave mode, the error calculator records the electric energy values of the tested electric energy meter and the standard electric energy meter obtained in each test, calculates a first metering error of the tested electric energy meter in the test based on the electric energy values of the tested electric energy meter and the standard electric energy meter, and takes a maximum value from a plurality of first metering error results obtained in the multiple tests as a first maximum metering error of the tested electric energy meter in the harmonic experiment.
The computer controls the program control power supply to output shock wave signals with different frequency values and respectively outputs the shock wave signals to the detected electric energy meter and the standard electric energy meter to be tested one by one, the error calculator records the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, a second metering error of the detected electric energy meter in the test is obtained through calculation based on the electric energy values of the detected electric energy meter and the standard electric energy meter, and the maximum value is taken from a plurality of second metering error results obtained through multiple tests as a second maximum metering error of the detected electric energy meter in a frequency fluctuation experiment.
It can be understood that the formula adopted by the error calculator to calculate the error based on the electric energy values of the detected electric energy meter and the standard electric energy meter is as follows:
wherein e represents the initial inherent error/the first metering error/the second metering error, w' represents the electric energy value of the detected electric energy meter, and w represents the electric energy value of the standard electric energy meter.
It can be understood that the error calculator specifically calculates the maximum comprehensive error of the detected electric energy meter by using the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electric energy meter to be tested, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
It can be understood that the invention is obtained by analyzing the probability distribution situation of the electric energy metering error caused by the harmonic wave change and the frequency change in the actual work, the electric energy metering error caused by the harmonic wave change and the frequency change is in rectangular distribution in probability, so that the coefficient 1/3 in the evolution operation in the maximum comprehensive error calculation formula is determined, the influence of the harmonic wave change and the frequency change in the actual work on the electric energy metering result is analyzed to have the symmetry of positive and negative deviation, and in order to ensure the symmetry of the rectangular interval distribution of the maximum comprehensive error calculation result, the factor of 2 times is taken for the evolution operation result in the maximum comprehensive error calculation formula, so as to accord with the characteristic of wide confidence interval of the electric energy metering error in the actual work of the electric energy meter.
Next, a process of testing the apparatus using the above embodiment will be described by way of a specific example.
Step 1: the environmental temperature of the experiment is set to be 25 +/-1 ℃ and the relative humidity is set to be 50 +/-20%. And starting the programmable power supply, supplying the voltage and current for normal operation to each component, and after the equipment is stabilized, setting the effective value of fundamental voltage to be 220V, the effective value of fundamental current to be 20A, the frequency of fundamental wave to be 50Hz and the phase to be 0 degrees. Measuring for three times by adopting a 0.5-grade detected electric energy meter and a standard electric energy meter, and calculating the initial inherent error of the detected electric energy meter when no harmonic wave input and frequency fluctuation exist in the experimental environment, wherein the experimental data are shown in table 1:
TABLE 1 initial intrinsic error of checked electric energy meter measured without harmonic input and frequency fluctuation
| voltage/V | current/A | Fundamental frequency/Hz | Standard power/W | Electric power error/%) |
| 200 | 20 | 50 | 4000 | 0.037 |
| 200 | 20 | 50 | 4000 | 0.058 |
| 200 | 20 | 50 | 4000 | 0.064 |
Thereby obtaining the maximum initial inherent error of the detected electric energy meter to be 0.064%.
Step 2: in accessing the harmonic generator into the circuit, the harmonic number and the output waveform in the harmonic generator are controlled by the computer, the harmonic number of the test is 2-16 by configuring the harmonic generator, the harmonic content is 40% (2) respectively in the test process, 51% (3), 20% (4), 22% (5), 20% (6), 18% (7), 15% (8), 15% (9), 12% (10), 11% (11), 7% (12), 9% (13), 9% (14), 9% (15), 8% (16), and the electric energy meter measurement error experiment of the tested intelligent electric meter under the influence of different harmonic numbers and contents is completed, the experiment data are shown in table 2:
table 2, metering error of detected electric energy meter under different harmonic wave input conditions
| Number of harmonics | Harmonic content | Electric power error/%) | Number of harmonics | Harmonic content | Electric power error/%) |
| 2 | 40％ | 0.1022 | 10 | 12％ | 1.1803 |
| 3 | 51％ | 0.1903 | 11 | 11％ | 1.3666 |
| 4 | 20％ | 0.2709 | 12 | 7％ | 1.5919 |
| 5 | 22％ | 0.3722 | 13 | 9％ | 1.7428 |
| 6 | 20％ | 0.4860 | 14 | 9％ | 2.031 |
| 7 | 18％ | 0.6143 | 15 | 9％ | 2.3021 |
| 8 | 15％ | 0.7503 | 16 | 8％ | 2.5942 |
| 9 | 15％ | 0.9156 |
Therefore, the maximum first metering error of the detected electric energy meter is obtained as follows: 2.5942 percent.
And step 3: the voltage of the test is set to be 220V, the current is 20A, the frequencies are respectively 49.5Hz, 50Hz, 50.5Hz, 51Hz and 51.5Hz, the phases are all 0 degrees, other harmonic content is not input, and the experimental data obtained by calculation are shown in table 3:
table 3, metering error of detected electric energy meter under frequency fluctuation condition
| frequency/Hz | Standard power/W | Error of electric energy |
| 49.5 | 4000 | 0.134％ |
| 50.0 | 4000 | 0.051％ |
| 50.5 | 4000 | 0.127％ |
| 51 | 4000 | 0.132％ |
| 51.5 | 4000 | 0.127％ |
Thereby obtaining the second maximum metering error of the detected electric energy meter to be 0.132%.
And 4, step 4: calculating the maximum comprehensive error based on the experimental data, wherein the formula is as follows:
thereby calculating the maximum composite error e c The content was 0.4908%. And the accuracy grade of the detected electric energy meter is 0.5 grade, the maximum comprehensive error calculated based on the experimental data does not exceed 0.5 percent, so the following conclusion can be obtained: the harmonic content and the frequency fluctuation have influence on the metering error of the intelligent electric meter, but the electric meter to be tested can still meet the metering requirement of 0.5-level precision; under the condition that the environmental temperature and humidity conditions are stable and appropriate, when the input voltage signal and the input current signal are only fundamental waves, the metering accuracy of the intelligent ammeter is high; the metering error of the intelligent ammeter is gradually increased along with the gradual increase of the harmonic times superposed in the fundamental waveThe method shows an ascending trend, wherein the error reaches 2.5942% when the harmonic number is 16 (the content is 8%); the metering error of the intelligent electric meter is increased under the condition of frequency fluctuation.
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 (10)
1. A method for testing influence of harmonic content and frequency fluctuation on metering errors of a smart meter is characterized by comprising the following steps:
inputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter, and measuring to obtain the maximum initial inherent error of the detected electric energy meter;
simultaneously inputting fundamental wave signals and different harmonic wave signals to the standard electric energy meter and the detected electric energy meter, and measuring to obtain a first maximum metering error of the detected electric energy meter;
only changing the frequency of the fundamental wave signal and measuring to obtain a second maximum metering error of the detected electric energy meter;
and calculating to obtain the maximum comprehensive error of the detected electric energy meter based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the detected electric energy meter.
2. The method for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter according to claim 1, wherein the fundamental wave signal is only input to the standard electric energy meter and the tested electric energy meter, and the process of measuring the maximum initial inherent error of the tested electric energy meter is specifically as follows:
setting experiment conditions, outputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter to carry out multiple experiments, measuring the electric energy values of the standard electric energy meter and the detected electric energy meter in each experiment, calculating to obtain the initial inherent error of the detected electric energy meter in a single experiment, and taking the maximum value from multiple initial inherent errors obtained from multiple experiment results as the maximum initial inherent error of the detected electric energy meter.
3. The method for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter according to claim 1, wherein the fundamental wave signal and the different harmonic signals are simultaneously input into the standard electric energy meter and the tested electric energy meter, and the process of measuring the first maximum metering error of the tested electric energy meter comprises the following steps:
inputting a plurality of single harmonic signals based on different harmonic times and harmonic contents;
respectively synthesizing the fundamental wave signal and the single harmonic signals into a plurality of test signals one by one, and respectively outputting the test signals to the tested electric energy meter and the standard electric energy meter in a full-wave mode to test one by one;
recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a first metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
and taking the maximum value from a plurality of first metering error results obtained from the multiple tests as the first maximum metering error of the detected electric energy meter in the harmonic experiment.
4. The method for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter according to claim 1, wherein the process of changing the frequency of the fundamental wave signal only and measuring the second maximum metering error of the tested smart meter comprises the following steps:
setting a frequency fluctuation range and a fluctuation interval of the fundamental wave signal to generate a plurality of test signals with different frequency values;
respectively outputting a plurality of test signals with different frequency values to the tested electric energy meter and the standard electric energy meter for testing one by one;
recording the electric energy values of the detected electric energy meter and the standard electric energy meter obtained in each test, and calculating to obtain a second metering error of the detected electric energy meter in the test based on the electric energy values of the detected electric energy meter and the standard electric energy meter;
and taking the maximum value from a plurality of second metering error results obtained from the plurality of tests as the second maximum metering error of the detected electric energy meter in the frequency fluctuation experiment.
5. The method for testing the influence of the harmonic content and the frequency fluctuation on the metering error of the smart meter according to claim 1, wherein the maximum comprehensive error of the tested smart meter is calculated by adopting the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electrical energy meter under test, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
6. A device for testing influence of harmonic content and frequency fluctuation on metering error of an intelligent electric meter is characterized by comprising a program-controlled power supply, a computer, a standard electric energy meter, an error calculator, a detected electric energy meter and a harmonic generator, wherein the computer is used for controlling working states of the program-controlled power supply, the harmonic generator and the error calculator, the program-controlled power supply is used for outputting fundamental wave signals to the standard electric energy meter and the detected electric energy meter, the harmonic generator is used for outputting different harmonic signals to the standard electric energy meter and the detected electric energy meter, the error calculator is used for measuring electric energy values of the detected electric energy meter and the standard electric energy meter in a pulse counting mode, the maximum initial inherent error of the detected electric energy meter is measured when only the fundamental wave signals are input to the standard electric energy meter and the detected electric energy meter, and the first maximum metering error of the detected electric energy meter is measured when the fundamental wave signals and the different harmonic signals are input to the standard electric energy meter and the detected electric energy meter simultaneously And measuring to obtain a second maximum metering error of the detected electric energy meter when only the frequency of the fundamental wave signal is changed, and calculating to obtain a maximum comprehensive error of the detected electric energy meter based on the maximum initial inherent error, the first maximum metering error and the second maximum metering error of the detected electric energy meter.
7. The apparatus according to claim 6, wherein the computer controls the programmable power supply to output the fundamental wave signal to the standard electric energy meter and the tested electric energy meter for a plurality of experiments, the error calculator measures the electric energy values of the standard electric energy meter and the tested electric energy meter in each experiment, calculates the initial intrinsic error of the tested electric energy meter in a single experiment, and takes the maximum value from a plurality of initial intrinsic errors obtained from the results of the plurality of experiments as the maximum initial intrinsic error of the tested electric energy meter.
8. The device for testing the influence of harmonic content and frequency fluctuation on the metering error of the smart meter according to claim 6, characterized in that the computer controls the harmonic generator to generate a plurality of single harmonic signals based on different harmonic orders and harmonic contents, simultaneously controlling the program-controlled power supply to synchronously output fundamental wave signals so as to respectively combine the fundamental wave signals with a plurality of single harmonic wave signals one by one into a plurality of test signals, respectively outputting the plurality of test signals to the tested electric energy meter and the standard electric energy meter in a full-wave mode to test one by one, the error calculator records the electric energy values of the tested electric energy meter and the standard electric energy meter obtained by each test, and calculating to obtain a first metering error of the detected electric energy meter in the test based on the electric energy value of the detected electric energy meter and the standard electric energy meter, and taking the maximum value from a plurality of first metering error results obtained by multiple tests as the first maximum metering error of the detected electric energy meter in the harmonic experiment.
9. The apparatus according to claim 6, wherein the computer controls the programmable power supply to output shock signals with different frequency values to the tested electric energy meter and the standard electric energy meter for testing one by one, the error calculator records the electric energy values of the tested electric energy meter and the standard electric energy meter obtained in each test, calculates a second metering error of the tested electric energy meter in the current test based on the electric energy values of the tested electric energy meter and the standard electric energy meter, and takes a maximum value from a plurality of second metering error results obtained in multiple tests as a second maximum metering error of the tested electric energy meter in the frequency fluctuation test.
10. The device for testing the influence of the harmonic content and the frequency fluctuation on the metering error of the smart meter according to claim 6, wherein the maximum comprehensive error of the tested smart meter is calculated by adopting the following formula:
wherein e is c Representing the maximum combined error of the electric energy meter under test, e freq Indicating the second maximum metering error of the electrical energy meter under test, e base Representing the maximum initial intrinsic error of the electric energy meter under test, e har The first maximum metering error of the detected electric energy meter is represented.
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| CN117405971A (en) * | 2023-10-09 | 2024-01-16 | 国网河南电力公司营销服务中心 | Power acquisition digitization method based on flow automation |
| CN118151087A (en) * | 2024-05-09 | 2024-06-07 | 江苏西欧电子有限公司 | Electric energy meter metering error analysis method and system based on electric power data acquisition |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117405971A (en) * | 2023-10-09 | 2024-01-16 | 国网河南电力公司营销服务中心 | Power acquisition digitization method based on flow automation |
| CN118151087A (en) * | 2024-05-09 | 2024-06-07 | 江苏西欧电子有限公司 | Electric energy meter metering error analysis method and system based on electric power data acquisition |
| CN118151087B (en) * | 2024-05-09 | 2024-08-23 | 江苏西欧电子有限公司 | Electric energy meter metering error analysis method and system based on electric power data acquisition |
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