Direct-current electric energy metering method considering dynamic characteristics and direct-current electric energy meter

Abstract

The invention discloses a direct-current electric energy metering method and a direct-current electric energy meter considering dynamic characteristics, and the method comprises the steps: collecting a voltage signal of a power supply as a first voltage signal, and taking an alternating-current component of the first voltage signal as a second voltage signal; collecting a current signal of a power supply as a first current signal, and taking an alternating current component of the first current signal as a second current signal; calculating the first voltage signal, the second voltage signal, the first current signal and the second current signal to obtain instantaneous power of the power supply; and accumulating the instantaneous power according to time to obtain actual consumed electric energy. According to the direct-current electric energy metering method, reactive power and harmonic waves are completely screened out during metering according to dynamic change characteristics of a power grid, and metering accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current metering, and in particular to a direct current electric energy metering method and a direct current electric energy meter taking into account dynamic characteristics. Background Art

[0002] DC energy meters are widely used in places that require DC power, such as DC panels, solar power supply, electric vehicle charging, telecommunication base stations, subways, etc. For DC loads, the DC power applied can be transformed by a DC / DC converter or rectified by AC power.

[0003] When the voltage is transformed by a DC / DC converter (for example, charging an electric car), there is also reactive power flowing between the charging battery and the power supply, which is caused by the fluctuation of the output voltage in the power electronic control and the difference between the battery voltage. Obviously, the reactive power is not consumed, and it should not be measured in the energy measurement of the DC grid.

[0004] When AC is rectified into DC, although the DC grid has been filtered, its voltage still contains rich harmonics, that is, the DC grid voltage contains both DC and AC components. If the harmonic voltage frequency of the grid voltage is the same as the reactive current frequency of the load, the traditional energy metering method will generate electrical energy. This part of the electrical energy is generated by the interaction between the reactive current and the voltage harmonics of the DC grid, which is "multi-metering" of electrical energy, thereby increasing the electrical energy measurement error of the DC energy meter.

[0005] In practice, reactive power and harmonics are not stable due to changes in working conditions. In addition, due to thermal effects, their waveforms will decay and are not completely symmetrical, resulting in their periodic integrals being non-zero. If this amount of electricity is measured for a long period of time, it is considered "over-measurement" of electricity. Summary of the invention

[0006] The present invention provides a DC electric energy metering method and a DC electric energy meter taking into account dynamic characteristics to solve the above-mentioned problem of "multiple metering" of electric energy.

[0007] The present invention is achieved through the following technical solutions:

[0008] A DC electric energy measurement method taking into account dynamic characteristics, comprising:

[0009] Collecting a voltage signal of a power supply as a first voltage signal, and taking an AC component of the first voltage signal as a second voltage signal;

[0010] Collecting a current signal of the power supply as a first current signal, and taking an AC component of the first current signal as a second current signal;

[0011] Calculating the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply;

[0012] The instantaneous power is accumulated over time to obtain the actual consumed electric energy.

[0013] As an optimization, taking the AC component of the first voltage signal as the second voltage signal is specifically:

[0014] Passing the first voltage signal through a first DC blocking capacitor to obtain the second voltage signal;

[0015] Taking the AC component of the first current signal as the second current signal is specifically:

[0016] The first current signal is passed through a second DC blocking capacitor to obtain the second current signal.

[0017] As an optimization, before taking the AC component of the first voltage signal, the first voltage signal is firstly low-pass filtered to obtain a first voltage signal with high-frequency voltage signals suppressed.

[0018] As an optimization, before taking the AC component of the first current signal, the first current signal is firstly low-pass filtered to obtain a first current signal with high-frequency current signals suppressed.

[0019] As an optimization, the specific process of preprocessing the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply is:

[0020] Multiplying the first voltage signal, the second voltage signal, the first current signal, and the second current signal in pairs respectively to obtain a first intermediate result, a second intermediate result, a third intermediate result, and a fourth intermediate result, wherein the first intermediate result is equal to the product of the first voltage signal and the first current signal, the second intermediate result is the product of the first voltage signal and the second current signal, the third intermediate result is the product of the second voltage signal and the first current signal, and the fourth intermediate result is the product of the second voltage signal and the second current signal;

[0021] The first intermediate result is subtracted from the second intermediate result to obtain a fifth intermediate result, and the instantaneous power is obtained by adding the difference between the fifth intermediate result and the third intermediate result and the fourth intermediate result.

[0022] The present invention also discloses a DC electric energy meter, which is used to implement the above-mentioned DC electric energy measurement method taking into account dynamic characteristics, comprising:

[0023] An acquisition module, used for acquiring a voltage signal and a current signal of a power supply, and using the voltage signal and the current signal as a first voltage signal and a first current signal respectively;

[0024] an AC component acquisition module, configured to acquire the AC components of the first voltage signal and the first current signal, and define the AC components of the first voltage signal and the first current signal as a second voltage signal and a second current signal, respectively;

[0025] a calculation module, configured to calculate the instantaneous power of the power supply according to the first voltage signal, the first current signal, the second voltage signal and the second current signal;

[0026] The electric energy metering module is used to accumulate the instantaneous power over time to obtain the actual consumed electric energy.

[0027] As an optimization, the acquisition module includes a voltage sensor and a current sensor, and the voltage sensor and the current sensor are respectively connected to the output end of the power supply.

[0028] As an optimization, the AC component acquisition module includes a first DC blocking capacitor for acquiring the AC component of the first voltage signal and a second DC blocking capacitor for acquiring the AC component of the first current signal, the input end of the first DC blocking capacitor is connected to the output end of the voltage sensor, and the input end of the second DC blocking capacitor is connected to the output end of the current sensor.

[0029] As an optimization, a first low-pass filter is provided between the first DC blocking capacitor and the voltage sensor, and a second low-pass filter is provided between the second DC blocking capacitor and the current sensor.

[0030] As an optimization, the calculation module includes a first multiplier, a second multiplier, a third multiplier, a fourth multiplier, a first difference module, a second difference module and a summation module, wherein:

[0031] The input end of the first multiplier is respectively connected to the voltage output end and the current output end of the acquisition module, and is used to respectively receive the first voltage signal and the first current signal and multiply the first voltage signal and the first current signal; the input end of the second multiplier is respectively connected to the voltage output end of the acquisition module and the current output end of the AC component acquisition module, and multiplies the first voltage signal and the second current signal, and is used to respectively receive the first voltage signal and the second current signal; the input end of the third multiplier is respectively connected to the current output end of the acquisition module and the voltage output end of the AC component acquisition module, and multiplies the second voltage signal and the first current signal, and is used to respectively receive the second voltage signal and the first current signal; the input end of the fourth multiplier is respectively connected to the voltage output end and the current output end of the AC component acquisition module, and multiplies the second voltage signal and the second current signal, and is used to respectively receive the second voltage signal and the second current signal;

[0032] The input end of the first difference module is connected to the output end of the first multiplier and the output end of the second multiplier respectively, and is used to calculate the output signal of the first multiplier minus the output signal of the second multiplier and output it;

[0033] The input end of the second difference module is respectively connected to the output end of the first difference module and the output end of the third multiplier, and is used to calculate the output signal of the first difference module minus the output signal of the third multiplier and output it;

[0034] The input end of the summing module is respectively connected to the output end of the second difference module and the output end of the fourth multiplier, and is used to calculate the sum of the output signal of the second difference module and the output signal of the fourth multiplier and output it to the electric energy metering module.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] By using the direct current electric energy metering method of the present invention, reactive power and harmonics are completely screened out during metering in view of the dynamic change characteristics of the power grid, thereby improving the accuracy of metering. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0038] Figure 1 A flow chart of a DC electric energy measurement method taking into account dynamic characteristics according to the present invention;

[0039] Figure 2 The figure is a schematic diagram of the structure of the DC electric energy meter described in the present invention. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0041] This embodiment 1 provides a DC power metering method taking into account dynamic characteristics, such as Figure 1 As shown, including:

[0042] S1. Collect a voltage signal of a power supply as a first voltage signal, and take an AC component of the first voltage signal as a second voltage signal.

[0043] S2. Collect a current signal of the power supply as a first current signal, and take an AC component of the first current signal as a second current signal.

[0044] In some embodiments, taking the AC component of the first voltage signal as the second voltage signal is specifically:

[0045] Passing the first voltage signal through a first DC blocking capacitor to obtain the second voltage signal;

[0046] Taking the AC component of the first current signal as the second current signal is specifically:

[0047] The first current signal is passed through a second DC blocking capacitor to obtain the second current signal.

[0048] Specifically, the voltage signal and the current signal of the power supply are collected by a voltage sensor and a current sensor respectively.

[0049] That is, the voltage sensor collects the voltage signal as the first voltage signal, and the first voltage signal passes through the first DC blocking capacitor to obtain its AC component as the second voltage signal;

[0050] The current sensor collects the current signal as a first current signal, and the first current signal passes through the second DC blocking capacitor to obtain the AC component thereof as a second current signal.

[0051] In some embodiments, before taking the AC component of the first voltage signal, the first voltage signal is low-pass filtered to obtain a first voltage signal with high-frequency voltage signals suppressed. Before taking the AC component of the first current signal, the first current signal is low-pass filtered to obtain a first current signal with high-frequency current signals suppressed.

[0052] In this way, the subsequent instantaneous power calculation can be made more accurate.

[0053] S3. Calculate the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply.

[0054] In some embodiments, the specific process of preprocessing the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply is:

[0055] Multiplying the first voltage signal, the second voltage signal, the first current signal, and the second current signal in pairs respectively to obtain a first intermediate result, a second intermediate result, a third intermediate result, and a fourth intermediate result, wherein the first intermediate result is equal to the product of the first voltage signal and the first current signal, the second intermediate result is the product of the first voltage signal and the second current signal, the third intermediate result is the product of the second voltage signal and the first current signal, and the fourth intermediate result is the product of the second voltage signal and the second current signal;

[0056] The first intermediate result is subtracted from the second intermediate result to obtain a fifth intermediate result, and the instantaneous power is obtained by adding the difference between the fifth intermediate result and the third intermediate result and the fourth intermediate result.

[0057] That is, the first voltage signal, the second voltage signal, the first current signal and the second current signal are multiplied in pairs; then the product of the first voltage signal and the first current signal is subtracted from the product of the first voltage signal and the first current signal, and then the product of the second voltage signal and the first current signal is subtracted, and finally the product of the second voltage signal and the second current signal is added to obtain the instantaneous power.

[0058] S4. Accumulate the instantaneous power over time to obtain actual power consumption.

[0059] Embodiment 2 further discloses a DC electric energy meter, which is used to implement a DC electric energy metering method taking into account dynamic characteristics of embodiment 1, comprising:

[0060] An acquisition module, used for acquiring a voltage signal and a current signal of a power supply, and using the voltage signal and the current signal as a first voltage signal and a first current signal respectively;

[0061] In some embodiments, the acquisition module includes a voltage sensor and a current sensor, and the voltage sensor and the current sensor are respectively connected to the output end of the power supply.

[0062] an AC component acquisition module, configured to acquire the AC components of the first voltage signal and the first current signal, and define the AC components of the first voltage signal and the first current signal as a second voltage signal and a second current signal, respectively;

[0063] In some embodiments, the AC component acquisition module includes a first DC blocking capacitor for acquiring the AC component of the first voltage signal and a second DC blocking capacitor for acquiring the AC component of the first current signal, the input end of the first DC blocking capacitor is connected to the output end of the voltage sensor, and the input end of the second DC blocking capacitor is connected to the output end of the current sensor.

[0064] The first DC blocking capacitor is connected to the voltage sensor, and is used to receive the first voltage signal and isolate its AC component as the second voltage signal. The second DC blocking capacitor is connected to the current sensor, and is used to receive the first current signal and isolate its AC component as the second current signal.

[0065] In some embodiments, a first low-pass filter is provided between the first DC blocking capacitor and the voltage sensor, and a second low-pass filter is provided between the second DC blocking capacitor and the current sensor.

[0066] a calculation module, configured to calculate the instantaneous power of the power supply according to the first voltage signal, the first current signal, the second voltage signal and the second current signal;

[0067] The electric energy metering module is used to accumulate the instantaneous power over time to obtain the actual consumed electric energy.

[0068] In some embodiments, the calculation module includes a first multiplier, a second multiplier, a third multiplier, a fourth multiplier, a first difference module, a second difference module and a summation module, wherein:

[0069] The input end of the first multiplier is respectively connected to the voltage output end and the current output end of the acquisition module, and is used to respectively receive the first voltage signal and the first current signal and multiply the first voltage signal and the first current signal; the input end of the second multiplier is respectively connected to the voltage output end of the acquisition module and the current output end of the AC component acquisition module, and multiplies the first voltage signal and the second current signal, and is used to respectively receive the first voltage signal and the second current signal; the input end of the third multiplier is respectively connected to the current output end of the acquisition module and the voltage output end of the AC component acquisition module, and multiplies the second voltage signal and the first current signal, and is used to respectively receive the second voltage signal and the first current signal; the input end of the fourth multiplier is respectively connected to the voltage output end and the current output end of the AC component acquisition module, and multiplies the second voltage signal and the second current signal, and is used to respectively receive the second voltage signal and the second current signal;

[0070] The output end of the first multiplier outputs a first intermediate result, the output end of the second multiplier outputs a second intermediate result, the output end of the third multiplier outputs a third intermediate result, and the output end of the fourth multiplier outputs a fourth intermediate result.

[0071] In this embodiment, the input end of the first multiplier is respectively connected to the output end of the first low-pass filter and the second low-pass filter, the input end of the second multiplier is respectively connected to the output end of the first low-pass filter and the second DC blocking capacitor, the input end of the third multiplier is respectively connected to the output end of the first DC blocking capacitor and the second low-pass filter, and the input end of the fourth multiplier is respectively connected to the output end of the first DC blocking capacitor and the second DC blocking capacitor.

[0072] The input end of the first difference module is respectively connected to the output end of the first multiplier and the output end of the second multiplier, and is used to calculate and output the output signal of the first multiplier minus the output signal of the second multiplier; the output end of the first difference module outputs a fifth intermediate result.

[0073] The input end of the second difference module is respectively connected to the output end of the first difference module and the output end of the third multiplier, and is used to calculate the output signal of the first difference module minus the output signal of the third multiplier and output it;

[0074] The input end of the summing module is respectively connected to the output end of the second difference module and the output end of the fourth multiplier, and is used to calculate the sum of the output signal of the second difference module and the output signal of the fourth multiplier and output it to the electric energy metering module.

[0075] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A DC electric energy measurement method taking into account dynamic characteristics, characterized in that: include: Collecting a voltage signal of a power supply as a first voltage signal, and taking an AC component of the first voltage signal as a second voltage signal; Collecting a current signal of the power supply as a first current signal, and taking an AC component of the first current signal as a second current signal; Calculating the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply; The instantaneous power is accumulated over time to obtain the actual consumed electric energy.

2. A DC electric energy measurement method taking into account dynamic characteristics according to claim 1, characterized in that: Taking the AC component of the first voltage signal as the second voltage signal is specifically: Passing the first voltage signal through a first DC blocking capacitor to obtain the second voltage signal; Taking the AC component of the first current signal as the second current signal is specifically: The first current signal is passed through a second DC blocking capacitor to obtain the second current signal.

3. A DC electric energy measurement method taking into account dynamic characteristics according to claim 2, characterized in that: Before obtaining the AC component of the first voltage signal, the first voltage signal is low-pass filtered to obtain a first voltage signal with high-frequency voltage signals suppressed.

4. A DC electric energy measurement method taking into account dynamic characteristics according to claim 2, characterized in that: Before obtaining the AC component of the first current signal, the first current signal is low-pass filtered to obtain a first current signal with high-frequency current signals suppressed.

5. A DC electric energy measurement method taking into account dynamic characteristics according to claim 1, characterized in that: The specific process of preprocessing the first voltage signal, the second voltage signal, the first current signal, and the second current signal to obtain the instantaneous power of the power supply is: Multiplying the first voltage signal, the second voltage signal, the first current signal, and the second current signal in pairs to obtain a first intermediate result, a second intermediate result, a third intermediate result, and a fourth intermediate result, respectively, wherein the first intermediate result is equal to the product of the first voltage signal and the first current signal, the second intermediate result is the product of the first voltage signal and the second current signal, the third intermediate result is the product of the second voltage signal and the first current signal, and the fourth intermediate result is the product of the second voltage signal and the second current signal; The first intermediate result is subtracted from the second intermediate result to obtain a fifth intermediate result, and the instantaneous power is obtained by adding the difference between the fifth intermediate result and the third intermediate result and the fourth intermediate result.

6. A DC electric energy meter, used for implementing a DC electric energy measurement method taking into account dynamic characteristics as claimed in any one of claims 1 to 5, characterized in that: include: An acquisition module, used for acquiring a voltage signal and a current signal of a power supply, and using the voltage signal and the current signal as a first voltage signal and a first current signal respectively; an AC component acquisition module, configured to acquire the AC components of the first voltage signal and the first current signal, and define the AC components of the first voltage signal and the first current signal as a second voltage signal and a second current signal, respectively; a calculation module, configured to calculate the instantaneous power of the power supply according to the first voltage signal, the first current signal, the second voltage signal and the second current signal; The electric energy metering module is used to accumulate the instantaneous power over time to obtain the actual consumed electric energy.

7. A DC electric energy meter according to claim 6, characterized in that: The acquisition module includes a voltage sensor and a current sensor, and the voltage sensor and the current sensor are respectively connected to the output end of the power supply.

8. A DC electric energy meter according to claim 6, characterized in that: The AC component acquisition module includes a first DC blocking capacitor for acquiring the AC component of the first voltage signal and a second DC blocking capacitor for acquiring the AC component of the first current signal, the input end of the first DC blocking capacitor is connected to the output end of the voltage sensor, and the input end of the second DC blocking capacitor is connected to the output end of the current sensor.

9. A DC electric energy meter according to claim 8, characterized in that: A first low-pass filter is provided between the first DC blocking capacitor and the voltage sensor, and a second low-pass filter is provided between the second DC blocking capacitor and the current sensor.

10. A DC electric energy meter according to any one of claims 6 to 9, characterized in that: The calculation module includes a first multiplier, a second multiplier, a third multiplier, a fourth multiplier, a first difference module, a second difference module and a summation module, wherein: The input end of the first multiplier is respectively connected to the voltage output end and the current output end of the acquisition module, and is used to respectively receive the first voltage signal and the first current signal and multiply the first voltage signal and the first current signal; the input end of the second multiplier is respectively connected to the voltage output end of the acquisition module and the current output end of the AC component acquisition module, and multiplies the first voltage signal and the second current signal, and is used to respectively receive the first voltage signal and the second current signal; the input end of the third multiplier is respectively connected to the current output end of the acquisition module and the voltage output end of the AC component acquisition module, and multiplies the second voltage signal and the first current signal, and is used to respectively receive the second voltage signal and the first current signal; the input end of the fourth multiplier is respectively connected to the voltage output end and the current output end of the AC component acquisition module, and multiplies the second voltage signal and the second current signal, and is used to respectively receive the second voltage signal and the second current signal; The input end of the first difference module is connected to the output end of the first multiplier and the output end of the second multiplier respectively, and is used to calculate the output signal of the first multiplier minus the output signal of the second multiplier and output it; The input end of the second difference module is respectively connected to the output end of the first difference module and the output end of the third multiplier, and is used to calculate the output signal of the first difference module minus the output signal of the third multiplier and output it; The input end of the summing module is respectively connected to the output end of the second difference module and the output end of the fourth multiplier, and is used to calculate the sum of the output signal of the second difference module and the output signal of the fourth multiplier and output it to the electric energy metering module.

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