Overhead hybrid power transmission line cable insulation monitoring method, device, medium and equipment

Abstract

The invention discloses a cable insulation monitoring method and device for an overhead hybrid power transmission line in the field of electrical equipment detection of a power system, and the method comprises the steps: introducing a total current signal of the operation of a three-phase lightning arrester and a current signal of a three-phase cable shielding layer into a control processing module for calculating phases; and the insulation hidden danger conditions of the cable terminal and the lightning arrester are monitored through the phase relation between the phase relation and cross judgment. According to the scheme, the problem that online monitoring of cable insulation in the prior art is immature and complex is solved, and the beneficial effects of simplifying monitoring means and enhancing operability are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment detection in power systems, and specifically to a method, device, medium, and equipment for cable insulation monitoring of overhead cable hybrid transmission lines. Background Art

[0002] In the relocation and renovation of overhead lines in 2021, the "Regulations on the Management of Transmission Line Relocation and Renovation of State Grid Jiangsu Electric Power Co., Ltd." clearly stipulates that "for important crossing sections of 110 kV and below, cable underground crossing methods should be adopted, and communication channels should be reserved synchronously." For 220 kV transmission lines, cables are generally used when there is insufficient overhead line space at the substation outlet. Due to the relatively weak insulation of cables and cable terminals, for high-voltage cables in the wild, especially those with voltage levels of 35 kV, 110 kV, and 220 kV, due to the requirements of power supply reliability, it is very difficult to cut off power to conduct cable insulation tests. Basically, they are all operating beyond the test cycle. The weakest point of high-voltage cable insulation is the cable head or the cable intermediate joint. The reason is that the manufacturing process of the cable head or the cable intermediate joint is complex and is made in an outdoor environment. It is highly technically required due to the influence of environmental temperature, humidity, dust, and electrical dimension accuracy. Hidden dangers such as insulation damage of the cable head or the cable intermediate joint caused by operating and stress conditions gradually reduce the insulation of the cable head or the cable intermediate joint, until it can no longer withstand the operating voltage and is damaged, resulting in line tripping. Currently, there are also some online monitoring methods. For example, the patent document with the application publication number CN115327319A discloses a method and system for monitoring the insulation state of a cable intermediate joint, which evaluates the insulation state of the cable intermediate joint by collecting insulation state data of the target cable intermediate joint, including partial discharge state quantities, temperature state data, and humidity state data, and obtains corresponding insulation state monitoring results. The patent document with the publication number CN101634684A discloses a high-voltage cable online insulation detection scheme, which checks the degree of insulation damage to the line to the ground by detecting the active power component of the zero-sequence leakage current of the cable. However, the feasibility of such methods is not good. Currently, the technology of live detection in power systems, such as online monitoring of cable insulation equipment or devices, is not yet mature, resulting in being postponed for consideration when implementing. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a method, device, medium, and equipment for cable insulation monitoring of overhead hybrid transmission lines to solve the problems of immaturity and complexity of online monitoring of cable insulation in the above prior art.

[0004] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0005] An overhead hybrid transmission line cable insulation monitoring method, which is applied to an insulation monitoring system and includes two groups of insulating rod clamp-on current sensors. One group is clamped on the connection lead between the body of each phase metal oxide arrester and the counter to extract the three-phase arrester running full current signal, and the other group is clamped on the connection lead from the outer skin of each phase cable shielding layer to the ground to extract the three-phase cable terminal shielding layer current signal. The two groups of signals are respectively connected to a control and processing module. The method adopts the following steps:

[0006] The control and processing module respectively calculates the phase values of the three-phase arrester running full current signals and the phase values of the three-phase cable terminal shielding layer current signals;

[0007] The control and processing module respectively calculates and compares the phase angles between the running full current signals of the arresters to be measured in each phase and the cable terminal shielding layer current signals: when there is no phase angle between the running full current signals of the arresters in each phase and the cable terminal shielding layer current signals and the phases of the two signals are both located at the standard phase, it is judged that the insulation of the arresters and cable terminals in this phase is good; when the phase of the running full current signal of the arrester is greater than the specified threshold of the phase of the cable terminal shielding layer current signal and the phase of the running full current signal of the arrester is standard, it is judged that there are potential insulation faults in the cable terminal of this phase; when the phase of the running full current signal of the arrester is less than the specified threshold of the cable terminal shielding layer current signal and the phase of the cable terminal shielding layer current signal is located at the standard phase, it is judged that there are potential insulation faults in the arrester of this phase.

[0008] Preferably, after the step of the control and processing module respectively calculating and comparing the phase angles between the running full current signals of the arresters to be measured in each phase and the cable terminal shielding layer current signals, the following steps are further included: calculating and comparing the relationships between the phase angles of the running full current signals of the arresters in each phase. When the angle between the phase of the running full current signal of a certain phase arrester and the phases of the running full current signals of the other two-phase arresters deviates from the specified threshold of 120°, it is judged that there are potential insulation faults in the arrester of this phase.

[0009] Preferably, after the step of the control and processing module respectively calculating and comparing the phase angles between the running full current signals of the arresters to be measured in each phase and the cable terminal shielding layer current signals, the following steps are further included: calculating and comparing the relationships between the phase angles of the cable terminal shielding layer current signals in each phase. When the angle between the phase of the cable terminal shielding layer current signal of a certain phase and the phases of the cable terminal shielding layer current signals of the other two phases deviates from the specified threshold of 120°, it is judged that there are potential insulation faults in the cable terminal of this phase.

[0010] Preferably, after the step of the control processing module calculating and comparing the phase angles between the running full current signals of the arresters to be measured in each phase and the current signals of the cable terminal shielding layer respectively, the following steps are further included: calculating and comparing the relationship between the phase of the current signal of a certain cable terminal shielding layer and the phase angles between the running full current signals of the arresters in the other two phases. When the angle between the phase of the current signal of a certain cable terminal shielding layer and the standard position is greater than the angle between the running full current signal of the arrester and the standard position, and both angles are greater than the specified threshold, it is determined that there are potential faults in the insulation of the cable terminal and the arrester in this phase, and the insulation hidden danger of the cable terminal is greater than that of the arrester insulation.

[0011] Preferably, after the step of the control processing module calculating and comparing the phase angles between the running full current signals of the arresters to be measured in each phase and the current signals of the cable terminal shielding layer respectively, the following steps are further included: calculating and comparing the relationship between the phase of the running full current signal of a certain arrester and the phase angles between the current signals of the cable terminal shielding layers in the other two phases. When the angle between the phase of the running full current signal of a certain arrester and the standard position is greater than the angle between the current signal of the cable terminal shielding layer and the standard position, and both angles are greater than the specified threshold, it is determined that there are potential faults in the insulation of the cable terminal and the arrester in this phase, and the insulation hidden danger of the arrester is greater than that of the cable terminal insulation.

[0012] Preferably, the clamp-on current sensor clamped on the connection lead between the metal oxide arrester body and the counter in each phase uses a clamp-on microampere current sensor.

[0013] Preferably, the range of the clamp-on microampere current sensor is 0.3 - 0.8 mA.

[0014] Preferably, the range of the clamp-on current sensor clamped on the connection lead from the outer skin of the cable shielding layer in each phase to the ground is 0.5 - 30 A.

[0015] Preferably, the specified threshold is 10°.

[0016] Based on the same inventive concept, the present application also discloses an overhead hybrid transmission line cable insulation monitoring device, including an insulating rod clamp-on current sensor and a control processing module. The insulating rod clamp-on current sensor is divided into three groups, with two in each group, and is respectively clamped on the connection lead between the metal oxide arrester body and the counter in each phase and the connection lead from the outer skin of the cable shielding layer in each phase to the ground. The clamp-on current sensor clamped on the connection lead between the metal oxide arrester body and the counter in each phase uses a clamp-on microampere current sensor. All groups of insulating rod clamp-on current sensors are connected to the control processing module, and the control processing module uses the above-mentioned overhead hybrid transmission line cable insulation monitoring method to perform on-line hidden danger monitoring on the cable terminal and the arrester on the overhead hybrid transmission line.

[0017] Based on the same inventive concept, the present application also discloses a storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the aforementioned method for monitoring the insulation of a cable in an overhead hybrid transmission line.

[0018] Based on the same inventive concept, the present application also discloses an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the aforementioned method for monitoring the insulation of a cable in an overhead hybrid transmission line.

[0019] Compared with the prior art, the beneficial effects of this solution are as follows: A method and device for monitoring the insulation of a cable in an overhead hybrid transmission line are provided. Utilizing the characteristics that the transmission high-voltage cable is generally a single-core cable and metal oxide arresters are equipped at both ends of the cable (i.e., the cable heads), current signals are respectively led out from the outer skin of the shielding layer of the single-core cable and the arrester. By using the methods of individual phase calculation and comparison, grouped calculation and comparison, and cross calculation and comparison, the qualitative state of the insulation hidden dangers of the cable terminals and arresters on the overhead hybrid transmission line is monitored and judged online. The metal oxide arrester is abbreviated as MOA in English, and zinc oxide arresters are generally used in the on-site environment. This monitoring method is both simple and does not require power outage, realizing an online monitoring method for qualitatively judging the insulation state of the cable in the overhead hybrid transmission line, achieving the beneficial effects of simplifying the monitoring means and enhancing the operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a wiring schematic diagram of an embodiment of the device for monitoring the insulation of a cable in an overhead hybrid transmission line according to this solution;

[0021] Figure 2 It is a standard schematic diagram of the three-phase phases of the cable shielding current as a reference quantity when the three-phase insulation is intact;

[0022] Figure 3 It is a standard schematic diagram of the three-phase full current phases of the arrester when the three-phase insulation is intact;

[0023] Figure 4 It is a phase diagram of the hidden danger of the arrester in phase A. I A_MOA lags behind I A_Ref by an angle δ, and the monitored value of δ is negative;

[0024] Figure 5 It is a phase diagram of the hidden danger of the cable in phase A. I A_MOA leads ahead of I A_Ref by an angle δ, and the monitored value of δ is positive;

[0025] Figure 6 It is a three-phase phase diagram of the hidden danger of the cable in phase A;

[0026] Figure 7 It is a three-phase full current phase diagram of the hidden danger of the arrester in phase A;

[0027] Figure 8 Schematic diagram of potential hazards in three-phase phases for the lightning arrester cable of phase A

[0028] Figure 9 Schematic diagram of potential hazards in phase for the lightning arrester cable of phase A

[0029] Among them, I A_Ref - Current of the shielding layer of phase A cable, I B_Ref - Current of the shielding layer of phase B cable, I C_Ref - Current of the shielding layer of phase C cable, U A - Voltage of phase A, I A_MOA - Total operating current of the lightning arrester of phase A, I B_MOA - Total current of the lightning arrester of phase B, I C_MOA - Total current of the lightning arrester of phase C Specific implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments

[0031] Metal oxide lightning arresters are provided on both sides of the cable terminal of the overhead hybrid transmission line for overvoltage protection. Where there is a cable, there must be a lightning arrester. Next, a method and device for monitoring the insulation of the cable of an overhead hybrid transmission line according to an embodiment of the present application will be described with reference to the accompanying drawings

[0032] First, the total current signals of the three-phase lightning arresters during operation are respectively led to the control and processing module, and the current signals of the three-phase cable shielding layers as the reference phase are also respectively led to the control and processing module. Then, the control and processing module is used to calculate the phase values of the total current signals of the three-phase lightning arresters during operation and the phase values of the current signals of the three-phase cable terminal shielding layers

[0033] When the insulation of the lightning arrester is intact, the lightning arrester is equivalent to a capacitor, and its total current is a pure capacitive current. The shielding layer of this phase of the cable is also equivalent to a capacitor, and the current of the cable terminal shielding layer is also a pure capacitive current. As shown in Figure 2 and Figure 3 , the total current of this phase and the current signal of the shielding layer of this phase of the cable as the reference phase are theoretically in the same phase, that is, the included angle is 0 degrees; when the insulation of the three-phase lightning arresters is intact, the phases of the total currents are 120 degrees different from each other; the phases of the current signals of the three-phase cable shielding layers as the reference phase are also 120 degrees different from each other

[0034] δ is the included angle between the total current I A_MOA of the lightning arrester of phase A and the current I A_Ref of the shielding layer of phase A cable. Assuming the relative voltage U A of phase A, I A_MOALeading I A_Ref Positive for leading, negative for lagging.

[0035] When there are insulation risks in arresters or cables, it can be judged according to different situations. For example Figure 5 , when the phase of the total operating current signal of the arrester is greater than the specified threshold of the current signal of the cable terminal shielding layer and the phase of the total operating current signal of the arrester is standard, δ is positive, and the resistive current of the corresponding phase of the cable exceeds the standard, that is, there is a risk in the cable insulation; for example Figure 4 , when the phase of the total operating current signal of the arrester is less than the specified threshold of the current signal of the cable terminal shielding layer and the phase of the current signal of the cable terminal shielding layer is at the standard phase, δ is negative, and the resistive current of the corresponding arrester exceeds the standard, that is, there is a risk in the arrester insulation.

[0036] When there are risks in both the arrester and the cable, the monitoring angle is normal, but they are no longer 120° different from the other two phases respectively. One is 120 + δ°, and the other is 120 - δ°. Comparing the phase angles between the total currents of the three-phase arresters and comparing the phase angles between the currents of the three-phase cable shielding layers can find that there are risks in the arresters and cables of the same phase at the same time. For example Figure 6 and Figure 7 show the phase angle relationship of their currents in the three-phase system when there are risks in the A-phase arrester or cable, where δ is the angle between the current I A_Ref of the cable shielding layer of the A-phase and the total operating current I A_MOA of the A-phase arrester and the standard phase, that is, the angle deviating from the standard 120°. That is, when the angle between the phase of the total operating current signal of a certain phase arrester and the phase of the total operating current signals of the other two-phase arresters deviates from the 120° specified threshold, it is judged that there is a potential insulation fault in the arrester of this phase. When the angle between the phase of the current signal of a certain phase cable terminal shielding layer and the phase of the current signals of the other two-phase cable terminal shielding layers deviates from the 120° specified threshold, it is judged that there is a potential insulation fault in the cable terminal of this phase.

[0037] When there are multiple insulation risks at the same time, such as faults in the cable and arrester of a certain phase at the same time, but the degree of risk is different. Cross-compare the phase angles between the total currents of three arresters and three cables in a group and the current of the cable shielding layer for mutual comparison and judgment, and conduct a review of the risks of arresters and cables. It is also possible that there are risks in all six of the three phases at the same time and the degree of risk is different. This situation is rare but possible, and this is an extremely low-probability event, resulting in similar phase shifts of the current. For example Figure 8 and Figure 9, δ1 is the offset angle of the arrester hidden danger, δ2 is the offset angle of the cable hidden danger. The arrester and the cable of phase A have hidden dangers at the same time, and the offset angle δ1 of the arrester hidden danger is smaller than the offset angle δ2 of the cable hidden danger. When monitoring the same phase, the value of δ2 - δ1 is positive, and it is negative when the hidden danger of the arrester is more serious than that of the cable. At this time, the value of the same phase may not exceed the standard, but in the three-phase system, this phase of cable and arrester have insulation hidden dangers can be found after calculation and correction. That is, calculate and compare the relationship between the phase angle of the current signal of the shielding layer of the cable terminal of a certain phase and the phase angle of the full operating current signal of the arresters of the other two phases. When the phase angle between the current signal of the shielding layer of the cable terminal of a certain phase and the standard position is greater than the phase angle between the full operating current signal of the arrester and the standard position, and both angles are greater than the specified threshold, it is determined that there are potential faults in the insulation of the cable terminal and the arrester of this phase, and the insulation hidden danger of the cable terminal is greater than that of the arrester; calculate and compare the relationship between the phase angle of the full operating current signal of the arrester of a certain phase and the phase angle of the current signal of the shielding layer of the cable terminals of the other two phases. When the phase angle between the full operating current signal of the arrester of a certain phase and the standard position is greater than the phase angle between the current signal of the shielding layer of the cable terminal and the standard position, and both angles are greater than the specified threshold, it is determined that there are potential faults in the insulation of the cable terminal and the arrester of this phase, and the insulation hidden danger of the arrester is greater than that of the cable terminal.

[0038] In this embodiment, the full current of the three-phase arresters is in the order of hundreds of microamperes during normal operation. The clamp-on current sensor clamped on the connection lead between the metal oxide arrester body of each phase and the counter uses a clamp-on microampere current sensor. The range of the clamp-on microampere current sensor is 300 - 800 μA, and the range of the clamp-on current sensor on the connection lead from the outer skin of the cable shielding layer to the ground is selected as 0.5 - 30 A.

[0039] Regarding the selection of the specified threshold, the dielectric loss angle and insulation characteristic comparison table can be referred to for qualitative judgment. When quantitative evaluation is required, tests can be carried out during power outage. In this embodiment, 10° is selected.

[0040] δ <![CDATA[<4 0 > <![CDATA[4 0 ~7 0 > <![CDATA[7 0 ~10 0 > <![CDATA[10 0 ~13 0 > <![CDATA[13 0 ~15 0 > <![CDATA[>15 0 > Performance Interfered Excellent Good Medium Poor Inferior

[0041] Dielectric loss angle and insulation characteristic comparison table

[0042] According to the same inventive concept, the present application also discloses an overhead hybrid transmission line cable insulation monitoring device, including an insulating rod clamp-on current sensor and a control and processing module, as Figure 1, the insulating rod clamp current sensor is divided into three groups, namely A, B, and C, according to the three-phase line, with two in each group: namely, clamp sensor A1, clamp sensor A2, clamp sensor B1, clamp sensor B2, clamp sensor C1, and clamp sensor C2, which are respectively clamped on the connection leads between the body of each metal oxide arrester and the counter and the outer skin of the cable shield layer leading to the connection lead to the ground. The bottom of each metal oxide arrester is fixed on the metal frame of each phase together with the bottom of the cable terminal through an insulating fixing piece. The top of the cable terminal is connected to the top of the metal oxide arrester and is respectively connected to the A, B, and C three-phase operating lines. The metal frame of each phase is fixed to the ground through a column. The high-voltage cable connected to the lower part of the cable terminal penetrates into the ground. The shield grounding wire of each high-voltage cable is led out from the outer skin of the shield layer and is connected to the grounding body in the ground through a connecting grounding lead. The arrester lead of the body of each metal oxide arrester is connected to the lightning strike counter, and the lightning strike counter is also connected to the grounding body in the ground through a grounding lead. The clamp current sensor clamped on the connection lead between the body of each arrester and the counter uses a clamp microampere current sensor. The insulating rod clamp current sensors of all groups are connected to the control and processing module, and the control and processing module uses the above-mentioned cable insulation monitoring method for overhead hybrid transmission lines to perform on-line hidden danger monitoring on the cable terminals and arresters on the overhead hybrid transmission lines.

[0043] After introducing the full current of the three-phase arresters and the shield layer current of the three-phase cable terminals into the control and processing module. Since the full current of the three-phase arresters is in the hundreds of microamperes level during normal operation, it needs to be linearly amplified without distortion to the tens of milliamperes level through the amplifier module and then connected to the operation and processing module, that is, the amplitude is linearly amplified during amplification while the phase angle remains unchanged. After the operation and processing module of the control and processing module performs physical and software filtering, the calculation of six current ADC acquisition data is carried out simultaneously for the AC signals with the integer multiple of the power frequency period as the period, that is, 1 or n cycles. The Fourier transform calculation is carried out by the operation and processing module to transform the time domain value to the frequency domain value. In this way, the complex numbers of a+jb (a is the real part and b is the imaginary part) after the Fourier transform of the six power frequency currents of the 50Hz fundamental wave can be obtained. The six phase data are calculated by the formula Phase = arctan(b / a). Phase is in radians, and the result range of arctan is [-π,π], and then it is converted to degrees. From these six phase data, the respective phase relationships of the full currents of the three-phase arresters, the respective phase relationships of the shield layer currents of the three-phase cable terminals, and the phase angles between the full currents of the arresters of the same phase in groups A, B, and C and the shield layer currents of the cable terminals are calculated. Ideally, the phase angle of the currents of the same phase is 0 degrees.

[0044] In this embodiment, the control and processing module further includes a human-computer interaction data display device module and a human-computer interaction input module. The human-computer interaction data display device module, the amplifier module, and the arithmetic processing module are all connected to the power supply module. The human-computer interaction data display device module is used to display multiple phase diagrams, and the human-computer interaction input module is used for switching and displaying the phase diagrams, which can be implemented in various ways such as using a keyboard or buttons. The calculation and comparison of data by the control and processing module can also be implemented in other ways, as long as the above-mentioned calculation, comparison, and judgment functions can be achieved.

[0045] Based on the same inventive concept, the present application also discloses a storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the overhead hybrid transmission line cable insulation monitoring method as described above.

[0046] Based on the same inventive concept, the present application also discloses an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the overhead hybrid transmission line cable insulation monitoring method as described above.

[0047] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0048] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. An insulation monitoring method for cables of an overhead hybrid transmission line, characterized in that, Applied to an insulation monitoring system, it includes two groups of insulating rod clamp current sensors. One group is clamped on the connection leads between the body of each phase metal oxide arrester and the counter to extract the three-phase arrester operating full current signals, and the other group is clamped on the connection leads from the outer skin of each phase cable shielding layer to the ground to extract the three-phase cable terminal shielding layer current signals. The two groups of signals are respectively connected to the control and processing module. The method adopts the following steps: The control and processing module respectively calculates the phase values of the three-phase arrester operating full current signals and the phase values of the three-phase cable terminal shielding layer current signals; The control and processing module respectively calculates and compares the phase angles between the measured three-phase arrester operating full current signals and the cable terminal shielding layer current signals: When there is no phase angle between the three-phase arrester operating full current signals and the cable terminal shielding layer current signals and the phases of both signals are within the standard phase, it is judged that the insulation of the arrester and cable terminal of this phase is in good condition; When the phase of the arrester operating full current signal is greater than the specified threshold of the phase of the cable terminal shielding layer current signal and the phase of the arrester operating full current signal is standard, it is judged that there are potential insulation faults in the cable terminal of this phase; When the phase of the arrester operating full current signal is less than the specified threshold of the cable terminal shielding layer current signal and the phase of the cable terminal shielding layer current signal is within the standard phase, it is judged that there are potential insulation faults in the arrester of this phase.

2. The method for monitoring the cable insulation of an overhead hybrid transmission line according to claim 1, characterized in that After the step of the control and processing module respectively calculating and comparing the phase angles between the measured three-phase arrester operating full current signals and the cable terminal shielding layer current signals, it further includes the step: calculating and comparing the relationships between the phase angles of the three-phase arrester operating full current signals. When the angle between the phase of a certain phase arrester operating full current signal and the phases of the other two-phase arrester operating full current signals deviates from the 120° specified threshold, it is judged that there are potential insulation faults in the arrester of this phase.

3. The method for monitoring the cable insulation of an overhead hybrid transmission line according to claim 2, characterized in that After the step of the control and processing module respectively calculating and comparing the phase angles between the measured three-phase arrester operating full current signals and the cable terminal shielding layer current signals, it further includes the step: calculating and comparing the relationships between the phase angles of the three-phase cable terminal shielding layer current signals. When the angle between the phase of a certain phase cable terminal shielding layer current signal and the phases of the other two-phase cable terminal shielding layer current signals deviates from the 120° specified threshold, it is judged that there are potential insulation faults in the cable terminal of this phase.

4. The method for monitoring the cable insulation of an overhead hybrid power transmission line according to claim 3, characterized in that After the step of the control and processing module respectively calculating and comparing the phase angles between the measured three-phase arrester operating full current signals and the cable terminal shielding layer current signals, it further includes the step: calculating and comparing the relationship between the phase angle of a certain phase cable terminal shielding layer current signal and the phase angles of the other two-phase arrester operating full current signals. When the angle between the phase of a certain phase cable terminal shielding layer current signal and the standard position is greater than the angle between the phase of the arrester operating full current signal and the standard position and both angles are greater than the specified threshold, it is judged that there are potential insulation faults in both the cable terminal and the arrester of this phase, and the insulation fault of the cable terminal is greater than that of the arrester.

5. The method for monitoring the cable insulation of an overhead hybrid transmission line according to claim 4, characterized in that After the control processing module calculates and compares the phase angles between the running full-current signals of the arresters to be measured in each phase and the current signals of the cable terminal shielding layer respectively, the steps further include: calculating and comparing the relationship between the phase of the running full-current signal of an arrester in a certain phase and the phase angles between the current signals of the cable terminal shielding layers in the other two phases. When the phase angle between the running full-current signal of an arrester in a certain phase and the standard position is greater than the phase angle between the current signal of the cable terminal shielding layer and the standard position, and both angles are greater than the specified threshold, it is determined that there are potential faults in both the cable terminal insulation and the arrester in this phase, and the insulation potential fault of the arrester is greater than that of the cable terminal insulation.

6. The method for monitoring the cable insulation of an overhead hybrid transmission line according to claim 1, wherein: The clamp-type current sensor clamped on the connection lead between the metal oxide arrester body and the counter in each phase uses a clamp-type microampere current sensor.

7. The method for monitoring the cable insulation of an overhead hybrid transmission line according to claim 6, characterized in that: The range of the clamp-type microampere current sensor is 0.3 - 0.8 mA.

8. The cable insulation monitoring method for the overhead hybrid transmission line according to claim 1, wherein: The range of the clamp-type current sensor clamped on the connection lead from the outer skin of the cable shielding layer in each phase to the ground is 0.5 - 30 A.

9. The cable insulation monitoring method for an overhead hybrid transmission line according to claim 5, characterized in that: The specified threshold is 10°.

10. An insulating monitoring device for an overhead hybrid transmission line cable, comprising an insulating rod clamp current sensor, characterized in that: It further includes a control processing module. The insulating rod clamp-type current sensors are divided into three groups, with two in each group, which are respectively clamped on the connection lead between the metal oxide arrester body and the counter in each phase and the connection lead from the outer skin of the cable shielding layer to the ground. The clamp-type current sensor clamped on the connection lead between the metal oxide arrester body and the counter in each phase uses a clamp-type microampere current sensor. All groups of insulating rod clamp-type current sensors are connected to the control processing module. The control processing module uses the overhead hybrid transmission line cable insulation monitoring method according to any one of claims 1 - 5 to perform on-line potential fault monitoring on the cable terminals and arresters on the overhead hybrid transmission line.

11. A storage medium, on which a computer program is stored, characterized in that: When the computer program is executed by a processor, it implements the overhead hybrid transmission line cable insulation monitoring method according to any one of claims 1 - 5.

12. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the overhead hybrid transmission line cable insulation monitoring method according to any one of claims 1 - 5.

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