CN110007199B - Method and device for determining voltage tolerance index of solid insulating material and intelligent terminal - Google Patents
Method and device for determining voltage tolerance index of solid insulating material and intelligent terminal Download PDFInfo
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- CN110007199B CN110007199B CN201910118723.4A CN201910118723A CN110007199B CN 110007199 B CN110007199 B CN 110007199B CN 201910118723 A CN201910118723 A CN 201910118723A CN 110007199 B CN110007199 B CN 110007199B
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Abstract
The invention provides a method and a device for determining a voltage tolerance index of a solid insulating material and an intelligent terminal, and relates to the technical field of material characteristics, wherein the method comprises the following steps: selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; calculating a voltage tolerance index corresponding to each group of target test parameters; respectively calculating error values between the voltage tolerance indexes corresponding to each group of target test parameters and preset reference voltage tolerance indexes; the voltage withstand index having the smallest error value is determined as the voltage withstand index of the solid insulating material. The invention can effectively improve the accuracy of the voltage tolerance index of the solid insulating material.
Description
Technical Field
The invention relates to the technical field of material characteristics, in particular to a method and a device for determining a voltage tolerance index of a solid insulating material and an intelligent terminal.
Background
The voltage tolerance index of the solid insulating material is an important parameter reflecting the performance change of the insulation under the action of a long-term electric field, so that a more accurate voltage tolerance index needs to be obtained through measurement. Usually, a constant stress method is adopted to measure the insulation failure under different constant electric fields EiTime tiUsing an inverse power model t as CE-nAnd fitting the n value as a voltage tolerance index of the material. However, the method has the disadvantages of long time consumption and low efficiency, and the large test time span causes a plurality of factors influencing the failure of the material, so that the data dispersion is very large. For example, the statistical result of the voltage tolerance index of various countries in the world to the crosslinked polyethylene insulating material is from 9 to 20.
In practice, a step stress method is often adopted to equivalently obtain the voltage tolerance index of the material, the method assumes that the solid insulating material breaks down under the condition of equal accumulated damage amount under different electric fields, a certain initial boosting voltage, a certain voltage step length and the duration time under each electric field are taken as test parameters, a gradually increasing electric field is applied to a test sample until the breakdown fails, and the voltage tolerance index of the material is further obtained by adopting a mathematical equivalence method according to the test parameters and the failure time. However, in the method, when the voltage tolerance index is determined through the test parameters, the test parameters are certain, and the selection of different test parameters has a large influence on the obtained n value result of the voltage tolerance index, so that the accuracy of the obtained n value needs to be improved.
Disclosure of Invention
In view of this, the present invention provides a method and an apparatus for determining a voltage tolerance index of a solid insulating material, and an intelligent terminal, which can effectively improve the accuracy of the voltage tolerance index of the solid insulating material.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, an embodiment of the present invention provides a method for determining a voltage tolerance index of a solid insulating material, where the method includes: selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve represents a relationship between an accumulated electrical damage amount of the solid insulating material and a voltage applied to the solid insulating material and a voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters include a starting voltage applied to the solid insulation material, a voltage increment, and a voltage application time increment; calculating a voltage tolerance index corresponding to each group of target test parameters; respectively calculating error values between the voltage tolerance indexes corresponding to each group of target test parameters and preset reference voltage tolerance indexes; the voltage withstand index having the smallest error value is determined as the voltage withstand index of the solid insulating material.
With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where before the step of selecting multiple sets of target test parameters based on the damage curve of the solid insulating material, the method further includes: acquiring an accumulated damage limit value of the solid insulating material, a preset reference starting voltage applied to the solid insulating material, a preset reference voltage increment and an application time increment of a preset reference voltage; wherein the cumulative damage limit value DCExpressed as:
wherein k represents the corresponding breakdown stage number when the change of the preset reference starting voltage reaches the preset breakdown voltage, t represents the time when the change of the preset reference starting voltage reaches the breakdown voltage, n0Is a reference voltage withstand index, UbRepresenting a predetermined breakdown voltage of the solid insulating material; and drawing a damage curve of the solid insulating material according to the accumulated damage limit value, the preset reference starting voltage, the preset reference voltage increment and the application time increment of the preset reference voltage.
With reference to the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, where the step of calculating the voltage tolerance index corresponding to each set of target test parameters includes: calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of sets of test parameters, m represents the number of times each set of test parameters was tested repeatedly, DwmShowing the test parameters of the w-th group in the repeated testsThe cumulative damage value obtained after m times; determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative damage matrix; and calculating the voltage tolerance index corresponding to each group of target test parameters according to the target function.
With reference to the second possible implementation manner of the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where the step of determining the objective function includes: the objective function is calculated according to the following formula:
wherein S (n) represents the normalized variance of the cumulative damage matrix D, n represents the voltage tolerance index, DijRepresents the cumulative damage value of the test parameters of the ith group obtained after j times of repeated tests,
represents the average value of the sum of each element in the cumulative damage matrix D, Δ t represents the amount of change in time, U0Representing the initial voltage, delta U representing the voltage change of the initial voltage after delta t along with the time change, i representing the time change delta t times, k representing the corresponding breakdown stage when the initial voltage change reaches the preset breakdown voltage, delta tendIndicating the holding time of the breakdown voltage.
With reference to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, wherein the step of calculating, according to an objective function, a voltage tolerance index corresponding to each set of target test parameters includes: the voltage withstand index n is calculated according to the following formula:
wherein, the normalized variance S (n) corresponds to a curve S-n of the standard variance S with the change of n, and λ represents the negative second derivative of the change curve S-n.
With reference to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the time variation Δ t has a constraint condition, and the constraint condition is expressed as:
wherein D iscRepresents the limit of the cumulative damage value.
In a second aspect, an embodiment of the present invention further provides an apparatus for determining a voltage tolerance index of a solid insulating material, including: the selection module is used for selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve represents a relationship between an accumulated electrical damage amount of the solid insulating material and a voltage applied to the solid insulating material and a voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters include a starting voltage applied to the solid insulation material, a voltage increment, and a voltage application time increment; the voltage tolerance index calculation module is used for calculating a voltage tolerance index corresponding to each group of target test parameters; the error value calculation module is used for calculating error values between the voltage tolerance indexes corresponding to each group of target test parameters and the preset reference voltage tolerance indexes; and the determining module is used for determining the voltage tolerance index with the minimum error value as the voltage tolerance index of the solid insulating material.
With reference to the second aspect, an embodiment of the present invention provides a first possible implementation manner of the second aspect, where the voltage tolerance index calculating module is configured to: calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of sets of test parameters, m represents the number of times each set of test parameters was tested repeatedly, DwmRepresents the cumulative loss of the w-th group of test parameters after m times of repeated testsA damage value; determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative damage matrix; and calculating the voltage tolerance index corresponding to each group of target test parameters according to the target function.
In a third aspect, an embodiment of the present invention provides an intelligent terminal, including a processor and a memory; the memory has stored thereon a computer program which, when executed by the processor, performs the method according to any one of the first to fifth possible implementation manners of the first aspect.
In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, performs the steps of the method in any one of the first to fifth possible implementation manners of the first aspect.
The embodiment of the invention provides a method and a device for determining a voltage tolerance index of a solid insulating material and an intelligent terminal. According to the invention, the voltage tolerance index is calculated through multiple groups of target test parameters, and the voltage tolerance index with the minimum error value with the preset reference voltage tolerance index is determined as the voltage tolerance index of the solid insulating material, so that the accuracy of the voltage tolerance index of the solid insulating material can be effectively improved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flow chart illustrating a method for determining parameters of a solid insulating material according to an embodiment of the present invention;
FIG. 2 is a flow chart illustrating another method for determining parameters of a solid insulation material provided by an embodiment of the present invention;
FIG. 3 is a graph illustrating cumulative damage values versus time for a step stress and a constant stress provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram showing voltage versus time for a solid insulation material in a loss region provided by an embodiment of the present invention;
FIG. 5 is a graph illustrating normalized variance of cumulative damage matrix of solid insulation material versus voltage tolerance index according to an embodiment of the present invention;
FIG. 6 is a graph showing the cumulative damage value versus time for a solid insulation material according to an embodiment of the present invention under different test parameters;
FIG. 7 is a graph showing normalized variance of cumulative damage matrix versus voltage tolerance index for a solid insulation material provided by an embodiment of the present invention under different test parameters;
fig. 8 is a block diagram showing a configuration of a parameter determining apparatus for a solid insulating material according to an embodiment of the present invention;
fig. 9 shows a schematic structural diagram of an intelligent terminal provided in an embodiment of the present invention.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to the method, the device and the intelligent terminal for determining the voltage tolerance index of the solid insulating material, which are provided by the embodiment of the invention, based on the facts that the test parameters are certain when the voltage tolerance index is determined through the test parameters, the selection of different test parameters has a large influence on the result of the obtained n value of the voltage tolerance index, and the accuracy of the obtained n value needs to be improved, the accuracy of the voltage tolerance index of the solid insulating material can be effectively improved.
For the convenience of understanding the present embodiment, a method for determining a voltage endurance index of a solid insulating material disclosed in the present embodiment will be described in detail.
Referring to a flowchart of a voltage tolerance index determination method of a solid insulating material shown in fig. 1, the method is performed by an intelligent terminal such as a computer, and the method includes the steps of:
s102, selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve represents a relationship between an accumulated electrical damage amount of the solid insulating material and a voltage applied to the solid insulating material and a voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters included the initial voltage applied to the solid insulation material, the voltage increment, and the voltage application time increment.
In one embodiment, before selecting a plurality of sets of target test parameters based on the damage curve of the solid insulation material, the accumulated damage limit value of the solid insulation material, the preset reference starting voltage applied to the solid insulation material, and the preset reference voltage increase may be obtainedThe amount and the application time increment of the preset reference voltage; wherein the cumulative damage limit value DCExpressed as:
wherein k represents the corresponding breakdown stage number when the change of the preset reference starting voltage reaches the preset breakdown voltage, t represents the time when the change of the preset reference starting voltage reaches the breakdown voltage, n0Is a reference voltage withstand index, UbRepresenting a predetermined breakdown voltage of the solid insulating material;
and drawing a damage curve of the solid insulating material according to the accumulated damage limit value, the preset reference starting voltage, the preset reference voltage increment and the application time increment of the preset reference voltage. And selecting multiple groups of target test parameters based on the damage curve, wherein for example, the initial voltage and the voltage increment applied to the solid insulating material in each group are the same, and the voltage application time increment in each group is different, namely, the voltage application time increment is used as a variable to carry out calculation analysis.
And step S104, calculating voltage tolerance indexes corresponding to each group of target test parameters.
And calculating an accumulated damage matrix corresponding to each group of target test parameters, determining a target function comprising the standardized variance of the accumulated damage matrix according to the accumulated damage matrix, and calculating the voltage tolerance index corresponding to each group of target test parameters through the target function.
And step S106, respectively calculating error values between the voltage tolerance indexes corresponding to each group of target test parameters and preset reference voltage tolerance indexes.
The preset reference voltage tolerance index can be obtained according to a constant stress test method, but the method has the defects of long time consumption and low efficiency, and the test time span is large, so that the factors influencing material failure are many, the data dispersion is very large, the number of the factors is small in practical application, and the voltage tolerance index obtained by the method can be used as an analysis basis.
In step S108, the voltage tolerance index with the smallest error value is determined as the voltage tolerance index of the solid insulating material.
An error value between the voltage tolerance index corresponding to each group of target test parameters and a preset reference voltage tolerance index is obtained through calculation, the voltage tolerance index with the minimum error value can be used as the voltage tolerance index of the solid insulating material, and the voltage tolerance index of the solid insulating material calculated under the test parameters is accurate.
According to the voltage tolerance index determining method of the solid insulating material provided by the embodiment of the invention, multiple groups of target test parameters are selected based on the damage curve of the solid insulating material, the voltage tolerance index corresponding to each group of target test parameters is calculated, and the error value between the voltage tolerance index corresponding to each group of target test parameters and the preset reference voltage tolerance index is calculated respectively, so that the target test parameter corresponding to the voltage tolerance index with the minimum error value is determined as the test parameter of the solid insulating material. According to the invention, the voltage tolerance index is calculated through multiple groups of target test parameters, and the voltage tolerance index with the minimum error value with the preset reference voltage tolerance index is determined as the voltage tolerance index of the solid insulating material, so that the accuracy of the voltage tolerance index of the solid insulating material can be effectively improved.
For ease of understanding, a method for determining a voltage tolerance index of another solid insulating material provided based on the present embodiment is given below, referring to a flowchart of a method for determining a voltage tolerance index of a solid insulating material shown in fig. 2, the method including the steps of:
step S202, selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve represents a relationship between an accumulated electrical damage amount of the solid insulating material and a voltage applied to the solid insulating material and a voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters included the initial voltage applied to the solid insulation material, the voltage increment, and the voltage application time increment.
Cumulative damage limit D of solid insulation materialCExpressed as:
wherein k represents the corresponding breakdown stage number when the change of the preset reference starting voltage reaches the preset breakdown voltage, t represents the time when the change of the preset reference starting voltage reaches the breakdown voltage, n0Is a reference voltage withstand index, UbRepresenting the preset breakdown voltage of the solid insulating material.
Reference voltage tolerance index n0Are empirical values and are obtained according to the constant stress test method. FIG. 3 is a graph showing the cumulative damage values of step stress and constant stress versus time, and FIG. 3 is a graph showing the cumulative damage limit DCRegions I, II, and III in fig. 3 are damage regions divided according to voltage and time, and the cumulative damage values with time for the constant stress test and the step stress test in fig. 3 are all located in region II, that is, the same region, indicating that the equivalence between the step stress and the constant stress is good.
As shown in fig. 4, which is a schematic diagram illustrating voltage and time relationship of a solid insulating material in a loss region, regions I, II and III in fig. 4 are damage regions divided according to voltage and time, that is, breakdown failure occurs by applying voltage to the solid insulating material, so that damage regions divided at different times according to breakdown failure are selected as failure times ta and tb respectively as boundaries of the regions I and II and the regions II and III (for example, ta may be selected to be 1 hour, and tb may be 1 year), and an intercept U of the ordinate of the D-t diagram is obtained by the two boundary linesa nAnd Ub nCalculated according to the following formula:
ln D＝lnt+n·ln U
wherein t is the life of the solid insulating material under constant electrical stress U, n is a voltage tolerance index, D is the accumulated electrical damage amount required by insulation failure, and both n and D are constants for a given solid insulating material.
The choice of the predetermined reference starting voltage of the solid insulating material mainly determines the starting position of the D-t curve, for example, the voltage tolerance index in region II shown in fig. 4, as long as the condition is satisfiedUa n<U0 n<Ub nThen, the starting point of the D-t curve is located in the area II, and the D-t curve can be drawn according to the following formula:
wherein D represents the cumulative damage value of the step stress test, n represents the empirical value of the voltage tolerance index, and U0Representing a preset reference starting voltage, delta t representing an application time increment of the preset reference voltage, delta U representing a preset reference voltage increment, i representing the time change delta t times, k representing a corresponding breakdown level when the preset reference starting voltage change reaches a preset breakdown voltage, and delta tendIndicating the holding time of the breakdown voltage.
The rate of increase of the curve is determined by both Δ U and Δ t, and Δ U is typically selected to be about 5% U in order to maintain the cumulative lesion growth rate at a suitable ratebΔ t has a selected range to limit the curve end point to lie within region II, and the selected range of Δ t, i.e., the constraint, is further described below.
Obviously, a D-t curve can be drawn according to a constant voltage method, and according to the principle that the main breakdown mechanisms are similar, as long as the D-t curves drawn by the constant voltage method and the step stress method are distributed in the same damage region, the test result can be considered to have certain equivalence.
The damage curve needs to satisfy the constraint condition, which is expressed as:
wherein D iscRepresents the limit of the cumulative damage value.
Step S204, calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of sets of test parameters, m represents the number of times each set of test parameters was tested repeatedly, DwmThe cumulative damage value obtained after repeating the test m times of the w-th group of test parameters is shown.
The cumulative damage matrix D is obtained by repeating the test m times for each test parameter when the number of test parameter combinations for selecting the step stress is w. Each element D in the matrixijCan be obtained by calculating the damage value of the last stage of the breakdown stage in the stepping stress test. The problem of solving the voltage tolerance index n of the sample is converted into an optimal solution for solving a value n, so that all elements in D are equal, the optimal solution is further converted into a mathematical optimization problem, wherein the mathematical optimization problem is that the objective function is minimum by taking n as an unknown number and taking the standardized variance S (n) of the cumulative damage matrix D as an objective function.
Step S206, determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative impairment matrix.
The objective function is calculated according to the following formula:
wherein S (n) represents the normalized variance of the cumulative damage matrix D, n represents the voltage tolerance index, DijRepresents the cumulative damage value of the test parameters of the ith group obtained after j times of repeated tests,
represents the average value of the sum of each element in the cumulative damage matrix D, Δ t represents the amount of change in time, U0Representing the initial voltage, delta U representing the voltage change of the initial voltage after delta t along with the time change, i representing the time change delta t times, k representing the corresponding breakdown stage when the initial voltage change reaches the preset breakdown voltage, delta tendIndicating the holding time of the breakdown voltage.
Specifically, the time variation Δ t has a constraint condition, which is expressed as:
wherein D iscRepresents the limit of the cumulative damage value.
And S208, calculating a voltage tolerance index corresponding to each group of target test parameters according to the target function.
The voltage withstand index n is calculated according to the following formula:
wherein, the normalized variance S (n) corresponds to a curve S-n of the standard variance S with the change of n, and λ represents the negative second derivative of the change curve S-n.
FIG. 5 is a graph showing the relationship between the normalized variance of the cumulative damage matrix of a solid insulating material and the voltage tolerance index, i.e., the graph of the curve S-n, S (n) having the minimum value Sminλ represents the negative second derivative of the variation curve S-n, i.e., the sharpness of the extreme peaks of the curve, and the larger λ is, the sharper the extreme peaks are, i.e., the better the uniqueness of n in the set of test data, i.e., the target test parameter. S in FIG. 5minThe corresponding lambda is the maximum sharp degree of the extreme peak of the curve, and n is taken as the voltage tolerance index of the set of test data, SminThe smaller the lambda is, the more reasonable the set of stepping stress test parameters is.
Step S210, respectively calculating an error value between the voltage tolerance index corresponding to each group of target test parameters and a preset reference voltage tolerance index.
The error values may each be expressed as a positive number, for example, the voltage tolerance index corresponding to the target test parameter is 0.2 smaller or 0.1 larger than the preset reference voltage tolerance index.
In step S212, the voltage tolerance index with the smallest error value is determined as the voltage tolerance index of the solid insulating material.
In one embodiment, to determine the parameters of the crosslinked polyethylene insulation, six different parameter protocols (a-F) were designed to conduct the step stress test, as shown in table 1.
For simplicity of analysis, U of the six sets of test parameters035kV and 2.5kV for both Δ U were taken, and the analysis was performed with the holding time at each voltage, i.e., the time change Δ t, as a variable. The test was repeated 9 times for each set of test parameters, taking into account the dispersion of sample failure. A. Two different deltat are selected in the group C, and the duration value of the deltat in the group A is shorter than that in the group C; B. d, E the number of test samples is enlarged, three different deltat are selected, wherein 3 deltat of group B are shorter than those of group D, E, and the distance between 3 deltat selected by group E is larger than that of group D; f selects six different delta t, and the delta t of the F group and the delta t of the E group are all selected from the interval [120s, 1200s]。
Table 1 step stress test parameter set (Δ U ═ 2.5kV, U0＝35kV)
The parameters in table 1 are taken into formula (5) to obtain D-t curves of six test groups, and fig. 6 shows a schematic diagram of the cumulative damage values under different test parameters and a time relationship, that is, a schematic diagram of the D-t curves corresponding to the six test parameters a to F. As can be seen from FIG. 6, the A, B two groups of D-t curves pass through I, II two regions, while the C, D, E, F four groups of test parameters only pass through the II region, the life index of the II region is required to be acquired according to the failure mechanism equivalence principle, and the C, D, E, F four groups of test parameters have better selection equivalence.
FIG. 7 is a schematic diagram showing the relationship between the normalized variance of the cumulative damage matrix and the voltage tolerance index under different test parameters, that is, the schematic diagram of the S-n curves corresponding to the above six sets of test parameters, and further obtaining S according to the S-n curvesminAnd lambda value, and further comparing the superiority of each group of test parameters:
table 2 sets of tests n, minS (n) and lambda
For C, D, E, F four groups of samples, the reason is thatOnly passes through the II area, and has better equivalence in terms of failure mechanism. But due to the number of Δ t and Δ tmax/ΔtminAnd the difference of the values is obtained, so that the calculation results n of the four groups of experiments are still different. The test in group E, though the amount of Δ t was comparable to that in group D, Δ tmax/ΔtminThe selection range of delta t is larger than the coverage area of the D group, and the sharpness parameter lambda of the D (n) curve is also larger than the experimental parameter of the D group, which shows that the n value is better to be selected uniquely than the D group. Δ t for groups F and Emax/ΔtminThe values are equal, the lambda of the matrix is smaller than that of the group E, but the dimension of the sample of the group F is twice that of the group E, and the minS (n) of the matrix is also smaller than that of the other five groups, so that the matrix D meets the solving condition better, and the result accuracy of the group F is better; Δ t of group D and group Cmax/ΔtminEqually, the more Δ t in group D, the smaller mins (n), however, the smaller n in group D, the acceptable difference due to sample preparation and experimental error. Considering λ and mins (n) together, the test results in the F group are optimal, and the actually obtained voltage endurance index n-12.0 is also the result closest to the constant stress method (n-12.2).
In summary, in the method for determining the voltage tolerance index of the solid insulating material provided by the embodiment of the present invention, the voltage tolerance index is calculated through a plurality of sets of target test parameters, and the voltage tolerance index having the smallest error value with the preset reference voltage tolerance index is determined as the voltage tolerance index of the solid insulating material, so that the accuracy of the voltage tolerance index of the solid insulating material can be effectively improved.
In correspondence to the foregoing method for determining the voltage tolerance index of the solid insulating material, an embodiment of the present invention provides a device for determining the voltage tolerance index of the solid insulating material, and referring to a block diagram of the structure of the device for determining the voltage tolerance index of the solid insulating material shown in fig. 8, the device includes the following modules:
a selecting module 802 for selecting a plurality of sets of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve represents a relationship between an accumulated electrical damage amount of the solid insulating material and a voltage applied to the solid insulating material and a voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters include a starting voltage applied to the solid insulation material, a voltage increment, and a voltage application time increment;
a voltage tolerance index calculation module 804, configured to calculate a voltage tolerance index corresponding to each group of target test parameters;
an error value calculating module 806, configured to calculate an error value between a voltage tolerance index corresponding to each set of target test parameters and a preset reference voltage tolerance index;
a determination module 808 is configured to determine the voltage withstand index with the smallest error value as the voltage withstand index of the solid insulating material.
According to the voltage tolerance index determining device for the solid insulating material, provided by the embodiment of the invention, the voltage tolerance index is calculated through multiple groups of target test parameters, and the voltage tolerance index with the minimum error value with the preset reference voltage tolerance index is determined as the voltage tolerance index of the solid insulating material, so that the accuracy of the voltage tolerance index of the solid insulating material can be effectively improved.
The voltage tolerance index calculation module 804 is further configured to: calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of sets of test parameters, m represents the number of times each set of test parameters was tested repeatedly, DwmRepresenting the cumulative damage value obtained after the test parameters of the w group are repeatedly tested for m times; determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative damage matrix; and calculating the voltage tolerance index corresponding to each group of target test parameters according to the target function.
The device provided by the embodiment has the same implementation principle and technical effect as the foregoing embodiment, and for the sake of brief description, reference may be made to the corresponding contents in the foregoing method embodiment for the portion of the embodiment of the device that is not mentioned.
An embodiment of the present invention provides an intelligent terminal, which is shown in fig. 9, and the intelligent terminal includes: a processor 90, a memory 91, a bus 92 and a communication interface 93, wherein the processor 90, the communication interface 93 and the memory 91 are connected through the bus 92; the processor 90 is arranged to execute executable modules, such as computer programs, stored in the memory 91.
The Memory 91 may include a high-speed Random Access Memory (RAM) and may further include a non-volatile Memory (non-volatile Memory), such as at least one disk Memory. The communication connection between the network element of the system and at least one other network element is realized through at least one communication interface 93 (which may be wired or wireless), and the internet, a wide area network, a local network, a metropolitan area network, and the like can be used.
Bus 92 may be an ISA bus, PCI bus, EISA bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one double-headed arrow is shown in FIG. 9, but this does not indicate only one bus or one type of bus.
The memory 91 is used for storing a program, the processor 90 executes the program after receiving an execution instruction, and the method executed by the apparatus defined by the flow process disclosed in any of the foregoing embodiments of the present invention may be applied to the processor 90, or implemented by the processor 90.
The processor 90 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuits of hardware or instructions in the form of software in the processor 90. The Processor 90 may be a general-purpose Processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like; the device can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, or a discrete hardware component. The various methods, steps and logic blocks disclosed in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in the memory 91, and the processor 90 reads the information in the memory 91 and performs the steps of the above method in combination with the hardware thereof.
Embodiments of the present invention further provide a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, performs the steps of the method of any one of the foregoing embodiments.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process of the system described above may refer to the corresponding process in the foregoing embodiments, and is not described herein again.
The method and the device for determining the voltage tolerance index of the solid insulating material and the computer program product of the intelligent terminal provided by the embodiment of the invention comprise a computer readable storage medium storing program codes, instructions included in the program codes can be used for executing the method described in the previous method embodiment, and specific implementation can refer to the method embodiment and is not described herein again.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (9)
1. A method of determining a voltage tolerance index of a solid insulating material, comprising:
selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve characterizes the cumulative amount of electrical damage to the solid insulation material as a function of voltage applied to the solid insulation material and voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters include a starting voltage applied to the solid insulation material, a voltage increment, and a voltage application time increment;
calculating a voltage tolerance index corresponding to each group of target test parameters;
respectively calculating an error value between a voltage tolerance index corresponding to each group of target test parameters and a preset reference voltage tolerance index;
determining a voltage tolerance index with a minimum error value as the voltage tolerance index of the solid insulation material;
wherein, before the step of selecting a plurality of sets of target test parameters based on the damage curve of the solid insulation material, the method further comprises:
acquiring an accumulated damage limit value of a solid insulating material, a preset reference starting voltage applied to the solid insulating material, a preset reference voltage increment and an application time increment of the preset reference voltage; wherein the cumulative damage limit value DCExpressed as:
wherein k represents a corresponding breakdown level when the change of the preset reference starting voltage reaches a preset breakdown voltage, t represents the time when the change of the preset reference starting voltage reaches the breakdown voltage, n0Is the reference voltage withstand index, UbRepresenting a predetermined breakdown voltage of the solid insulating material;
and drawing a damage curve of the solid insulating material according to the accumulated damage limit value, the preset reference starting voltage, the preset reference voltage increment and the application time increment of the preset reference voltage.
2. The method of claim 1, wherein the step of calculating the voltage tolerance index for each set of the target test parameters comprises:
calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of groups of the test parameters, and m represents the weight of the test parameters in each groupNumber of retests, DwmRepresenting the cumulative damage value of the test parameters of the w group after repeated tests for m times;
determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative damage matrix;
and calculating the voltage tolerance index corresponding to each group of target test parameters according to the target function.
3. The method of claim 2, wherein the step of determining an objective function from the cumulative impairment matrix comprises:
the objective function is calculated according to the following formula:
wherein S (n) represents the normalized variance of the cumulative damage matrix D, n represents the voltage tolerance index, DijRepresents the cumulative damage value of the test parameters in the ith group after j times of repeated tests,
represents an average value of the sum of each element in the cumulative damage matrix D, Δ t represents a time variation, U0Representing the initial voltage, delta U representing the voltage change of the initial voltage after delta t along with the time change, i representing the time change delta t, k representing the corresponding breakdown stage number when the initial voltage change reaches the preset breakdown voltage, delta tendRepresenting the holding time of the breakdown voltage.
4. The method of claim 3, wherein the step of calculating the voltage tolerance index for each set of the target test parameters according to the objective function comprises:
the voltage withstand index n is calculated according to the following formula:
wherein the normalized variance S (n) corresponds to a curve S-n of the standard variance S with n, where λ represents the negative second derivative of the curve S-n.
5. The method according to claim 3, wherein the time variation Δ t has a constraint represented by:
wherein D iscRepresents a limit value for the cumulative damage value.
6. An apparatus for determining a voltage tolerance index of a solid insulating material, comprising:
the selection module is used for selecting a plurality of groups of target test parameters based on the damage curve of the solid insulating material; wherein the damage curve characterizes the cumulative amount of electrical damage to the solid insulation material as a function of voltage applied to the solid insulation material and voltage application time; the target test parameters are parameters for designing a step stress test to obtain a voltage tolerance index of the solid insulating material; the target test parameters include a starting voltage applied to the solid insulation material, a voltage increment, and a voltage application time increment;
the voltage tolerance index calculation module is used for calculating a voltage tolerance index corresponding to each group of target test parameters;
the error value calculation module is used for calculating the error value between the voltage tolerance index corresponding to each group of target test parameters and a preset reference voltage tolerance index;
the determining module is used for determining the voltage tolerance index with the minimum error value as the voltage tolerance index of the solid insulating material;
wherein, before the step of selecting a plurality of sets of target test parameters based on the damage curve of the solid insulation material, the apparatus further comprises:
acquiring an accumulated damage limit value of a solid insulating material, a preset reference starting voltage applied to the solid insulating material, a preset reference voltage increment and an application time increment of the preset reference voltage; wherein the cumulative damage limit value DCExpressed as:
wherein k represents a corresponding breakdown level when the change of the preset reference starting voltage reaches a preset breakdown voltage, t represents the time when the change of the preset reference starting voltage reaches the breakdown voltage, n0Is the reference voltage withstand index, UbRepresenting a predetermined breakdown voltage of the solid insulating material;
and drawing a damage curve of the solid insulating material according to the accumulated damage limit value, the preset reference starting voltage, the preset reference voltage increment and the application time increment of the preset reference voltage.
7. The apparatus of claim 6, wherein the voltage tolerance index calculation module is configured to:
calculating an accumulated damage matrix corresponding to each group of target test parameters; wherein the cumulative damage matrix D is represented as:
wherein w represents the number of sets of the test parameters, m represents the number of times of repeating the test for each set of the test parameters, DwmRepresenting the cumulative damage value of the test parameters of the w group after repeated tests for m times;
determining a target function according to the accumulated damage matrix; wherein the objective function comprises a normalized variance of the cumulative damage matrix;
and calculating the voltage tolerance index corresponding to each group of target test parameters according to the target function.
8. An intelligent terminal is characterized by comprising a processor and a memory;
the memory has stored thereon a computer program which, when executed by the processor, performs the method of any of claims 1 to 5.
9. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method according to any one of the claims 1 to 5.
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| CN110658426B (en) * | 2019-10-09 | 2021-06-29 | 深圳华络电子有限公司 | Method for testing failure mode and withstand voltage value of inductor |
| CN112285513B (en) * | 2020-10-29 | 2023-12-05 | 重庆大学 | Method for defining oil paper insulation rapid development type discharge under alternating current voltage based on voltage tolerance index |
| CN112417597B (en) * | 2020-11-19 | 2023-06-23 | 潍柴动力股份有限公司 | Method, device, equipment and storage medium for determining material characteristics of vehicle |
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