CN112924742A - Current measurement time adjusting method and device and storage medium - Google Patents
Current measurement time adjusting method and device and storage medium Download PDFInfo
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Abstract
The invention discloses a method for adjusting the measurement time of current, which comprises the following steps: obtaining polarization current and depolarization current at the current measured time; calculating the resistance value in each measuring branch according to the polarization current and the depolarization current; calculating a current polarization fitting parameter, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, ending the polarization current measurement; and calculating a current depolarization fitting parameter, and if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is smaller than a preset second change rate threshold value, ending the depolarization current measurement. The method for adjusting the current measuring time can adaptively adjust the measuring time of the cable polarization and depolarization current method, and improve the measuring efficiency. The invention also discloses a device for adjusting the current measuring time and a storage medium.
Description
Technical Field
The invention relates to the technical field of electrical equipment measurement, in particular to a method and a device for adjusting current measurement time and a storage medium.
Background
Currently, the Polarization and Depolarization Current (PDC) method, which is a nondestructive diagnostic method, is widely used in the diagnosis of the insulation state of a cable. The insulation diagnosis method based on the PDC is characterized in that parameters capable of reflecting the insulation state are extracted according to the polarization depolarized current of the cable insulation, and the insulation state is evaluated by combining the existing research criteria. Therefore, complete and accurate polarization depolarization current can be conveniently and quickly obtained, and great significance is brought to the improvement of the effectiveness and the application range of the PDC-based insulation diagnosis method.
In the prior art, the polarization current and depolarization current of the cable are measured, and a polarization duration t is generally preset1And depolarization duration t2Firstly, a DC voltage U is applied to the cable insulationcMeasuring the current flowing through the insulation to obtain a polarization current, and keeping the polarization current for a preset polarization time period t1Second; then removing the direct current voltage at two ends of the insulation and carrying out short circuit, measuring to obtain the current flowing through the insulation, namely the depolarized current, and continuously setting the polarization time length t2And second. Because the insulation states of the cables to be tested are different, the polarization currents and the depolarization currents of the cables to be tested are different. For the cable with better insulation condition, the polarization time is short, the polarization current decays fast, and the steady state value can be reached in 200s generally. For cables with poor insulation, the polarization time is long, the polarization current decays slowly, and may decay at 500s, and in order to ensure that the measured polarization and depolarization currents reach steady state values, the polarization and depolarization currents need to be measured for about 1000 s. Therefore, for a cable with unknown insulation conditions, the polarization and depolarization current measurement time is typically set to 1000s in order to ensure that the measured polarization and depolarization currents contain sufficient insulation information. Therefore, the time for measuring the polarization/depolarization current of the cable is 2000s, the measurement time is longer, and therefore, the time for polarization and depolarization of the cable needs to be optimized, and the measurement time of the polarization/depolarization current method of the cable needs to be reduced.
Disclosure of Invention
The embodiment of the invention provides a method for adjusting the measurement time of current, which can adaptively adjust the measurement time of a cable polarization and depolarization current method and improve the measurement efficiency.
The embodiment of the invention provides a method for adjusting current measurement time, which comprises the following steps:
obtaining polarization current and depolarization current at the current measured time;
calculating the resistance value in each measuring branch according to the polarization current and the depolarization current;
calculating a current polarization fitting parameter according to the polarization current at the current measured time and the resistance value, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, finishing the polarization current measurement;
and calculating a current depolarization fitting parameter according to the depolarization current at the current measured time and the resistance value, and finishing depolarization current measurement if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is less than a preset second change rate threshold value.
As an improvement of the above scheme, the resistance values in the measurement branches specifically include:
a first resistance in the first measurement branch, a second resistance in the second measurement branch, and a third resistance in the third measurement branch;
the first measuring branch, the second measuring branch and the third measuring branch are connected in parallel.
As an improvement of the above scheme, the calculating a resistance value in each measurement branch according to the polarization current and the depolarization current specifically includes:
the resistance value in the measuring branch is calculated by:
in the formula ip(t) is the polarization current at the present measured time, t0For the current measured time, A0pIs composed of
A1pIs composed of
A2pIs composed of
A3pIs composed of
U is the voltage of the cable to be tested, R0For the resistance of the cable to be tested, R1Is the first resistance, R2Is the second resistance, R3Is the third resistance; tau is1pIs R1C1，τ2pIs R2C2，τ3pIs R3C3，C1Is the first capacitor, C2Is said second capacitance, C3As a result of the third capacitance, the second capacitance,
the polarization currents of the first branch circuit, the second branch circuit and the third branch circuit are respectively.
As an improvement of the above scheme, the current polarization fitting parameters comprise Akd(t0) And τkd(t0)；
Calculating a rate of change of the current polarization fitting parameter from the polarization fitting parameter at the previous time by:
in the formula, Akp(t0)，τkp(t0) Fitting parameters for the current polarization with k ═ 1,2,3, i.e., Akp(t0) Is represented by A1p、A2p、A3p；τkp(t0) Denotes τ1p、τ2p、τ3p；Akp(t0-1)、τkp(t0-1) fitting parameters for the polarization at the previous time instant.
As an improvement of the above scheme, the calculating a resistance value in each measurement branch according to the polarization current and the depolarization current specifically includes:
the resistance value in the measuring branch is calculated by:
in the formula id(t) is the depolarizing current at the current measured time, t0For the current measured time, A1dIs composed of
A2dIs composed of
A3dIs composed of
U is the voltage of the cable to be tested, R1Is the first resistance, R2Is the second resistance, R3Is the third resistance.
As an improvement of the above scheme, the current depolarization fitting parameter comprises Akd(t0) And τkd(t0)；
Calculating a rate of change of the current depolarization fit parameter from a depolarization fit parameter at a previous time by:
in the formula, Akd(t0)，τkd(t0) Fitting a parameter for the current depolarization, k ═ 1,2,3, i.e. Akd(t0) Is represented by A1d、A2d、A3d；Akd(t0-1)、τkd(t0-1) fitting parameters for depolarization at said previous time instant.
As a modification of the above, the first change rate threshold value is 1%, and the second change rate threshold value is 1%.
Correspondingly, an embodiment of the present invention provides a device for adjusting current measurement time, including:
the current acquisition unit is used for acquiring polarization current and depolarization current at the current measured time;
the resistance calculation unit is used for calculating the resistance value in each measuring branch according to the polarization current and the depolarization current;
the polarization time adjusting unit is used for calculating a current polarization fitting parameter according to the polarization current at the current measured time and the resistance value, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, the polarization current measurement is finished;
and the depolarization time adjusting unit is used for calculating a current depolarization fitting parameter according to the depolarization current at the current measured time and the resistance value, and ending the depolarization current measurement if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is smaller than a preset second change rate threshold value.
Correspondingly, a third embodiment of the present invention provides a device for adjusting current measurement time, including: the device comprises a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to realize a method for adjusting the measurement time of the current according to the first embodiment of the invention.
Correspondingly, an embodiment four of the present invention provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, the apparatus where the computer-readable storage medium is located is controlled to execute the method for adjusting current measurement time according to the embodiment one of the present invention.
The method, the device and the storage medium for adjusting the current measuring time provided by the embodiment of the invention have the following beneficial effects:
compared with the existing polarization/depolarization current measuring method with fixed measuring time, the method has the advantages that the measuring time can be greatly shortened on the premise that effective insulation information contained in the polarization/depolarization current is not reduced, the limitation on the cable insulation using scene measured by the polarization/depolarization current method is reduced, the application range of the method is enlarged, the self-adaptive adjustment of the measuring time of the cable polarization and depolarization current method is realized, and the measuring efficiency is improved.
Drawings
Fig. 1 is a schematic flow chart of a method for adjusting a measurement time of a current according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of an extended Debye three-branch model of a cable according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a cable polarization current provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram of a cable polarization current fitting parameter provided by an embodiment of the invention;
fig. 5 is a schematic diagram of a change rate of a cable polarization current fitting parameter according to an embodiment of the present invention.
Fig. 6 is a schematic structural diagram of a current measurement time adjustment apparatus according to a second embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
Referring to fig. 1, a schematic flow chart of a method for adjusting a measurement time of a current according to an embodiment of the present invention includes:
s10, acquiring polarization current and depolarization current at the current measured time;
s20, calculating resistance values in each measuring branch according to the polarization current and the depolarization current;
s30, calculating a current polarization fitting parameter according to the polarization current and the resistance value at the current measured time, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, ending the polarization current measurement;
and S40, calculating a current depolarization fitting parameter according to the depolarization current and the resistance value at the current measured time, and ending the depolarization current measurement if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is smaller than a preset second change rate threshold value.
Further, the resistance values in the measurement branches specifically include:
a first resistance in the first measurement branch, a second resistance in the second measurement branch, and a third resistance in the third measurement branch;
the first measuring branch, the second measuring branch and the third measuring branch are connected in parallel.
Specifically, referring to fig. 2, it is a schematic diagram of an extended Debye three-branch model of a cable according to an embodiment of the present invention; when the cable is aged, due to the fact that dielectric properties of an aged area and a non-aged area are different, three different polarization mechanisms exist in the cable insulation, and three groups of resistance-capacitance series branches are used for representing, and therefore an extended Debye three-branch equivalent model of the cable is defined, wherein R is0、C0Respectively a cable body resistance and a cable body capacitance; r1-C1The series branch represents the insulated bulk polarization; r2-C2Characterizing polarization of the insulating amorphous-to-crystalline interface region; r3-C3The arm characterizes the metal salt and hydrated ion polarization in the interface due to aging. For the extended Debye three-branch equivalent model of the cable, the polarization current ip(t) and depolarization Current id(t) can be expressed in terms of model parameters as:
further, calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula ip(t) is the polarization current at the present measured time, t0For the current measured time, A0pTo represent
A1pTo represent
A2pTo represent
A3pTo represent
U is the voltage of the cable to be tested, R0For the resistance of the cable to be tested, R1Is a first resistance, R2Is a second resistance, R3Is a third resistor; tau is1pIs R1C1，τ2pIs R2C2，τ3pIs R3C3，C1Is a first capacitor, C2Is a second capacitor, C3Is a third capacitance, and is a third capacitance,
the polarization currents of the first branch circuit, the second branch circuit and the third branch circuit are respectively.
Specifically, due to the limitation of the measuring instrument, the current waveforms of the polarization current and the depolarization current in the 1 st second often have great deviation, and need to be removed in advance, otherwise, the current waveforms will be removedResults of the fitting are uncontrollably varied, so that 1 < t0。
Further, the current polarization fitting parameters include Akd(t0) And τkd(t0)；
Calculating the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment by the following formula:
in the formula, Akp(t0)，τkp(t0) Fitting parameters for the current polarization, k ═ 1,2,3, i.e. Akp(t0) Is represented by A1p、A2p、A3p；τkp(t0) Denotes τ1p、τ2p、τ3p；Akp(t0-1)、τkp(t0-1) is the polarization fit parameter at the last instant.
In a particular embodiment, the time t is measured0Increase of (A)0p,A1p,τ1p,A2p,τ2p,A3p,τ3pAlso with t0Changes, can be expressed as to t0Function of (c):
A0p(t0),A1p(t0),τ1p(t0),A2p(t0),τ2p(t0),A3p(t0),τ3p(t0)；
the rate of change of the fitting parameters is defined,
if it is
And if the measured values are smaller than the first change rate threshold value, the measurement of the polarization current of the cable to be measured is finished, and the measurement of the depolarized current is started.
Further, calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula id(t) is the depolarizing current at the current measured time, t0For the current measured time, A1dIs composed of
A2dIs composed of
A3dIs composed of
U is the voltage of the cable to be tested, R1Is a first resistance, R2Is a second resistance, R3Is a third resistor.
Further, the current depolarization fitting parameters include Akd(t0) And τkd(t0)；
Calculating the rate of change of the current depolarization fitting parameter and the depolarization fitting parameter at the previous time by the following formula:
in the formula, Akd(t0)，τkd(t0) Fitting parameters for the current depolarization with k ═ 1,2,3, i.e. Akd(t0) Is represented by A1d、A2d、A3d；Akd(t0-1)、τkd(t0-1) fitting parameters for depolarization at the previous time instant.
In a specific embodiment, the measured depolarization current is analyzed in real time as the depolarization current is measured. Let the time currently measured be t0And second. T is0>At 10, for 1s to t0Depolarization current id(t) fitting was performed as follows.
With time of measurement t0Increase of (A)1d,τ1d,A2d,τ2d,A3d,τ3dAlso with t0Changes, can be expressed as to t0Function of (c):
A1d(t0),τ1d(t0),A2d(t0),τ2d(t0),A3d(t0),τ3d(t0)
the rate of change of the fitting parameters is defined,
if it is
And if the measured depolarized current is smaller than the second change rate threshold value, the measurement of the depolarized current of the cable to be measured is finished.
Further, the first rate of change threshold is 1% and the second rate of change threshold is 1%.
In particular, the polarization and depolarization process when the cable measures lasts for a certain time t0Thereafter, although the measured polarization and depolarization currents have not stabilized yet, t0Tau for branch already longer than relaxation time3At this time, alreadyEach parameter in the extended Debye three-branch equivalent model can be accurately fitted, the polarization and depolarization time is prolonged, and the fitting parameter change in the equivalent model is small and is generally less than 1%.
In a specific embodiment, the polarization time of the polarization current is intelligently controlled by analyzing and measuring the polarization current of the cable in real time. Fig. 3 shows the real-time polarization current of the measuring cable. Let the time currently measured be t0Second, real time for 1s to t0Polarization current i ofp(t) fitting was performed according to the equation (1), and the fitting parameters are shown in FIG. 4. The rate of change of the fitting parameters was calculated as shown in fig. 5. When the polarization current measurement time is 340 seconds, the change rate of all fitting parameters is less than 1%, and the polarization measurement is finished.
The method for adjusting the current measuring time provided by the embodiment of the invention has the following beneficial effects:
compared with the existing polarization/depolarization current measuring method with fixed measuring time, the method has the advantages that the measuring time can be greatly shortened on the premise that effective insulation information contained in the polarization/depolarization current is not reduced, the limitation on the cable insulation using scene measured by the polarization/depolarization current method is reduced, the application range of the method is enlarged, the self-adaptive adjustment of the measuring time of the cable polarization and depolarization current method is realized, and the measuring efficiency is improved.
Referring to fig. 6, a schematic structural diagram of a current measurement time adjusting device according to a second embodiment of the present invention is shown, including:
a current obtaining unit 10, configured to obtain a polarization current and a depolarization current at a current measured time;
a resistance calculation unit 20, configured to calculate a resistance value in each measurement branch according to the polarization current and the depolarization current;
the polarization time adjusting unit 30 is configured to calculate a current polarization fitting parameter according to the polarization current and the resistance value at the current measured time, and end the polarization current measurement if a change rate of the current polarization fitting parameter and the polarization fitting parameter at the previous time is smaller than a preset first change rate threshold;
and the depolarization time adjusting unit 40 is configured to calculate a current depolarization fitting parameter according to the depolarization current and the resistance value at the current measured time, and end depolarization current measurement if a change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the previous time is smaller than a preset second change rate threshold.
Further, the resistance values in the measurement branches specifically include:
a first resistance in the first measurement branch, a second resistance in the second measurement branch, and a third resistance in the third measurement branch;
the first measuring branch, the second measuring branch and the third measuring branch are connected in parallel.
Further, calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula ip(t) is the polarization current at the present measured time, t0For the current measured time, A0pIs composed of
A1pIs composed of
A2pIs composed of
A3pIs composed of
U is the voltage of the cable to be tested, R0For the resistance of the cable to be tested, R1Is a first resistance, R2Is as followsTwo resistors, R3Is a third resistor; tau is1pIs R1C1，τ2pIs R2C2，τ3pIs R3C3，C1Is a first capacitor, C2Is a second capacitor, C3Is a third capacitance, and is a third capacitance,
the polarization currents of the first branch circuit, the second branch circuit and the third branch circuit are respectively.
Further, the current polarization fitting parameters include Akd(t0) And τkd(t0)；
Calculating the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment by the following formula:
in the formula, Akp(t0)，τkp(t0) Fitting parameters for the current polarization, k ═ 1,2,3, i.e. Akp(t0) Is represented by A1p、A2p、A3p；τkp(t0) Denotes τ1p、τ2p、τ3p；Akp(t0-1)、τkp(t0-1) is the polarization fit parameter at the last instant.
Further, calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula id(t) is currently measuredDepolarisation current at quantum time, t0For the current measured time, A1dIs composed of
A2dIs composed of
A3dIs composed of
U is the voltage of the cable to be tested, R1Is a first resistance, R2Is a second resistance, R3Is a third resistor.
Further, the current depolarization fitting parameters include Akd(t0) And τkd(t0)；
Calculating the rate of change of the current depolarization fitting parameter and the depolarization fitting parameter at the previous time by the following formula:
in the formula, Akd(t0)，τkd(t0) Fitting parameters for the current depolarization with k ═ 1,2,3, i.e. Akd(t0) Is represented by A1d、A2d、A3d；Akd(t0-1)、τkd(t0-1) fitting parameters for depolarization at the previous time instant.
Further, the first rate of change threshold is 1% and the second rate of change threshold is 1%.
The device for adjusting the current measuring time provided by the embodiment of the invention has the following beneficial effects:
compared with the existing polarization/depolarization current measuring method with fixed measuring time, the method has the advantages that the measuring time can be greatly shortened on the premise that effective insulation information contained in the polarization/depolarization current is not reduced, the limitation on the cable insulation using scene measured by the polarization/depolarization current method is reduced, the application range of the method is enlarged, the self-adaptive adjustment of the measuring time of the cable polarization and depolarization current method is realized, and the measuring efficiency is improved.
Correspondingly, the third embodiment of the present invention provides a device for adjusting measurement time of current, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the method for adjusting measurement time of current according to the first embodiment of the present invention is implemented. The current measuring time adjusting device can be a desktop computer, a notebook computer, a palm computer, a cloud server and other computing equipment. The measuring time adjusting device of the current can comprise, but is not limited to, a processor and a memory.
Correspondingly, an embodiment four of the present invention provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, the apparatus where the computer-readable storage medium is located is controlled to execute the method for adjusting current measurement time according to the embodiment one of the present invention.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, said processor being the control center of said current measuring time adjusting device, the various parts of the whole current measuring time adjusting device being connected by means of various interfaces and lines.
The memory may be used to store the computer program and/or module, and the processor may implement various functions of the current measuring time adjusting apparatus by operating or executing the computer program and/or module stored in the memory and calling data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like. In addition, the memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
Wherein, the module/unit integrated with the measuring time adjusting device of the current can be stored in a computer readable storage medium if the module/unit is realized in the form of a software functional unit and sold or used as a separate product. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like.
It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. In addition, in the drawings of the embodiment of the apparatus provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, and may be specifically implemented as one or more communication buses or signal lines. One of ordinary skill in the art can understand and implement it without inventive effort.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A method of adjusting a measurement time of a current, comprising:
obtaining polarization current and depolarization current at the current measured time;
calculating the resistance value in each measuring branch according to the polarization current and the depolarization current;
calculating a current polarization fitting parameter according to the polarization current at the current measured time and the resistance value, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, finishing the polarization current measurement;
and calculating a current depolarization fitting parameter according to the depolarization current at the current measured time and the resistance value, and finishing depolarization current measurement if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is less than a preset second change rate threshold value.
2. The method according to claim 1, wherein the resistance values in the measurement branches specifically include:
a first resistance in the first measurement branch, a second resistance in the second measurement branch, and a third resistance in the third measurement branch;
the first measuring branch, the second measuring branch and the third measuring branch are connected in parallel.
3. The method according to claim 2, wherein the calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula ip(t) is the polarization current at the present measured time, t0For the current measured time, A0pIs composed of
A1pIs composed of
A2pIs composed of
A3pIs composed of
U is the voltage of the cable to be tested, R0For the resistance of the cable to be tested, R1Is the first resistance, R2Is the second resistance, R3Is the third resistance; tau is1pIs R1C1，τ2pIs R2C2，τ3pIs R3C3，C1Is the first capacitor, C2Is said second capacitance, C3As a result of the third capacitance, the second capacitance,
the polarization currents of the first branch circuit, the second branch circuit and the third branch circuit are respectively.
4. The method of claim 3, wherein the current polarization fitting parameter comprises Akd(t0) And τkd(t0)；
Calculating a rate of change of the current polarization fitting parameter from the polarization fitting parameter at the previous time by:
in the formula, Akp(t0)，τkp(t0) Fitting parameters for the current polarization with k ═ 1,2,3, i.e., Akp(t0) Is represented by A1p、A2p、A3p；τkp(t0) Denotes τ1p、τ2p、τ3p；Akp(t0-1)、τkp(t0-1) fitting parameters for the polarization at the previous time instant.
5. The method according to claim 2, wherein the calculating the resistance value in each measuring branch according to the polarization current and the depolarization current specifically comprises:
the resistance value in the measuring branch is calculated by:
in the formula id(t) is the depolarizing current at the current measured time, t0For the current measured time, A1dIs composed of
A2dIs composed of
A3dIs composed of
U is the voltage of the cable to be tested, R1Is the first resistance, R2Is the second resistance, R3Is the third resistance.
6. The method of claim 5, wherein the current depolarization fitting parameter comprises Akd(t0) And τkd(t0)；
Calculating a rate of change of the current depolarization fit parameter from a depolarization fit parameter at a previous time by:
in the formula, Akd(t0)，τkd(t0) Fitting a parameter for the current depolarization with k ═ 12,3, i.e. Akd(t0) Is represented by A1d、A2d、A3d；Akd(t0-1)、τkd(t0-1) fitting parameters for depolarization at said previous time instant.
7. A method of regulating the measurement time of an electric current according to claims 1 to 6, characterized in that said first threshold value of rate of change is 1% and said second threshold value of rate of change is 1%.
8. An apparatus for adjusting a measurement time of an electric current, comprising:
the current acquisition unit is used for acquiring polarization current and depolarization current at the current measured time;
the resistance calculation unit is used for calculating the resistance value in each measuring branch according to the polarization current and the depolarization current;
the polarization time adjusting unit is used for calculating a current polarization fitting parameter according to the polarization current at the current measured time and the resistance value, and if the change rate of the current polarization fitting parameter and the polarization fitting parameter at the last moment is smaller than a preset first change rate threshold value, the polarization current measurement is finished;
and the depolarization time adjusting unit is used for calculating a current depolarization fitting parameter according to the depolarization current at the current measured time and the resistance value, and ending the depolarization current measurement if the change rate of the current depolarization fitting parameter and the depolarization fitting parameter at the last moment is smaller than a preset second change rate threshold value.
9. An apparatus for adjusting a measurement time of an electric current, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor implementing a method for adjusting a measurement time of an electric current according to any one of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, comprising a stored computer program, wherein the computer program, when executed, controls an apparatus in which the computer-readable storage medium is located to perform a method of adjusting a measurement time of an electric current according to any one of claims 1 to 7.
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