ROV umbilical cable insulation defect real-time monitoring and phase selection method and device

Abstract

The invention relates to an ROV umbilical cable insulation defect real-time monitoring and phase selection method and device, and belongs to the technical field of ROV power supply safety, and the ROV umbilical cable insulation defect real-time monitoring and phase selection method comprises an insulation defect monitoring step and an insulation defect phase selection step. Wherein the insulation defect monitoring step comprises the steps of monitoring current at a neutral point in real time, and detecting whether an insulation defect exists or not; the insulation defect phase selection step comprises the following steps: if an insulation defect is detected, respectively measuring the current of each single phase in a three-phase circuit, judging the phase with the insulation defect, and controlling to cut off a three-phase main circuit. According to the ROV umbilical cable insulation defect real-time monitoring and phase selection method, the insulation defect is detected in the early stage, the defect is prevented from further developing into a ground fault, meanwhile, equipment is protected, and the maintenance time is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of ROV power supply safety, and in particular relates to a method and a device for real-time monitoring and phase selection of insulation defects of an ROV umbilical cable. Background Art

[0002] Operational ROVs are cable-type unmanned remote-controlled submersibles and are important tools for exploring the ocean. Umbilical cables are the link between ROVs and ship bases, and the reliability of their power supply directly affects the efficiency and quality of ROV underwater operations. Unlike land cables, ROV umbilical cables are dynamic cables, which are subject to bending, twisting and other forces caused by tides and ROV movement during underwater operations. Although they have been designed and manufactured to have strong resistance to friction and distortion, they are still very likely to suffer from reduced electrical performance due to reduced mechanical performance in complex underwater working conditions and environments, which is mainly manifested in reduced insulation performance of the ROV umbilical cables and insulation defects.

[0003] Insulation defect is a state before it develops into a fault. The main feature of insulation defect is that it still has a large insulation resistance to the ground. For industrial ROV umbilical cables, the insulation resistance is generally greater than 10 megohms during normal operation. The insulation resistance in the early stage of insulation defect is about 2-10 megohms. With the development of time and insulation degradation, the insulation resistance continues to decrease, and then develops into a fault. After the grounding fault, the insulation resistance is very small, at a few ohms. Therefore, in the early stage of the insulation defect, the three-phase current in the three-phase circuit will not fluctuate greatly, and it is difficult to determine the phase where the insulation defect occurs by current fluctuations. When a single-phase grounding fault occurs, the current difference between the fault phase and the non-fault phase is obvious. For industrial ROVs, in order to protect the safety of underwater equipment operations, it is generally required to cut off all power supplies in the early stage of the insulation defect to protect the equipment and avoid the development of a grounding fault. Therefore, it is necessary to accurately locate the phase where the insulation defect occurs after the insulation defect occurs to maintain the umbilical cable.

[0004] In the prior art, Chinese invention patent CN108169624B provides a method for locating the source of a circuit fault. The patent determines whether a single-phase grounding fault occurs based on the voltage signal on the neutral point, and then determines the three-phase line and fault phase where the single-phase grounding fault occurs based on the electrical signals on the parallel lines at the input end and the parallel lines at the output end of the two three-phase lines. The patent solves the problems of fault detection and phase selection, but for insulation defects with small current fluctuations, this method cannot accurately locate the phase where the insulation defect occurs.

[0005] Therefore, how to provide a monitoring and phase selection method for insulation defects is a technical problem that urgently needs to be solved. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method and device for real-time monitoring and phase selection of insulation defects of an ROV umbilical cable. By real-time monitoring of the current at the neutral point and accurately locating the phase where the insulation defect occurs, the relevant circuits can be cut off in time, so that insulation defects can be detected at an early stage to prevent the defects from further developing into ground faults, while protecting equipment and reducing maintenance time.

[0007] The present invention provides a real-time monitoring and phase selection method for insulation defects of an ROV umbilical cable, comprising the following steps: Insulation defect monitoring: real-time monitoring of the current at the neutral point to detect whether there are insulation defects; Insulation defect phase selection: If an insulation defect is detected, the current of each single phase in the three-phase circuit is measured separately to determine the phase where the insulation defect occurs, and control to cut off the three-phase main circuit.

[0008] This technical solution can detect insulation defects at an early stage by real-time monitoring of the current at the neutral point, accurately locating the phase where the insulation defect occurs, and promptly cutting off the relevant circuits, thereby preventing the defect from further developing into a ground fault, while protecting the equipment and reducing maintenance time.

[0009] In some of the embodiments, in the insulation defect phase selection step, the current of each single phase in the three-phase circuit is measured respectively, and the current of each phase is compared to determine that the phase with a current much smaller than that of other phases is the phase where the insulation defect occurs.

[0010] In some embodiments, when measuring the current of each single phase in a three-phase circuit, the large reactance and the first microammeter are connected in series, and the series circuit of the large reactance and the first microammeter is recorded as a measurement circuit. The first end of the measurement circuit is grounded, and the second end is connected in parallel with the single phases in the three-phase circuit. The single-phase current is obtained through the reading of the first microammeter, and the phase that is much smaller than the current of other phases is judged as the phase where the insulation defect occurs. By setting a large reactance, the technical solution can ignore the small impedance of the line itself, which helps to improve the stability of current detection.

[0011] In some embodiments, the principle of obtaining the single-phase current through the first microammeter reading and determining the phase where the insulation defect occurs is: the current of the phase where the insulation defect occurs is recorded as , the normal phase current is , using the equivalent circuit to and Calculate and determine the insulation defect occurrence phase according to formula (1). The expression of formula (1) is: (1).

[0012] In some embodiments, equivalent circuits are used to respectively and The calculation method includes: let the insulation defect point be point D, then the current of the phase where point D is located is ; The line impedance of the phase where the insulation defect occurs is equivalent to , the insulation resistance of point D to ground is equivalent to , the line impedance of the normal phase is equivalent to , the line impedance of the measurement circuit is equivalent to ; When the measuring circuit is connected to the phase where the insulation defect occurs, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as , calculated using formula (2) , the expression of formula (2) is: (2); When the measuring circuit is connected to the normal phase, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as The line voltage between the phase where the insulation defect occurs and the normal phase connected in parallel with the measuring circuit is , calculated using formula (3) , the expression of formula (3) is: (3).

[0013] In some of the embodiments, in the insulation defect monitoring step, when an unbalanced current is generated at the neutral point, it is determined that an insulation defect exists.

[0014] In some of the embodiments, in the insulation defect monitoring step, when an insulation defect is detected, a circuit for monitoring the current at the neutral point is cut off.

[0015] In some of the embodiments, in the insulation defect monitoring step, an alarm signal is triggered when an insulation defect is detected.

[0016] In addition, the present invention also provides a ROV umbilical cable insulation defect real-time monitoring and phase selection device, which adopts the ROV umbilical cable insulation defect real-time monitoring and phase selection method as described above, including: A neutral point monitoring circuit, one end of which is connected to the neutral point of the ROV umbilical cable power supply side, and the other end is grounded; the neutral point monitoring circuit comprises a second microammeter and a DC power supply, and the second microammeter is used to monitor the current at the neutral point in real time; The three-phase monitoring circuit has a connector switch at one end, the connector switch is connected in parallel with one of the phases in the three-phase circuit, and the other end is grounded; the three-phase monitoring circuit is also provided with a large reactance and a first microammeter connected in series with the connector switch; the connector switch is used to switch the circuit to be monitored by the three-phase monitoring circuit, and the first microammeter is used to measure the current of each single phase in the three-phase circuit; The control module is respectively connected to the neutral point monitoring circuit and the three-phase monitoring circuit for communication. When the neutral point monitoring circuit determines that an insulation defect occurs, the control module controls the neutral point detection circuit to disconnect and controls the three-phase monitoring circuit to start working. The control module is also connected to the three-phase main circuit for communication. After the three-phase monitoring circuit determines that an insulation defect occurs, the control module cuts off the three-phase main circuit.

[0017] This technical solution uses a neutral point monitoring circuit and a three-phase monitoring circuit in combination, so that the device can detect insulation defects in time at the early stage and quickly cut off the corresponding circuit through the control module to prevent the defect from further developing into a more serious fault.

[0018] In some of the embodiments, the three-phase monitoring circuit also includes three single-phase taps, each of which is connected in parallel with one of the single-phase lines; when the control module controls the three-phase monitoring circuit to start working, the connector conversion switch is connected to the three single-phase taps to measure the current of each phase circuit.

[0019] Based on the above scheme, the ROV umbilical cable insulation defect real-time monitoring and phase selection method in the embodiment of the present invention can detect insulation defects at an early stage by real-time monitoring of the current at the neutral point, accurately locating the phase where the insulation defect occurs, and timely cutting off the relevant circuits, thereby preventing the defect from further developing into a ground fault, while protecting the equipment and reducing maintenance time. The combined use of the neutral point monitoring circuit and the three-phase monitoring circuit of the ROV umbilical cable insulation defect real-time monitoring and phase selection device enables the device to detect problems in time at the early stage of insulation defects, and quickly cut off the corresponding circuit through the control module to prevent the defect from further developing into a more serious fault. This multi-level monitoring and control method greatly improves the operating safety and reliability of the ROV umbilical cable, while reducing the maintenance cost and time of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 This is a circuit diagram of the ROV umbilical cable insulation defect real-time monitoring and phase selection device in Example 1 of the present invention; Figure 2 It is an equivalent circuit diagram when the measurement circuit in the ROV umbilical cable insulation defect real-time monitoring and phase selection method in Example 1 of the present invention is incorporated into the insulation defect occurrence phase; Figure 3 This is an equivalent circuit diagram when the measurement circuit in the ROV umbilical cable insulation defect real-time monitoring and phase selection method in Example 1 of the present invention is incorporated into the normal phase.

[0021] In the figure: 1. Connector conversion switch; 2. Large reactance; 3. First microammeter; 4. Second microammeter; 5. First switch; 6. Second switch. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The terms "system", "unit" and "module" used in this document are a method for distinguishing different components, elements, parts, portions or assemblies at different levels, and these terms may be replaced by other expressions that can achieve the same purpose.

[0026] In one embodiment of the ROV umbilical cable insulation defect real-time monitoring and phase selection method and device of the present invention, the ROV umbilical cable insulation defect real-time monitoring and phase selection method includes an insulation defect monitoring step and an insulation defect phase selection step; wherein the insulation defect monitoring step includes: real-time monitoring of the current at the neutral point to detect whether there is an insulation defect; the insulation defect phase selection step includes: if an insulation defect is detected, measuring the current of each single phase in the three-phase circuit respectively, determining the phase where the insulation defect occurs, and controlling the cutting off of the three-phase main circuit.

[0027] In the above exemplary embodiment, the ROV umbilical cable insulation defect real-time monitoring and phase selection method can detect insulation defects at an early stage by real-time monitoring of the current at the neutral point, accurately locating the phase where the insulation defect occurs, and timely cutting off the relevant circuits, thereby preventing the defect from further developing into a ground fault, while protecting the equipment and reducing the maintenance time. Therefore, the ROV umbilical cable insulation defect real-time monitoring and phase selection method in the embodiment of the present invention not only enhances the durability of the ROV umbilical cable in a complex underwater environment, but also effectively reduces the operation interruption caused by the degradation of electrical performance, providing a more reliable technical guarantee for ocean exploration.

[0028] In some embodiments, in the insulation defect phase selection step, the current of each single phase in the three-phase circuit is measured respectively, and each phase current is compared to determine that the phase with a current much smaller than that of other phases is the phase where the insulation defect occurs.

[0029] Furthermore, when measuring the current of each single phase in the three-phase circuit, the large reactance 2 and the first microammeter 3 are connected in series, and the series circuit of the large reactance 2 and the first microammeter 3 is recorded as a measurement circuit. The first end of the measurement circuit is grounded, and the second end is connected in parallel with the single phase in the three-phase circuit. The single-phase current is obtained through the reading of the first microammeter 3, and the phase that is much smaller than the other phase currents is judged to be the phase where the insulation defect occurs. It can be understood that the impedance of each phase circuit itself is generally in the ohm level, and when an insulation defect occurs, a megohm-level impedance to the ground will be generated. Therefore, by setting the large reactance 2, the small impedance of the line itself can be ignored. At this time, the main factor affecting the current size of the phase where the insulation defect occurs and the normal phase is the voltage, which helps to improve the stability of the current detection. At this time, the reading of the first microammeter 3 is more reliable; if the large reactance 2 is not set, but a small resistor is set, the small resistor will be ignored.

[0030] It should be noted that the size of the large reactance 2 is in the megaohm range.

[0031] In some embodiments, the principle of obtaining the single-phase current through the reading of the first microammeter 3 and determining the phase where the insulation defect occurs is: the current of the phase where the insulation defect occurs is recorded as , the normal phase current is , using the equivalent circuit to and Calculate and determine the insulation defect occurrence phase according to formula (1). The expression of formula (1) is: (1).

[0032] In some embodiments, equivalent circuits are used to respectively and The calculation method includes: let the insulation defect point be point D, then the current of the phase where point D is located is ; The line impedance of the phase where the insulation defect occurs is equivalent to , the insulation resistance of point D to ground is equivalent to , the line impedance of the normal phase is equivalent to , the line impedance of the measurement circuit is equivalent to ; When the measuring circuit is connected to the phase where the insulation defect occurs, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as , calculated using formula (2) , the expression of formula (2) is: (2); When the measuring circuit is connected to the normal phase, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as The line voltage between the phase where the insulation defect occurs and the normal phase connected in parallel with the measuring circuit is , calculated using formula (3) , the expression of formula (3) is: (3).

[0033] It should be noted that and The magnitudes of are greater than or equal to 0 and less than or equal to the phase voltage.

[0034] In some embodiments, in the insulation defect monitoring step, when an unbalanced current is generated at the neutral point, it is determined that an insulation defect exists.

[0035] In some embodiments, in the insulation defect monitoring step, when an insulation defect is detected, a circuit for monitoring the current at the neutral point is cut off.

[0036] In some embodiments, in the insulation defect monitoring step, when an insulation defect is detected, an alarm signal is triggered.

[0037] Based on the above ROV umbilical cable insulation defect real-time monitoring and phase selection method, such as Figure 1As shown, the present invention also provides a ROV umbilical cable insulation defect real-time monitoring and phase selection device, which adopts the above-mentioned ROV umbilical cable insulation defect real-time monitoring and phase selection method, including a neutral point monitoring circuit, a three-phase monitoring circuit and a control module; wherein one end of the neutral point monitoring circuit is connected to the neutral point of the ROV umbilical cable power supply side, and the other end is grounded; the neutral point monitoring circuit includes a second microammeter 4 and a DC power supply, and the second microammeter 4 is used to monitor the current at the neutral point in real time; one end of the three-phase monitoring circuit is provided with a joint conversion switch 1, the joint conversion switch 1 is connected in parallel with one of the phases in the three-phase circuit, and the other end is grounded; The three-phase monitoring circuit is also provided with a large reactance 2 and a first microammeter 3 connected in series with the connector conversion switch 1; the connector conversion switch 1 is used to switch the circuit to be monitored by the three-phase monitoring circuit, and the first microammeter 3 is used to measure the current of each single phase in the three-phase circuit; the control module is respectively communicated with the neutral point monitoring circuit and the three-phase monitoring circuit, and when the neutral point monitoring circuit determines that an insulation defect occurs, the control module controls the neutral point detection circuit to disconnect, and controls the three-phase monitoring circuit to start working; the control module is also communicated with the three-phase main circuit, and after the three-phase monitoring circuit determines that an insulation defect occurs, the control module cuts off the three-phase main circuit.

[0038] In the above exemplary embodiment, the device can realize rapid detection and positioning of insulation defects by adopting the real-time monitoring and phase selection method of ROV umbilical cable insulation defects. The combined use of the neutral point monitoring circuit and the three-phase monitoring circuit enables the device to detect problems in time at the early stage of insulation defects, and quickly cut off the corresponding circuit through the control module to prevent the defects from further developing into more serious faults. This multi-level monitoring and control method greatly improves the operating safety and reliability of the ROV umbilical cable, while reducing the maintenance cost and time of the equipment.

[0039] In some embodiments, Figure 1 As shown, the three-phase monitoring circuit also includes three single-phase taps, each of which is connected in parallel with one of the single-phase lines; when the control module controls the three-phase monitoring circuit to start working, the connector conversion switch 1 is connected to the three single-phase taps to measure the current of each phase circuit.

[0040] In some embodiments, Figure 1 As shown, the neutral point monitoring circuit is provided with a first switch 5 for cutting off the circuit; when the neutral point monitoring circuit determines that an insulation defect occurs, the control module controls the first switch 5 to be disconnected. By setting the first switch 5, the control module can cut off the circuit in time after an insulation defect is found, prevent the fault from expanding, and enhance the safety of the system.

[0041] In some embodiments, Figure 1 As shown in FIG. 1 , the neutral point monitoring circuit is provided with a large impedance. Adding a large impedance to the neutral point monitoring circuit helps to improve the stability of current detection and the reliability of insulation defect detection.

[0042] In some embodiments, Figure 1 As shown, each single-phase line is provided with a second switch 6 for cutting off the circuit, and the second switches 6 are all connected to the control module in communication; after the three-phase monitoring circuit determines the phase where the insulation defect occurs, the control module controls all the second switches 6 to be disconnected. Each single-phase line is provided with a second switch 6 and connected to the control module. After determining the phase of the insulation defect, the control module disconnects all related circuits to further protect the equipment and ensure the overall stable operation of the system.

[0043] Furthermore, if Figure 1 As shown, the control module is respectively communicated with the connector conversion switch 1 and the first microammeter 3. The control module is used to switch the circuit connected to the connector conversion switch 1, compare the current of each single phase obtained by the three-phase monitoring circuit, and determine that the phase that is much smaller than the current of other phases is the phase where the insulation defect occurs.

[0044] In some embodiments, the control module is also provided with an alarm unit; when an insulation defect is detected, the alarm unit sends an alarm signal. The control module is equipped with an alarm unit, and when an insulation defect is detected, the alarm unit sends an alarm signal, which can quickly respond to the insulation defect and effectively prevent potential equipment damage and safety accidents.

[0045] By using the ROV umbilical cable insulation defect real-time monitoring and phase selection device in the above-mentioned embodiments, it is possible to determine whether the umbilical cable circuit has insulation defects, and to locate the phase where the insulation defects occur. The other positive technical effects of the ROV umbilical cable insulation defect real-time monitoring and phase selection method in the above-mentioned embodiments are also applicable to the ROV umbilical cable insulation defect real-time monitoring and phase selection device, which will not be repeated here.

[0046] Example 1 Combine the following Figure 1-Figure 3 The specific structure and working process of an embodiment of the ROV umbilical cable insulation defect real-time monitoring and phase selection method and device of the present invention are described as follows: (1) The ROV umbilical cable insulation defect real-time monitoring and phase selection device is used to detect the insulation monitoring and phase selection of the three-phase circuits A, B, and C of the ROV umbilical cable, including: A neutral point monitoring circuit, one end of which is connected to the neutral point of the ROV umbilical cable power supply side, and the other end is grounded; the neutral point monitoring circuit includes a second microammeter 4 and a DC power supply, and the second microammeter 4 is used to monitor the current at the neutral point in real time; the neutral point monitoring circuit is provided with a first switch 5 for cutting off the circuit; the neutral point monitoring circuit is provided with a large impedance; A three-phase monitoring circuit has a connector switch 1 at one end, the connector switch 1 is connected in parallel with one phase of the three-phase circuit, and the other end is grounded; specifically, Figure 1As shown, the A-phase circuit is connected to the A-phase tap, the B-phase circuit is connected to the B-phase tap, the C-phase circuit is connected to the C-phase tap, and the joint changeover switch 1 switches the phase to be measured by connecting to the A-phase tap, the B-phase tap, or the C-phase tap respectively; the three-phase monitoring circuit is also provided with a large reactance 2 and a first microammeter 3 connected in series with the joint changeover switch 1; the joint changeover switch 1 is used to switch the circuit to be monitored by the three-phase monitoring circuit, and the first microammeter 3 is used to measure the current of each single-phase in the three-phase circuit; each single-phase circuit is provided with a second switch 6 for cutting off the circuit; The control module is respectively connected to the neutral point monitoring circuit and the three-phase monitoring circuit for communication. When the neutral point monitoring circuit determines that an insulation defect occurs, the control module controls the first switch 5 to disconnect to disconnect the neutral point detection circuit, and controls the three-phase monitoring circuit to start working; each single-phase line is provided with a second switch 6 for cutting off the circuit, and the second switches 6 are all connected to the control module for communication; after the three-phase monitoring circuit determines that an insulation defect occurs, the control module controls all the second switches 6 to disconnect; the control module is also provided with an alarm unit.

[0047] (2) The real-time monitoring and phase selection method of ROV umbilical cable insulation defects includes the following steps: Insulation defect monitoring: monitor the current at the neutral point in real time to detect whether there is an insulation defect; specifically, when an unbalanced current is generated at the neutral point, it is determined that an insulation defect exists; when an insulation defect is detected, the circuit monitoring the current at the neutral point is cut off and an alarm signal is triggered.

[0048] Insulation defect phase selection: If an insulation defect is detected, the current of each single phase in the three-phase circuit is measured respectively, and each phase current is compared. The phase with a current much smaller than that of other phases is determined to be the phase where the insulation defect occurs, and the three-phase main circuit is cut off; When measuring the current of each single phase in the three-phase circuit, the large reactance 2 and the first microammeter 3 are connected in series, and the series circuit of the large reactance 2 and the first microammeter 3 is recorded as a measuring circuit. The first end of the measuring circuit is grounded, and the second end is connected in parallel with the single phases in the three-phase circuit respectively. The single-phase current is obtained through the reading of the first microammeter 3, and the phase with a current much smaller than that of other phases is judged as the phase where the insulation defect occurs; In this embodiment, it is assumed that the insulation defect point occurs at point D of phase A. When the joint conversion switch 1 is connected to the tap of phase A, the measurement circuit is connected to the phase where the insulation defect occurs. The current of phase A where the insulation defect occurs is recorded as ,like Figure 2 As shown in the figure, the power supply side represents the ABC three-phase power supply of the ROV umbilical cable, which is a three-phase neutral point ungrounded system. Equivalent to the A phase line impedance, Equivalent to the B phase line impedance, Equivalent to the C phase line impedance, It is equivalent to the insulation resistance to ground of point D when the insulation defect occurs; point E is the grid connection point where the measuring circuit and the insulation defect occur. Equivalent to the line impedance of the measurement circuit, is the voltage difference between point E and point D; according to formula (2), the calculation formula of phase A current in this embodiment can be expressed as: (4); When the tap changer 1 is connected to the C phase tap, the measurement circuit is connected to the normal phase C phase, and the C phase current is recorded as ,like Figure 3 As shown, the voltage difference between the measuring circuit and the grid connection point E' and point D of phase C is The line voltage between A and C is , According to formula (3), the calculation formula of phase C current in this embodiment can be expressed as: (5); According to formula (1) and Satisfaction relationship: ; According to the reading of the first microammeter 3, the actual measurement meets , it can be determined that phase A has insulation defects.

[0049] Through the description of multiple embodiments of the method and device for real-time monitoring and phase selection of ROV umbilical cable insulation defects of the present invention, it can be seen that the method and device for real-time monitoring and phase selection of ROV umbilical cable insulation defects of the present invention have at least one or more of the following advantages: 1. The real-time monitoring and phase selection method for insulation defects of ROV umbilical cables provided by the present invention can detect insulation defects at an early stage by real-time monitoring of the current at the neutral point, accurately locating the phase where the insulation defects occur, and timely cutting off the relevant circuits, thereby preventing the defects from further developing into ground faults, while protecting the equipment and reducing the maintenance time; 2. The real-time monitoring and phase selection method for insulation defects of ROV umbilical cables provided by the present invention can ignore the small impedance of the line itself by setting the large reactance 2. At this time, the main factor affecting the current magnitude of the phase where the insulation defect occurs and the normal phase is the voltage, which helps to improve the stability of current detection. At this time, the reading of the first microammeter 3 is more reliable; 3. The ROV umbilical cable insulation defect real-time monitoring and phase selection device provided by the present invention, through the combined use of the neutral point monitoring circuit and the three-phase monitoring circuit, enables the device to promptly detect the problem at the early stage of the insulation defect, and quickly cut off the corresponding circuit through the control module to prevent the defect from further developing into a more serious fault. This multi-level monitoring and control method greatly improves the operating safety and reliability of the ROV umbilical cable, while reducing the maintenance cost and time of the equipment.

[0050] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0051] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for real-time monitoring and phase selection of insulation defects of ROV umbilical cable, characterized in that: The following steps are involved: Insulation defect monitoring: real-time monitoring of the current at the neutral point to detect whether there are insulation defects; Insulation defect phase selection: If an insulation defect is detected, the current of each single phase in the three-phase circuit is measured separately to determine the phase where the insulation defect occurs, and control to cut off the three-phase main circuit.

2. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 1 is characterized in that: In the insulation defect phase selection step, the current of each single phase in the three-phase circuit is measured respectively, and each phase current is compared to determine that the phase with a current much smaller than that of other phases is the phase where the insulation defect occurs.

3. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 1 or 2, characterized in that: When measuring the current of each single phase in a three-phase circuit, the large reactance and the first microammeter are connected in series. The series circuit of the large reactance and the first microammeter is recorded as a measuring circuit. The first end of the measuring circuit is grounded, and the second end is connected in parallel with the single phases in the three-phase circuit. The single-phase current is obtained through the reading of the first microammeter, and the phase with a current much smaller than that of other phases is judged to be the phase where the insulation defect occurs.

4. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 3 is characterized in that: The principle of obtaining the single-phase current through the first microammeter reading and determining the phase where the insulation defect occurs is: the current of the phase where the insulation defect occurs is , the normal phase current is , using the equivalent circuit to and Calculate and determine the insulation defect occurrence phase according to formula (1). The expression of formula (1) is: （1）。 5. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 4 is characterized in that: Using equivalent circuits and The calculation method includes: let the insulation defect point be point D, then the current of the phase where point D is located is ; The line impedance of the phase where the insulation defect occurs is equivalent to , the insulation resistance of point D to ground is equivalent to , the line impedance of the normal phase is equivalent to , the line impedance of the measurement circuit is equivalent to ; When the measuring circuit is connected to the phase where the insulation defect occurs, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as , calculated using formula (2) , the expression of formula (2) is: （2）； When the measuring circuit is connected to the normal phase, the voltage difference between the grid connection point of the measuring circuit and the phase where the insulation defect occurs and point D is recorded as The line voltage between the phase where the insulation defect occurs and the normal phase connected in parallel with the measuring circuit is , calculated using formula (3) , the expression of formula (3) is: （3）。 6. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 1 is characterized in that: In the insulation defect monitoring step, when an unbalanced current is generated at the neutral point, it is determined that an insulation defect exists.

7. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 1 or 6, characterized in that: In the insulation defect monitoring step, when an insulation defect is detected, a circuit for monitoring the current at the neutral point is cut off.

8. The ROV umbilical cable insulation defect real-time monitoring and phase selection method according to claim 1 or 6, characterized in that: In the insulation defect monitoring step, when an insulation defect is detected, an alarm signal is triggered.

9. A real-time monitoring and phase selection device for insulation defects of ROV umbilical cable, characterized in that: The method for real-time monitoring and phase selection of insulation defects of an ROV umbilical cable according to any one of claims 1 to 8 comprises: A neutral point monitoring circuit, one end of which is connected to the neutral point of the ROV umbilical cable power supply side, and the other end is grounded; the neutral point monitoring circuit comprises a second microammeter and a DC power supply, and the second microammeter is used to monitor the current at the neutral point in real time; The three-phase monitoring circuit has a connector switch at one end, the connector switch is connected in parallel with one of the phases in the three-phase circuit, and the other end is grounded; the three-phase monitoring circuit is also provided with a large reactance and a first microammeter connected in series with the connector switch; the connector switch is used to switch the circuit to be monitored by the three-phase monitoring circuit, and the first microammeter is used to measure the current of each single phase in the three-phase circuit; The control module is respectively connected to the neutral point monitoring circuit and the three-phase monitoring circuit for communication. When the neutral point monitoring circuit determines that an insulation defect occurs, the control module controls the neutral point detection circuit to disconnect and controls the three-phase monitoring circuit to start working. The control module is also connected to the three-phase main circuit for communication. After the three-phase monitoring circuit determines that an insulation defect occurs, the control module cuts off the three-phase main circuit.

10. The ROV umbilical cable insulation defect real-time monitoring and phase selection device according to claim 9, characterized in that: The three-phase monitoring circuit also includes three single-phase taps, each of which is connected in parallel with one of the single-phase lines; when the control module controls the three-phase monitoring circuit to start working, the connector conversion switch is connected to the three single-phase taps to measure the current of each phase circuit.

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