CN113358914B - Voltage measurement circuit, voltage measurement method thereof and voltage measurement equipment - Google Patents
Voltage measurement circuit, voltage measurement method thereof and voltage measurement equipment Download PDFInfo
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Abstract
When the voltage of a conductor to be measured is measured, the conductor to be measured is coupled into the circuit only through the first probe and the second probe, coupling capacitance is formed between the conductor to be measured and the probes for electrical coupling, and then aliasing signals obtained by measuring the two ends of the voltage divider are analyzed by the voltage analysis device, so that the voltage of the conductor to be measured can be obtained. The voltage measuring circuit is small in size, the defect that an electromagnetic voltage transformer is exposed does not exist, the insulation of a conductor to be measured does not need to be damaged in the whole measuring process, and the voltage measuring circuit is not required to be powered off during installation, use and dismantling. Therefore, a large number of measuring points can be arranged at low labor cost, the measuring process is not influenced by line insulation, and the measuring reliability is high.
Description
Technical Field
The present disclosure relates to the field of power measurement technologies, and in particular, to a voltage measurement circuit, a voltage measurement method thereof, and a voltage measurement device.
Background
The voltage measurement is widely applied to electric power systems, such as relay protection, electric energy metering, intelligent equipment control, online overvoltage monitoring and other fields. The accuracy, reliability, convenience and rapidity of voltage measurement are related to the reliable implementation of electric energy metering, relay protection, power system monitoring and diagnosis, power system fault analysis and the like. At present, the most common voltage measuring device used in power systems is an electromagnetic voltage transformer.
However, with the rapid development of national economy and the technological progress in the aspect of power systems, power production and capacity transmission are greatly improved, and the operating voltage level of a power grid is gradually improved, so that the defects of the electromagnetic voltage transformer are gradually exposed. On one hand, the electromagnetic voltage transformer has the defects of heavy volume, high price, explosion danger caused by short circuit, iron core saturation prevention during use, only alternating current signal measurement, low frequency, incapability of measuring high-frequency signals and the like.
On the other hand, when voltage data of a certain point of a power grid needs to be collected, power failure construction is mostly adopted, and an electromagnetic voltage transformer is hung on a line to obtain required voltage information. When the electromagnetic voltage transformer is installed, a metal part of a circuit is required to be led out, and then the electromagnetic voltage transformer is connected to carry out voltage measurement. However, in the actual voltage measurement, the situation that the insulation layer cannot be peeled off or the insulation is not damaged is often encountered in a more complicated environment. Therefore, the conventional voltage measurement scheme has poor measurement reliability.
Disclosure of Invention
Based on this, it is necessary to provide a voltage measurement circuit, a voltage measurement method thereof, and a voltage measurement device, aiming at the problem of poor measurement reliability of the conventional voltage measurement scheme.
A voltage measurement circuit comprising: a first probe; the second probe is coupled with the first probe to connect the conductor to be tested; the first probe is connected with a first end of the voltage dividing device; the second end of the voltage divider is connected with the reference voltage signal source, the reference voltage signal source is connected with the second probe, and the voltage frequency of the reference voltage signal source is different from that of the conductor to be detected; and the voltage analysis device is connected with the first end and the second end of the voltage divider and used for acquiring aliasing signals at the two ends of the voltage divider for analysis to obtain the voltage value of the conductor to be detected.
In one embodiment, the voltage dividing device is a voltage dividing capacitor.
In one embodiment, the voltage analysis apparatus includes a voltage collector and a signal processor, the voltage collector is connected to the first end and the second end of the voltage divider, and the signal processor is connected to the voltage collector.
In one embodiment, the first probe and the second probe are both metal plates.
In one embodiment, when the voltage measuring circuit is used for measuring phase voltage, the first probe is attached to the outer surface of the phase line to be measured, and the second probe is attached to the outer surface of the zero line; when the voltage measuring circuit is used for measuring the line voltage between any two phases, the first probe is attached to the outer surface of the first phase line, and the second probe is attached to the outer surface of the second phase line.
A voltage measurement method of the voltage measurement circuit comprises the following steps: acquiring aliasing signals at two ends of the voltage divider; according to the aliasing signal, obtaining a measurement voltage division value at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently, and a reference voltage division value at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently; and obtaining the voltage of the conductor to be measured according to the voltage of the reference voltage signal source, the reference divided voltage value and the measurement divided voltage value.
In an embodiment, the step of obtaining, according to the aliasing signal, a measured divided voltage value at two ends of the voltage divider when the voltage of the conductor to be measured acts on the voltage measurement circuit alone, and a reference divided voltage value at two ends of the voltage divider when the voltage of the reference voltage signal source acts on the voltage measurement circuit alone includes: and filtering the aliasing signal to respectively obtain the measurement partial pressure values at two ends of the voltage divider when the voltage of the conductor to be measured acts on the voltage measurement circuit independently and the reference partial pressure values at two ends of the voltage divider when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
In an embodiment, the step of obtaining, according to the aliasing signal, a measured divided voltage value at two ends of the voltage divider when the voltage of the conductor to be measured acts on the voltage measurement circuit alone, and a reference divided voltage value at two ends of the voltage divider when the voltage of the reference voltage signal source acts on the voltage measurement circuit alone includes: and carrying out Fourier transform processing on the aliasing signal to obtain a measurement voltage division value at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently, and a reference voltage division value at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
In one embodiment, the obtaining the voltage of the conductor to be tested according to the voltage of the reference voltage signal source, the reference divided voltage value and the measurement divided voltage value includes:
wherein, UsFor the voltage of the conductor to be measured, UrIs the voltage of a reference voltage signal source, VrFor reference to the value of the partial pressure, VsTo measure the partial pressure value.
A voltage measuring device comprises the voltage measuring circuit, and a voltage analyzing device of the voltage measuring circuit measures the voltage of a conductor to be measured according to the method.
According to the voltage measuring circuit, the voltage measuring method and the voltage measuring equipment, when the voltage of the conductor to be measured is measured, the conductor to be measured is coupled into the circuit only through the first probe and the second probe, the coupling capacitor is formed between the conductor to be measured and the probes for electrical coupling, and then the voltage analyzing device is used for analyzing aliasing signals obtained by measuring two ends of the voltage divider component, so that the voltage of the conductor to be measured can be obtained. The voltage measuring circuit is small in size, the defect that an electromagnetic voltage transformer is exposed does not exist, the insulation of a conductor to be measured does not need to be damaged in the whole measuring process, and the voltage measuring circuit is not required to be powered off during installation, use and dismantling. Therefore, a large number of measuring points can be arranged at low labor cost, the measuring process is not influenced by line insulation, and the measuring reliability is high.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a voltage measurement circuit according to an embodiment;
FIG. 2 is a schematic diagram of an embodiment of a voltage measurement circuit connected to a conductor under test;
FIG. 3 is an equivalent schematic diagram of a voltage measurement circuit according to an embodiment;
FIG. 4 is an equivalent schematic diagram of a voltage measurement circuit in another embodiment;
FIG. 5 is a schematic diagram of a short circuit structure of a reference voltage signal source of the voltage measurement circuit according to an embodiment;
FIG. 6 is a schematic diagram of a short-circuit structure of a to-be-tested conductor of the voltage measurement circuit in one embodiment;
FIG. 7 is an impedance equivalent diagram of a voltage measurement circuit according to an embodiment;
FIG. 8 is an impedance equivalent diagram of a voltage measurement circuit in another embodiment;
FIG. 9 is a schematic diagram of another embodiment of a voltage measurement circuit;
FIG. 10 is a schematic diagram of another embodiment of a voltage measurement circuit connected to a conductor under test;
FIG. 11 is an equivalent schematic diagram of a voltage measurement circuit according to yet another embodiment;
FIG. 12 is an equivalent schematic diagram of a voltage measurement circuit according to yet another embodiment;
FIG. 13 is a schematic diagram of a voltage measurement circuit connected to a conductor under test in an embodiment;
FIG. 14 is an equivalent schematic diagram of a voltage measurement circuit according to yet another embodiment;
FIG. 15 is a flow chart illustrating a measurement method of the voltage measurement circuit according to an embodiment;
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are illustrated in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Referring to fig. 1, a voltage measurement circuit includes: a first probe 10; the second probe 20 couples the conductor to be tested in together with the first probe 10; voltage divider C1The first probe 10 is connected with a voltage divider C1A first end of (a); reference voltage signal source 40, voltage divider C1Is connected to a reference voltage signal source 40, the reference voltage signal source 40 is connected to the second probe 20, the reference voltageThe voltage frequency of the signal source 40 is different from the voltage frequency of the conductor to be measured; a voltage analyzer 30 connected to the voltage divider C1For obtaining the voltage divider C1And analyzing the aliasing signals at the two ends to obtain the voltage value of the conductor to be measured.
Specifically, in the voltage measurement circuit provided in this embodiment, the first probe 10 and the second probe 20 are used to couple in the conductor to be measured, so as to form an equivalent closed loop. The coupling access means that in the process of accessing the conductor to be measured, the probe and the conductor to be measured are only arranged in an attaching mode (an insulating layer still exists in the middle), the outer insulating layer of the conductor to be measured does not need to be stripped, at the moment, the probe forms electrical coupling with the conductor to be measured through parasitic capacitance, coupling capacitance is formed between the conductor to be measured and the probe, and therefore a non-invasive voltage measurement scheme is achieved.
It will be appreciated that the manner in which the first probe 10 and the second probe 20 couple in the conductor to be measured during the actual measurement process is not exclusive. In one embodiment, there may be electrical coupling between the first probe head 10 and the second probe head 20 and the conductor to be measured, and neither the first probe head 10 nor the second probe head 20 directly contact the conductor to be measured. In another embodiment, there may be an electrical coupling between the first probe 10 and the conductor to be measured, the first probe 10 not directly contacting the conductor to be measured, and the second probe 20 having a direct metallic contact with the ground. In the actual measurement process, different choices should be made in connection with the type of voltage that needs to be measured.
In an embodiment, referring to fig. 2 and fig. 3 in combination, taking the measurement of the phase voltage as an example, after the conductor to be measured is connected to the voltage measurement circuit provided in this embodiment, the circuit diagram thereof may be equivalent to that shown in fig. 3. In this embodiment, the first probe 10 is attached to the outer surface of the phase line to be measured, and the second probe 20 is directly attached to the outer surface of the neutral line, wherein the voltage of the conductor to be measured (i.e. the phase line) is UsIs actually a frequency of fsOf the sinusoidal signal, coupling capacitor C0I.e. the coupling capacitance between the phase line and the first probe head 10, coupling capacitance C2I.e. representing the neutral line and the second probe20 coupling capacitance, UrIt represents the voltage of the reference voltage signal source 40, actually a frequency frOf sinusoidal signal frAnd fsAre not identical. In the actual test process, considering that the potential of the zero line is usually 0, the reference voltage signal source 40 and the voltage of the conductor to be tested are actually common to the ground, so from the viewpoint of the circuit, the circuit shown in fig. 3 can be further simplified and equivalent to that shown in fig. 4.
According to the circuit superposition theorem, if a plurality of sinusoidal alternating-current power supplies with different frequencies act together in the linear alternating-current circuit, after the linear alternating-current circuit reaches a stable state, the voltage passing through any element in the circuit is equal to the sum of the voltages generated by the element when the power supplies act independently. Thus, the circuit shown in FIG. 4 can be decoupled as fsAnd frTwo frequencies, respectively at power frequency fsAnd a reference frequency frAnd a lower observation circuit. When the power supply U is testedsWhen present alone, reference signal UrShort-circuiting treatment can be performed. When reference signal UrWhen existing alone, the power supply U to be testedsShort-circuiting treatment can be performed. At power frequency fsLower, partial pressure device C1Voltage on is detected as VsNamely, obtaining a measured partial pressure value; at a reference frequency frLower, partial pressure device C1Voltage on is detected as VrI.e. a reference partial pressure value is obtained. At this time, the power frequency fsThe circuit observed below is shown in FIG. 5 at a reference frequency frThe observed circuit is shown in fig. 6.
At power frequency f, according to the relation between capacitance and frequencysLower, coupling capacitance C0Partial pressure device C1Capacitor C of1Coupling capacitor C2The impedance of (d) can be expressed as:
further, power frequency fsThe equivalent impedance circuit is shown in FIG. 7, in which the voltage divider C is based on the voltage dividing formula1Measured partial pressure values V at both endssCan be expressed as:
finally Z iss0、Zs1And Zs2Substituting the expression of (a) to obtain:
and power frequency fsIn the same way, the reference frequency f can be obtainedrLower, coupling capacitance C0Partial pressure device C1Capacitor C of1Coupling capacitor C2The impedance of (d) can be expressed as:
power frequency f corresponding to this momentrThe equivalent circuit is shown in FIG. 8, where the voltage divider C is based on the voltage dividing formula1Reference partial pressure value V at both endsrCan be expressed as:
finally Z isr0、Ze1And Zr2Substituting the expression of (a) to obtain:
binding VrAnd VsAs can be seen from the final expression of (c),
in actual circuit detection, VrAnd VsCan be obtained by circuit analysis, calculation and detection, and UrThe voltage of the reference voltage signal source 40, the specific value of which is determined when the reference voltage signal source 40 is selected, is obtained according to the expression
The voltage U of the conductor to be measured can be directly obtainedsThe size of (2).
It should be noted that in one embodiment, voltage divider device C1Is a voltage dividing capacitor.
Specifically, in this embodiment, in order to match with the coupling capacitance between the probe and the conductor to be measured, the corresponding voltage divider C is provided1The voltage dividing capacitor is also adopted to realize the voltage dividing operation of the capacitor, so that the voltage dividing device C1The two ends can acquire voltage aliasing signals for analysis. In one embodiment, the voltage-dividing capacitance is much greater than the coupling capacitance formed between the probe and the conductor under test, typically on the order of nanofarads (nf). It is understood that in other embodiments, other devices or devices with capacitive voltage dividing characteristics may be used as the voltage dividing device C1As long as the function of capacitive voltage division can be achieved.
Referring to fig. 9, in an embodiment, the voltage analysis apparatus 30 includes a voltage collector 31 and a signal processor 32, wherein the voltage collector 31 is connected to the voltage divider C1First end of andand a second end, the signal processor 32 is connected to the voltage collector 31.
Specifically, the specific type of the voltage collector 31 is not exclusive, and in one embodiment, the voltage collector may be a device composed of an amplifying unit, a filtering unit, a collecting unit, a frequency dividing unit, a communication unit, and the like, as long as the voltage dividing device C can be implemented1And voltage signals at two ends can be acquired. The voltage collector 31 collects a voltage signal (the voltage signal is generally V)rAnd VSAlias of (b) the acquired voltage signals are sent to the signal processor 32 for processing to obtain VrAnd VsFinally combined with the voltage U of the reference voltage signal source 40rThe final voltage value U of the conductor to be measured can be obtaineds。
Further, in one embodiment, the first probe 10 and the second probe 20 are both metal plates.
Specifically, in order to ensure that a coupling capacitor can be formed between the probe and the conductor to be measured, the first probe 10 and the second probe 20 are both implemented in the form of metal plates, and in the actual measurement process, the first probe 10 and the second probe 20 are only required to be fixedly attached to the conductor to be measured in the modes of clamps and the like.
In one embodiment, when the voltage measuring circuit is used for measuring phase voltage, the first probe 10 is attached to the outer surface of the phase line to be measured, and the second probe 20 is attached to the outer surface of the zero line; when the voltage measuring circuit is used for measuring the line voltage between any two phases, the first probe 10 is attached to the outer surface of the first phase line, and the second probe 20 is attached to the outer surface of the second phase line.
Specifically, the voltage measurement circuit provided by this embodiment can measure the phase voltage of any phase line in a three-phase power grid, measure the phase voltage between any two phases, and the like, and in different measurement schemes, the first probe 10 and the second probe 20 have different ways of coupling the conductor to be measured into the circuit. In some applications, such as a switch cabinet, a power distribution room, etc., the switch cabinet housing itself may provide a ground connection, such that the second probe 20 may be selectively electrically connected to the switch cabinet housing as a ground connection, and when a ground line exists around the power transmission line, the second probe 20 may also be directly connected to the ground line.
The line voltage U between the A phase and the B phase is combinedABThe measurements are explained. Referring to fig. 10, the detection method is similar to the measurement of the phase voltage, except that the first probe 10 and the second probe 20 are respectively attached to the outer surface of the a-phase power transmission line and the outer surface of the B-phase power transmission line, and the B-phase power transmission line is used as a reference (the phase voltage measurement uses the zero line voltage as a reference), and the voltage of the corresponding conductor to be measured is represented as UAB。
When a coupling capacitance is formed between the conductor to be measured and the probe, the measurement schematic diagram shown in fig. 10 may be equivalent to the circuit diagram shown in fig. 11. Further, the A-phase voltage U is generated in the power systemAAnd phase voltage U of phase BBShare a common neutral point. Therefore, the line voltage U between the A phase and the B phaseABCan be expressed as: u shapeAB＝UA-UBTherefore, the circuit diagram shown in fig. 11 can be further simplified to obtain the equivalent circuit diagram shown in fig. 12. Wherein the voltage (i.e. line voltage) of the conductor to be tested is UABIs actually a frequency of fABOf the sinusoidal signal, coupling capacitor C3I.e. represents the coupling capacitance between the a-phase transmission line and the first probe 10, the coupling capacitance C4I.e. representing the coupling capacitance, U, between the B-phase transmission line and the second probe 20rIt represents the voltage of the reference voltage signal source 40, actually a frequency frOf the sinusoidal signal. According to the same analysis method for measuring the phase voltage in the above embodiment, the measured voltage division value V can be obtained finallyABAnd a reference partial pressure VrRatio of (a) to (b)
Can finally obtain
The voltage analysis device 30 only needs to analyze the acquired aliasing signals to obtain the measured voltage division value VABAnd a reference partial pressure VrThe voltage of the reference voltage signal source 40 will be combined to obtain the measured line voltage UABThe size of (2).
In another embodiment, when voltage measurement is performed in a scenario such as a switch cabinet, the second probe 20 is directly grounded, and the second probe 20 does not have a coupling capacitor, and the corresponding equivalent circuit may be shown in fig. 13 and 14, and in the simplified equivalent circuit diagram shown in fig. 14, a decoupling analysis manner similar to the phase voltage is adopted, and the voltage frequency f of the conductor to be measured is measuredsThen, the measured partial pressure value V can be obtainedsComprises the following steps:
at the frequency f of the reference voltage sourcerReference partial pressure value VrThen it is:
at this time also have
By the same method, the reference partial pressure value V is obtainedrAnd measuring the partial pressure value VsAfter the size of the conductor to be tested, the voltage detection operation of the conductor to be tested can be realized.
When the voltage of the conductor to be measured is measured, the voltage measuring circuit only needs to couple the conductor to be measured into the circuit through the first probe 10 and the second probe 20, a coupling capacitor is formed between the conductor to be measured and the probes for electrical coupling, and then the voltage analyzing device 30 is used for electrically coupling the voltage divider C1And analyzing the aliasing signals obtained by measuring the two ends to obtain the voltage of the conductor to be measured. The voltage measuring circuit is small in size, the defect that an electromagnetic voltage transformer is exposed does not exist, the insulation of a conductor to be measured does not need to be damaged in the whole measuring process, and the voltage measuring circuit is not required to be powered off during installation, use and dismantling. Therefore, can be lowerA large number of measuring points are arranged at the labor cost, the measuring process is not influenced by circuit insulation, and the measuring reliability is high.
Referring to fig. 15, a voltage measuring method of the voltage measuring circuit includes steps S100, S200 and S300.
S100, acquiring aliasing signals at two ends of a voltage divider; step S200, obtaining measurement partial pressure values at two ends of the voltage dividing device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently according to the aliasing signals, and reference partial pressure values at two ends of the voltage dividing device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently; and step S300, obtaining the voltage of the conductor to be measured according to the voltage of the reference voltage signal source, the reference divided voltage value and the measured divided voltage value.
Specifically, in the voltage measurement circuit provided in this embodiment, the first probe 10 and the second probe 20 are used to couple and connect the conductor to be measured, so as to form an equivalent closed loop, and in the process of connecting the conductor to be measured, the probes and the conductor to be measured are only attached, and the external insulating layer of the conductor to be measured does not need to be peeled off, thereby implementing a non-invasive voltage measurement scheme. After the conductor to be tested and the probe are attached, a coupling capacitor is formed between the conductor to be tested and the probe. The voltage analyzing device 30 is connected to the voltage dividing device C1After the conductor to be tested is connected in, the voltage divider C1The two ends of the voltage source are used for acquiring an aliasing signal composed of a measured voltage division value and a reference voltage division value, then the aliasing signal is processed by the voltage analysis device 30 to respectively obtain the measured voltage division value and the reference voltage division value, and finally the magnitude of the voltage signal flowing through the conductor to be measured is obtained by combining the voltage value of the reference voltage signal source 40 and calculation.
It should be noted that the manner of obtaining the measured divided voltage value and the reference divided voltage value from the alias signal is not exclusive, and in one embodiment, the step S200 includes: and filtering the aliasing signals to respectively obtain the measurement voltage division values at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently and the reference voltage division values at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
In particular, when the voltage of the conductor to be measured is applied to the voltage measuring circuit alone, at the voltage dividing device C1The frequency of the voltage signal collected is the same as the voltage frequency of the conductor to be measured, and when the reference signal voltage is applied to the voltage measuring circuit alone, the voltage dividing device C1The frequency of the voltage signal collected at this point is the same as the voltage frequency of the reference voltage signal source 40. Therefore, when the voltage of the conductor to be measured and the voltage of the reference signal are simultaneously applied, the voltage dividing device C1The acquired aliasing signals simultaneously comprise signals of two different frequencies. At this time, the signals of two different frequency components can be separated only by filtering processing through the filter, and then the measured partial pressure value and the reference partial pressure value are obtained respectively.
It can be understood that the voltage analyzing device 30 is a pair of voltage dividing devices C1The filtering method of the aliasing signals collected at the two ends is not exclusive, and in one embodiment, the voltage analysis device 30 may include a hardware filter, and the filtering process is implemented by a hardware circuit. In another embodiment, the method can also be realized by a software filtering mode.
It should be noted that, in another embodiment, step S200 includes: and carrying out Fourier transform processing on the aliasing signals to obtain the measurement voltage division values at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently and the reference voltage division values at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
Specifically, based on the above principle, according to the difference between the reference divided voltage value and the measured divided voltage value in frequency, the aliasing signal may be decomposed into linear superposition of each frequency component in a fourier transform manner, so as to obtain the reference divided voltage value and the measured divided voltage value.
In one embodiment, obtaining the voltage of the conductor to be tested according to the voltage of the reference voltage signal source 40, the reference divided voltage value and the measured divided voltage value includes:
wherein, UsFor the voltage of the conductor to be measured, UrIs the voltage of a reference voltage signal source 40, VrFor reference to the value of the partial pressure, VsTo measure the partial pressure value.
Specifically, referring to fig. 2 and fig. 3, taking the measurement of the phase voltage as an example, after the conductor to be measured is connected to the voltage measurement circuit provided in this embodiment, the circuit diagram thereof may be equivalent to that shown in fig. 3. In this embodiment, the first probe 10 is attached to the outer surface of the phase line to be measured, and the second probe 20 is directly attached to the outer surface of the neutral line, wherein the voltage of the conductor to be measured (i.e. the phase line) is UsIs actually a frequency of fsOf the sinusoidal signal, coupling capacitor C0I.e. the coupling capacitance between the phase line and the first probe head 10, coupling capacitance C2I.e. representing the coupling capacitance, U, between the neutral line and the second probe 20rIt represents the voltage of the reference voltage signal source 40, actually a frequency frOf the sinusoidal signal. In the actual test process, considering that the potential of the zero line is usually 0, the reference voltage signal source 40 and the voltage of the conductor to be tested are actually common to the ground, so from the viewpoint of the circuit, the circuit shown in fig. 3 can be further simplified and equivalent to that shown in fig. 4.
According to the circuit superposition theorem, if a plurality of sinusoidal alternating-current power supplies with different frequencies act together in the linear alternating-current circuit, after the linear alternating-current circuit reaches a stable state, the voltage passing through any element in the circuit is equal to the sum of the voltages generated by the element when the power supplies act independently. Thus, the circuit shown in FIG. 4 can be decoupled as fsAnd frTwo frequencies, respectively at power frequency fsAnd a reference frequency frAnd a lower observation circuit. When the power supply U is testedsWhen present alone, reference signal UrShort-circuiting treatment can be performed. When reference signal UrWhen existing alone, the power supply U to be testedsShort-circuiting treatment can be performed. At power frequency fsLower, partial pressure device C1Voltage on is detected as VsNamely, obtaining a measured partial pressure value; at a reference frequency frLower, partial pressure device C1Voltage detecting junction onThe fruit is VrI.e. a reference partial pressure value is obtained. At this time, the power frequency fsThe circuit observed below is shown in FIG. 5 at a reference frequency frThe observed circuit is shown in fig. 6.
At power frequency f, according to the relation between capacitance and frequencysLower, coupling capacitance C0Partial pressure device C1Capacitor C of1Coupling capacitor C2The impedance of (d) can be expressed as:
further, power frequency fsThe equivalent impedance circuit is shown in FIG. 7, in which the voltage divider C is based on the voltage dividing formula1Measured partial pressure values V at both endssCan be expressed as:
finally Z iss0、Zs1And Zs2Substituting the expression of (a) to obtain:
and power frequency fsIn the same way, the reference frequency f can be obtainedrLower, coupling capacitance C0Partial pressure device C1Capacitor C of1Coupling capacitor C2The impedance of (d) can be expressed as:
power frequency f corresponding to this momentrThe equivalent circuit is shown in FIG. 8, where the voltage divider C is based on the voltage dividing formula1Reference partial pressure value V at both endsrCan be expressed as:
finally Z isr0、Zr1And Zr2Substituting the expression of (a) to obtain:
binding VrAnd VsAs can be seen from the final expression of (c),
in actual circuit detection, VrAnd VsCan be obtained by circuit analysis, calculation and detection, and UrThe voltage of the reference voltage signal source 40, the specific value of which is determined when the reference voltage signal source 40 is selected, is obtained according to the expression
The voltage U of the conductor to be measured can be directly obtainedsThe size of (2).
The voltage measuring method of the voltage measuring circuit only needs to measure the voltage of the conductor to be measuredThe conductor to be tested is coupled into the circuit through the first probe 10 and the second probe 20, a coupling capacitor is formed between the conductor to be tested and the probes for electrical coupling, and then the voltage divider C is subjected to voltage analysis by the voltage analysis device 301And analyzing the aliasing signals obtained by measuring the two ends to obtain the voltage of the conductor to be measured. The voltage measuring circuit is small in size, the defect that an electromagnetic voltage transformer is exposed does not exist, the insulation of a conductor to be measured does not need to be damaged in the whole measuring process, and the voltage measuring circuit is not required to be powered off during installation, use and dismantling. Therefore, a large number of measuring points can be arranged at low labor cost, the measuring process is not influenced by line insulation, and the measuring reliability is high.
A voltage measuring device comprises the voltage measuring circuit, and a voltage analyzing device 30 of the voltage measuring circuit measures the voltage of a conductor to be measured according to the method.
Specifically, as shown in the above embodiments and the accompanying drawings, the first probe 10 and the second probe 20 are adopted to couple in the conductor to be measured to form an equivalent closed loop, and in the process of connecting in the conductor to be measured, the probes and the conductor to be measured are only attached, and the external insulating layer of the conductor to be measured does not need to be peeled off, so that a non-invasive voltage measurement scheme is implemented. After the conductor to be tested and the probe are attached, a coupling capacitor is formed between the conductor to be tested and the probe. The voltage analyzing device 30 is connected to the voltage dividing device C1After the conductor to be tested is connected in, the voltage divider C1The two ends of the voltage source are used for acquiring an aliasing signal composed of a measured voltage division value and a reference voltage division value, then the aliasing signal is processed by the voltage analysis device 30 to respectively obtain the measured voltage division value and the reference voltage division value, and finally the magnitude of the voltage signal flowing through the conductor to be measured is obtained by combining the voltage value of the reference voltage signal source 40 and calculation.
When the voltage of the conductor to be measured is measured, the voltage measuring equipment only needs to couple the conductor to be measured into the circuit through the first probe 10 and the second probe 20, and the conductor to be measured and the probes form a coupling connectionThe coupling capacitor is electrically coupled, and the voltage divider C is analyzed by the voltage analyzer 301And analyzing the aliasing signals obtained by measuring the two ends to obtain the voltage of the conductor to be measured. The voltage measuring circuit is small in size, the defect that an electromagnetic voltage transformer is exposed does not exist, the insulation of a conductor to be measured does not need to be damaged in the whole measuring process, and the voltage measuring circuit is not required to be powered off during installation, use and dismantling. Therefore, a large number of measuring points can be arranged at low labor cost, the measuring process is not influenced by line insulation, and the measuring reliability is high.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A voltage measurement circuit, comprising:
a first probe;
the second probe is coupled with the first probe to connect the conductor to be tested;
the first probe is connected with a first end of the voltage dividing device;
the second end of the voltage divider is connected with the reference voltage signal source, the reference voltage signal source is connected with the second probe, and the voltage frequency of the reference voltage signal source is different from that of the conductor to be detected;
voltage analysis apparatus, connectingConnect the first end and the second end of bleeder component for acquire the aliasing signal at bleeder component both ends is analyzed, obtains when the voltage of the conductor that awaits measuring acts on voltage measurement circuit alone the measurement partial pressure value at bleeder component both ends, and when the voltage of reference voltage signal source acts on voltage measurement circuit alone the reference partial pressure value at bleeder component both ends, according to the voltage of reference voltage signal source, reference partial pressure value with measure the partial pressure value and acquire the voltage of the conductor that awaits measuring specifically includes:
wherein, UsFor the voltage of the conductor to be measured, UrIs the voltage of a reference voltage signal source, VrFor reference to the value of the partial pressure, VsTo measure the partial pressure value.
2. The voltage measurement circuit of claim 1, wherein the voltage divider device is a voltage divider capacitor.
3. The voltage measurement circuit of claim 1, wherein the voltage analysis device comprises a voltage collector and a signal processor, the voltage collector is connected to the first end and the second end of the voltage divider, and the signal processor is connected to the voltage collector.
4. The voltage measurement circuit of claim 1, wherein the first probe and the second probe are both metal plates.
5. The voltage measuring circuit according to claim 1, wherein when the voltage measuring circuit is used for measuring phase voltage, the first probe is attached to the outer surface of the phase line to be measured, and the second probe is attached to the outer surface of the zero line; when the voltage measuring circuit is used for measuring the line voltage between any two phases, the first probe is attached to the outer surface of the first phase line, and the second probe is attached to the outer surface of the second phase line.
6. A voltage measuring method of a voltage measuring circuit according to any one of claims 1 to 5, comprising:
acquiring aliasing signals at two ends of the voltage divider;
according to the aliasing signal, obtaining a measurement voltage division value at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently, and a reference voltage division value at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently;
and obtaining the voltage of the conductor to be measured according to the voltage of the reference voltage signal source, the reference divided voltage value and the measurement divided voltage value.
7. The voltage measurement method according to claim 6, wherein the step of obtaining, according to the aliasing signal, a measured divided voltage value across the voltage divider device when the voltage of the conductor to be measured is applied to the voltage measurement circuit alone, and a reference divided voltage value across the voltage divider device when the voltage of the reference voltage signal source is applied to the voltage measurement circuit alone includes:
and filtering the aliasing signal to respectively obtain the measurement partial pressure values at two ends of the voltage divider when the voltage of the conductor to be measured acts on the voltage measurement circuit independently and the reference partial pressure values at two ends of the voltage divider when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
8. The voltage measurement method according to claim 6, wherein the step of obtaining, according to the aliasing signal, a measured divided voltage value across the voltage divider device when the voltage of the conductor to be measured is applied to the voltage measurement circuit alone, and a reference divided voltage value across the voltage divider device when the voltage of the reference voltage signal source is applied to the voltage measurement circuit alone includes:
and carrying out Fourier transform processing on the aliasing signal to obtain a measurement voltage division value at two ends of the voltage division device when the voltage of the conductor to be measured acts on the voltage measurement circuit independently, and a reference voltage division value at two ends of the voltage division device when the voltage of the reference voltage signal source acts on the voltage measurement circuit independently.
9. A voltage measuring device comprising a voltage measuring circuit according to any one of claims 1 to 5, the voltage analyzing apparatus of the voltage measuring circuit performing voltage measurement of a conductor to be measured according to the method of any one of claims 6 to 8.
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| CN115524533B (en) * | 2022-10-25 | 2023-06-27 | 南方电网数字电网研究院有限公司 | Electrical quantity integrated measurement device and method |
| CN115932373B (en) * | 2022-11-22 | 2023-10-20 | 南方电网数字电网研究院有限公司 | Voltage measuring probe, single-phase line and three-phase line voltage measuring method |
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