Method for measuring resonance parameter Q value in high-voltage series resonance test

Abstract

The invention discloses a method for measuring a resonance parameter Q value in a high-voltage series resonance test, and belongs to the technical field of resonance parameter measurement. Based on a high-voltage series resonance test device, the high-voltage series resonance test device comprises a variable-frequency power source, an excitation transformer and an LC series circuit, and the low-voltage end of the excitation transformer is connected with the variable-frequency power source; the high-voltage end is connected with the LC series circuit; the method comprises the following steps: carrying out automatic frequency sweeping by using a high-voltage series resonance test device, and obtaining a resonant frequency omega0 and a resonant current I0 in an LC series circuit corresponding to the resonant frequency omega0 in the automatic frequency sweeping process; in the automatic frequency sweeping process, recording sampling data of each sampling point according to the sampling step length, and obtaining sampling frequencies omega 1 and omega 2 corresponding to the sampling current # imgabs0 # according to the recorded sampling data; and calculating a resonance parameter Q value according to # imgabs 1 #. According to the invention, the resonance parameter Q value of the high-voltage series resonance test can be accurately measured under the condition of considering the corona.

Description

Technical Field

[0001] The invention belongs to the technical field of resonance parameter measurement, and in particular relates to a method for measuring a resonance parameter Q value in a high-voltage series resonance test. Background Art

[0002] In the high voltage and ultra-high voltage AC withstand voltage test, a series resonant circuit is generally used to generate high voltage. The "variable frequency power supply" generates a variable frequency AC voltage, which is boosted to U by the "excitation transformer". s , and then input the LC series circuit composed of "resonant inductor", "test capacitor" and "capacitor voltage divider C1, C2". Once the frequency of the variable frequency power supply output voltage is the same as the natural frequency of the inductor and capacitor series circuit, the circuit reaches resonance. 0 The high voltage U required for the test can be obtained at both ends 0 In the prior art, the Q value of the LC series circuit is equal to the test capacitance C 0 The high voltage U at both ends 0 The voltage U after the "excitation transformer" is stepped up s However, the Q value of the LC series circuit obtained by the above method is established without considering the non-pure resistive loss (corona) of the circuit, but it is not established when corona is considered, which leads to a large measurement error of the resonance parameter Q value in the high-voltage series resonance test in the prior art. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for measuring the resonant parameter Q value in a high-voltage series resonance test, which can accurately measure the resonant parameter Q value of the high-voltage series resonance test while taking into account the corona generated by capacitors and reactors.

[0004] The present invention provides the following technical solutions:

[0005] A method for measuring a resonance parameter Q value in a high-voltage series resonance test is based on a high-voltage series resonance test device, wherein the high-voltage series resonance test device comprises a variable-frequency power supply, an excitation transformer and an LC series circuit, wherein a low-voltage end of the excitation transformer is connected to the variable-frequency power supply, and a high-voltage end is connected to the LC series circuit; the method comprises:

[0006] The high voltage series resonance test device is used to automatically sweep the frequency, and the resonant frequency ω is obtained during the automatic sweep process. 0 and the resonant frequency ω 0 The corresponding resonant current I in the LC series circuit 0 ;

[0007] During the automatic frequency sweep, the sampling data of each sampling point is recorded according to the sampling step length, and the sampling current is obtained according to the recorded sampling data: The corresponding sampling frequency ω 1 and ω 2 ;

[0008] Calculate the resonance parameter Q value according to the following formula;

[0009]

[0010] Optionally, record the sampling data of each sampling point according to the sampling step, and obtain the sampling current according to the recorded sampling data as The corresponding sampling frequency ω 1 and ω 2 , and the specific process is as follows:

[0011] Record the sampling data of each sampling point according to the sampling step. The sampling data includes the sampling frequency ω i and the sampling current I corresponding to the sampling frequency ω i , where the sampling current I i is the current in the LC series circuit; i

[0012] Divide all the sampling currents I i into two groups. The sampling frequencies corresponding to the sampling currents in the first group are all less than the resonance frequency ω 0 , and the sampling frequencies corresponding to the sampling currents in the second group are all greater than the resonance frequency ω 0 ;

[0013] Traverse the sampling currents in the first group and select the two sampling currents I closest to a1 and I a2 ; Traverse the sampling currents in the second group and select the two sampling currents I closest to b1 and I b2 , where

[0014] The sampling frequencies corresponding to the sampling currents I a1 and I a2 are ω a1 and ω a2 . Based on the values of the sampling frequencies ω a1 and ω a2 , use the interpolation calculation method to obtain the frequency ω 1 ;

[0015] The sampling frequencies corresponding to the sampling currents I b1 and I b2 are ω b1 and ω b2 . Based on the sampling frequencies ω b1 and ω b2The value of ω is obtained by interpolation calculation. 2 .

[0016] Optionally, the selected current value is closest to the two sampled currents I a1 and I a2 . Specifically, traverse the first group of sampled currents, calculate the difference between the current value of each sampled current in the first group and , and find the two current values I a1 and I a2 with the smallest difference;

[0017] The selected current value is closest to the two sampled currents I b1 and I b2 . Specifically, traverse the second group of sampled currents, calculate the difference between the current value of each sampled current in the second group and , and find the two current values I b1 and I b2 .

[0018] Optionally, based on the values of the sampling frequencies ω a1 and ω a2 , the value of ω 1 is obtained by interpolation calculation, and the formula is:

[0019]

[0020] Based on the values of the sampling frequencies ω b1 and ω b2 , the value of ω 2 is obtained by interpolation calculation, and the formula is:

[0021]

[0022] Optionally, the LC series circuit includes a current transformer; the current transformer is connected to the sampling module through a tap; the sampling module includes a current-voltage conversion unit, an effective value conversion unit, an analog-to-digital conversion unit, a main control unit, and a RAM storage unit;

[0023] During the automatic frequency sweep, the current transformer obtains the AC current signal of the LC series circuit through the tap;

[0024] The obtained AC current signal is converted into an AC voltage signal through the current-voltage conversion unit;

[0025] The AC voltage signal is converted into a DC voltage signal through the effective value conversion unit and then into a digital signal through the analog-to-digital conversion unit;

[0026] The main control unit is used to read digital signals, convert the digital signals back into corresponding voltage values, and then calculate the original current value according to the resistance value of the current-voltage conversion unit and the turns ratio of the current transformer. The calculated original current value is the sampled current.

[0027] The RAM storage unit stores the sampled current during the entire automatic frequency sweep process.

[0028] Optionally, the LC series circuit includes a resonant inductor, a capacitive voltage divider, and a test capacitor C0; the capacitive voltage divider and the test capacitor C0 are connected in parallel and then connected in series with the resonant inductor and the high-voltage terminal of the exciting transformer to form a loop.

[0029] Optionally, the capacitive voltage divider includes a measuring capacitive voltage divider C1 and a measuring capacitive voltage divider C2; the line after the series connection of the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 is grounded.

[0030] Optionally, the capacitive voltage divider includes a measuring capacitive voltage divider C1, a measuring capacitive voltage divider C2, a standard capacitive voltage divider C3, and a standard capacitive voltage divider C4; the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 are connected to form a first series branch, the standard capacitive voltage divider C3 and the standard capacitive voltage divider C4 are connected to form a second series branch, the first series branch and the second series branch are connected in parallel, and the input end is connected to the input end of the test capacitor C0, and the output end is connected to the output end of the test capacitor C0.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This application proposes a new Q-value measurement method, aiming to accurately measure the quality factor (Q-value) through the frequency sweep process of the high-voltage series resonance test even considering the corona effect that may occur in the actual application of capacitors and reactors. Specifically, during the frequency sweep process, this method makes full use of the resonant frequency ω 0 and its corresponding current value I 0 , by accurately sampling and recording the two sampling frequency points ω and ω 1 and ω 2 whose current values are closest to 0 , combined with the resonant frequency ω itself, it can not only avoid the influence of complex factors such as corona on the measurement results, but also ensure the accuracy and stability of Q-value calculation. This application not only simplifies the cumbersome data processing process in the traditional measurement steps, but also greatly improves the reliability of the measurement, making it easy to achieve efficient and accurate measurement of the Q-value even in a complex environment where there is corona phenomenon in capacitors and reactors.

[0033] Figure 1It is a schematic diagram of the circuit connection of the first high-voltage series resonance test device of the present invention;

[0034] Figure 2 It is a schematic diagram of the circuit connection of the second high-voltage series resonance test device of the present invention;

[0035] Figure 3 It is the amplitude-frequency characteristic diagram of the LC series loop of the present invention;

[0036] Figure 4 It is the structural block diagram of the sampling module of the present invention. Detailed implementation mode

[0037] Now, the present invention will be further described in detail with reference to the accompanying drawings.

[0038] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the term "including" and any variation thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0039] A method for measuring the resonance parameter Q value in a high-voltage series resonance test, based on a high-voltage series resonance test device, as Figure 1 and Figure 2 shown, the high-voltage series resonance test device includes a variable-frequency power supply, an excitation transformer and an LC series circuit. The low-voltage end of the excitation transformer is connected to the variable-frequency power supply, and the high-voltage end is connected to the LC series circuit. The LC series circuit includes a resonance inductor, a capacitive voltage divider and a test capacitor C0; after the capacitive voltage divider and the test capacitor C0 are connected in parallel, they are connected in series with the resonance inductor and the high-voltage end of the excitation transformer to form a loop.

[0040] As Figure 2As shown, in this embodiment, the capacitive voltage divider includes a measuring capacitive voltage divider C1, a measuring capacitive voltage divider C2, a standard capacitive voltage divider C3, and a standard capacitive voltage divider C4; the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 are connected to form a first series branch, the standard capacitive voltage divider C3 and the standard capacitive voltage divider C4 are connected to form a second series branch, the first series branch and the second series branch are connected in parallel, and the input end is connected to the input end of the test capacitor C0, and the output end is connected to the output end of the test capacitor C0, that is, the test capacitor C0 is the third branch, and the first series branch, the second series branch, and the third branch are connected in parallel, and after being connected in parallel, they form a loop with the resonant inductor and the high-voltage end of the exciting transformer.

[0041] Of course, in some other embodiments, such as Figure 1 As shown, the capacitive voltage divider includes a measuring capacitive voltage divider C1 and a measuring capacitive voltage divider C2; the line after the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 are connected in series is grounded, the input end of the measuring capacitive voltage divider C1 is connected to the input end of the test capacitor C0, and the output end of the measuring capacitive voltage divider C2 is connected to the output end of the test capacitor C0.

[0042] A method for measuring the Q value of the resonant parameter in a high-voltage series resonance test specifically includes the following steps:

[0043] S1: Use a high-voltage series resonance test device to perform automatic frequency sweeping, and obtain the resonant frequency ω 0 and the resonant frequency ω 0 corresponding resonant current I in the LC series circuit 0 .

[0044] The method of automatic frequency sweeping can refer to the prior art. The purpose of automatic frequency sweeping is to find the natural frequency of the LC series circuit. After finding the natural frequency, the variable-frequency power supply outputs the same voltage signal, and the circuit reaches resonance at this frequency. At this time, the voltage and current on the test capacitor C0 are both the maximum values; the frequency sweeping process is: keep the output voltage U of the exciting transformer unchanged, change the output frequency of the variable-frequency power supply, and the frequency of the sweeping frequency that obtains the maximum current is the resonant frequency ω 0 .

[0045] S2: During the automatic frequency sweeping process, record the sampling data of each sampling point according to the sampling step size, and obtain the sampling current as corresponding frequency ω 1 and ω 2 .

[0046] Step S2 specifically includes:

[0047] Step S21: Record the sampling data of each sampling point according to the sampling step size. The sampling data includes the sampling frequency ω iand the sampling frequency ω i corresponding sampling current I i , where the sampling current I i is the current in the LC series circuit.

[0048] Step S22: Divide all the sampling currents I i into two groups. The sampling frequencies corresponding to the sampling currents in the first group are all less than the resonance frequency ω 0 , and the sampling frequencies corresponding to the sampling currents in the second group are all greater than the resonance frequency ω 0 .

[0049] Since the amplitude-frequency characteristic curve of the LC series circuit is as Figure 3 shown, there are two sampling frequencies corresponding to the sampling current , that is, ω 1 and ω 2 . Among them, the value of ω 1 is less than the resonance frequency ω 0 , and the value of ω 2 is greater than the resonance frequency ω 0 .

[0050] Step S23: Traverse the sampling currents in the first group and select two sampling currents I and I a1 whose current values are closest to a2 ; traverse the sampling currents in the second group and select two sampling currents I and I b1 whose current values are closest to b2 , where

[0051] Specifically, traverse the sampling currents in the first group, calculate the difference between the current value of each sampling current in the first group and , and find the two current values I a1 and I a2 with the smallest difference.

[0052] Traverse the sampling currents in the second group, calculate the difference between the current value of each sampling current in the second group and , and find the two current values I b1 and I b2 with the smallest difference.

[0053] Step S24: The sampling frequencies corresponding to the sampling currents I a1 and I a2 are ω a1 and ω a2 . Based on the values of the sampling frequencies ω a1 and ω a2 , use the interpolation calculation method to obtain the frequency ω 1; Sampling current I b1 and I b2 The corresponding sampling frequencies are ω b1 and ω b2 , Based on the values of the sampling frequencies ω b1 and ω b2 , The method of interpolation calculation is used to obtain the frequency ω 2 .

[0054] Specifically, the formula for obtaining the frequency ω 1 is:

[0055]

[0056] The formula for obtaining the frequency ω 2 is:

[0057]

[0058] S3: Calculate the resonance parameter Q value according to the following formula;

[0059]

[0060] Specifically, in the case of no non - pure - resistive loss (corona), the formula used to calculate the Q value is:

[0061]

[0062] where, U s is the output voltage of the exciting transformer, and U 0 is the high voltage required for the test across the specimen.

[0063] However, in the series resonance high - voltage test, there is corona to varying degrees, so the Q value cannot be calculated using formula (1).

[0064] In this embodiment, as Figure 2 shown, U S is the output voltage of the exciting transformer, R is the pure resistance in the circuit, L is the inductance of the reactor, and the equivalent capacitance of the capacitor C 0 -C 4 is C.

[0065] The current in the circuit at the frequency ω is:

[0066]

[0067] At resonance, the frequency ω 0 is:

[0068]

[0069] According to the definition of the Q value: (4)

[0070]

[0071] Among them, U in formula (5) m is Figure 2 in the amplitude, and I is the current amplitude in the loop. The curve corresponding to formula (5) is as Figure 3 shown.

[0072] Due to resonance Therefore, the loop current I 0 amplitude is:[[]]

[0073]

[0074] In formula (5), when , combining formula (5) and formula (6) gives:[[]] At this time, there is an equation:[[]]

[0075]

[0076] Regarding ω as the unknown in formula (7) and solving this equation, there are two reasonable solutions:[[]]

[0077]

[0078]

[0079] The ω 1 , ω 2 corresponding current

[0080] After subtracting formula (9) from formula (8), formula (10) is obtained:[[]]

[0081]

[0082] Combining formula (10) and formula (4) gives:[[]]

[0083]

[0084] In this application, further, as Figure 1 and Figure 4 shown, the LC series circuit includes a current transformer; the current transformer is connected to the sampling module through a tap; the sampling module includes a current-voltage conversion unit, an effective value conversion unit, an analog-to-digital conversion unit, a main control unit, and a RAM storage unit.

[0085] Specifically, during the automatic frequency sweeping process, the current transformer obtains the AC current signal of the LC series circuit through the tap; converts the obtained AC current signal into an AC voltage signal through the current-voltage conversion unit; converts the AC voltage signal into a DC voltage signal through the effective value conversion unit, and then converts it into a digital signal through the analog-to-digital conversion unit; the main control unit is used to read the digital signal, convert the digital signal back into the corresponding voltage value, and then calculate the original current value according to the resistance value of the current-voltage conversion unit and the transformation ratio of the current transformer. The calculated original current value is the sampled current; the RAM storage unit stores the sampled current during the entire automatic frequency sweeping process.

[0086] The specific structures and working principles of the current-voltage conversion unit, effective value conversion unit, analog-to-digital conversion unit, main control unit, and RAM storage unit in this application can refer to the prior art.

[0087] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0088] The above is only the preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A method for measuring the resonance parameter Q value in a high voltage series resonance test, characterized in that: Based on a high-voltage series resonance test device, the high-voltage series resonance test device includes a variable frequency power supply, an excitation transformer and an LC series circuit, the low-voltage end of the excitation transformer is connected to the variable frequency power supply, and the high-voltage end is connected to the LC series circuit; the method includes: Automatic frequency sweeping is performed using a high-voltage series resonance test device, and the resonance frequency ω0 and the resonance current I0 in the LC series circuit corresponding to the resonance frequency ω0 are obtained during the automatic frequency sweeping process; During the automatic frequency sweep, the sampling data of each sampling point is recorded according to the sampling step length, and the sampling current is obtained according to the recorded sampling data: The corresponding sampling frequencies ω1 and ω2; The resonance parameter Q value is calculated according to the following formula; 2. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 1, characterized in that: The sampling data of each sampling point is recorded according to the sampling step length, and the sampling current is obtained according to the recorded sampling data: The corresponding sampling frequencies ω1 and ω2, the specific process is: According to the sampling step, the sampling data of each sampling point is recorded. The sampling data includes the sampling frequency ω i and the sampling frequency ω i The corresponding sampling current I i , where the sampling current I i is the current in the LC series circuit; All sampled current I i Divided into two groups, the sampling frequencies corresponding to the sampling currents of the first group are all less than the resonance frequency ω0, and the sampling frequencies corresponding to the sampling currents of the second group are all greater than the resonance frequency ω0; Traverse the first group of sampled currents and select the current value closest to Two sampling currents I a1 and I a2 ; Traverse the second group of sampled currents and select the current value closest to Two sampling currents I b1 and I b2 ,in, Sampling current I a1 and I a2 The corresponding sampling frequency is ω a1 and ω a2 , based on the sampling frequency ω a1 and ω a2 The value of is obtained by interpolation calculation method to obtain the frequency ω1; Sampling current I b1 and I b2 The corresponding sampling frequency is ω b1 and ω b2 , based on the sampling frequency ω b1 and ω b2 The frequency ω2 is obtained by interpolation calculation.

3. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 2 is characterized in that: The selected current value is closest to Two sampling currents I a1 and I a2 Specifically, traverse the first group of sampled currents, calculate the current value of each sampled current in the first group and The difference between the two current values ​​I a1 and I a2 ; The selected current value is closest to Two sampling currents I b1 and I b2 Specifically, traverse the second group of sampling currents, calculate the current value of each sampling current in the second group and The difference between the two current values ​​I b1 and I b2 .

4. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 2, characterized in that: Based on the sampling frequency ω a1 and ω a2 The formula for obtaining the frequency ω1 by interpolation calculation is: The sampling frequency ω b1 and ω b2 The formula for obtaining the frequency ω2 by interpolation calculation is:

5. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 1, characterized in that: The LC series circuit includes a current transformer; the current transformer is connected to a sampling module through a tap; the sampling module includes a current-voltage conversion unit, an effective value conversion unit, an analog-to-digital conversion unit, a main control unit and a RAM storage unit; During the automatic frequency scanning process, the current transformer obtains the AC current signal of the LC series circuit through the tap; The acquired AC current signal is converted into an AC voltage signal through a current-voltage conversion unit; The AC voltage signal is converted into a DC voltage signal through an effective value conversion unit, and then converted into a digital signal through an analog-to-digital conversion unit; The main control unit is used to read the digital signal, convert the digital signal back to the corresponding voltage value, and then calculate the original current value according to the resistance value of the current-voltage conversion unit and the transformation ratio of the current transformer. The original current value obtained by calculation is the sampling current; The RAM storage unit stores the sampled current during the entire automatic frequency sweep process.

6. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 1, characterized in that: The LC series circuit includes a resonant inductor, a capacitive voltage divider and a test capacitor C0; the capacitive voltage divider and the test capacitor C0 are connected in parallel and then connected in series with the resonant inductor and the high-voltage end of the excitation transformer to form a loop.

7. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 6, characterized in that: The capacitive voltage divider comprises a measuring capacitive voltage divider C1 and a measuring capacitive voltage divider C2; and a circuit after the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 are connected in series is grounded.

8. The method for measuring the resonance parameter Q value in the high voltage series resonance test according to claim 6, characterized in that: The capacitive voltage divider includes a measuring capacitive voltage divider C1, a measuring capacitive voltage divider C2, a standard capacitive voltage divider C3 and a standard capacitive voltage divider C4; the measuring capacitive voltage divider C1 and the measuring capacitive voltage divider C2 are connected to form a first series branch, the standard capacitive voltage divider C3 and the standard capacitive voltage divider C4 are connected to form a second series branch, the first series branch and the second series branch are connected in parallel, and the input end is connected to the input end of the test capacitor C0, and the output end is connected to the output end of the test capacitor C0.

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