Electric energy metering and sampling device and method based on split digital mutual inductor

Abstract

The invention discloses an electric energy metering and sampling device and method based on split digital mutual inductors. The electric energy metering and sampling device comprises an electric energy meter and a plurality of external mutual inductors. A waveform sampling unit, a first metering unit and a first transmission unit are arranged on an external mutual inductor, waveform and metering information are transmitted to an electric energy meter through an information transmission channel, the electric energy meter is provided with a waveform acquisition unit, a second metering unit, a calculation and analysis unit and a second transmission unit, and the electric energy meter carries out further metering analysis on the waveform. A single electric energy meter can be connected with a plurality of external mutual inductors at the same time, precision loss of traditional secondary mutual inductance measurement is avoided, load identification and line loss statistics can be carried out while electric quantity metering is carried out, and the new design enables the installation and use environment of the electric energy meter to be well improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electric energy metering, and in particular relates to an electric energy metering sampling device and method based on a split digital mutual inductor. Background Art

[0002] Currently, smart energy meters generally measure energy in high-current scenarios through inductive measurement, which measures the power consumption, current, voltage, frequency, active power, reactive power, apparent power, power factor and other parameters of the measured high-current load through inductive measurement of current or voltage.

[0003] Existing electric energy meter induction measurement includes two methods: direct access and high current user secondary mutual inductance access. Due to the limited size and weight of the electric energy meter, it is impossible to build in a larger mutual inductor. The direct access measurement method uses the current conductor to pass through the built-in micro current mutual inductor of the electric energy meter. The measured current cannot be too large, otherwise it will exceed its measurement range.

[0004] Secondary mutual inductance measurement first senses and measures the large current through an external transformer. The induced current is used as the input of the secondary induction measurement. That is, the current wire of the external transformer passes through the built-in micro current transformer (secondary measurement transformer) of the energy meter, thereby completing the indirect measurement of the measured current. The disadvantages of this measurement method include: 1. The external transformer converts the large current into a small current, and there is a loss of accuracy from analog signal to analog signal. Then the micro transformer performs another analog signal conversion, and the overall accuracy loss is greater; 2. When there are even DC harmonics in the original signal, at present, the micro-transformer is either not DC-resistant and has a large direct error, or DC-resistant but requires calibration, which has a high production cost and cannot guarantee the accuracy of the full current range during calibration. For the specific principle, please refer to the Chinese authorized invention patent with announcement number CN113009404B and the name "A method for calibrating DC even harmonic errors and electric energy meter"; 3. If load identification is performed for users, especially industrial users, the secondary mutual inductance access measurement solution cannot directly obtain the front-end signal after two transmissions, the waveform loss is large, and the identification accuracy is not high; 4. In the existing secondary mutual inductance access installation scheme, the external mutual inductor must be installed under the electric energy meter and correspond one-to-one with the electric energy meter. That is to say, the electric energy meter is very close to the high current environment, and the promotion and application efficiency is not high. It may be environmentally unfriendly to the precision device such as the electric energy meter. Summary of the invention

[0005] In view of the above problems, the present invention designs an electric energy metering sampling device and method based on a split digital mutual inductor, which directly senses and digitizes large currents for transmission and metering without the need for secondary mutual inductance, thereby overcoming the above technical problems in one package and having obvious technical effects.

[0006] To achieve the above-mentioned purpose, the present invention designs an electric energy metering sampling device based on a split digital mutual inductor, the electric energy metering sampling device comprises an electric energy meter and several external mutual inductors; the external mutual inductor comprises a waveform sampling unit, a first metering unit and a first transmission unit, the electric energy meter comprises a waveform acquisition unit, a second metering unit, a calculation and analysis unit and a second transmission unit; the waveform sampling unit and the first metering unit are respectively electrically connected to the first transmission unit, the waveform acquisition unit, the second metering unit and the calculation and analysis unit are respectively electrically connected to the second transmission unit, and the waveform acquisition unit is electrically connected to the second metering unit, and the second metering unit is electrically connected to the calculation and analysis unit; the first transmission unit and the second transmission unit are electrically connected, including a radio connection and / or a wired electrical connection; The external transformer includes a digital current transformer and / or a digital voltage transformer, which is used to transmit a sampling waveform and / or electric energy metering data.

[0007] The division of modules or units here is not unique, and can be divided according to the preferences or habits of users or programmers, such as merging the shape acquisition unit and the second metering unit into a waveform acquisition and metering unit, or merging the second metering unit and the calculation and analysis unit into a metering and analysis unit, etc. As long as the functional design is consistent with the essence of the present invention, it should be within the protection scope of the present invention.

[0008] The beneficial effects and principles of the present invention are analyzed as follows: (1) Digital or analog sampling of the induced current or voltage is performed directly through an external transformer, and the waveform signal and electric energy metering data are transmitted to the electric energy meter through the data transmission channel, eliminating the micro-transformer setting of the secondary induction measurement in the traditional electric energy meter, and the overall measurement accuracy loss is small; (2) Improving the measurement accuracy of the full current range through digital calibration of DC even harmonics: When there are DC even harmonics in the original signal of traditional electric energy meters, the current stage of the micro-transformer is either not DC-resistant and the direct error is large, or it is DC-resistant, but calibration is required, the production cost is very high, and the accuracy of the full current range cannot be guaranteed during calibration. During the measurement and calculation analysis, the present invention fits the DC even harmonic errors corresponding to different power factors and different current value ranges of the electric energy meter, obtains several fitting formulas and stores them, and performs FFT transformation (Fourier transform) and judgment on the real-time data of the primary current waveform. When there are DC even harmonics, the fitting formula corresponding to the current current effective value and power factor is used to calculate the measurement error and compensate the metering value of the electric energy meter. For the specific principle, please refer to the Chinese authorized invention patent with announcement number CN113009404B and the name "A method for calibrating DC even harmonic errors and electric energy meter"; (3) Aiming at the load identification needs of users, especially industrial users, the electric energy meter of the present invention has a load identification function, and because only one induction measurement is performed, the front-end signal can be directly obtained, the waveform and precision loss are small, and the identification accuracy is high; (4) The measurement signal of the external transformer of the present invention can be transmitted digitally, with almost no accuracy loss and a long signal transmission distance. Therefore, the corresponding electric energy meter does not need to be installed near the external transformer, and the installation and monitoring environment of the electric energy meter will be effectively improved. In the existing secondary mutual inductance access installation scheme, the external transformer must be installed below the electric energy meter and has a one-to-one correspondence with the electric energy meter. That is to say, the electric energy meter may be very close to the large current environment, and the installation and use will be restricted. The promotion and application efficiency of smart electric energy meters is not high, and there may be environmental unfriendly problems for precision devices such as electric energy meters. The present invention can perfectly solve this problem; (5) The traditional connection between external transformers and electric energy meters corresponds one to one, and the utilization rate of electric energy meters is not high. In the present invention, one electric energy meter can be connected to multiple external transformers, especially the digital transmission signal has no loss, which is convenient for one-to-many. As long as the calculation and storage capacity of the electric energy meter is sufficient, the current level of electronic technology can fully meet the storage and calculation requirements of the electric energy meter. For example, for the inlet and outlet of the transformer in the distribution room, six or more external transformers can be installed, but only one electric energy meter is needed. That is, many electric energy meters were needed in the distribution room before, but now only a few transformers and one electric energy meter are needed.

[0009] Furthermore, the waveform sampling unit collects original waveform information, and the waveform includes an analog waveform signal or a digital waveform signal. The digital waveform signal refers to a digitized waveform signal, which is stored and / or transmitted once every N cycles.

[0010] Furthermore, the first metering unit performs metering calculations using the sampled waveform information, generally acquiring waveform data once within N cycles and performing a metering calculation once.

[0011] Furthermore, the waveform acquisition unit acquires the waveform sampled by the external transformer waveform sampling unit through the first transmission unit and the second transmission unit, which is used for the electric energy meter to perform metering analysis on the original waveform signal and can be compared and analyzed with the metering result of the transformer.

[0012] Furthermore, the second metering unit performs metering calculation on the waveform acquired by the waveform acquisition unit; the metering result of the second metering unit is compared with the result of the first metering unit to ensure the accuracy of the metering. If there is any abnormality, manual intervention can be performed to retransmit the waveform signal and re-measure.

[0013] Furthermore, the calculation and analysis unit may preset parameters or models for the waveform sampling unit, the first metering unit, the waveform acquisition unit and the second metering unit.

[0014] Furthermore, the calculation and analysis unit uses waveform and / or metering information to perform load identification calculations.

[0015] Furthermore, an electric energy meter is electrically connected to a plurality of external transformers, and a calculation and analysis unit of the electric energy meter simultaneously carries out line loss statistics.

[0016] On the other hand, an electric energy metering sampling method based on a split digital transformer is based on any one of the electric energy metering sampling devices described above, and executing the electric energy metering method comprises the following steps: S1. The transformer samples the waveform under test, and the waveform sampling is stored once every N cycles, and cached twice; S2, the mutual inductor performs electric energy measurement, and the mutual inductor measurement unit (first measurement unit) performs electric energy measurement calculation according to the waveform sampling result; S3, the mutual inductor transmits the sampling waveform and electric energy measurement result to the electric energy meter; S4, the electric energy meter measures the electric energy; S5. The calculation unit performs load identification calculation, mainly using the acquired waveform to perform load identification calculation.

[0017] Furthermore, when an electric energy meter is electrically connected to a plurality of external transformers arranged at corresponding end nodes of a line loss statistical section, the electric energy metering method further comprises: S6. The calculation and analysis unit performs line loss statistics. There is no order of precedence for steps S6 and S5. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of an electric energy metering sampling device based on a split digital transformer; Figure 2 It is a schematic diagram of another electric energy metering sampling device based on split digital transformer; Figure 3 The invention discloses a flow chart of an electric energy metering sampling method based on a split digital transformer. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example 1

[0020] like Figure 1 As shown, an electric energy metering sampling device based on a split digital mutual inductor is characterized in that the electric energy metering sampling device includes an electric energy meter and several external mutual inductors; the external mutual inductor includes a waveform sampling unit, a first metering unit and a first transmission unit, and the electric energy meter includes a waveform acquisition unit, a second metering unit, a calculation and analysis unit and a second transmission unit; the waveform sampling unit and the first metering unit are electrically connected to the first transmission unit respectively, the waveform acquisition unit, the second metering unit and the calculation and analysis unit are electrically connected to the second transmission unit respectively, and the waveform acquisition unit is electrically connected to the second metering unit, and the second metering unit is electrically connected to the calculation and analysis unit; the first transmission unit and the second transmission unit are electrically connected, including a wireless connection and / or a wired electrical connection; in this embodiment, for 220V load electricity consumption, one electric energy meter corresponds to one external mutual inductor, and the sensing elements in the mutual inductor, the sampling unit, the transmission unit, the metering unit circuit, etc. all adopt the existing technology, and the calculation and analysis unit is generally used to analyze the data of the first and second metering units, waveform data analysis, etc.; The external transformer includes a digital current transformer and / or a digital voltage transformer, which is used to transmit a sampling waveform and / or electric energy metering data.

[0021] Preferably, the waveform sampling unit collects original waveform information, and the waveform includes an analog waveform signal or a digital waveform signal. The digital waveform signal refers to a digitized waveform signal, which is stored and / or transmitted once every N cycles. In this embodiment, the original waveform signal is cached twice, one of which is used for transmission and the other is used for local digital sampling. Since electricity metering does not require complete sampling of each power frequency cycle, where N≥1 is a natural number, this embodiment sets N=10, and the sampling frequency is generally set to not less than twice the mains power frequency. In this embodiment, the sampling frequency is set to 10KHz to ensure that various abnormal fluctuation information is sampled in a timely manner.

[0022] Preferably, the first metering unit uses the sampled waveform information to perform metering calculations, generally acquiring waveform data once within N cycles and performing a metering calculation. The metering parameters include all power parameters, such as phase voltage / line voltage (V), current (I), frequency (F), power (active power P, reactive power Q, apparent power S), power factor (PF), electric energy (active electric energy Wh, reactive electric energy Vrh, and total electric energy accumulation), etc.

[0023] Preferably, the waveform acquisition unit acquires the waveform sampled by the external transformer waveform sampling unit through the first transmission unit and the second transmission unit, which is used for the electric energy meter to perform metering analysis on the original waveform signal and can be compared and analyzed with the metering result of the transformer.

[0024] Preferably, the second metering unit performs metering calculations on the waveform acquired by the waveform acquisition unit; the metering result of the second metering unit is compared with the result of the first metering unit to ensure the accuracy of the metering. If there is an abnormality, manual intervention can be performed to retransmit the waveform signal and re-meter. In addition to all power parameters, the second metering unit also performs multi-rate power metering, four-quadrant power metering, power quality monitoring (harmonics, voltage flicker, voltage imbalance, etc.) and assessment management.

[0025] Preferably, the calculation and analysis unit can preset parameters or models for the waveform sampling unit, the first metering unit, the waveform acquisition unit and the second metering unit, and the parameters include sampling period or frequency, storage period, transmission period and parameters of the metering model, etc., such as parameters of the electric energy indication integration method or the frequency cycle integration method, etc. Example 2

[0026] The difference from Example 1 is that the calculation and analysis unit described in this embodiment uses waveform and / or metering information to perform load identification calculations, and mainly performs load identification through transient, steady-state, current, power, harmonic content and other analyses of the waveform. For specific methods, please refer to the Chinese patent with publication number CN111948446A and name "An adaptive load identification method and smart electricity meter". Example 3

[0027] The difference from Embodiment 1 is that in this embodiment, one electric energy meter is electrically connected to multiple external transformers, and the calculation and analysis unit of the electric energy meter simultaneously carries out line loss statistics. The calculation and analysis unit of the electric energy meter has the function of synchronously carrying out line loss statistics, such as Figure 2As shown, in this embodiment, a transformer in the power distribution room is provided with three inputs and six outputs, and each output line is equipped with an external transformer, with a total of n=9 external transformers, and all the above external transformers are electrically connected to the same electric energy meter in the monitoring room. In this way, compared with the traditional installation mode, which has one electric energy meter at the front end of the transformer and one electric energy meter for each output line at the rear end, with a total of several electric energy meters, the present invention only needs one electric energy meter, which not only saves resources, but also can conveniently and accurately calculate the line loss at the edge according to the electric energy meter data at the front and rear ends collected by the main station and the loss of the transformer, that is, the line loss can be calculated in real time in the electric energy meter of the electric energy metering sampling device; in particular, since the electric energy metering of the present invention does not have the loss of secondary conversion, the electric energy metering accuracy is higher, and thus the statistical accuracy of line loss is higher. Example 4

[0028] An electric energy measurement sampling method based on split digital transformer, such as Figure 3 As shown, it is characterized in that, based on the electric energy metering sampling device described in any one of embodiments 1 to 4 and their preferred solutions, executing the electric energy metering method includes the following steps: S1. The transformer samples the waveform under test, and the waveform sampling is stored once every N cycles, and cached twice; S2, the mutual inductor performs electric energy measurement, and the mutual inductor measurement unit (first measurement unit) performs electric energy measurement calculation according to the waveform sampling result; S3, the mutual inductor transmits the sampling waveform and electric energy measurement result to the electric energy meter; S4. The electric energy meter measures electric energy. The electric energy meter must obtain waveform data once every N cycles for measurement calculation and compare it with the measurement data obtained at the transformer to ensure measurement accuracy. The comparison can be completed in the second metering unit or in the calculation and analysis unit. If the comparison is inconsistent (or exceeds the preset allowable deviation range), a prompt or alarm is issued for manual analysis. The specific method of manual analysis includes re-analyzing and measuring the waveform, or retransmitting the waveform data for analysis and measurement again, or combining the previous and subsequent waveform data for analysis and measurement, etc.

[0029] S5. The calculation unit performs load identification calculation, mainly using the acquired waveform to perform load identification calculation.

[0030] Preferably, when an electric energy meter is electrically connected to a plurality of external transformers arranged at corresponding end nodes of a line loss statistical section, the electric energy meter itself can obtain the accumulated information of power consumption of different nodes, thereby providing conditions for the electric energy meter to accurately perform line loss statistics. Generally, the two end nodes for calculating line loss should have power metering results at the same time. For example, three incoming lines and six outgoing lines of a transformer in a power distribution room with three incoming lines and six outgoing lines are all provided with external transformers. The electric energy metering method further includes the following steps: S6. The calculation and analysis unit performs line loss statistics. There is no order of precedence for steps S6 and S5.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. For example, the first metering unit is combined with the waveform sampling unit, the first metering unit is combined with the first transmission unit, or the waveform sampling unit, the first metering unit, and several modules in the first transmission unit are separated from the external mutual inductor, or the waveform acquisition unit, the second metering unit, the calculation and analysis unit, and the second transmission unit in the electric energy meter are recombined, etc.

Claims

1. An electric energy metering sampling device based on a split digital transformer, characterized in that: The electric energy metering sampling device comprises an electric energy meter and several external mutual inductors; the external mutual inductor comprises a waveform sampling unit, a first metering unit and a first transmission unit, and the electric energy meter comprises a waveform acquisition unit, a second metering unit, a calculation and analysis unit and a second transmission unit; the waveform sampling unit and the first metering unit are electrically connected to the first transmission unit respectively, the waveform acquisition unit, the second metering unit and the calculation and analysis unit are electrically connected to the second transmission unit respectively, and the waveform acquisition unit is electrically connected to the second metering unit, and the second metering unit is electrically connected to the calculation and analysis unit; the first transmission unit and the second transmission unit are electrically connected, including a radio connection and / or a wired electrical connection; The external transformer includes a digital current transformer and / or a digital voltage transformer, which is used to transmit a sampling waveform and / or electric energy metering data.

2. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The waveform sampling unit collects original waveform information, the waveform includes an analog waveform signal or a digital waveform signal, and is stored and / or transmitted once every N cycles.

3. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The first metering unit performs metering calculation using the sampled waveform information.

4. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The waveform acquisition unit acquires the waveform sampled by the external transformer waveform sampling unit through the first transmission unit and the second transmission unit.

5. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The second metering unit performs metering calculation on the waveform acquired by the waveform acquiring unit.

6. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The calculation and analysis unit presets parameters or models for the waveform sampling unit, the first metering unit, the waveform acquisition unit, and the second metering unit.

7. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: The calculation and analysis unit performs load identification calculations using waveforms and / or metering information.

8. The electric energy metering sampling device based on split digital mutual inductor according to claim 1 is characterized in that: One electric energy meter is electrically connected to multiple external transformers.

9. An electric energy measurement sampling method based on a split digital transformer, characterized in that: Based on the electric energy metering sampling device according to any one of claims 1 to 8, executing the electric energy metering method comprises the following steps: S1, the transformer samples the waveform under test; S2, transformer for electric energy measurement; S3, the mutual inductor transmits the sampling waveform and electric energy measurement result to the electric energy meter; S4, the electric energy meter measures the electric energy; S5. The calculation unit performs load identification calculation.

10. The electric energy metering sampling method based on split digital mutual inductor according to claim 9 is characterized in that: When an electric energy meter is electrically connected to a plurality of external transformers arranged at corresponding end nodes of a line loss statistical section, the electric energy metering method further comprises: S6. The calculation and analysis unit performs line loss statistics. There is no order of precedence for steps S6 and S5.

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