CN112630542B - Loss test method, medium and system for filter capacitor - Google Patents

Abstract

The invention discloses a loss test method, medium and system of a filter capacitor. The loss test method comprises the following steps: building a loss test circuit of the filter capacitor unit; testing the dielectric loss factors of filter capacitor elements to be tested corresponding to different frequencies; calculating the average value of the dielectric loss factors of all filter capacitor elements to be tested corresponding to the same frequency; drawing a dielectric loss factor curve by taking the frequency as an abscissa and the mean value of the dielectric loss factors as an ordinate; testing to obtain a loss value of the filter capacitor unit corresponding to the frequency of 50Hz under rated voltage; calculating the loss value of the connecting row corresponding to the frequency of 50 Hz; calculating the loss value of the filter capacitor unit corresponding to each preset frequency; and calculating the sum of the loss value of the filter capacitor unit corresponding to the frequency of 50Hz under the rated voltage and the loss values of the filter capacitor units corresponding to all preset frequencies to obtain the total loss value of the filter capacitor unit. The test result of the invention is more accurate.

Description

Loss testing method, medium and system of a filter capacitor

technical field

The present invention relates to the technical field of filter capacitors, in particular to a loss testing method, medium and system for filter capacitors.

Background technique

The rated current of the capacitor is determined by the root mean square value of the fundamental current and all harmonic currents. The algorithm has the following problems: ① The dielectric structure of the capacitor element has different dielectric losses at different frequencies, and all harmonics have the same thermal effect. The conversion is not accurate; ② The pole plate of the capacitor element is made of aluminum foil and has distributed inductance and distributed resistance. The distributed inductance and distributed resistance make the current of different frequencies have different distributions on the capacitor element, which also leads to different frequencies. The power loss of the capacitor element is different under the current.

Therefore, simply taking the root mean square value of each harmonic current as the rated current of the filter capacitor, the loss of the filter capacitor obtained is not very accurate, and cannot reflect the influence of the loss of the filter capacitor on the selection and design.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method, medium and system for testing the loss of a filter capacitor, so as to solve the problem that the loss of the filter capacitor obtained in the prior art is inaccurate.

P_B表示频率50Hz对应的所述连接排的损耗值，P_T表示额定电压下频率50Hz对应的所述滤波电容器单元的损耗值，I₅₀表示频率50Hz对应的电流有效值，C表示所述滤波电容器单元的电容值，tan₅₀δ表示频率50Hz对应的所述滤波电容器元件的介质损耗因数，tan₅₀δ通过查询所述介质损耗因数曲线获得；采用滤波电容器损耗计算式计算每一预设频率对应的所述滤波电容器单元的损耗值，其中，所述滤波电容器损耗计算式为

P_n表示预设频率f_n对应的所述滤波电容器单元的损耗值，

表示预设频率f_n对应的电流有效值，

表示预设频率f_n对应的所述滤波电容器元件的介质损耗因数，

通过查询所述介质损耗因数曲线获得；计算额定电压下频率50Hz对应的滤波电容器单元的损耗值与所有预设频率对应的所述滤波电容器单元的损耗值的和，得到所述滤波电容器单元的总损耗值。A first aspect provides a loss test method for a filter capacitor, including: building a loss test circuit for a filter capacitor unit, wherein the loss test circuit includes a filter capacitor unit and a loss test bridge, wherein the filter capacitor unit It includes: a filter capacitor element and a connection row, one pole plate of each filter capacitor element is connected to one end of the connection row, the other pole plate of each filter capacitor element is welded with a fuse, and the loss test electric One end of the bridge is connected to the other end of the connection row, and the other end of the loss test bridge is connected to the fuse of the filter capacitor element; within a preset frequency range, the medium of the filter capacitor element corresponding to different frequencies is tested Loss factor; calculate the average value of the dielectric loss factor of all the filter capacitor elements corresponding to the same frequency; take the frequency as the abscissa, and the average value of the dielectric loss factor as the ordinate, draw the dielectric loss factor curve; test to obtain the frequency under the rated voltage The loss value of the filter capacitor unit corresponding to 50Hz; the loss value of the connection bank corresponding to the frequency of 50Hz is calculated using the connection bank loss calculation formula, wherein the connection bank loss calculation formula is:

P _B represents the loss value of the connecting bar corresponding to a frequency of 50 Hz, P _T represents the loss value of the filter capacitor unit corresponding to a frequency of 50 Hz under rated voltage, I ₅₀ represents the effective current value corresponding to a frequency of 50 Hz, and C represents the filter Capacitance value of the capacitor unit, tan ₅₀ δ represents the dielectric loss factor of the filter capacitor element corresponding to a frequency of 50 Hz, and tan ₅₀ δ is obtained by querying the dielectric loss factor curve; the filter capacitor loss calculation formula is used to calculate the corresponding value of each preset frequency The loss value of the filter capacitor unit, wherein, the filter capacitor loss calculation formula is

P _n represents the loss value of the filter capacitor unit corresponding to the preset frequency f _n ,

represents the rms value of the current corresponding to the preset frequency f _n ,

represents the dielectric loss factor of the filter capacitor element corresponding to the preset frequency f _n ,

Obtained by querying the dielectric loss factor curve; calculating the sum of the loss value of the filter capacitor unit corresponding to the frequency of 50Hz under the rated voltage and the loss values of the filter capacitor units corresponding to all preset frequencies, to obtain the total value of the filter capacitor unit. loss value.

In a second aspect, a computer-readable storage medium is provided, where computer program instructions are stored on the computer-readable storage medium; when the computer program instructions are executed by a processor, the filter capacitors according to the embodiments of the first aspect are implemented loss test method.

A third aspect provides a loss testing system for a filter capacitor, comprising: the computer-readable storage medium according to the embodiment of the second aspect.

In this way, the embodiment of the present invention, based on a more detailed mathematical and physical model, takes into account the different heating losses of the filter capacitor at different frequencies, which is more in line with the actual situation, and the verification result of the heating loss of the high-voltage filter capacitor is also more accurate. Based on this, product design, selection and application are more reasonable, which is beneficial to improve the reliability of high-voltage filter capacitor equipment.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the drawings that are used in the description of the embodiments of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention. , for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative labor.

1 is a flowchart of a method for testing loss of a filter capacitor according to an embodiment of the present invention;

2 is a schematic diagram of a loss test circuit of a filter capacitor according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a dielectric loss factor curve according to a specific embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention discloses a loss testing method of a filter capacitor. As shown in Figure 1, the loss test method includes the following steps:

Step S1: Build a loss test circuit of the filter capacitor unit.

Wherein, as shown in FIG. 2 , the loss test circuit includes: a filter capacitor unit and a loss test bridge 4 . The filter capacitor unit includes: filter capacitor element 1 and connection row 3 . The plurality of filter capacitor elements 1 included in the filter capacitor unit are all the same. One pole plate of each filter capacitor element 1 is connected to one end of the connection row 3 . A fuse 2 is welded to the other plate of each filter capacitor element 1 . One end of the loss test bridge 4 is connected to the other end of the connection row 3 . The other end of the loss test bridge 4 is connected to the fuse 2 of the filter capacitor element 1 . The filter capacitor element 1 is prepared according to the existing normal process, packaged according to the normal process, and the fuse 2 is welded. The other side of the fuse 2 is not soldered to the connection row 3. Then, the entire filter capacitor 1, the fuse 2, and the connection row 3 are subjected to vacuum impregnation treatment.

Step S2: within a preset frequency range, test the dielectric loss factor of the filter capacitor elements corresponding to different frequencies.

Specifically, as shown in FIG. 2 , the other end of the loss test bridge 4 is connected to the fuse 2 of the filter capacitor element 1 one at a time for testing. The dielectric loss factor is the component loss tangent tanδ. The preset frequency range and the test frequency can be determined according to the actual situation. In a specific embodiment of the present invention, the frequency to be tested is an integer multiple of 50 Hz, and the interval between two adjacent frequencies is the same, for example, 50 Hz, 100 Hz, 150 Hz, 200 Hz . . .

Step S3: Calculate the average value of the dielectric loss factors of all filter capacitor elements corresponding to the same frequency.

For example, if there are 15 filter capacitor elements, the average value of the dielectric loss factor of the 15 filter capacitor elements at the same frequency is calculated.

Step S4: Using the frequency as the abscissa and the mean value of the dielectric loss factor as the ordinate, draw a dielectric loss factor curve.

Step S5: Test to obtain the loss value of the filter capacitor unit corresponding to the frequency of 50 Hz under the rated voltage.

This value can be obtained by direct testing with existing equipment. Generally, the loss value of three identical filter capacitor units can be measured, and the average value is taken as the loss value of the filter capacitor unit. This value includes filter capacitor element losses and connection bank losses.

Step S6: Calculate the loss value of the connection bank corresponding to the frequency of 50 Hz by using the connection bank loss calculation formula.

Specifically, the calculation formula of connection row loss is:

Among them, _PB represents the loss value of the connection bar corresponding to the frequency of 50Hz. P _T represents the loss value of the filter capacitor unit corresponding to a frequency of 50 Hz under the rated voltage. I ₅₀ represents the rms value of the current corresponding to a frequency of 50 Hz, which is the current loaded when measuring PT _. C represents the capacitance value of the filter capacitor unit, which has been calibrated when the filter capacitor unit leaves the factory. tan ₅₀ δ represents the dielectric loss factor of the filter capacitor element corresponding to a frequency of 50 Hz, and tan ₅₀ δ is obtained by querying the dielectric loss factor curve, that is, querying the value of the ordinate when the abscissa is 50 Hz in the dielectric loss factor curve.

Step S7: Calculate the loss value of the filter capacitor unit corresponding to each preset frequency by using the filter capacitor loss calculation formula.

Specifically, the calculation formula for the loss of the filter capacitor is:

表示预设频率f_n对应的滤波电容器元件的介质损耗因数，

通过查询介质损耗因数曲线获得。其他参数如前文所述，在此不再赘述。Wherein, P _n represents the loss value of the filter capacitor unit corresponding to the preset frequency f _n . I _fn represents the effective value of the current corresponding to the preset frequency f _n , which is a preset value and is related to the working conditions of the filter capacitor.

represents the dielectric loss factor of the filter capacitor element corresponding to the preset frequency f _n ,

Obtained by querying the dielectric loss factor curve. Other parameters are as described above and will not be repeated here.

Step S8: Calculate the sum of the loss value of the filter capacitor unit corresponding to the frequency of 50 Hz under the rated voltage and the loss values of the filter capacitor units corresponding to all preset frequencies to obtain the total loss value of the filter capacitor unit.

specific,

Among them, P represents the total loss value of the filter capacitor to be measured. For example, the preset frequency may be 250Hz, 350Hz, 550Hz, or 750Hz, which is specifically determined according to the operating conditions of the filter capacitor, which is generally determined when designing the filter capacitor.

The technical solution of the present invention will be further described below with a specific embodiment.

For a filter capacitor unit whose model is AAM11.6-22.04-1W, the RMS current of each harmonic current is shown in Table 1.

Table 1 Current effective value of each harmonic current

harmonic order Frequency (Hz) Valid value (A) 1 50 45.81 5 250 107.37 7 350 77.56 11 550 15.23 13 650 7.2

The number of filter capacitor elements included in the filter capacitor unit to be tested is 15. The capacitance value of the filter capacitor element is 11.2uF, and the capacitance of the filter capacitor unit can be calculated from the capacitance value of the filter capacitor element according to the connection form of the filter capacitor element it includes. The preset frequency range is 50Hz～5000Hz. The dielectric dissipation factor of the filter capacitor element is tested every 50Hz. After calculating the average value of the dielectric loss factor of 15 filter capacitor elements at the same frequency, draw the dielectric loss factor curve as shown in Figure 3. The loss value P _T =462.5W of the filter capacitor unit to be tested corresponding to the frequency of 50Hz is obtained by testing at the rated voltage. In the dielectric loss factor curve in Fig. 3, query tan ₅₀ δ=0.0011 corresponding to 50 Hz. Calculate the loss value P _B =117W of the connection bar. Query the dielectric loss factor corresponding to each preset frequency 250Hz, 350Hz, 550Hz, 750Hz in the dielectric loss factor curve in Figure 3, obtain the current RMS value corresponding to each preset frequency 250Hz, 350Hz, 550Hz, 750Hz, and calculate The resulting total loss values of the filter capacitors are shown in Table 2.

Table 2 Parameter values corresponding to each preset frequency

The total capacity of the capacitor unit calculated by the current root mean square method of the prior art is 763.6kvar, which is usually calculated according to the existing power frequency loss. The power frequency loss tangent of the capacitor unit is 0.0015, and the total loss value is 1165W, which is less than The loss value obtained by the method of the embodiment of the present invention. Since the method of the prior art does not consider the change of the loss of the filter capacitor unit with frequency, resulting in that the increase of the loss at high frequency is not taken into account, the method of the embodiment of the present invention is more accurate than the method of the prior art.

An embodiment of the present invention also discloses a computer-readable storage medium, where computer program instructions are stored on the computer-readable storage medium; when the computer program instructions are executed by a processor, the loss test of the filter capacitor described in the foregoing embodiment is implemented method.

An embodiment of the present invention also discloses a loss testing system for a filter capacitor, comprising: the computer-readable storage medium described in the above-mentioned embodiments.

In summary, the embodiment of the present invention is based on a more detailed mathematical and physical model, and considers the different heating losses of the filter capacitors at different frequencies, which is more in line with the actual situation, and the verification results of the heating losses of the high-voltage filter capacitors are also more accurate. , based on this, the product design, selection and application are more reasonable, which is conducive to improving the reliability of high-voltage filter capacitor equipment.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (4)

1. a loss testing method of filter capacitor, is characterized in that, comprises: Build a loss test circuit for a filter capacitor unit, wherein the loss test circuit includes a filter capacitor unit and a loss test bridge, wherein the filter capacitor unit includes a filter capacitor element and a connection row, each of the filter capacitor elements One pole plate is connected to one end of the connection row, the other pole plate of each filter capacitor element is welded with a fuse, one end of the loss test bridge is connected to the other end of the connection row, and the loss test The other end of the bridge is connected to the fuse of the filter capacitor element; In the preset frequency range, test the dielectric loss factor of the filter capacitor element corresponding to different frequencies; calculating the average value of the dielectric loss factors of all the filter capacitor elements corresponding to the same frequency; Taking the frequency as the abscissa and the mean value of the dielectric loss factor as the ordinate, draw the dielectric loss factor curve; The loss value of the filter capacitor unit corresponding to the frequency of 50Hz under the rated voltage is obtained by testing; The loss value of the connection bar corresponding to the frequency of 50Hz is calculated by using the connection bar loss calculation formula, wherein the connection bar loss calculation formula is:

P _B represents the loss value of the connecting bar corresponding to a frequency of 50 Hz, P _T represents the loss value of the filter capacitor unit corresponding to a frequency of 50 Hz under rated voltage, I ₅₀ represents the effective current value corresponding to a frequency of 50 Hz, and C represents the filter Capacitance value of the capacitor unit, tan ₅₀ δ represents the dielectric loss factor of the filter capacitor element corresponding to a frequency of 50 Hz, and tan ₅₀ δ is obtained by querying the dielectric loss factor curve; The loss value of the filter capacitor unit corresponding to each preset frequency is calculated using the filter capacitor loss calculation formula, wherein the filter capacitor loss calculation formula is:

P _n represents the loss value of the filter capacitor unit corresponding to the preset frequency f _n ,

represents the rms value of the current corresponding to the preset frequency f _n ,

represents the dielectric loss factor of the filter capacitor element corresponding to the preset frequency f _n ,

Obtained by querying the dielectric loss factor curve; Calculate the sum of the loss value of the filter capacitor unit corresponding to a frequency of 50 Hz under the rated voltage and the loss values of the filter capacitor unit corresponding to all preset frequencies to obtain the total loss value of the filter capacitor unit. 2. The method for testing the loss of a filter capacitor according to claim 1, wherein in the step of testing the dielectric loss factor of the filter capacitor element corresponding to different frequencies, the frequency is an integer multiple of 50Hz, and The interval between two adjacent said frequencies is the same. 3. A computer-readable storage medium, characterized in that: computer program instructions are stored on the computer-readable storage medium; when the computer program instructions are executed by a processor, any one of claims 1 to 2 is implemented. The loss test method of the filter capacitor described above. 4 . A loss testing system for filter capacitors, comprising: the computer-readable storage medium according to claim 3 .

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