A power factor measurement method, measurement device and electronic device

Abstract

The application discloses a power factor measurement method, a measurement device and electronic equipment. The power factor measurement method comprises the following steps: a first coupling device is used to sense a first coupling capacitance between the first coupling device and a to-be-measured wire, the first coupling capacitance is coupled with a measurement capacitance to form an electric circuit; first waveform information of a voltage on the measurement capacitance is obtained; a first reference voltage signal with a different frequency from a voltage of the to-be-measured wire is output to the electric circuit according to the first waveform information, and second waveform information of the voltage on the measurement capacitance is obtained; current waveform information of the to-be-measured wire is obtained; a third reference voltage signal with a same frequency as a current of the to-be-measured wire and a reverse phase is output to the electric circuit according to the current waveform information and the second waveform information, and third waveform information of the voltage on the measurement capacitance is obtained; and a power factor of the to-be-measured wire is determined according to the second waveform information and the third waveform information. The power factor is measured by adjusting a reference voltage signal.

Description

Technical Field

[0001] This invention relates to the field of power factor measurement technology, and particularly to a power factor measurement method, measuring device, and electronic device. Background Technology

[0002] In AC circuits, the power factor is the ratio of active power to apparent power. In sinusoidal steady-state AC circuits, the power factor is the cosine of the phase angle by which the current lags behind the voltage.

[0003] The power factor has a direct and significant impact on the efficiency of the power system. Although it does not directly affect the active power consumption of the load itself, it significantly affects the current, line loss, equipment capacity utilization, and electricity cost in the transmission and distribution system.

[0004] Existing power factor measurement methods generally include the impulse factor method, the DC component method, and the phase difference method. The impulse factor method and the DC component method require a 0° closing angle for accurate calculation, increasing testing time and difficulty. The phase difference method detects the phase difference between voltage and current signals at the same position and then calculates the power factor. It measures the voltage signal using a voltage transformer and the current signal using a current transformer, detecting the rising edge and period of the voltage signal and the rising edge of the current signal to obtain the signal period, the phase difference between voltage and current, and the power factor. However, this method cannot measure the power factor of the system during a short circuit.

[0005] In summary, it is of great significance to study an easy-to-implement method for measuring power factor. Summary of the Invention

[0006] The purpose of this invention is to propose a non-contact power factor measurement method, measuring device, and electronic device to improve the problems of complexity and difficulty in implementation of existing power factor measurement methods.

[0007] To achieve the above objectives, a first aspect of the present invention provides a power factor measurement method, the power factor measurement method comprising the following steps: S100 senses the first coupling capacitance between itself and the wire under test through the first coupling device. The first coupling capacitance is coupled to the measuring capacitor to form an electrical circuit. S200 acquires the first waveform information of the voltage across the measuring capacitor; S300 outputs a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information, and obtains the second waveform information of the voltage on the measuring capacitor; S400 acquires the current waveform information of the conductor under test; S500 outputs a third reference voltage signal to the electrical circuit based on the second waveform information and the current waveform information. This third reference voltage signal is in the same frequency but out of phase with the current of the conductor under test. S500 also acquires the third waveform information of the voltage on the measuring capacitor. S600 determines the power factor of the conductor under test based on the second waveform information and the third waveform information.

[0008] According to some embodiments of the present invention, the step of outputting a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information, and acquiring second waveform information of the voltage on the measuring capacitor, includes: S310 determines the voltage frequency of the conductor under test based on the first waveform information; S320 outputs a first reference voltage signal to the electrical circuit; the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz; S330 acquires the second waveform information of the voltage across the measuring capacitor; the frequency of the second waveform information includes at least two waveforms of different frequencies.

[0009] According to some embodiments of the present invention, the step of outputting a third reference voltage signal with the same frequency but opposite phase to the current in the electrical circuit based on the second waveform information and the current waveform information, and obtaining the third waveform information of the voltage across the measuring capacitor, includes: S510 determines the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information; S520 determines the current phase of the conductor under test based on the current waveform information; S530 outputs a third reference voltage signal for the electrical circuit; the voltage frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the ratio of the voltage amplitude of the conductor under test to the voltage division ratio, and its voltage phase is the opposite of the current phase. S540 acquires the third waveform information of the voltage across the measuring capacitor, wherein the third waveform information includes only a waveform of one frequency.

[0010] According to some embodiments of the present invention, determining the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information includes: S511 determines the correspondence between voltage frequency and voltage division amplitude based on the second waveform information; S512, based on the aforementioned correspondence, takes the voltage division amplitude corresponding to the voltage frequency of the first reference voltage signal as the voltage division amplitude of the first reference voltage signal, and takes the voltage division amplitude corresponding to the voltage frequency of the conductor under test as the voltage division amplitude of the conductor under test. S513 based on the voltage amplitude of the first reference voltage signal The first reference voltage divider amplitude And the second formula: Determine the voltage division ratio of the measuring capacitor. ; S514 measures the voltage division ratio of the capacitor. The voltage division amplitude of the conductor under test And the third formula: Determine the voltage amplitude of the conductor under test. .

[0011] According to some embodiments of the present invention, determining the power factor of the conductor under test based on the second waveform information and the third waveform information includes: S610 determines the current voltage division amplitude Vm of the measured capacity based on the third waveform information; S620 based on the voltage amplitude of the conductor under test The measured voltage division ratio K, the current voltage division amplitude Vm, and the first formula: Determine the current-voltage phase difference of the conductor under test. ; S630 uses the cosine of the current-voltage phase difference to determine the power factor of the conductor under test.

[0012] To achieve the above objectives, a second aspect of the present invention provides a power factor measuring device, wherein the power factor measuring device uses the aforementioned power factor measuring method to perform power factor measurement. The power factor measuring device includes: The first coupling device is coupled to the wire under test to form a first coupling capacitor; The capacitance is measured and coupled to the first coupling device to form an electrical circuit; A reference signal source, coupled to the electrical circuit, is used to input a reference voltage signal to the electrical circuit; A current sensing component for sensing the current waveform information of the conductor under test; The processing unit, electrically coupled to the measuring capacitor, the reference signal source, and the current sensing component, is configured to: acquire first waveform information of the voltage across the measuring capacitor when the conductor under test acts solely on the measuring capacitor; output a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information and acquire second waveform information of the voltage across the measuring capacitor; sense the current waveform information of the conductor under test; output a third reference voltage signal with the same frequency but opposite phase to the current of the conductor under test to the electrical circuit based on the second waveform information and the current waveform information and acquire third waveform information of the voltage across the measuring capacitor; and determine the power factor of the conductor under test based on the second waveform information and the third waveform information.

[0013] According to some embodiments of the present invention, the processing unit is further configured to determine the voltage frequency of the conductor under test based on the first waveform information; The processing unit is also configured to output a first reference voltage signal for the electrical circuit, wherein the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz; The processing unit is also used to acquire second waveform information of the voltage on the measuring capacitor, wherein the frequency of the second waveform information includes at least two waveforms of different frequencies.

[0014] According to some embodiments of the present invention, the processing unit is further configured to determine the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information; The processing unit is also used to determine the current phase of the conductor under test based on the current waveform information; The processing unit is also configured to output a third reference voltage signal for the electrical circuit, wherein the frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the ratio of the voltage amplitude of the conductor under test to the voltage division ratio, and its voltage phase is the opposite phase of the current phase. The processing unit is also used to acquire third waveform information of the voltage on the measuring capacitor; the third waveform information includes only one frequency waveform.

[0015] According to some embodiments of the present invention, the processing unit is further configured to determine the correspondence between voltage frequency and voltage division amplitude based on the second waveform information; the processing unit is further configured to, based on the correspondence, use the voltage division amplitude corresponding to the voltage frequency of the first reference voltage signal as the voltage division amplitude of the first reference voltage signal, and use the voltage division amplitude corresponding to the voltage frequency of the conductor under test as the voltage division amplitude of the conductor under test; the processing unit is further configured to, based on the voltage amplitude of the first reference voltage signal... The first reference voltage divider amplitude And the second formula: Determine the voltage division ratio of the measuring capacitor. The processing unit is further configured to base its calculations on the voltage division ratio of the measured capacitor. The voltage division amplitude of the conductor under test And the third formula: Determine the voltage amplitude of the conductor under test. .

[0016] According to some embodiments of the present invention, the processing unit is further configured to determine the current voltage division amplitude Vm of the measured capacitance based on the third waveform information; the processing unit is further configured to determine the voltage amplitude of the conductor under test based on the voltage division amplitude of the conductor under test. The measured voltage division ratio K, the current voltage division amplitude Vm, and the first formula: Determine the current-voltage phase difference of the conductor under test. The processing unit is further configured to determine the cosine value of the current-voltage phase difference as the power factor of the conductor under test.

[0017] According to some embodiments of the present invention, the first reference voltage signal and the third reference voltage signal are generated by pulse width modulation phase shifting.

[0018] According to some embodiments of the present invention, the measuring capacitor and the reference signal source are disposed inside the shield.

[0019] To achieve the above objectives, a third aspect of the present invention provides an electronic device, the electronic device including a power factor measuring device; The power factor measuring device is either the power factor measuring device described above or a power factor measuring device that uses the power factor measuring method described above to measure the power factor.

[0020] Therefore, compared with the prior art, the present invention has the following beneficial effects: The power factor measurement method of this invention includes: sensing a first coupling capacitor between a first coupling device and a conductor under test, wherein the first coupling capacitor and a measuring capacitor are coupled to form an electrical circuit; acquiring first waveform information of the voltage across the measuring capacitor; outputting a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information, and acquiring second waveform information of the voltage across the measuring capacitor; acquiring current waveform information of the conductor under test; outputting a third reference voltage signal with the same frequency but opposite phase to the current of the conductor under test to the electrical circuit based on the current waveform information, and acquiring third waveform information of the voltage across the measuring capacitor; and determining the power factor of the conductor under test based on the second and third waveform information. This invention achieves power factor measurement by adjusting the reference voltage signal, and has the advantages of simple structure and ease of implementation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating a power factor measurement method according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the power factor measuring device according to an embodiment of the present invention.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] In AC circuits, the power factor is the ratio of active power to apparent power. In sinusoidal steady-state AC circuits, the power factor is the cosine of the phase angle by which the current lags behind the voltage.

[0028] The power factor has a direct and significant impact on the efficiency of the power system. Although it does not directly affect the active power consumption of the load itself, it significantly affects the current, line loss, equipment capacity utilization, and electricity cost in the transmission and distribution system.

[0029] Existing power factor measurement methods generally include the impulse factor method, the DC component method, and the phase difference method. The impulse factor method and the DC component method require a 0° closing angle for accurate calculation, increasing testing time and difficulty. The phase difference method detects the phase difference between voltage and current signals at the same position and then calculates the power factor. It measures the voltage signal using a voltage transformer and the current signal using a current transformer, detecting the rising edge and period of the voltage signal and the rising edge of the current signal to obtain the signal period, the phase difference between voltage and current, and the power factor. However, this method cannot measure the power factor of the system during a short circuit.

[0030] In summary, it is of great significance to study an easy-to-implement method for measuring power factor.

[0031] This invention discloses a non-contact power factor measurement method to improve the problems of existing power factor measurement methods being complex and difficult to implement.

[0032] like Figure 1 As shown, the power factor measurement method provided in this embodiment of the invention includes the following steps: S100 senses the first coupling capacitance between itself and the wire under test through the first coupling device. The first coupling capacitance is coupled with the measuring capacitance to form an electrical circuit.

[0033] The purpose of this step is to electrically couple the wire under test to form an equivalent closed loop through the first coupling capacitor and the measuring capacitor.

[0034] In this embodiment of the invention, the first coupling device is attached to the wire under test, and it is not necessary to peel off the outer insulation layer of the wire under test, thus realizing non-contact or non-invasive acquisition of the voltage information of the wire under test.

[0035] It should be understood that when the conductor under test is the only voltage source of the electrical circuit, the frequency at which the voltage across the capacitor is measured is the voltage frequency of the conductor under test.

[0036] S200 acquires the first waveform information of the voltage across the measuring capacitor.

[0037] The purpose of this step is to further obtain the voltage frequency of the conductor under test through the first waveform information.

[0038] In this embodiment of the invention, the voltage on the measuring capacitor is amplified by a voltage signal processing unit, and the amplified voltage on the voltage divider capacitor is converted into a discrete digital signal. The discrete digital signal is then subjected to spectrum analysis by Fourier transform to obtain the first waveform information of the voltage on the measuring capacitor.

[0039] S300 outputs a first reference voltage signal with a different frequency than the voltage of the conductor under test to the electrical circuit based on the first waveform information, and acquires the second waveform information of the voltage on the measuring capacitor.

[0040] The purpose of this step is to output a reference voltage signal with a different frequency than the voltage of the conductor under test to the electrical circuit, and to obtain information on the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test through the second waveform information.

[0041] It should be understood that the reference voltage signal can be input into the electrical circuit through a reference signal source, and thus the conductor under test and the reference voltage signal serve as the common voltage source for the electrical circuit. In this case, the frequency of the voltage across the capacitor being measured includes the first voltage frequency of the conductor under test and the second voltage frequency of the reference voltage signal.

[0042] When the first voltage frequency of the conductor under test is different from the second voltage frequency of the reference voltage signal, the voltage division amplitude of the first voltage frequency in the waveform information of the voltage across the measuring capacitor is the voltage division amplitude of the conductor under test, and the voltage division amplitude of the second voltage frequency is the voltage division amplitude of the reference voltage signal. The ratio of the voltage division amplitude of the conductor under test to the voltage amplitude of the conductor under test and the ratio of the voltage division amplitude of the reference voltage signal to the voltage amplitude of the reference voltage signal are both voltage division ratios of the measuring capacitor.

[0043] It should be understood that in the electrical circuit of this embodiment of the invention, the ratio of the voltage division amplitude of the first reference voltage signal acting on the measuring capacitor to the voltage amplitude of the first reference voltage signal, and the ratio of the voltage division amplitude of the wire under test acting on the measuring capacitor to the voltage amplitude of the wire under test, are both the voltage division ratio K of the measuring capacitor. Given that the voltage division amplitude of the wire under test, the voltage division amplitude of the first reference voltage signal, and the voltage amplitude of the first reference voltage signal are all known, the voltage amplitude of the wire under test can be further obtained.

[0044] Specifically, step S300 includes steps S310 to S330.

[0045] S310 determines the voltage frequency of the conductor under test based on the first waveform information.

[0046] This step can obtain the voltage frequency and voltage phase information from the first waveform information through a phase-locked loop circuit.

[0047] S320 outputs a first reference voltage signal for the electrical circuit; the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz.

[0048] It should be noted that the voltage frequency of the first reference voltage signal should be different from the voltage frequency of the conductor under test, and the difference is not limited to less than 20Hz. There is no specific limitation here.

[0049] It should be noted that this step can also simultaneously output a first reference voltage signal and a second reference voltage signal to the electrical circuit, and verify the accuracy of the test results using the second reference voltage signal. The second reference voltage signal has a different frequency from both the first reference voltage signal and the voltage of the conductor under test. The voltage division ratio of the measuring capacitor is determined when the ratio of the voltage division amplitude of the first reference voltage signal to the voltage amplitude of the first reference voltage signal and the ratio of the voltage division amplitude of the second reference voltage signal to the voltage amplitude of the second reference voltage signal are the same.

[0050] S330 acquires the second waveform information of the voltage across the measuring capacitor; the frequency of the second waveform information includes at least two waveforms of different frequencies.

[0051] The voltage across the measuring capacitor is amplified by an amplifier circuit. An analog-to-digital converter then converts the amplified voltage across the voltage divider capacitor into a discrete digital signal. A Fourier transform module performs spectral analysis on the discrete digital signal to obtain the second waveform information of the voltage across the measuring capacitor. This second waveform information includes waveforms at at least two frequencies: the voltage frequency of the first reference voltage signal and the voltage frequency of the conductor under test.

[0052] It should be noted that the voltage frequency included in the second waveform information is not limited to the voltage frequency of the first reference voltage signal and the voltage frequency of the conductor under test, but may also include the voltage frequency of the second reference voltage signal.

[0053] The S400 acquires the current waveform information of the conductor under test.

[0054] The purpose of this step is to obtain the current phase information of the conductor under test.

[0055] Specifically, the current waveform information of the conductor under test is obtained non-contactly through a magnetoresistive array sensor.

[0056] It should be noted that, in addition to magnetoresistive array sensors, other current sensors with magnetoresistive effects or other non-contact current sensors for acquiring current information can also be used; no specific limitations are made here.

[0057] Based on the second waveform information and the current waveform information, S500 outputs a third reference voltage signal to the electrical circuit that is in the same frequency but out of phase with the current of the conductor under test, and acquires the third waveform information of the voltage on the measuring capacitor.

[0058] The purpose of this step is to output a reference voltage signal that is out of phase with the current based on the current phase information of the conductor under test, and to output a reference voltage signal that has the same voltage frequency, voltage amplitude and a certain phase difference as the voltage of the conductor under test.

[0059] Assume the angular frequency of the conductor under test is ω, and the phase difference between the current and voltage of the conductor under test is... The voltage amplitude of the conductor under test is Let the voltage division ratio of the measuring capacitor be K, and let the real-time voltage of the wire under test be [value]. Under the premise that the voltage amplitude and frequency of the third reference voltage signal are the same as those of the voltage amplitude and frequency of the conductor under test, and the voltage phase of the third reference voltage signal is out of phase with the current phase of the conductor under test, the real-time voltage value of the third reference voltage signal is The measured real-time voltage value V of the capacitor conforms to: V Then measure the current voltage division amplitude of the capacitor. conform to: .

[0060] Specifically, step S500 includes steps S510 to S540.

[0061] S510 determines the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information.

[0062] This step uses a phase-locked loop circuit to obtain the voltage division amplitude of the first reference voltage signal corresponding to the frequency of the first reference voltage signal and the voltage division amplitude of the conductor under test corresponding to the frequency of the conductor under test in the second waveform information; the ratio of the voltage division amplitude of the first reference voltage signal to the voltage division amplitude of the first reference voltage signal is determined as the voltage division ratio of the measuring capacitor, and the ratio of the voltage division amplitude of the conductor under test to the voltage division ratio of the measuring capacitor is taken as the voltage amplitude of the conductor under test.

[0063] Specifically, step S510 includes steps S511 to S513.

[0064] S511 determines the correspondence between voltage frequency and voltage division amplitude based on the second waveform information.

[0065] S512 uses the voltage divider amplitude corresponding to the voltage frequency of the first reference voltage signal as the voltage divider amplitude of the first reference voltage signal, and uses the voltage divider amplitude corresponding to the voltage frequency of the conductor under test as the voltage divider amplitude of the conductor under test. S513 based on the voltage amplitude of the first reference voltage signal First reference voltage divider amplitude And the second formula: Determine the voltage division ratio of the measuring capacitor. ; S514 is based on the measured capacitor voltage division ratio Voltage amplitude of the conductor under test And the third formula: determines the voltage amplitude of the conductor under test. .

[0066] The S520 determines the current phase of the conductor under test based on the current waveform information.

[0067] This step obtains the current phase of the conductor under test. Given that the current phase is known, setting the voltage phase of the third reference voltage signal can obtain the phase shift of the conductor under test.

[0068] S530 outputs a third reference voltage signal for the electrical circuit; the voltage frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the voltage amplitude of the conductor under test, and its voltage phase is the opposite of the current phase.

[0069] The S540 acquires the third waveform information of the voltage across the measuring capacitor; the third waveform information includes only one frequency waveform.

[0070] The S600 determines the power factor of the conductor under test based on the second and third waveform information.

[0071] Because the second waveform information includes the voltage division ratio K of the measuring capacitor and the voltage amplitude of the conductor under test. The information in the third waveform includes the current voltage division amplitude of the measured capacitor. The information includes the voltage division ratio K of the capacitor being measured and the voltage amplitude of the conductor under test. and the current voltage drop across the measuring capacitor. Given the known facts, we can use the first formula: Determine the phase difference between the current and voltage of the conductor under test. .

[0072] Specifically, step S600 includes steps S610 to S630.

[0073] S610 determines the voltage amplitude Vm of the measured capacity based on the third waveform information; S620 is based on the voltage amplitude of the conductor under test. Measure the partial voltage ratio K, the current partial voltage amplitude Vm, and the first formula: Determine the phase difference between the current and voltage of the conductor under test. ; The S630 uses the cosine of the phase difference between current and voltage to determine the power factor of the conductor under test.

[0074] Specifically, the power factor PF conforms to the formula: PF = cos ,pass Determine the value of the power factor.

[0075] This invention also provides a power factor measuring device.

[0076] like Figure 2 As shown, the power factor measuring device includes a first coupling device 100, a measuring capacitor 200, a reference signal source 300, a current sensing component 400, and a processing unit.

[0077] The first coupling device 100 is coupled to the wire under test 600 to form a first coupling capacitor; the measuring capacitor is coupled to the first coupling device to form an electrical circuit.

[0078] The reference signal source 300 is coupled to the electrical circuit and is used to input a reference voltage signal to the electrical circuit. The current sensing component is used to sense the current waveform information of the conductor under test; The processing unit is electrically coupled to the measuring capacitor 200, the reference signal source 300, and the current sensing component 400, respectively.

[0079] The processing unit is used to acquire the first waveform information of the voltage across the measuring capacitor when the conductor under test acts alone on the measuring capacitor.

[0080] Specifically, when the conductor under test acts alone on the measuring capacitor, the processing unit obtains the first waveform information of the voltage on the measuring capacitor through the voltage processing unit 510 coupled to the measuring capacitor.

[0081] The processing unit is also used to output a first reference voltage signal with a different frequency from the voltage of the conductor under test for the electrical circuit based on the first waveform information, and to obtain the second waveform information of the voltage on the measuring capacitor.

[0082] The processing unit is also used to sense the current waveform information of the conductor under test.

[0083] Specifically, the processing unit obtains the current waveform information sensed by the current sensing component through the current processing unit 530.

[0084] The processing unit is also used to output a third reference voltage signal that is in the same frequency but out of phase with the current of the conductor under test to the electrical circuit based on the second waveform information and the current waveform information through the signal processing unit, and to obtain the third waveform information of the voltage of the measuring capacitor through the voltage processing unit 510.

[0085] The processing unit is also used to determine the power factor of the conductor under test based on the second waveform information and the third waveform information by the signal processing unit 530.

[0086] The processing unit is also used to determine the voltage frequency of the conductor under test based on the first waveform information.

[0087] The processing unit is also used to output a first reference voltage signal for the electrical circuit, wherein the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz.

[0088] The processing unit is also used to acquire second waveform information of the voltage on the measuring capacitor, wherein the frequency of the second waveform information includes at least two waveforms of different frequencies.

[0089] The processing unit is also used to determine the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information.

[0090] The processing unit is also used to determine the current phase of the conductor under test based on the current waveform information.

[0091] The processing unit is also used to output a third reference voltage signal for the electrical circuit, wherein the frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the voltage amplitude of the conductor under test, and its voltage phase is the opposite of the current phase.

[0092] The processing unit is also used to acquire third waveform information of the voltage across the measuring capacitor; the third waveform information includes only one frequency waveform.

[0093] The processing unit is also used to determine the correspondence between voltage frequency and voltage division amplitude based on the second waveform information.

[0094] The processing unit is also used to, based on the correspondence, take the voltage division amplitude corresponding to the voltage frequency of the first reference voltage signal as the voltage division amplitude of the first reference voltage signal, and take the voltage division amplitude corresponding to the voltage frequency of the conductor under test as the voltage division amplitude of the conductor under test.

[0095] The processing unit is also used to determine the voltage amplitude of the first reference voltage signal. First reference voltage divider amplitude And the second formula: Determine the voltage division ratio of the measuring capacitor. .

[0096] The processing unit is also used to measure the voltage division ratio of the capacitor. Voltage amplitude of the conductor under test And the third formula: Determine the voltage amplitude of the conductor under test. .

[0097] The processing unit is also used to determine the current voltage division amplitude Vm of the measured capacitance based on the third waveform information; the processing unit is also used to determine the voltage amplitude of the conductor under test based on the voltage division amplitude of the conductor under test. Measure the partial voltage ratio K, the current partial voltage amplitude Vm, and the first formula: Determine the phase difference between the current and voltage of the conductor under test. .

[0098] The processing unit is also used to determine the cosine value of the phase difference between current and voltage as the power factor of the conductor under test.

[0099] In this embodiment of the invention, the first reference voltage signal and the third reference voltage signal are generated by pulse width modulation phase shifting.

[0100] In this embodiment of the invention, both the measuring capacitance and the reference signal source are located inside the shield.

[0101] This invention also discloses an electronic device, which includes a power factor measuring device; the power factor measuring device is the power factor measuring device described above or a power factor measuring device that implements power factor measurement using the power factor measuring method described above.

[0102] Therefore, compared with the prior art, the present invention has the following beneficial effects: The power factor measurement method of this invention includes: sensing a first coupling capacitor between a first coupling device and a conductor under test, wherein the first coupling capacitor and a measuring capacitor are coupled to form an electrical circuit; acquiring first waveform information of the voltage across the measuring capacitor; outputting a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information, and acquiring second waveform information of the voltage across the measuring capacitor; acquiring current waveform information of the conductor under test; outputting a third reference voltage signal with the same frequency but opposite phase to the current of the conductor under test to the electrical circuit based on the current waveform information, and acquiring third waveform information of the voltage across the measuring capacitor; and determining the power factor of the conductor under test based on the second and third waveform information. This invention achieves power factor measurement by adjusting the reference voltage signal, and has the advantages of simple structure and ease of implementation.

[0103] The above are merely exemplary embodiments of the present invention and do not limit the scope of the patent of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A method for measuring power factor, characterized in that, Includes the following steps: The first coupling device senses the first coupling capacitance between itself and the wire under test, and the first coupling capacitance is coupled to the measuring capacitor to form an electrical circuit. Obtain the first waveform information of the voltage across the measuring capacitor; Based on the first waveform information, the electrical circuit outputs a first reference voltage signal that is at a different frequency from the voltage of the conductor under test, and obtains the second waveform information of the voltage on the measuring capacitor; Obtain the current waveform information of the conductor under test; Based on the second waveform information and the current waveform information, the electrical circuit outputs a third reference voltage signal that is in the same frequency but out of phase with the current of the conductor under test, and obtains the third waveform information of the voltage on the measuring capacitor. The power factor of the conductor under test is determined based on the second waveform information and the third waveform information.

2. The power factor measurement method according to claim 1, characterized in that, The step of outputting a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information, and acquiring the second waveform information of the voltage on the measuring capacitor, includes: The voltage frequency of the conductor under test is determined based on the first waveform information; A first reference voltage signal is output to the electrical circuit; the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz; Obtain the second waveform information of the voltage across the measuring capacitor; the frequency of the second waveform information includes at least two waveforms of different frequencies.

3. The power factor measurement method according to claim 2, characterized in that, The step of outputting a third reference voltage signal that is in phase with and in the same frequency as the current output to the electrical circuit based on the second waveform information and the current waveform information, and acquiring the third waveform information of the voltage across the measuring capacitor, includes: The voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test are determined based on the second waveform information. The current phase of the conductor under test is determined based on the current waveform information; A third reference voltage signal is output for the electrical circuit; the voltage frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the ratio of the voltage amplitude of the conductor under test to the voltage division ratio, and its voltage phase is the opposite of the current phase. Obtain the third waveform information of the voltage across the measuring capacitor, wherein the third waveform information includes only a waveform of one frequency.

4. The power factor measurement method according to claim 3, characterized in that, Determining the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information includes: The correspondence between voltage frequency and voltage divider amplitude is determined based on the second waveform information. Based on the aforementioned correspondence, the voltage division amplitude corresponding to the voltage frequency of the first reference voltage signal is taken as the voltage division amplitude of the first reference voltage signal; the voltage division amplitude corresponding to the voltage frequency of the conductor under test is taken as the voltage division amplitude of the conductor under test. Based on the voltage amplitude of the first reference voltage signal The first reference voltage divider amplitude And the second formula: Determine the voltage division ratio of the measuring capacitor. ; Based on the measured capacitor voltage division ratio The voltage division amplitude of the conductor under test And the third formula: Determine the voltage amplitude of the conductor under test. .

5. The power factor measurement method according to claim 4, characterized in that, Determining the power factor of the conductor under test based on the second waveform information and the third waveform information includes: The current voltage division amplitude of the measuring capacitor is determined based on the third waveform information. ; Based on the voltage amplitude of the conductor under test The voltage division ratio K of the measured capacity, and the current voltage division amplitude. And the first formula: Determine the current-voltage phase difference of the conductor under test. ; The cosine value of the phase difference between the current and voltage is determined as the power factor of the conductor under test.

6. A power factor measuring device, characterized in that, Power factor measurement is performed using the power factor measurement method described in any one of claims 1-5. The power factor measuring device includes: The first coupling device is coupled to the wire under test to form a first coupling capacitor; The capacitance is measured and coupled to the first coupling device to form an electrical circuit; A reference signal source, coupled to the electrical circuit, is used to input a reference voltage signal to the measuring capacitor of the electrical circuit; A current sensing component for sensing the current waveform information of the conductor under test; The processing unit, electrically coupled to the measuring capacitor, the reference signal source, and the current sensing component, is configured to: acquire first waveform information of the voltage across the measuring capacitor when the conductor under test acts solely on the measuring capacitor; output a first reference voltage signal with a different frequency from the voltage of the conductor under test to the electrical circuit based on the first waveform information and acquire second waveform information of the voltage across the measuring capacitor; sense the current waveform information of the conductor under test; output a third reference voltage signal with the same frequency but opposite phase to the current of the conductor under test to the electrical circuit based on the second waveform information and the current waveform information and acquire third waveform information of the voltage across the measuring capacitor; and determine the power factor of the conductor under test based on the second waveform information and the third waveform information.

7. The power factor measuring device according to claim 6, characterized in that, The processing unit is also used to determine the voltage frequency of the conductor under test based on the first waveform information; The processing unit is also configured to output a first reference voltage signal for the electrical circuit, wherein the frequency difference between the first reference voltage signal and the voltage of the conductor under test is less than 20Hz; The processing unit is also used to acquire second waveform information of the voltage on the measuring capacitor, wherein the frequency of the second waveform information includes at least two waveforms of different frequencies.

8. The power factor measuring device according to claim 7, characterized in that, The processing unit is also used to determine the voltage division ratio of the measuring capacitor and the voltage amplitude of the conductor under test based on the second waveform information; The processing unit is also used to determine the current phase of the conductor under test based on the current waveform information; The processing unit is also configured to output a third reference voltage signal for the electrical circuit, wherein the frequency of the third reference voltage signal is the voltage frequency of the conductor under test, its voltage amplitude is the ratio of the voltage amplitude of the conductor under test to the voltage division ratio, and its voltage phase is the opposite phase of the current phase. The processing unit is also used to acquire third waveform information of the voltage on the measuring capacitor, wherein the third waveform information includes only a waveform of one frequency.

9. The power factor measurement method according to claim 6, characterized in that, The first reference voltage signal and the third reference voltage signal are generated by pulse width modulation phase shifting; and / or, The measuring capacitor and the reference signal source are located inside the shield.

10. An electronic device, characterized in that, The electronic device includes a power factor measuring device; The power factor measuring device is the power factor measuring device according to any one of claims 6-9 or the power factor measuring device that implements power factor measurement using the power factor measuring method according to any one of claims 1-5.

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