Cable joint sealing live-line test method, system and device

Abstract

The invention discloses a cable joint sealing live-line test method, system and device, and the method comprises the steps: obtaining the sum of the three-phase voltages of a first-side cable and the sum of the three-phase voltages of a second-side cable of three-phase joint sealing if an outgoing line is a cross transposition grounding box; performing three-phase joint sealing defect judgment according to a difference value between the sum of the three-phase voltages of the first-side cable and the sum of the three-phase voltages of the second-side cable; and if the outgoing line is a direct grounding box, obtaining the sum of the three-phase voltages of the three-phase joint sealing first side / second side cable and the common grounding lead voltage of the direct grounding box, and performing three-phase joint sealing defect judgment according to the difference between the sum of the three-phase voltages of the first side / second side cable and the common grounding lead voltage. According to the invention, the cable joint sealing live-line test is realized, and compared with the traditional power-off test, only the difference between the currents at the two sides of the joint group needs to be compared in a live-line state, the power-off test is not needed, the test is simple and efficient, and the problem that defects are difficult to find in the power-off test does not exist.

Description

Technical Field

[0001] The invention relates to a cable joint sealing live testing method, system and device, belonging to the technical field of power transmission and transformation. Background Art

[0002] The joints of high-voltage cables (hereinafter referred to as "cables") are mostly located underground, and the channel environment is humid or even flooded. When the outer sheath seal of the cable line joint fails, water vapor or water will penetrate into the metal shell of the cable joint. Since the water inlet shell of the cable joint is connected to the metal shell of the cable body, the electromagnetic induction of the core current during the operation of the cable will cause an induced voltage to exist in the metal sheath of the cable and the metal shell of the joint. The intrusion of water vapor or water will cause electrochemical corrosion at the connection between the cable joint and the cable body, causing water to penetrate the metal sheath and even cause cable failure. The traditional cable joint sealing test method is mainly the outer sheath withstand voltage test under power outage. Due to the operating environment, if there is a joint sealing defect, there is no graphite conductive layer on its surface, and water vapor has not yet penetrated or there is no water accumulation in the channel, a conductive channel cannot be formed, which will make it difficult to find defects and seriously affect the safe operation of the cable. Summary of the invention

[0003] The invention provides a cable joint sealing live testing method, system and device, which solve the problems disclosed in the background technology.

[0004] According to one aspect of the present disclosure, a cable joint sealing live testing method is provided, comprising: If the object to be tested is a three-phase joint seal, and the outgoing line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and make a three-phase joint seal defect judgment based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range; wherein the three-phase voltage vector directions of the cables on the first side are consistent, the three-phase voltage vector directions of the cables on the second side are consistent, and the three-phase voltage vector directions of the cables on the first side are opposite to those of the cables on the second side; the leakage current is obtained based on the vector sum calculation; If the object to be tested is a three-phase joint seal and the outgoing line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common ground lead voltage of the direct grounding box, and judge the three-phase joint seal defect based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, as well as the comparison result of the leakage current with the preset range; wherein, the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common ground lead voltage of the direct grounding box.

[0005] Further, according to the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range, the three-phase joint sealing defect judgment is performed, including: If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the first preset range, it is determined that the three-phase joint seal has a first-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the second preset range, it is determined that the three-phase joint seal has a second-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within a third preset range, it is determined that the three-phase joint seal has a third level defect.

[0006] Furthermore, the leakage current is the ratio of the vector sum to the proportionality coefficient; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage on the cable S, the voltage vector directions obtained by the three-phase sensing device on the first side are consistent, the voltage vector directions obtained by the three-phase sensing device on the second side are consistent, the voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the proportionality coefficient is the ratio of the voltage vector sum obtained by all sensing devices to the current of the cable S.

[0007] Furthermore, the voltage measurement error under the current load current of the cable is predetermined, and the predetermined process includes: Get the current of each phase cable under the current load current; Calculate the voltage measurement error based on the maximum current.

[0008] Furthermore, the voltage measurement error is the product of the maximum current and the proportional coefficient; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage on the cable S, the voltage vector directions obtained by the three-phase sensing device on the first side are consistent, the voltage vector directions obtained by the three-phase sensing device on the second side are consistent, the voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the proportional coefficient is the ratio of the voltage vector sum obtained by all sensing devices to the current of the cable S.

[0009] Furthermore, the voltage measurement error under the current load current of the cable is predetermined, and the predetermined process includes: Get the current of each phase cable under the current load current; On the cable corresponding to the maximum current, the vector sum of all voltages is obtained, and the vector sum is used as the voltage measurement error; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained by the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained by the three-phase sensing device on the second side, the three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage at the same position on the cable corresponding to the maximum current, the voltage vector directions obtained by the three-phase sensing device on the first side are consistent, the voltage vector directions obtained by the three-phase sensing device on the second side are consistent, the voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the vector sum of all voltages is the voltage vector sum obtained by all sensing devices.

[0010] According to another aspect of the present disclosure, a cable joint sealing live testing system is provided, comprising: The first test module, if the object to be tested is a three-phase joint seal, and the outlet line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and judge the three-phase joint seal defect according to the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range; wherein, the three-phase voltage vector direction of the cable on the first side is consistent, the three-phase voltage vector direction of the cable on the second side is consistent, and the three-phase voltage vector direction of the cable on the first side is opposite to the three-phase voltage vector direction of the cable on the second side; the leakage current is obtained according to the vector sum calculation; The second test module, if the object to be tested is a three-phase joint seal and the outgoing line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common grounding lead voltage of the direct grounding box, and judge the three-phase joint seal defect based on the comparison result with the voltage measurement error under the current load current of the cable, and the comparison result with the leakage current and the preset range; wherein, the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common grounding lead voltage of the direct grounding box.

[0011] Furthermore, in the first test module and the second test module, the three-phase joint sealing defect judgment is performed according to the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range, including: If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the first preset range, it is determined that the three-phase joint seal has a first-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the second preset range, it is determined that the three-phase joint seal has a second-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within a third preset range, it is determined that the three-phase joint seal has a third level defect.

[0012] According to another aspect of the present disclosure, there is provided a cable joint sealing live testing device, comprising a testing host; If the object to be tested is a three-phase joint seal, and the outlet line is a cross-transposition grounding box, the device also includes a three-phase sensing device on the first side and a three-phase sensing device on the second side, the three-phase sensing device on the first side obtains the three-phase voltage of the cable on the first side of the three-phase joint seal, and the three-phase voltage vector directions of the cable on the first side are consistent, the three-phase sensing device on the second side obtains the three-phase voltage of the cable on the second side of the three-phase joint seal, and the three-phase voltage vector directions of the cable on the second side are consistent, and the three-phase voltage vector direction of the cable on the first side is opposite to the three-phase voltage vector direction of the cable on the second side, and the output end of the three-phase sensing device on the first side and the output end of the three-phase sensing device on the second side are connected in series and then connected to the test host; If the object to be tested is a three-phase joint seal, and the outlet line is a direct grounding box, the device further comprises a common grounding side induction device and a first side / second side three-phase induction device, the common grounding side induction device obtains the common grounding lead voltage, the first side / second side three-phase induction device respectively obtains the three-phase voltage of the first side / second side cable of the three-phase joint seal, the three-phase voltage vector direction of the first side / second side cable is opposite to the common grounding lead voltage vector direction of the direct grounding box, and the output end of the common grounding side induction device and the output end of the first side / second side three-phase induction device are connected in series and then connected to the test host; The test host adopts the above-mentioned cable joint sealing live test method to perform the cable joint sealing test.

[0013] Further, the test host includes an operational amplifier circuit, a filter, an analog-to-digital converter, a controller, and a display; The operational amplifier circuit, the filter and the analog-to-digital converter sequentially perform operational amplification, filtering and analog-to-digital conversion on the received voltage vector sum; The controller uses a preset calculation method to perform calculations based on the voltage vector sum after analog-to-digital conversion; wherein the preset calculation method includes the above-mentioned cable joint sealing live test method; The display shows the calculation results of the controller.

[0014] The beneficial effects achieved by the present invention are as follows: the present invention judges the sealing defects of the three-phase joint according to the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, or the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common ground lead voltage of the direct grounding box, thereby realizing the live test of the cable joint seal. Compared with the traditional power-off test, it is only necessary to compare the difference in voltage on both sides of the joint group in the live state, without the need for power-off test. The test is simple and efficient, and there is no problem of defects being difficult to find in the power-off test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the cable line connector; Figure 2 A flow chart of the cable joint seal live test method; Figure 3 Block diagram of the cable joint seal live test system; Figure 4 This is a schematic diagram of a cable joint seal live test device; Figure 5 This is the wiring diagram of the cable joint sealed live test device when the outgoing line is a cross-transposed grounding box; Figure 6 for Figure 5 Equivalent schematic diagram of ; Figure 7 This is the equivalent wiring diagram of the cable joint sealed live test device when the outlet line is a direct grounding box. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is obvious that the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0017] Unless specifically stated otherwise, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0018] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0019] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0020] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0021] It should be noted that similar symbols and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

[0022] At the same time, in the description of the embodiments of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features.

[0023] In order to solve the problems existing in traditional power outage testing, the present disclosure proposes a cable joint seal live testing method, system and device, which specifically realizes three-phase joint seal defect detection by comparing the total voltage on both sides of the three-phase joint seal.

[0024] See also Figure 1 , Figure 1 It is a schematic diagram of the cable line joint. In the figure, the three thick lines are three-phase cables, namely A, B, and C phase cables. There are three-phase joint seals in the three-phase cable. The seals in the same column in the figure are A, B, and C phase joint seals from top to bottom. The outgoing lines can be directly grounded boxes or cross-transposed grounded boxes.

[0025] Due to the different output lines, the test should be carried out in different situations. Figure 2 , Figure 2 This is a flow chart of the cable joint seal live test method. Figure 2 The method can be executed by a test host, which can be a terminal device or a server. The terminal device can include but is not limited to mobile phones, computers, smart wearable devices, smart vehicle-mounted devices, etc., which are not limited in the embodiments of the present application; the server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, big data and artificial intelligence platforms, etc., which are not limited in the embodiments of the present application. Optionally, the cable joint sealing live test method can also be collaboratively executed by multiple electronic devices with computing power. For the sake of ease of explanation, the subsequent embodiments are described as being executed by the test host.

[0026] Figure 2 The cable joint sealing live testing method may at least include the following steps S101 to S102: Step S101, if the object to be tested is a three-phase joint seal and the outgoing line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and judge the three-phase joint seal defect based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current with the preset range; wherein, the three-phase voltage vector directions of the cables on the first side are consistent, the three-phase voltage vector directions of the cables on the second side are consistent, and the three-phase voltage vector directions of the cables on the first side are opposite to those of the cables on the second side; the leakage current is obtained based on the vector sum calculation.

[0027] It should be noted that the form of connecting a coaxial cable with a connector to a grounding box is a professional term in this field.

[0028] by Figure 1 Taking a three-phase joint seal in a column as an example, the first side can be defined as the left side of the seal, and the second side can be defined as the right side of the seal. The voltage of each phase cable on the left side can be obtained through the existing induction device, and the voltage of each phase cable on the right side can also be obtained through the induction device. The vector sum of the voltage can be calculated in the test host, or the connection method can be used to achieve the voltage vector addition. For example, the installation direction of the induction device on the same side is consistent, and the installation direction on different sides is inconsistent. In this way, the voltage sum can be directly obtained on the test host. Since the second method is more convenient, the second method is mainly used here.

[0029] Without considering the voltage measurement error caused by the inconsistency of the mutual inductance coefficient of the induction device, if there is a defect in the seal, the sum of the three-phase voltages on both sides is consistent. If there is a defect, the sum of the three-phase voltages on the left side will be greater than the sum of the three-phase voltages on the right side. Since there will definitely be a voltage measurement error in actual measurement, it is necessary to determine the voltage measurement error first. The voltage measurement error can be set based on experience. However, in order to ensure the accuracy of the measurement, in some embodiments, the voltage measurement error will be measured in advance. The method may include the following two methods: Method 1: Obtain the current of each phase cable under the current load current, and calculate the voltage measurement error based on the maximum current; wherein the voltage measurement error is the product of the maximum current and the proportionality coefficient.

[0030] Assuming that the currents of the three-phase cables under the current load current are I11, I12, and I13 respectively, and I10=MAX[I11,I12,I13], then the voltage measurement error △U=K1×I10; among them, I11, I12, and I13 are the currents of the A-phase, B-phase, and C-phase cables respectively, and the unit is ampere, MAX means taking the maximum value, I10 is the maximum current among I11, I12, and I13, K1 is the proportional coefficient, and the unit is Ω, and the unit of △U is V.

[0031] It should be noted that the proportionality coefficient is obtained in advance through experiments. It is assumed that the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage on the cable S (that is, the same cable). The voltage vector directions obtained by the three-phase sensing device on the first side are consistent, and the voltage vector directions obtained by the three-phase sensing device on the second side are consistent. The voltage vector direction obtained by the three-phase sensing device on the first side is opposite to the voltage vector direction obtained by the three-phase sensing device on the second side. The proportionality coefficient is the ratio of the sum of the voltage vectors obtained by all sensing devices to the current of the cable S.

[0032] Method 2: Obtain the current of each phase cable under the current load current; obtain the vector sum of all voltages on the cable corresponding to the maximum current, and use the vector sum as the voltage measurement error; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage at the same position on the cable corresponding to the maximum current. The voltage vector directions obtained by the three-phase sensing device on the first side are consistent, and the voltage vector directions obtained by the three-phase sensing device on the second side are consistent. The voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the vector sum of all voltages is the voltage vector sum obtained by all sensing devices.

[0033] Similar to the above, after determining the maximum current, take the cable corresponding to the maximum current. Since the three-phase voltages on both sides are obtained through 6 sensing devices, 3 measure the three phases on the left side (defined as the left sensing device), and 3 measure the three phases on the right side (defined as the right sensing device). All 6 sensing devices measure the voltage at the same position of the cable corresponding to the maximum current. Then the voltage vector sum of all sensing devices can be calculated, which is equivalent to the difference between the total voltage of the left sensing device and the total voltage of all right sensing devices. This voltage vector sum is used as the voltage measurement error.

[0034] After the voltage measurement error, the above-mentioned three-phase joint sealing defect judgment is performed based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range, which may include: if the vector sum is greater than the voltage measurement error under the current load current of the cable, and according to the leakage current within the first preset range, it is determined that the three-phase joint sealing has a first-level defect; if the vector sum is greater than the voltage measurement error under the current load current of the cable, and according to the leakage current within the second preset range, it is determined that the three-phase joint sealing has a second-level defect; if the vector sum is greater than the voltage measurement error under the current load current of the cable, and according to the leakage current within the third preset range, it is determined that the three-phase joint sealing has a third-level defect; wherein the leakage current is the ratio of the difference to the proportional coefficient, which can be expressed by the formula Ix=U3 / K1, and U3 is the vector sum.

[0035] It should be noted that, assuming that the voltage measurement error is △U, the first preset range is (0, 20mA), the first level defect is a general defect, the second preset range is [20mA, 5A), the second level defect is a serious defect, the third preset range is greater than or equal to 5A, and the third level defect is a critical defect, then the specific process of the above judgment can be as follows: S1) If U3 is less than or equal to △U, it is judged that there is no defect; if U3 is greater than △U, it is judged that there is a defect and go to S2); S2) If Ix is within the first preset range, it is determined to be a general defect; if Ix is within the second preset range, it is determined to be a serious defect; if Ix is within the third preset range, it is determined to be a critical defect.

[0036] Step S102, if the object to be tested is a three-phase joint seal and the outlet line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common grounding lead voltage of the direct grounding box, and judge the three-phase joint seal defect based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current with the preset range; wherein the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common grounding lead voltage of the direct grounding box.

[0037] Similarly, Figure 1 Take a three-phase joint seal in a test as an example, the first side can be defined as the left side of the seal, and this side is connected to the direct grounding box, and the second side is the right side of the seal. The existing induction device can be used to obtain the common ground lead voltage, and the induction device can also be used to obtain the voltage of each phase cable on the right side. The vector sum of the voltage can be calculated in the test host, or the connection method can be used to achieve voltage vector addition. Since the second method is more convenient, the second method is mainly used here.

[0038] The defect judgment in step S102 is similar to that in step S101 and will not be described again here.

[0039] The above method judges the three-phase joint sealing defects based on the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, or the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common ground lead voltage of the direct grounding box, thereby realizing the live test of the cable joint seal. Compared with the traditional power-off test, it is only necessary to compare the difference in voltage on both sides of the joint group in the live state, and no power-off test is required. The test is simple and efficient, and there is no problem of defects being difficult to find in the power-off test.

[0040] See also Figure 3 , Figure 3 The block diagram of the cable joint seal live test system is shown in Figure 1. Figure 3 The embodiment is a virtual system that can be loaded and executed by a computer device, and the computer device may include the above-mentioned test host, Figure 3 The device may include a first test module and a second test module, which, when used to perform the above-mentioned cable joint sealing live test method, can: The first test module is configured to, if the object to be tested is a three-phase joint seal and the outgoing line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and make a three-phase joint seal defect judgment based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current with the preset range; wherein the three-phase voltage vector directions of the cables on the first side are consistent, the three-phase voltage vector directions of the cables on the second side are consistent, and the three-phase voltage vector directions of the cables on the first side are opposite to those of the cables on the second side; the leakage current is obtained based on the vector sum calculation.

[0041] The second test module is configured to, if the object to be tested is a three-phase joint seal and the outgoing line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common grounding lead voltage of the direct grounding box, and make a three-phase joint seal defect judgment based on the comparison result of the vector sum with the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current with the preset range; wherein the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common grounding lead voltage of the direct grounding box.

[0042] In order to ensure the accuracy of the test, in some embodiments, the voltage measurement error needs to be taken into account. Therefore, in some embodiments, the first test module and the second test module perform a three-phase joint sealing defect judgment based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range, including: If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the first preset range, it is determined that the three-phase joint seal has a first-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the second preset range, it is determined that the three-phase joint seal has a second-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within a third preset range, it is determined that the three-phase joint seal has a third level defect.

[0043] The above system determines the defects of the three-phase joint seal based on the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, or the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common ground lead voltage of the direct grounding box, thereby realizing the live test of the cable joint seal. Compared with the traditional power-off test, it is only necessary to compare the difference in voltage on both sides of the joint group in the live state, without the need for power-off test. The test is simple and efficient, and there is no problem of defects being difficult to find in the power-off test.

[0044] In order to adapt to the above method and system, the present disclosure also discloses a cable joint sealing live test device, which at least includes a test host and an induction device for sensing cable voltage; wherein the test host adopts the above cable joint sealing live test method to perform a cable joint sealing test.

[0045] The number of the above-mentioned sensing devices is determined according to the sealing connection of the cable joint, as follows: If the object to be tested is a three-phase joint seal and the outgoing line is a cross-transposed grounding box, refer to Figure 4 The device also includes a three-phase sensing device on the first side and a three-phase sensing device on the second side. The three-phase sensing device on the first side obtains the three-phase voltage of the cable on the first side of the three-phase joint seal, and the three-phase voltage vector directions of the cables on the first side are consistent. The three-phase sensing device on the second side obtains the three-phase voltage of the cable on the second side of the three-phase joint seal, and the three-phase voltage vector directions of the cables on the second side are consistent. The three-phase voltage vector direction of the cable on the first side is opposite to that of the cable on the second side. The output end of the three-phase sensing device on the first side, the output end of the three-phase sensing device on the second side and the test host are connected in series.

[0046] It should be noted that the induction device here can adopt a Rogowski coil sensor, which is an electromagnetic induction device used to measure current. The size of its output voltage signal is proportional to the rate of change of the current passing through the coil. It can be directly put on the conductor to be measured (i.e., the cable). The alternating current flowing through the conductor will generate an alternating magnetic field around the conductor, thereby inducing an alternating voltage signal in the coil that is proportional to the rate of change of the current. This voltage signal can be integrated by an integrator to obtain an output voltage that is proportional to the current to be measured.

[0047] by Figure 1 For example, if the object to be tested is a three-phase joint seal and the outgoing line is a cross-transposed grounding box, then the three-phase induction device on the first side can be represented by the letter CT 1A , CT 1B and CT 1C The second side three-phase induction device can be represented by the letter CT 2A , CT 2B and CT 2C , see Figure 5 and 6 , CT 1A and CT 2A Hang on the A-phase cable on both sides of the A-phase connector seal, CT 1B and CT 2B Hang on the B-phase cable on both sides of the B-phase connector seal, CT 1C and CT 2C Hang on the C-phase cable on both sides of the C-phase connector seal, CT 1A , CT 1B and CT 1C The installation direction is consistent, CT 2A , CT 2B and CT 2C The installation direction is the same as CT 1A , CT 1B and CT 1C The installation direction is opposite (in order to obtain the total voltage of two channels with opposite signs, the combination of the two voltages is equivalent to the subtraction of the two total voltages), CT 1A , CT 1B , CT 1C , CT 2A , CT 2B and CT 2C The output ends are connected in series and then connected to the test host, which is equivalent to the voltage vector input test host.

[0048] If the object to be tested is a sealed three-phase joint and the outlet is a directly grounded box, the device also includes a common ground side induction device and a first side / second side three-phase induction device (equivalent to Figure 4On the basis of, two sensing devices on one side are removed), the sensing device on the common grounding side obtains the common grounding lead voltage, the three-phase sensing devices on the first side / second side respectively obtain the three-phase voltage of the cable on the first side / second side of the three-phase joint seal, the three-phase voltage vector direction of the cable on the first side / second side is opposite to the common grounding lead voltage vector direction of the direct grounding box, the output end of the sensing device on the common grounding side and the output end of the three-phase sensing device on the first side / second side are connected in series and then connected to the test host.

[0049] See also Figure 7 The device also includes a common ground side induction device and a three-phase induction device on the second side (i.e. the right side), which are represented by letters CT G , CT 2A , CT 2B and CT 2C , CT G Hooked on the common ground lead, CT 2A Hang on the A-phase cable on the right side of the A-phase connector seal, CT 2B Hang on the B-phase cable on the right side of the B-phase connector seal, CT 2C Hook on the C-phase cable on the right side of the C-phase connector seal, CT 2A , CT 2B and CT 2C The installation direction is the same as CT G The installation direction is opposite, CT G、 CT 2A , CT 2B and CT 2C The output ends are connected in series and then connected to the test host, which is equivalent to the voltage vector input test host.

[0050] It should be noted that the test host can adopt an existing smart terminal, such as a desktop computer, tablet, etc., and of course a specially designed test host can also be used. The main components of the designed test host include at least an operational amplifier circuit, a filter, an analog-to-digital converter, a controller, a display, and a power supply for supplying power to various electrical components.

[0051] The operational amplifier circuit, the filter and the analog-to-digital converter sequentially perform operational amplifier, filtering and analog-to-digital conversion on the received vector sum.

[0052] The controller uses a preset calculation method to perform calculations based on the vector sum after analog-to-digital conversion; wherein the preset calculation method includes the above-mentioned cable joint sealing live test method, and may also include the calculation of the cable current, that is, in the process of determining the voltage measurement error, the cable current is calculated based on the received voltage.

[0053] The display shows the calculation results of the controller, such as the sealing defect judgment result, the cable current, the voltage, etc.

[0054] Combination Figures 4 to 6 , the working process of the above device can be as follows: 1) Test and analyze the voltage measurement error under the current load current; Select any induction device (i.e. Rogowski coil sensor) to measure the voltage of each phase cable. According to the linear relationship between voltage and current, the current of each phase cable can be obtained, which are 702A, 727A and 674A respectively. Then it can be determined that the current of phase B cable is the largest. 1A , CT 1B , CT 1C , CT 2A , CT 2B and CT 2C The voltage at the same position was measured and the voltage measurement error was △U=0.007V.

[0055] 2) Adoption Figure 5 The above device is installed in a manner as described above.

[0056] 3) Turn on the above device, receive the voltage vector sum, and make defect judgment based on the voltage vector sum.

[0057] The voltage vector sum is 0.035V, which is greater than △U, indicating that there is a defect. Further calculation shows that Ix=U3 / K1=0.035 / 0.025=1.4A, and 1.4A is within the third preset range, indicating that there is a serious defect.

[0058] The above device can preferentially realize the cable joint sealing live test, which is simple and efficient compared with the traditional power-off test.

[0059] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0060] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0061] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0062] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0063] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A cable joint sealing live testing method, characterized in that: include: If the object to be tested is a three-phase joint seal, and the outgoing line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and make a three-phase joint seal defect judgment based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range; wherein the three-phase voltage vector directions of the cables on the first side are consistent, the three-phase voltage vector directions of the cables on the second side are consistent, and the three-phase voltage vector directions of the cables on the first side are opposite to those of the cables on the second side; the leakage current is obtained based on the vector sum calculation; If the object to be tested is a three-phase joint seal and the outgoing line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common ground lead voltage of the direct grounding box, and judge the three-phase joint seal defect based on the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, as well as the comparison result of the leakage current with the preset range; wherein, the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common ground lead voltage of the direct grounding box.

2. The method according to claim 1, characterized in that Based on the comparison results of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison results of the leakage current and the preset range, the three-phase joint sealing defect judgment is performed, including: If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the first preset range, it is determined that the three-phase joint seal has a first-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the second preset range, it is determined that the three-phase joint seal has a second-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within a third preset range, it is determined that the three-phase joint seal has a third level defect.

3. The method according to claim 2, characterized in that The leakage current is the ratio of the vector sum to the proportionality coefficient; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage on the cable S. The voltage vector directions obtained by the three-phase sensing device on the first side are consistent, and the voltage vector directions obtained by the three-phase sensing device on the second side are consistent. The voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side. The proportionality coefficient is the ratio of the voltage vector sum obtained by all sensing devices to the current of the cable S.

4. The method according to claim 2, characterized in that: The voltage measurement error under the current load current of the cable is predetermined, and the predetermined process includes: Get the current of each phase cable under the current load current; Calculate the voltage measurement error based on the maximum current.

5. The method according to claim 4, characterized in that The voltage measurement error is the product of the maximum current and the proportionality coefficient; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained through the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained through the three-phase sensing device on the second side. The three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage on the cable S, the voltage vector directions obtained by the three-phase sensing device on the first side are consistent, the voltage vector directions obtained by the three-phase sensing device on the second side are consistent, the voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the proportionality coefficient is the ratio of the voltage vector sum obtained by all sensing devices to the current of the cable S.

6. The method according to claim 2, characterized in that The voltage measurement error under the current load current of the cable is predetermined, and the predetermined process includes: Get the current of each phase cable under the current load current; On the cable corresponding to the maximum current, the vector sum of all voltages is obtained, and the vector sum is used as the voltage measurement error; wherein, the three-phase voltage of the cable on the first side of the joint seal is obtained by the three-phase sensing device on the first side, and the three-phase voltage of the cable on the second side of the joint seal is obtained by the three-phase sensing device on the second side, the three-phase sensing device on the first side and the three-phase sensing device on the second side obtain the voltage at the same position on the cable corresponding to the maximum current, the voltage vector directions obtained by the three-phase sensing device on the first side are consistent, the voltage vector directions obtained by the three-phase sensing device on the second side are consistent, the voltage vector directions obtained by the three-phase sensing device on the first side are opposite to the voltage vector directions obtained by the three-phase sensing device on the second side, and the vector sum of all voltages is the voltage vector sum obtained by all sensing devices.

7. A cable joint sealing live test system, characterized in that: include: The first test module, if the object to be tested is a three-phase joint seal, and the outlet line is a cross-transposition grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side of the three-phase joint seal and the three-phase voltage of the cable on the second side, and judge the three-phase joint seal defect according to the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range; wherein, the three-phase voltage vector direction of the cable on the first side is consistent, the three-phase voltage vector direction of the cable on the second side is consistent, and the three-phase voltage vector direction of the cable on the first side is opposite to the three-phase voltage vector direction of the cable on the second side; the leakage current is obtained according to the vector sum calculation; The second test module, if the object to be tested is a three-phase joint seal and the outgoing line is a direct grounding box, obtain the vector sum of the three-phase voltage of the cable on the first side / second side of the three-phase joint seal and the common grounding lead voltage of the direct grounding box, and judge the three-phase joint seal defect based on the comparison result with the voltage measurement error under the current load current of the cable, and the comparison result with the leakage current and the preset range; wherein, the vector direction of the three-phase voltage of the cable on the first side / second side is opposite to the vector direction of the common grounding lead voltage of the direct grounding box.

8. The system according to claim 7, characterized in that In the first test module and the second test module, the three-phase joint sealing defect judgment is performed according to the comparison result of the vector sum and the voltage measurement error under the current load current of the cable, and the comparison result of the leakage current and the preset range, including: If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the first preset range, it is determined that the three-phase joint seal has a first-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within the second preset range, it is determined that the three-phase joint seal has a second-level defect; If the vector sum is greater than the voltage measurement error under the current load current of the cable and the leakage current is within a third preset range, it is determined that the three-phase joint seal has a third level defect.

9. A cable joint sealing live test device, characterized in that: Includes test host; If the object to be tested is a three-phase joint seal, and the outlet line is a cross-transposition grounding box, the device also includes a three-phase sensing device on the first side and a three-phase sensing device on the second side, the three-phase sensing device on the first side obtains the three-phase voltage of the cable on the first side of the three-phase joint seal, and the three-phase voltage vector directions of the cables on the first side are consistent, the three-phase sensing device on the second side obtains the three-phase voltage of the cable on the second side of the three-phase joint seal, and the three-phase voltage vector directions of the cables on the second side are consistent, and the three-phase voltage vector direction of the cables on the first side is opposite to that of the cables on the second side, and the output end of the three-phase sensing device on the first side and the output end of the three-phase sensing device on the second side are connected in series and then connected to the test host; If the object to be tested is a three-phase joint seal, and the outlet line is a direct grounding box, the device further comprises a common grounding side induction device and a first side / second side three-phase induction device, the common grounding side induction device obtains the common grounding lead voltage, the first side / second side three-phase induction device respectively obtains the three-phase voltage of the first side / second side cable of the three-phase joint seal, the three-phase voltage vector direction of the first side / second side cable is opposite to the common grounding lead voltage vector direction of the direct grounding box, and the output end of the common grounding side induction device and the output end of the first side / second side three-phase induction device are connected in series and then connected to the test host; The test host adopts the method described in any one of claims 1 to 6 to perform a cable joint sealing test.

10. The device according to claim 9, characterized in that The test host includes an operational amplifier circuit, a filter, an analog-to-digital converter, a controller, and a display; The operational amplifier circuit, the filter and the analog-to-digital converter sequentially perform operational amplification, filtering and analog-to-digital conversion on the received voltage vector sum; The controller performs calculations according to the voltage vector sum after analog-to-digital conversion using a preset calculation method; wherein the preset calculation method includes the method described in any one of claims 1 to 6; The display shows the calculation results of the controller.

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