Ultra-low frequency dielectric loss correction system, method, device, equipment, medium and product

Abstract

The invention discloses an ultra-low frequency dielectric loss correction system, method, device and equipment, a medium and a product. An ultra-low frequency dielectric loss correction system comprises a leakage current measurement subsystem, an ultra-low frequency dielectric loss measurement subsystem and an ultra-low frequency dielectric loss correction subsystem. The leakage current measurement subsystem is used for measuring the leakage current value of the cable to be measured; the ultralow-frequency dielectric loss measurement subsystem is used for measuring an initial ultralow-frequency dielectric loss value and a capacitive current value of the cable to be measured; and the ultra-low frequency dielectric loss correction subsystem is used for acquiring the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determining a target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value. Errors caused by the influence of leakage current in ultralow frequency dielectric loss measurement are effectively overcome, so that a more accurate target ultralow frequency dielectric loss value can be determined, and the accuracy of ultralow frequency dielectric loss measurement is remarkably improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of safe operation of cables, and in particular to an ultra-low frequency dielectric loss correction system, method, device, equipment, medium and product. Background Art

[0003] In order to detect the insulation status of cables, a variety of detection methods have emerged. These methods include offline detection methods and online detection methods. Offline detection methods include withstand voltage test, insulation resistance test, oscillation wave test, ultra-low frequency dielectric loss (dissipation) test, etc. Among them, ultra-low frequency dielectric loss test can accurately reflect whether the tested cable has water ingress, moisture and other problems, and can quantitatively reflect the aging and deterioration of cable insulation, so it has been widely used in cable detection. In addition, due to its low detection frequency (0.01-0.1Hz), ultra-low frequency dielectric loss detection can detect long-length cables at a smaller capacity.

[0004] However, in order to analyze the aging characteristics of cables, it is often necessary to test cable samples, such as taking 1-10 meter short samples for testing. The existing detection method is to apply high temperature and high voltage to the sampled broken cable to accelerate the aging of its insulation, and at the same time measure the ultra-low frequency dielectric loss value of the cable at different aging stages to obtain the degree of cable insulation aging based on ultra-low frequency dielectric loss, and complete the health status judgment. However, in actual experiments, it was found that the existing ultra-low frequency dielectric loss test method has low measurement accuracy for short cable samples, and the error with the theoretical value is very large. Therefore, there are great difficulties in the ultra-low frequency measurement of short sample cables. Summary of the invention

[0005] The present invention provides an ultra-low frequency dielectric loss correction system, method, device, equipment, medium and product to solve the problem of low measurement accuracy in existing ultra-low frequency dielectric loss test methods.

[0006] According to one aspect of the present invention, there is provided an ultra-low frequency dielectric loss correction system, comprising a leakage current measurement subsystem, an ultra-low frequency dielectric loss measurement subsystem and an ultra-low frequency dielectric loss correction subsystem;

[0007] The leakage current measurement subsystem is used to measure the leakage current value of the cable to be tested;

[0008] The ultra-low frequency dielectric loss measurement subsystem is used to measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested;

[0009] The ultra-low frequency dielectric loss correction subsystem is used to obtain the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determine the target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value.

[0010] According to another aspect of the present invention, there is provided an ultra-low frequency dielectric loss correction method, which is applied to the ultra-low frequency dielectric loss correction subsystem as described in any embodiment of the present invention, and the method comprises:

[0011] Obtain the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested;

[0012] Based on the initial ultra-low frequency dielectric loss value and the capacitive current value and the leakage current value, a target ultra-low frequency dielectric loss value is determined.

[0013] According to another aspect of the present invention, there is provided an ultra-low frequency dielectric loss correction device, which is configured in the ultra-low frequency dielectric loss correction subsystem according to any embodiment of the present invention, and the device comprises:

[0014] An acquisition module is used to obtain the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested;

[0015] A determination module is used to determine a target ultra-low frequency dielectric loss value based on the initial ultra-low frequency dielectric loss value and the capacitive current value and the leakage current value.

[0016] According to another aspect of the present invention, an electronic device is provided, configured as the ultra-low frequency dielectric loss correction subsystem according to any embodiment of the present invention, the electronic device comprising:

[0017] at least one processor; and

[0018] a memory communicatively connected to the at least one processor; wherein,

[0019] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the ultra-low frequency dielectric loss correction method described in any embodiment of the present invention.

[0020] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the ultra-low frequency dielectric loss correction method described in any embodiment of the present invention when executed.

[0021] According to another aspect of the present invention, a computer program product is provided. The computer program product includes a computer program. When the computer program is executed by a processor, the ultra-low frequency dielectric loss correction method described in any embodiment of the present invention is implemented.

[0022] An ultra-low frequency dielectric loss correction system provided by an embodiment of the present invention includes a leakage current measurement subsystem, an ultra-low frequency dielectric loss measurement subsystem and an ultra-low frequency dielectric loss correction subsystem; the leakage current measurement subsystem is used to measure the leakage current value of the cable to be tested; the ultra-low frequency dielectric loss measurement subsystem is used to measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested; the ultra-low frequency dielectric loss correction subsystem is used to obtain the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determine the target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value. By adopting the above technical scheme, the leakage current measurement subsystem, the ultra-low frequency dielectric loss measurement subsystem and the ultra-low frequency dielectric loss correction subsystem are integrated. The leakage current measurement subsystem can measure the leakage current value of the cable to be tested, and the ultra-low frequency dielectric loss measurement subsystem can measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested. The ultra-low frequency dielectric loss correction subsystem is used to comprehensively consider these factors, effectively overcoming the error caused by the influence of leakage current in the ultra-low frequency dielectric loss measurement, so that a more accurate target ultra-low frequency dielectric loss value can be determined, which significantly improves the accuracy of the ultra-low frequency dielectric loss measurement.

[0023] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a structural schematic diagram of an ultra-low frequency dielectric loss correction system provided by Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of equivalent current analysis of a cable to be tested provided by the first embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of a phase relationship before and after correction provided by an embodiment of the present invention;

[0028] Figure 4 A circuit diagram of a leakage current measurement subsystem during a test process provided by an embodiment of the present invention;

[0029] Figure 5It is a circuit diagram of an ultra-low frequency dielectric loss measurement subsystem during a test process provided by an embodiment of the present invention;

[0030] Figure 6 This is an equivalent two-port network circuit model diagram of an XLPE insulated cable provided by an embodiment of the present invention when used as a current transmission line;

[0031] Figure 7 is a schematic diagram of a leakage current flowing in an XLPE insulated cable provided by an embodiment of the present invention;

[0032] Figure 8 is a flow chart of an ultra-low frequency dielectric loss correction method provided by Embodiment 2 of the present invention;

[0033] Fig. 9 It is a structural schematic diagram of an ultra-low frequency dielectric loss correction device provided by Embodiment 3 of the present invention;

[0034] Fig.10 It is a structural schematic diagram of an electronic device provided in Embodiment 4 of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] Embodiment 1

[0038] Figure 11 is a schematic diagram of the structure of an ultra-low frequency dielectric loss correction system provided in Embodiment 1 of the present invention, comprising a leakage current measurement subsystem 100, an ultra-low frequency dielectric loss measurement subsystem 110 and an ultra-low frequency dielectric loss correction subsystem 120. The ultra-low frequency dielectric loss correction subsystem in the ultra-low frequency dielectric loss correction system can be implemented in the form of hardware and / or software, and is generally integrated in a computer device.

[0039] Specifically, the leakage current measurement subsystem 100 is used to measure the leakage current value of the cable to be tested; the ultra-low frequency dielectric loss measurement subsystem 110 is used to measure the initial ultra-low frequency dielectric loss value and the capacitive current value of the cable to be tested; the ultra-low frequency dielectric loss correction subsystem 120 is used to obtain the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determine the target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value.

[0040] In this embodiment, the cable to be tested can be understood as a cable that needs to be measured for ultra-low frequency dielectric loss. The cable can be a short cable of 1-10 meters. In this embodiment, the cable to be tested can be a cross-linked polyethylene insulated (XLPE) cable. The capacitive current value can be understood as the current value generated by the insulating medium of the cable to be tested as a capacitor charging and discharging under the action of the AC voltage, which is about 90° out of phase with the voltage. For example, when the electrical performance of the cable to be tested is tested, since the outer sheath and conductor of the cable to be tested can be equivalent to a capacitor, when the ultra-low frequency sinusoidal voltage is applied to the cable to be tested, the insulating medium of the cable to be tested will generate a corresponding current value according to the rate of change of the voltage, and this current value is the capacitive current value. There is a 90° phase difference between the capacitive current value and the ultra-low frequency sinusoidal voltage.

[0041] Among them, leakage current can be understood as the current formed between mutually insulated metal parts in electrical equipment, or between live parts and grounded parts, through the surrounding medium or insulating surface when there is no fault voltage applied. This current is usually caused by equipment insulation failure, equipment damage, poor grounding or other electrical faults. Although the leakage current is very small, it is enough to directly affect the accuracy of dielectric loss measurement. In an embodiment of the present invention, the leakage current is the current leaked from the outer surface of the exposed insulation of the cable to be tested, which is an interference current that affects the ultra-low frequency dielectric loss value. It is worth noting that when the length of the cable to be tested is long, that is, greater than the preset threshold, the leakage current can be ignored, but when the cable length is short, that is, less than or equal to the preset threshold, the leakage current cannot be ignored, because it will cause a large error in the measurement result of the ultra-low frequency dielectric loss, which has a great impact on the dielectric loss measurement of the short sample cable.

[0042] Among them, the initial ultra-low frequency dielectric loss value can be understood as the dielectric loss of the cable under test under the action of ultra-low frequency voltage. It should be noted that when measuring the dielectric loss of the cable under test, since it is impossible to apply leakage current shielding electrodes at both ends of the cable, there is a certain error between the measured initial ultra-low frequency dielectric loss value and the true value. The target ultra-low frequency dielectric loss value can be understood as the value obtained after correcting the initial ultra-low frequency dielectric loss value.

[0043] Specifically, Figure 2 Schematic diagram of equivalent current analysis of a cable to be tested provided by the first embodiment of the present invention. Figure 2 As shown in the figure, when the ultra-low frequency voltage U is applied to the cable to be tested, affected by the equivalent resistors R1, R2 and the equivalent capacitor C, three currents will be generated inside the cable to be tested, namely, the body current I R1 , leakage current I R2 And the capacitive current I c , where the main insulation body current I R1 It can be understood as the current conducted through the main insulation of the cable under test after the ultra-low frequency voltage is applied to the main insulation. This current can characterize the radial insulation capacity of the cable insulation. The larger the current, the worse the insulation condition.

[0044] Under ideal conditions, the ultra-low frequency dielectric loss value is only related to the body current and capacitive current of the main insulation, that is:

[0045]

[0046] However, in actual situations, the body current of the main insulation will be affected by the leakage current, resulting in the measured ultra-low frequency dielectric loss value being:

[0047]

[0048] In order to avoid the influence of leakage current, the leakage current of the cable to be tested is measured through the constructed leakage current measurement subsystem, and the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested are measured through the constructed ultra-low frequency dielectric loss measurement subsystem, and then the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value are obtained through the ultra-low frequency dielectric loss correction subsystem, and based on the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value, the preset algorithm is used to determine the target ultra-low frequency dielectric loss value. Among them, the preset algorithm is a pre-set algorithm used to calculate the target ultra-low frequency dielectric loss value, for example, the preset algorithm can be the least squares method, etc.

[0049] An ultra-low frequency dielectric loss correction system provided by an embodiment of the present invention includes a leakage current measurement subsystem, an ultra-low frequency dielectric loss measurement subsystem and an ultra-low frequency dielectric loss correction subsystem; the leakage current measurement subsystem is used to measure the leakage current value of the cable to be tested; the ultra-low frequency dielectric loss measurement subsystem is used to measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested; the ultra-low frequency dielectric loss correction subsystem is used to obtain the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determine the target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value. By adopting the above technical scheme, the leakage current measurement subsystem, the ultra-low frequency dielectric loss measurement subsystem and the ultra-low frequency dielectric loss correction subsystem are integrated. The leakage current measurement subsystem can measure the leakage current value of the cable to be tested, and the ultra-low frequency dielectric loss measurement subsystem can measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested. The ultra-low frequency dielectric loss correction subsystem is used to comprehensively consider these factors, effectively overcoming the error caused by the influence of leakage current in the ultra-low frequency dielectric loss measurement, so that a more accurate target ultra-low frequency dielectric loss value can be determined, which significantly improves the accuracy of the ultra-low frequency dielectric loss measurement.

[0050] In some embodiments, the ultra-low frequency dielectric loss correction subsystem is used to multiply the initial ultra-low frequency dielectric loss value by the capacitive current value to obtain a target product, subtract the leakage current value from the target product to obtain a target difference, and divide the target difference by the capacitive current value to obtain a target ultra-low frequency dielectric loss value.

[0051] Specifically, the initial ultra-low frequency dielectric loss value is measured when the body current of the main insulation is affected by the leakage current. Therefore, in order to obtain a more accurate ultra-low frequency dielectric loss, it is necessary to avoid the influence of the leakage current, that is, to correct the initial ultra-low frequency dielectric loss value in the following way:

[0052] After obtaining the initial ultra-low frequency dielectric loss value, capacitive current value and leakage current, the initial ultra-low frequency dielectric loss value is multiplied by the capacitive current value to obtain the target product. From formula (3), it can be seen that the target product represents the sum of the two current components, the body current and the leakage current. Then, the leakage current value is subtracted from the target product to obtain the target difference, that is, the body current value I of the main insulation that is not affected by the leakage current. R1 , as shown in formula (4):

[0053]

[0054] Then, according to the calculated target difference, the target ultra-low frequency dielectric loss value tgδ of the cable to be tested can be calculated by formula (5):

[0055]

[0056] Optional, Figure 3 1 is a schematic diagram of a phase relationship before and after correction provided by an embodiment of the present invention. Figure 3 As shown in the figure, when the ultra-low frequency voltage U is known, the initial ultra-low frequency dielectric loss value tgδ1 is determined by the body current I of the main insulation. R1 , leakage current I R2 And the capacitive current I c The target initial ultra-low frequency dielectric loss value is determined by removing the interference of leakage current, that is, the body current I R1 and capacitive current I c Determined. Figure 3 It can be seen that the existence of leakage current will lead to an increase in the dielectric loss angle, and then increase the dielectric loss value. By correcting the dielectric loss, the influence of leakage current can be effectively eliminated, the resistive current deviation can be reduced, and the calculation accuracy of dielectric loss can be effectively improved.

[0057] In some embodiments, the leakage current measurement subsystem includes an ultra-low frequency voltage source, a current acquisition device, two shielding rings and a control unit. The cable to be tested includes a main insulation, a cable conductor and an outer sheath. The control unit is communicatively connected to the ultra-low frequency voltage source, and the ultra-low frequency voltage source is communicatively connected to the cable conductor. The two shielding rings are respectively connected to the main insulation at both ends of the cable to be tested, and are connected to the ground electrode via the current acquisition device, and the outer sheath is grounded; the control unit is used to control the ultra-low frequency voltage source to generate a first ultra-low frequency voltage of a preset period to apply voltage to the cable to be tested; the current acquisition device is used to measure the leakage current value of the cable to be tested, and the leakage current value is the sum of the currents on the two shielding rings.

[0058] In this embodiment, the ultra-low frequency voltage source can be understood as a voltage source that can generate an extremely low frequency (much lower than the conventional AC frequency, such as 50 Hz or 60 Hz). The current acquisition device is a device for collecting leakage current. The shielding ring is a ring-shaped protective fitting used to reduce external interference and guide the leakage current back to the power supply. It ensures the accuracy of the measurement result and reduces the influence of the external electromagnetic field on the circuit by providing a current flow path. The control unit is used to control the output voltage of the ultra-low frequency voltage source.

[0059] The preset period can be understood as the time period during which the control unit pre-sets and controls the ultra-low frequency voltage source to generate voltage. This period is fixed and is used to ensure that the ultra-low frequency voltage source applies voltage to the cable to be tested at the same time interval during each measurement. For example, this preset period can be a 1 / 4 period. The first ultra-low frequency voltage can be an ultra-low frequency sinusoidal voltage.

[0060] In this embodiment, considering that the ultra-low frequency dielectric loss is the dielectric loss of a complete cycle of measurement, and the power frequency signal is a sinusoidal voltage, after determining the current in 1 / 4 cycle, the current value of the entire cycle can be obtained. Therefore, in order to have the same voltage effect as the actual measurement of ultra-low frequency dielectric loss, a 1 / 4 cycle ultra-low frequency voltage is used. For example, when measuring at a frequency of 0.1Hz, the voltage waveform duration is 2.5s. Similarly, at 0.01Hz, the voltage application duration is 25s. The applied voltage can reach the maximum voltage value U at the 1 / 4T moment. In actual measurement, only a 1 / 4 cycle voltage is applied to the connecting cable once.

[0061] Specifically, Figure 4 A circuit diagram of a leakage current measurement subsystem during a test process provided by an embodiment of the present invention. Figure 4 As shown, it includes a control unit 41, an ultra-low frequency voltage source 42 and a current acquisition device 43, a cable to be tested 44, a shielding ring 45 and a shielding ring 46, wherein the cable to be tested 44 is a cable with outer sheaths 441 at both ends stripped off and main insulation 442 exposed, and the cable has a cable conductor 443 inside.

[0062] The circuit connection method of the system is as follows: one end of the ultra-low frequency voltage source 42 is connected to the control unit 41, and the other end is connected to the cable conductor 443 of the cable 44 to be tested, and is grounded at the same time; the shielding ring 45 and the shielding ring 46 are respectively deployed on the main insulation 442 at both ends of the cable 44 to be tested. To ensure the accuracy of the measurement, the two shielding rings need to be as close to the outer sheath as possible, but cannot touch the outer sheath; the outer sheath 441 of the cable 44 to be tested is grounded; the current acquisition device 43 is connected to the two shielding rings and is grounded, so that the current on the two shielding rings flows into the ground electrode via the current acquisition device.

[0063] The workflow of the leakage current measurement subsystem test is as follows:

[0064] The control unit controls the ultra-low frequency voltage source to generate a first ultra-low frequency voltage of 1 / 4 cycle, and acts on the cable conductor of the cable to be tested. The current value passing through the two shielding rings is collected by the current acquisition device. Since the outer sheath of the power supply to be tested has been grounded, the collected current value is the leakage current value flowing through the two exposed main insulation surfaces, that is, the leakage current value is the sum of the currents on the two shielding rings. Through the above technical solution, the leakage current can be accurately measured, laying the foundation for further improving the accuracy of ultra-low frequency dielectric loss measurement.

[0065] It is worth noting that since the leakage current is a purely resistive current and there is no capacitive current component, the measured current and the applied voltage value always maintain the same phase.

[0066] In some embodiments, the ultra-low frequency dielectric loss measurement subsystem includes an ultra-low frequency dielectric loss tester, which is communicatively connected to the cable conductor of the cable to be tested; the ultra-low frequency dielectric loss tester is used to output a second ultra-low frequency voltage of a preset period to the cable to be tested, and obtain the capacitive current value and initial ultra-low frequency dielectric loss value of the cable to be tested.

[0067] In this embodiment, the second ultra-low frequency voltage is output by the ultra-low frequency dielectric loss tester, and the second ultra-low frequency voltage is the same as the first ultra-low frequency voltage. The ultra-low frequency dielectric loss tester is used to apply the same voltage as the ultra-low frequency voltage source to the cable to be tested, and then measure the capacitive current value and the initial ultra-low frequency dielectric loss value.

[0068] Specifically, Figure 5 FIG. 1 is a circuit diagram of an ultra-low frequency dielectric loss measurement subsystem during a test process provided by an embodiment of the present invention. Figure 5 As shown, it includes an ultra-low frequency dielectric loss tester 51 and a cable to be tested 52. The outer sheaths 521 at both ends of the cable to be tested 52 are peeled off to expose the main insulation 522 and the internal cable conductor 523. One end of the ultra-low frequency dielectric loss tester 51 is connected to the cable conductor 523 of the cable to be tested 52 and grounded at the same time. The outer sheath 521 of the cable to be tested 52 is grounded.

[0069] The working process of the ultra-low frequency dielectric loss measurement subsystem test: The ultra-low frequency dielectric loss tester applies an ultra-low frequency voltage value with a peak value of U to the cable conductor of the cable to be tested. The voltage frequency can be any voltage between 0.01 and 0.1 Hz. After the measurement is completed, the applied voltage value U, the capacitive current value, and the initial ultra-low frequency dielectric loss value are obtained through the ultra-low frequency dielectric loss tester. Through the above scheme, the measurement of the capacitive current value and the initial ultra-low frequency dielectric loss value is realized, laying the foundation for the correction of ultra-low frequency dielectric loss.

[0070] In some embodiments, the current acquisition device is an ammeter, and / or the first ultra-low frequency voltage is an ultra-low frequency sinusoidal voltage.

[0071] The detection principle of leakage current is as follows: Figure 6 1 is an equivalent two-port network circuit model diagram of an XLPE insulated cable provided by an embodiment of the present invention when used as a current transmission line. Figure 6 Shown: Z c is the equivalent impedance of the core wire (such as the copper conductor in the figure); Z s is the impedance of the semiconducting layer; Z i is the equivalent impedance of XLPE insulation; Z mL and Z mR are the equivalent impedances of the left and right metal sheaths (such as the lead sheath in the figure). i Much larger than Z s, and the main analysis is the power frequency component, so the model ignores the impedance effect of the semi-conductive layer. During operation, the voltage excitation acts on the core wire (copper conductor).

[0072] Figure 7 Schematic diagram of leakage current flowing in an XLPE insulated cable provided by an embodiment of the present invention, such as Figure 7 As shown, after applying the ultra-low frequency voltage U, the leakage current I i It is the current flowing from the core through the main insulation to the metal sheath. It can flow into the grounding point from the left and right sides in the metal sheath, which are I L and I R Among them, I i ,I L and I R is the current vector, including current amplitude and current phase.

[0073] After considering the cross-connection of the sheath, Z mL The equivalent impedance Z of each section on the left side of the cable sheath to the ground mL1 ,…,Z mLk The vector sum, Z mR The equivalent impedance Z of each section on the right side of the cable sheath to the ground mR1 ,…,Z mRk The vector sum is shown in the following two equations:

[0074] Z mL =Z mL1 +…+Z mLk (6)

[0075] Z mR =Z mR1 +…+Z mRk (7)

[0076] Among them, the equivalent impedance of the sheath is Z m As shown in the formula:

[0077] Z m =Z mL +Z mR (8)

[0078] I L and I R The proportion of distribution is determined by Z mL and Z mR Decision, namely:

[0079]

[0080] 2 Components I L ,I R The leakage current I i The relationship always holds, as shown below:

[0081] I i =I L +I R (11)

[0082] Since the insulation resistance of XLPE is relatively high, the main difficulty in detection lies in the detection of tiny leakage current signals. The common current measurement methods are as follows:

[0083] Amperemeter: When conducting DC withstand voltage tests on large motors, high-voltage cables and other equipment on site, the usual practice is to connect the ammeter directly in series to the high-voltage terminal to measure the leakage current through the test object. Current high-voltage microammeters all use the method of instant reading, but due to the large capacitance of the test object and the influence of external environmental conditions, the measured data varies within a large numerical range, generally ranging from a few to several thousand microamperes, thus affecting the accuracy and reliability of the measurement.

[0084] Current transformer: Based on the principle of electromagnetic coupling, the magnetic field generated by the changing current on the primary side is induced on the secondary side through the magnetic circuit to generate current. The main areas of current research and application are the measurement of electrical quantities when electrical isolation is required in high voltage and large current, including current measurement in smart substations, high-voltage GIS equipment, high-voltage DC converter stations, etc. Common current transformers can be divided into zero flux type, optical type, and photoelectric type. The main problem with the application of current transformers in leakage current detection is that the sensor is not sensitive enough when detecting small currents, and there are currently no high-precision current sensors for DC detection. Even for current sensors used to measure AC, the required primary current range is above 100mA, which cannot meet the requirements.

[0085] Therefore, an ammeter is selected to measure the leakage current. At the same time, in order to achieve measurement accuracy, the measurement range of the ammeter is required to cover the range of 1pA-10nA.

[0086] In an embodiment, the first ultra-low frequency voltage is an ultra-low frequency sinusoidal voltage.

[0087] Optionally, the second ultra-low frequency voltage is the same as the first ultra-low frequency voltage, so the second ultra-low frequency voltage is an ultra-low frequency sinusoidal voltage.

[0088] Embodiment 2

[0089] Figure 8 : is a flow chart of an ultra-low frequency dielectric loss correction method provided in Embodiment 2 of the present invention. The method is applied to an ultra-low frequency dielectric loss correction subsystem of any embodiment of the present invention. Figure 8 As shown, the method includes:

[0090] S210, obtaining a leakage current value, an initial ultra-low frequency dielectric loss value, and a capacitive current value of the cable to be tested.

[0091] Specifically, the leakage current value of the cable to be tested measured by the leakage current measurement subsystem and the initial ultra-low frequency dielectric loss value and capacitive current value measured by the ultra-low frequency dielectric loss measurement subsystem are obtained.

[0092] S220: Determine a target ultra-low frequency dielectric loss value based on the initial ultra-low frequency dielectric loss value, the capacitive current value, and the leakage current value.

[0093] Specifically, the initial ultra-low frequency dielectric loss value is multiplied by the capacitive current value to obtain a target product, the leakage current value is subtracted from the target product to obtain a target difference, and the target difference is divided by the capacitive current value to obtain a target ultra-low frequency dielectric loss value.

[0094] The technical solution provided in the second embodiment of the present invention obtains the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value of the cable to be tested, and determines the target ultra-low frequency dielectric loss value based on the initial ultra-low frequency dielectric loss value, the capacitive current value and the leakage current value, thereby effectively overcoming the error caused by the influence of leakage current in the ultra-low frequency dielectric loss measurement, thereby being able to determine a more accurate target ultra-low frequency dielectric loss value, and significantly improving the accuracy of the ultra-low frequency dielectric loss measurement.

[0095] Embodiment 3

[0096] Fig. 9 is a schematic diagram of the structure of an ultra-low frequency dielectric loss correction device provided in Embodiment 3 of the present invention. The device is configured in an ultra-low frequency dielectric loss correction subsystem provided in any embodiment of the present invention. Fig. 9 As shown, the device comprises:

[0097] An acquisition module 310 is used to acquire a leakage current value, an initial ultra-low frequency dielectric loss value, and a capacitive current value of the cable to be tested;

[0098] The determination module 320 is used to determine a target ultra-low frequency dielectric loss value based on the initial ultra-low frequency dielectric loss value and the capacitive current value and the leakage current value.

[0099] The ultra-low frequency dielectric loss correction device provided in the embodiment of the present invention effectively overcomes the error caused by leakage current in ultra-low frequency dielectric loss measurement, thereby being able to determine a more accurate target ultra-low frequency dielectric loss value and significantly improving the accuracy of ultra-low frequency dielectric loss measurement.

[0100] The ultra-low frequency dielectric loss correction device provided in the embodiment of the present invention can execute the ultra-low frequency dielectric loss correction method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0101] Embodiment 4

[0102] Fig.10: is a structural schematic diagram of an electronic device provided in Embodiment 4 of the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0103] like Fig.10 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0104] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0105] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the ultra-low frequency dielectric loss correction method.

[0106] In some embodiments, the ultra-low frequency dielectric loss correction method may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the ultra-low frequency dielectric loss correction method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to execute the ultra-low frequency dielectric loss correction method in any other appropriate manner (e.g., by means of firmware).

[0107] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0108] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0109] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0110] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0111] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0112] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0113] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0114] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0115] An embodiment of the present invention further provides a computer program product, including a computer program and / or instructions, which, when executed by a processor, implements the ultra-low frequency dielectric loss correction method provided in any embodiment of the present application.

[0116] In the process of implementation, the computer program product can be written in one or more programming languages ​​or a combination thereof to perform the computer program code of the present invention, including object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0117] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An ultra-low frequency dielectric loss correction system, characterized in that: Including leakage current measurement subsystem, ultra-low frequency dielectric loss measurement subsystem and ultra-low frequency dielectric loss correction subsystem; The leakage current measurement subsystem is used to measure the leakage current value of the cable to be tested; The ultra-low frequency dielectric loss measurement subsystem is used to measure the initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested; The ultra-low frequency dielectric loss correction subsystem is used to obtain the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value, and determine the target ultra-low frequency dielectric loss value based on the leakage current value, the initial ultra-low frequency dielectric loss value and the capacitive current value.

2. The system according to claim 1, characterized in that The ultra-low frequency dielectric loss correction subsystem is used to multiply the initial ultra-low frequency dielectric loss value by the capacitive current value to obtain a target product, subtract the leakage current value from the target product to obtain a target difference, and divide the target difference by the capacitive current value to obtain a target ultra-low frequency dielectric loss value.

3. The system according to claim 1, characterized in that The leakage current measurement subsystem includes an ultra-low frequency voltage source, a current acquisition device, two shielding rings and a control unit. The cable to be tested includes a main insulation, a cable conductor and an outer sheath. The control unit is communicatively connected to the ultra-low frequency voltage source, and the ultra-low frequency voltage source is communicatively connected to the cable conductor. The two shielding rings are respectively connected to the main insulation at both ends of the cable to be tested, and are connected to the ground electrode via the current acquisition device, and the outer sheath is grounded. The control unit is used to control the ultra-low frequency voltage source to generate a first ultra-low frequency voltage of a preset period to apply voltage to the cable to be tested; The current acquisition device is used to measure the leakage current value of the cable to be tested, and the leakage current value is the sum of the currents on the two shielding rings.

4. The system according to claim 1, characterized in that The ultra-low frequency dielectric loss measurement subsystem comprises an ultra-low frequency dielectric loss tester, and the ultra-low frequency dielectric loss tester is communicatively connected with the cable conductor of the cable to be tested; The ultra-low frequency dielectric loss tester is used to output a second ultra-low frequency voltage of a preset period to the cable to be tested, and to obtain a capacitive current value and an initial ultra-low frequency dielectric loss value of the cable to be tested.

5. The system according to claim 3, characterized in that The current acquisition device is an ammeter, and / or the first ultra-low frequency voltage is an ultra-low frequency sinusoidal voltage.

6. A method for correcting ultra-low frequency dielectric loss, characterized in that: Applied in the ultra-low frequency dielectric loss correction subsystem according to any one of claims 1 to 5, the method comprises: Obtain the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested; Based on the initial ultra-low frequency dielectric loss value and the capacitive current value and the leakage current value, a target ultra-low frequency dielectric loss value is determined.

7. An ultra-low frequency dielectric loss correction device, characterized in that: Configured in the ultra-low frequency dielectric loss correction subsystem according to any one of claims 1 to 5, the device comprises: An acquisition module is used to obtain the leakage current value, initial ultra-low frequency dielectric loss value and capacitive current value of the cable to be tested; A determination module is used to determine a target ultra-low frequency dielectric loss value based on the initial ultra-low frequency dielectric loss value and the capacitive current value and the leakage current value.

8. An electronic device, characterized in that: The electronic device is configured as an ultra-low frequency dielectric loss correction subsystem as claimed in any one of claims 1 to 5, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the ultra-low frequency dielectric loss correction method as claimed in claim 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the ultra-low frequency dielectric loss correction method as claimed in claim 6 is implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the ultra-low frequency dielectric loss correction method according to claim 6 is implemented.

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