Distributed seawater pipeline dissimilar metal galvanic couple insulation monitoring system and method

Abstract

The invention discloses a distributed seawater pipeline dissimilar metal galvanic couple insulation monitoring system, which is connected with a plurality of to-be-monitored dissimilar metal galvanic couple structures, and comprises a plurality of monitoring units which are respectively connected with the plurality of to-be-monitored dissimilar metal galvanic couple structures and are connected with one another in series; the cabin monitoring station is in data connection with the adjacent monitoring unit; wherein each monitoring unit comprises a power supply module; a main control and data storage module; the voltage detection and statistics module is used for measuring the direct-current voltage at the two ends of the corresponding dissimilar metal couple structure in the initial state of no insulation fault, and calculating the average equivalent potential of the dissimilar metal couple structure based on the direct-current voltage measured in a period of time; the voltage detection statistics module also monitors the actual direct current voltage at the two ends of the corresponding dissimilar metal couple structure in real time; and the isolation communication control module communicates with other monitoring units and / or a cabin monitoring station.

Description

Technical Field

[0001] The present invention relates to a monitoring system and method, and in particular to a system and method for monitoring the insulation of metal couples. Background Art

[0002] The dissimilar metal connection parts of the ship's seawater piping system, such as the steel filter fixedly connected to the copper-nickel alloy pipe through flanges and bolts, form a galvanic structure under the seawater medium, and form a galvanic current in the case of direct connection, resulting in electrochemical corrosion. In order to inhibit electrochemical corrosion, the fastening connection of dissimilar metal materials in the seawater piping system in the ship construction specifications is usually isolated by electrical insulation component materials. This technology can isolate the galvanic current and is an effective way to prevent and reduce electrochemical corrosion between dissimilar metals.

[0003] Since dissimilar metal structures are exposed to the harsh working conditions of metal structure stress changes and seawater medium for a long time, the insulating materials installed between dissimilar metals may be accidentally damaged, or the aging of the insulating materials may cause the insulation performance to fail, which in turn causes corrosion currents between dissimilar metal structures. Therefore, after installing these electrical insulation component materials between a large number of equipment and pipe systems, it is necessary to continuously monitor the insulation status of the insulating materials installed in the dissimilar metal structures during the operation of the equipment, evaluate and determine the integrity of the electrical insulation protection structure and the performance status of the insulating materials, so as to alarm when the insulation value drops to a certain set value due to the damage of the insulating materials, and then take measures to repair or replace the insulating materials.

[0004] However, considering that ship seawater pipeline equipment is usually installed in a small lower-level engine room, if a centralized monitoring method is adopted, the monitoring of the pipeline thermocouple measuring points requires connecting more cables, which complicates the installation of the monitoring instrument. Summary of the invention

[0005] One of the purposes of the present invention is to provide a distributed seawater pipeline dissimilar metal galvanic insulation monitoring system, which has a small-volume monitoring unit that can be installed near the dissimilar metal galvanic couple of the pipeline, access the dissimilar metal galvanic detection point with a very short wire, and connect in series in a simple way, which greatly simplifies the installation and reduces the connection cables. Each monitoring unit installed near the bottom cabin pipeline is connected to the cabin monitoring station through cable interconnection, and the monitoring data is collected in the cabin monitoring station, so that the insulation status of the dissimilar metal galvanic couple of the seawater pipeline can be conveniently monitored online.

[0006] In order to achieve the above-mentioned purpose, the present invention proposes a distributed seawater pipeline dissimilar metal galvanic insulation monitoring system, which is connected to a plurality of dissimilar metal galvanic structures to be monitored, wherein each dissimilar metal galvanic structure includes a first metal element, a second metal element connected to the first metal element, and an insulator arranged between the first metal element and the second metal element, wherein the first metal element and the second metal element are made of different metals respectively; wherein the monitoring system includes:

[0007] A plurality of monitoring units are respectively connected to a plurality of heterogeneous metal couple structures to be monitored, and the monitoring units are connected in series with each other;

[0008] A cabin monitoring station which is data-connected to the monitoring unit closest to it;

[0009] Each monitoring unit includes:

[0010] A power supply module, which provides a DC power supply to the monitoring unit;

[0011] Main control and data storage module;

[0012] A voltage detection and statistics module, which, based on the control of the main control and data storage modules, measures the DC voltage at both ends of the corresponding dissimilar metal galvanic structure in an initial state where no insulation failure occurs, and calculates the average equivalent potential of the dissimilar metal galvanic structure based on the DC voltage measured over a period of time; the voltage detection and statistics module also monitors the actual DC voltage at both ends of the corresponding dissimilar metal galvanic structure in real time;

[0013] The isolated communication control module is based on the control of the main control and data storage module to communicate with other monitoring units and / or cabin monitoring stations.

[0014] Furthermore, in the distributed seawater pipeline dissimilar metal galvanic insulation monitoring system described in the present invention, each monitoring unit also includes a characteristic detection module, which includes a controlled resistance network. The characteristic detection module, based on the control of the main control and data storage module, connects a series of resistors with different resistance values ​​to the corresponding dissimilar metal galvanic structure to be monitored to determine the average equivalent internal resistance of the dissimilar metal galvanic structure to be monitored (more precisely, determine the insulator of the dissimilar metal galvanic structure).

[0015] Furthermore, in the distributed seawater pipeline dissimilar metal galvanic insulation monitoring system described in the present invention, each monitoring unit also includes an AC impedance measurement module, which, based on the control of the main control and data storage module, applies an AC excitation signal to the corresponding dissimilar metal galvanic structure to be monitored to measure its AC impedance (more precisely, measures the AC impedance of the insulator of the dissimilar metal galvanic structure).

[0016] Furthermore, in the distributed seawater pipeline dissimilar metal couple insulation monitoring system described in the present invention, each monitoring unit is correspondingly arranged in a shell, and a rubber shock absorber is provided on the shell.

[0017] Furthermore, in the distributed seawater pipeline dissimilar metal couple insulation monitoring system of the present invention, the engine room monitoring station comprises:

[0018] A main control module having a data storage unit;

[0019] A display screen connected to the main control module;

[0020] A communication control module, which communicates with the monitoring unit;

[0021] The AC / DC power conversion module converts the input AC power into DC power to power the main control module, display screen, and communication control module, and outputs DC power to the power supply module of the monitoring unit.

[0022] Another object of the present invention is to provide a monitoring method based on a distributed seawater pipeline dissimilar metal couple insulation monitoring system.

[0023] Based on the above purpose, the present invention provides a monitoring method based on the above-mentioned distributed seawater pipeline dissimilar metal galvanic insulation monitoring system, wherein when the interval between each dissimilar metal galvanic structure to be monitored is greater than or equal to a set distance threshold, and when the seawater pipeline is full of seawater, the monitoring method comprises the steps of:

[0024] Calculate the average equivalent potential E of each dissimilar metal couple structure pj ;

[0025] Real-time monitoring of the actual DC voltage across the two ends of each dissimilar metal couple structure;

[0026] Based on the actual DC voltage U jc The average equivalent potential E pj The comparison result outputs an alarm signal.

[0027] Further, in some embodiments of the monitoring method of the present invention, based on the actual DC voltage U jc The average equivalent potential E pj The comparison result of outputting an alarm signal specifically includes the following steps: jc <E pj / 2, output alarm signal.

[0028] Furthermore, in the monitoring method of the present invention, when the intervals between the dissimilar metal couple structures to be monitored are less than a set distance threshold, and when the seawater pipeline is full of seawater, the monitoring method further comprises the steps of:

[0029] Construct the insulation fault voltage feature set U of each adjacent dissimilar metal couple structure to be monitored gi = {U i1 , U i2 , U i3 ...U im}, where m represents the serial number of the adjacent dissimilar metal couple structure to be tested, i represents the simulated insulation fault number, i = 1, 2, 3...n;

[0030] Construct the insulation fault voltage change rate feature set ΔU of each adjacent dissimilar metal couple structure to be monitored gi / Δt={ΔU i1 / Δt、ΔU i2 / Δt、ΔU i3 / Δt……ΔU im / Δt}, where ΔU i1 , ΔU i2 , ΔU i3 ……ΔU i4m Indicates the voltage change of each insulation fault in the sampling time interval Δt;

[0031] During actual monitoring, the insulation fault voltage and insulation fault voltage change rate of each adjacent dissimilar metal couple structure to be monitored are monitored in real time, and compared with the insulation fault voltage feature set and the insulation fault voltage change rate feature set, and the insulation fault is located based on the comparison result.

[0032] Furthermore, in the monitoring method of the present invention, an insulation fault voltage feature set U of each adjacent heterogeneous metal couple structure to be monitored is constructed. gi = {U i1 , U i2 , U i3 ...U im}Specific steps include:

[0033] Calculate the average equivalent internal resistance r of each adjacent dissimilar metal couple structure to be monitored 0pj1 、r 0pj2 、r 0pj3 ……r 0pjm ;

[0034] Set the analog resistance r 01 <r 0pj1 、r 02 <r 0pj2 、r 03 <r 0pj3 ……r 0m <r 0pjm In the initial state where no insulation failure occurs in the heterogeneous metal couple structure, the simulated resistance r 01、r 02 、r 03 ……r 0m Connect the corresponding dissimilar metal couple structures to be monitored to simulate the insulation damage failure state;

[0035] Under the simulated insulation damage failure state, measure and record each insulation fault voltage U i1 , U i2 , U i3 , U im , to obtain the insulation fault voltage characteristic set U gi = {U i1 , U i2 , U i3 ...U im}.

[0036] Furthermore, in the monitoring method of the present invention, when there is no seawater or the seawater pipeline is not filled with seawater, the monitoring method comprises the steps of:

[0037] Applying an AC excitation signal to each dissimilar metal couple structure to be monitored to measure its AC impedance;

[0038] The measured AC impedance is compared with the set insulation fault resistance threshold to determine whether an insulation fault has occurred.

[0039] The distributed seawater pipeline dissimilar metal couple insulation monitoring system and method of the present invention have the following advantages and beneficial effects:

[0040] The monitoring unit in the distributed seawater pipeline dissimilar metal couple insulation monitoring system of the present invention is small in size and can be easily installed near the dissimilar metal couple of the seawater pipeline, thereby facilitating monitoring.

[0041] The monitoring unit of the distributed seawater pipeline dissimilar metal galvanic insulation monitoring system of the present invention is connected to the dissimilar metal galvanic detection point with a very short wire and connected in series in a simple manner, which greatly simplifies the installation and reduces the connection cables.

[0042] The distributed seawater pipeline dissimilar metal galvanic insulation monitoring system of the present invention connects the monitoring data obtained by each monitoring unit to the engine room monitoring station through cable interconnection, thereby enabling convenient online monitoring of the dissimilar metal galvanic insulation status of the seawater pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The structure of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown in one embodiment.

[0044] Figure 2The distributed structure of the monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown in one embodiment.

[0045] Figure 3 The three-dimensional structural diagram of the monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown.

[0046] Figure 4 The front structural diagram of a monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown.

[0047] Figure 5 A module architecture diagram of a monitoring unit of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to an embodiment of the present invention is shown.

[0048] Figure 6 A module architecture diagram of a cabin monitoring station of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is shown.

[0049] Figure 7 The equivalent circuit diagram of the dissimilar metal couple structure in a seawater pipeline filled with seawater is shown.

[0050] Figure 8 The equivalent circuit diagram of the dissimilar metal couple structure in the seawater pipeline is shown when it is not filled with seawater.

[0051] Fig. 9 A schematic diagram of the circuit structure of an AC impedance measurement module of a monitoring unit of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0052] The distributed seawater pipeline dissimilar metal couple insulation monitoring system and method of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments of the specification, but this description does not constitute an improper limitation on the technical solution of the present invention.

[0053] The present invention proposes a distributed seawater pipeline dissimilar metal galvanic insulation monitoring system and method, which is used to monitor the insulation fault of the dissimilar metal galvanic structure on the seawater pipeline. The dissimilar metal galvanic structure includes a first metal element, a second metal element connected to the first metal element, and an insulator arranged between the first metal element and the second metal element, wherein the first metal element and the second metal element are made of different metals.

[0054] Figure 1The structure of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown in one embodiment.

[0055] like Figure 1 As shown, in some embodiments, the monitoring system includes: a plurality of monitoring units, such as Figure 1 The four monitoring units shown are respectively connected to four heterogeneous metal couple structures to be monitored, and the monitoring units are connected in series with each other via cables; the cabin monitoring station is connected to the adjacent monitoring units via cable data.

[0056] Figure 2 The distributed structure of the monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown in one embodiment.

[0057] For example, Figure 2 As shown, in a specific example, each monitoring unit installed near the bottom cabin pipeline is interconnected through a 4-core cable (including CAN communication line and 24V power line) through a plug port, and then connected to the cabin monitoring station to collect monitoring data at the monitoring station. A single cable can be conveniently fixed and hidden under the bottom rib of the cabin.

[0058] Each monitoring unit is designed as a dual-channel small-volume unit so that it can be connected to the dissimilar metal couple monitoring points on both sides of common seawater pipeline equipment such as filters and valves. Figure 3 The three-dimensional structural diagram of the monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown.

[0059] Figure 4 The front structural diagram of a monitoring unit of the distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is schematically shown.

[0060] like Figure 3 and Figure 4 As shown, in some embodiments, each monitoring unit is correspondingly arranged in its own housing. The housing includes a mounting plate 11 and a box body 12 which are separately arranged and connected to each other, and a plug port 14 for connecting cables is provided at the bottom of the box body 12. The housing can be made of 316 stainless steel, and sealing strips are used between the mounting plate 11 and the box body 12, and between the plug port 14 and the box body 12 for watertight treatment. A rubber shock absorber is also installed on the box body 12 for shock absorption.

[0061] When in use, the mounting plate 11 can be bonded to the hull steel plate near the monitoring point with epoxy resin, for example, no more than 0.5 meters away from the dissimilar metal couple structure to be measured, so that it can access the measurement signal with a very short cable.

[0062] Figure 5 A module architecture diagram of a monitoring unit of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to an embodiment of the present invention is shown.

[0063] In this embodiment, the monitoring unit includes: a power supply module (i.e. Figure 5 The DC / DC isolation DC conversion module is connected to one of the four plug ports, the isolation communication control module is connected to another of the four plug ports, and the channel switching module is connected to two plug ports.

[0064] The function of the DC / DC isolated DC conversion module is to convert the 24V DC power supply connected by the cable from the cabin monitoring station into the 5V, 3.3V, and ±5V DC power supplies required by the monitoring unit.

[0065] The function of the AC impedance measurement module is to apply an AC excitation signal to the corresponding dissimilar metal couple structure to be monitored to measure its AC impedance based on the control of the main control and data storage modules when there is no seawater in the "dry state" and "semi-dry and wet state" in the seawater pipeline.

[0066] The function of the voltage detection and statistics module is to measure the voltage at both ends of the heterogeneous metal couple structure and calculate the average value based on the control of the main control and data storage modules. That is, first, for the corresponding heterogeneous metal couple structure, the DC voltage at both ends is measured in the initial state where no insulation failure occurs, and the average equivalent potential of the heterogeneous metal couple structure is calculated based on the DC voltage measured over a period of time. During actual monitoring, the actual DC voltage at both ends of the corresponding heterogeneous metal couple structure is monitored in real time.

[0067] The characteristic detection module includes a controlled resistor network, whose function is to connect a series of resistors with different resistance values ​​to the corresponding dissimilar metal couple structure to be monitored based on the control of the main control and data storage module, so as to determine the average equivalent internal resistance of the dissimilar metal couple structure to be monitored.

[0068] The function of the isolation communication control module is to communicate with other monitoring units or cabin monitoring stations via the CAN bus based on the control of the main control and data storage modules.

[0069] The main control and data storage module is the core of the monitoring unit. It controls and completes various functions of the monitoring unit and stores monitoring data within a certain period of time.

[0070] The function of the mode switching control module is to switch the AC impedance measurement, DC voltage measurement, average equivalent potential calculation, and average equivalent internal resistance calculation based on the control of the main control and data storage modules.

[0071] The function of the channel switching module connecting two connectors is to switch the access of two input signals.

[0072] Figure 6 A module architecture diagram of a cabin monitoring station of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to the present invention is shown.

[0073] like Figure 6 As shown, in some embodiments, the cabin monitoring station includes: a main control module; a display touch screen, which is connected to the main control module; a communication control module, which communicates with the monitoring unit; an AC / DC power conversion module, which converts the input alternating current into direct current to power the main control module, the display screen, and the communication control module, and also outputs direct current to the power supply module of the monitoring unit.

[0074] The data from each monitoring unit is transmitted to the main control module, which has a data storage unit that can summarize and store the initial performance data and real-time monitoring data of all heterogeneous metal couple structures uploaded by the monitoring units, and has adjacent heterogeneous metal couple structure grouping data and insulation fault feature collection data, and has the function of storing operation display alarm data. The cabin monitoring station can work in "data display and storage" mode and "alarm" mode.

[0075] Among them, in the "data display and storage" mode: when the various heterogeneous metal couple structures of the seawater pipeline are in normal condition, the cabin monitoring station will display and store the monitoring data transmitted by each monitoring unit.

[0076] In the "alarm" mode: when the monitoring data of one or more dissimilar metal galvanic structures indicate that they have insulation failure and are in the "alarm" state, the cabin monitoring station will classify the names and numbers of the dissimilar metal galvanic structures in the "alarm" state, list them in the "alarm column", and start the alarm. If there is a fault in an adjacent dissimilar metal galvanic structure, it can also be compared with the stored fault feature set of the corresponding group number to confirm the location number of the dissimilar metal galvanic structure with insulation failure, list it in the "alarm column" and alarm.

[0077] In some embodiments, the present invention further provides a monitoring method based on the above-mentioned distributed seawater pipeline dissimilar metal couple insulation monitoring system, and the monitoring method includes multiple modes:

[0078] Wherein, when the intervals between the dissimilar metal couple structures to be monitored are greater than or equal to a set distance threshold (e.g., 2 m), and when the seawater pipeline is full of seawater, the monitoring method may include the steps of:

[0079] Calculate the average equivalent potential E of each dissimilar metal couple structure pj ;

[0080] Real-time monitoring of the actual DC voltage across the two ends of each dissimilar metal couple structure;

[0081] Based on the actual DC voltage U jc The average equivalent potential E pj The comparison result outputs an alarm signal.

[0082] This implementation method is to regard the dissimilar metal couple structure of the seawater pipeline filled with seawater as an equivalent voltage source, and in the initial state where the electrical insulation components of the dissimilar metal couple structure are intact (assuming that the insulation resistance R i →∞), the main control and data storage module can control the voltage detection and statistics module to measure the voltage at both ends of the heterogeneous metal couple structure, and then perform statistical average calculation on the measured values ​​obtained within a period of time (for example, within 24 hours), and the average equivalent potential E of the heterogeneous metal couple structure can be obtained. pj .

[0083] In addition, the main control and data storage module can also control the characteristic detection module to convert a series of resistors with different resistance values ​​r i (i=1, 2, 3…9, 10) are connected to both ends of the heterogeneous metal couple structure. At the same time, the main control module also controls the voltage detection and statistics module to measure the voltage u at both ends of the heterogeneous metal couple structure. i (i=1, 2, 3…9, 10), calculate the equivalent internal resistance r corresponding to each measurement 0i =r i ((E pj / u i )-1), then calculate r 0i The arithmetic mean of (i = 1, 2, 3 ... 9, 10) is obtained, and the average equivalent power supply internal resistance r is obtained. 0pj The basic characteristics of the dissimilar metal couple structure to be tested can be stored in the main control and data storage module.

[0084] Figure 7 An equivalent circuit diagram showing a dissimilar metal couple structure filled with seawater in a seawater pipeline.

[0085] Assume that the average potential of the equivalent power source of the dissimilar metal couple structure is E pj , the average equivalent internal resistance is r 0pjThe insulation resistance of the insulator installed between the dissimilar metal couple structures is R i , at this time, the corrosion current I fs =E pj / (r 0pj +R i ) cannot be measured directly. Figure 7 The equivalent circuit shown in the figure shows that the voltage value that can be measured at both ends of the dissimilar metal couple structure is U jc =R i (E pj / (r 0pj +R i )), when the insulation performance of the insulator is intact, R i →∞, then U jc ≈E pj ; If the insulator is in a short-circuit state, R i =0,U jc =0, the resulting short-circuit corrosion current I dl =E pj / r 0pj .

[0086] In practical applications, the insulator is damaged after long-term use and the insulation value decreases. i Down to 2r 0pj , U jc =E pj (2 / 3) = 2E pj / 3, corresponding to I fs =E pj / 3r 0pj =I dl / 3, if R i Down to r 0pj , U jc =E pj (1 / 2) = E pj / 2, corresponding to I fs =E pj / 2r 0pj =I dl / 3.

[0087] Based on this, in a preferred embodiment, attention can be paid to I fs =I dl / 2 to I fs =I dl / 3 interval, taking the laboratory test data of the galvanic couple composed of two dissimilar metal materials, 912 steel and B10 copper-nickel alloy, as an example, its I dl The corresponding annual corrosion rate is about 0.45mm / a. fs =I dl / 2 to I fs =Idl / 3, the corresponding annual corrosion rate is about 0.2mm / a to 0.1mm / a.

[0088] Therefore, the real-time monitoring voltage U jc =2E pj / 3 to U jc =E pj / 2 as the warning interval, and when U jc <E pj / 2, output alarm signal.

[0089] In the actual ship seawater pipeline system, if the distance between the different metal couple structures is far (for example, greater than or equal to 2 meters), the influence between them can be ignored, and the insulation fault monitoring and judgment can be carried out according to the law of the single different metal couple structure as mentioned above, for example, by monitoring the voltage U jc <E pj / 2 as the basic alarm signal.

[0090] However, when the distance between the different metal couple structures is relatively close (for example, within 2 meters), the electrical performance parameters of the equivalent primary cells of the different metal couple structures are intertwined and affect each other because they are in the same pipe system and flow through the seawater medium. When the insulation of one of the couple structures is damaged, it may significantly affect other adjacent different metal couple structures, and can significantly increase or decrease the measured voltage of the different metal couple structures in the same system. If the external characteristic parameters such as voltage, internal resistance, and output current are measured and analyzed according to the law of a single different metal couple structure, it is very likely that the fault of the electrical insulation component will be misjudged.

[0091] Therefore, in another embodiment of the present invention, when the interval between the dissimilar metal couple structures to be monitored is less than a set distance threshold (e.g., 2 m), and when the seawater pipeline is full of seawater, the monitoring method may further include the steps of:

[0092] Construct the insulation fault voltage feature set U of each adjacent dissimilar metal couple structure to be monitored gi = {U i1 , U i2 , U i3 ...U im}, where m represents the serial number of the adjacent dissimilar metal couple structure to be tested, i represents the simulated insulation fault number, i = 1, 2, 3...n;

[0093] Construct the insulation fault voltage change rate feature set ΔU of each adjacent dissimilar metal couple structure to be monitored gi / Δt={ΔU i1 / Δt、ΔU i2 / Δt、ΔU i3 / Δt……ΔU im / Δt}, where ΔU i1 , ΔU i2 , ΔU i3 ……ΔU i4m Indicates the voltage change of each insulation fault in the sampling time interval Δt;

[0094] During actual monitoring, the insulation fault voltage and insulation fault voltage change rate of each adjacent dissimilar metal couple structure to be monitored are monitored in real time, and compared with the insulation fault voltage feature set and the insulation fault voltage change rate feature set, and the insulation fault is located based on the comparison result.

[0095] Among them, the insulation fault voltage feature set U of each adjacent heterogeneous metal couple structure to be monitored is constructed. gi = {U i1 , U i2 , U i3 ...U im}Specific steps include:

[0096] Calculate the average equivalent internal resistance r of each adjacent dissimilar metal couple structure to be monitored 0pj1 、r 0pj2 、r 0pj3 ……r 0pjm ;

[0097] Set the analog resistance r 01 <r 0pj1 、r 02 <r 0pj2 、r 03 <r 0pj3 ……r 0m <r 0pjm In the initial state where no insulation failure occurs in the heterogeneous metal couple structure, the simulated resistance r 01 、r 02 、r 03 ……r 0m Connect the corresponding dissimilar metal couple structures to be monitored to simulate the insulation damage failure state;

[0098] Under the simulated insulation damage failure state, measure and record each insulation fault voltage U i1 , U i2 , U i3 , U im , to obtain the insulation fault voltage characteristic set U gi = {U i1 , U i2 , U i3 ...U im}.

[0099] by Figure 1 Taking the layout shown in the figure as an example, if the four dissimilar metal couple structures are numbered D1, D2, D3, and D4 from left to right, the cabin monitoring station controls the first and second monitoring units to perform coordinated detection. First, the main control and data storage module controls the characteristic detection module to calculate the average equivalent internal resistance of the equivalent voltage source of the four dissimilar metal couple structures, respectively. 0pj1 、r 0pj2 、r 0pj3 、r 0pj4 , the voltage detection statistics module can measure the voltage values ​​of U1, U2, U3, and U4. Set r 01 <r 0pj1 、r 02 <r 0pj2 、r 03 <r 0pj3 、r 04 <r 0pj4 In the initial state where the insulators of the heterogeneous metal couple structures are intact, the main control and data storage module control characteristic detection module respectively sets r 01 、r 02 、r 03 、r 04 Connect D1, D2, D3, and D4 to simulate the insulation failure of the heterogeneous metal couple structure. Measure and record each stable fault voltage U during the process. i1 , U i2 , U i3 , U i4 (i=1, 2, 3…n, n is the number of simulated fault sorting), thus obtaining a set of voltage characteristics that can be identified when each fault occurs: U gi = {U i1 , U i2 , U i3 , U i4}.

[0100] At the same time, the change of each fault voltage ΔU in a certain detection sampling time interval Δt is measured and recorded during the process. i1 , ΔU i2 , ΔU i3 , ΔU i4 , and calculate its rate of change ΔU i1 / Δt、ΔU i2 / Δt、ΔU i3 / Δt、ΔU i4 / Δt, the voltage change rate feature set for fault identification can be obtained through the change amount, polarity and change rate of the fault voltage:

[0101] ΔU gi / Δt={ΔU i1 / Δt、ΔUi2 / Δt、ΔU i3 / Δt、ΔU i4 / Δt};

[0102] For the four mutually influencing heterogeneous metal couple structures D1, D2, D3, and D4, there can be a total of 15 fault combinations, i.e., i=1, 2, 3…15. By connecting the resistance through the characteristic detection module and simulating the insulation damage failure of the heterogeneous metal couple structure, the following 15 fault feature sets are obtained:

[0103] i=1, fault 1, D1 is faulty, D2, D3, and D4 are normal, and the fault feature set is:

[0104] U g1 = {U 11 , U 12 , U 13 , U 14}

[0105] ΔU g1 / Δt={ΔU 11 / Δt、ΔU 12 / Δt、ΔU 13 / Δt、ΔU 14 / Δt};

[0106] i=2, fault 2, D2 is faulty, D1, D3, and D4 are normal, and the fault feature set is:

[0107] U g2 = {U 21 , U 22 , U 23 , U 24}

[0108] ΔU g2 ={ΔU 21 / Δt、ΔU 22 / Δt、ΔU 23 / Δt、ΔU 24 / Δt};

[0109] …………;

[0110] i=15, D1, D2, D3, and D4 are all faulty, and the fault feature set is:

[0111] U g15 = {U 151 , U 152 , U 153 , U 154}

[0112] ΔU g2 ={ΔU 151 / Δt、ΔU152 / Δt、ΔU 153 / Δt、ΔU 154 / Δt};

[0113] The above fault voltage characteristic set U gi And the voltage change rate characteristic set ΔU gi / Δt and the corresponding adjacent dissimilar metal couple structure group number can be stored in the data storage unit of the cabin monitoring station.

[0114] In actual monitoring, if a fault occurs in an adjacent dissimilar metal couple structure, such as Figure 1 Fault 1 defined in the layout, i.e., D1 fault, D2, D3, and D4 are normal. The actually detected insulation fault voltage and insulation fault voltage change rate can be compared with the fault voltage feature set Ugi and voltage change rate feature set ΔUgi / Δt stored in the data storage unit to confirm the position number of the faulty electrical insulation component.

[0115] There is another situation, when the seawater pipeline is in a "dry state" without seawater or a "semi-dry state" not filled with seawater, it is impossible to monitor insulation faults using the equivalent voltage source method. At this time, due to the residual seawater electrolyte components in the dissimilar metal couple structure of the seawater pipeline, the sodium and potassium ion components in the seawater electrolyte, the moisture in the humid air, and the dissimilar metal materials at both ends form an equivalent voltage source in series in the insulation resistance loop. At this time, the equivalent circuit for measuring its insulation value R is as follows: Figure 8 shown.

[0116] Due to E dx The existence of the insulation resistance R cannot be accurately measured by using the DC measurement method. The AC measurement method must be used, that is, an AC voltage is connected to both ends a and b to offset E. dx Therefore, an AC current excitation source is connected to a and b, and then the voltage at both ends is measured to calculate the insulation resistance value R.

[0117] Based on this, in another embodiment, when there is no seawater or the seawater pipeline is not filled with seawater, the monitoring method of the present invention may further include the steps of:

[0118] The AC impedance measurement module applies an AC excitation signal to each dissimilar metal couple structure to be monitored to measure its AC impedance;

[0119] The measured AC impedance is compared with the set insulation fault resistance threshold to determine whether an insulation fault has occurred.

[0120] The insulation fault resistance threshold can be set as required, for example, 1000Ω.

[0121] In some embodiments, the AC impedance measurement module includes an MCU with built-in A / D and D / A interfaces and peripheral device circuits. For example, Fig. 9 A schematic diagram of the circuit structure of an AC impedance measurement module of a monitoring unit of a distributed seawater pipeline dissimilar metal couple insulation monitoring system according to an embodiment of the present invention is shown.

[0122] like Fig. 9 As shown, PA4 and PA5 in the circuit are the D / A output ports of the MCU, and PA1, PA2, and PA3 are the A / D sampling input ports of the MCU. The AC excitation signal with an amplitude of ±2V and a frequency of 1KHZ output by PA4 and PA5 and amplified by the filter is connected to ends a and b. The voltage drop signal of the AC current signal generated by it on the current limiting resistor is connected to the sampling input of PA1 and PA2 through the operational amplifier, and the AC voltage signal at ends a and b is sampled and input by PA1 and PA3 at the same time. The D / A output and A / D input are controlled by the same MCU, so the voltage, current, and phase in the circuit can be easily calculated, so that the AC impedance of the heterogeneous metal couple structure of the seawater pipeline can be easily calculated, and it can be used as its insulation resistance R in the "dry state" and "semi-dry and wet state" to compare with the insulation fault resistance threshold.

[0123] The circuit structure is compact and simple, which is beneficial to improving the integration and reducing the size of the monitoring unit.

[0124] It should be noted that the prior art in the protection scope of the present invention is not limited to the embodiments given in the present application documents. All prior art that does not contradict the scheme of the present invention, including but not limited to prior patent documents, prior public publications, prior public uses, etc., can be included in the protection scope of the present invention.

[0125] In addition, it should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0126] It should be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with by those skilled in the art from the contents disclosed in the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A distributed seawater pipeline dissimilar metal galvanic insulation monitoring system, which is connected to a plurality of dissimilar metal galvanic structures to be monitored, wherein each dissimilar metal galvanic structure comprises a first metal element, a second metal element connected to the first metal element, and an insulator arranged between the first metal element and the second metal element, wherein the first metal element and the second metal element are made of different metals respectively; characterized in that: The monitoring system comprises: A plurality of monitoring units are respectively connected to a plurality of heterogeneous metal couple structures to be monitored, and the monitoring units are connected in series with each other; A cabin monitoring station which is data-connected to a monitoring unit adjacent to it; Each monitoring unit includes: A power supply module, which provides a DC power supply to the monitoring unit; Main control and data storage module; A voltage detection and statistics module, which, based on the control of the main control and data storage modules, measures the DC voltage at both ends of the corresponding dissimilar metal galvanic structure in an initial state where no insulation failure occurs, and calculates the average equivalent potential of the dissimilar metal galvanic structure based on the DC voltage measured over a period of time; the voltage detection and statistics module also monitors the actual DC voltage at both ends of the corresponding dissimilar metal galvanic structure in real time; The isolated communication control module is based on the control of the main control and data storage module to communicate with other monitoring units and / or cabin monitoring stations.

2. The distributed seawater pipeline dissimilar metal couple insulation monitoring system according to claim 1, characterized in that: Each monitoring unit also includes a characteristic detection module, which includes a controlled resistance network. Based on the control of the main control and data storage module, the characteristic detection module connects a series of resistors with different resistance values ​​to the corresponding dissimilar metal couple structure to be monitored to determine the average equivalent internal resistance of the dissimilar metal couple structure to be monitored.

3. The distributed seawater pipeline dissimilar metal couple insulation monitoring system according to claim 1, characterized in that: Each monitoring unit also includes an AC impedance measurement module, which applies an AC excitation signal to the corresponding dissimilar metal couple structure to be monitored based on the control of the main control and data storage module to measure its AC impedance.

4. The distributed seawater pipeline dissimilar metal couple insulation monitoring system according to claim 1, characterized in that: Each monitoring unit is correspondingly arranged in a shell, and a rubber shock absorber is arranged on the shell.

5. The distributed seawater pipeline dissimilar metal couple insulation monitoring system according to claim 1, characterized in that: The cabin monitoring station comprises: A main control module having a data storage unit; A display screen connected to the main control module; A communication control module, which communicates with the monitoring unit; The AC / DC power conversion module converts the input AC power into DC power to power the main control module, display screen, and communication control module, and outputs DC power to the power supply module of the monitoring unit.

6. A monitoring method based on the distributed seawater pipeline dissimilar metal couple insulation monitoring system as claimed in claim 1, characterized in that: When the intervals between the dissimilar metal couple structures to be monitored are greater than or equal to a set distance threshold, and when the seawater pipeline is full of seawater, the monitoring method comprises the steps of: Calculate the average equivalent potential E of each dissimilar metal couple structure pj ; Real-time monitoring of the actual DC voltage across the two ends of each dissimilar metal couple structure; Based on the actual DC voltage U jc The average equivalent potential E pj The comparison result outputs an alarm signal.

7. The monitoring method according to claim 6, characterized in that: Based on the actual DC voltage U jc The average equivalent potential E pj The comparison result of outputting an alarm signal specifically includes the following steps: jc <E pj / 2, output alarm signal.

8. The monitoring method according to claim 6, characterized in that: When the intervals between the dissimilar metal couple structures to be monitored are less than a set distance threshold, and when the seawater pipeline is full of seawater, the monitoring method further comprises the steps of: Construct the insulation fault voltage feature set U of each adjacent dissimilar metal couple structure to be monitored gi = {U i1 , U i2 , U i3 ...U im }, where m represents the serial number of the adjacent dissimilar metal couple structure to be tested, i represents the simulated insulation fault number, i = 1, 2, 3...n; Construct the insulation fault voltage change rate feature set ΔU of each adjacent dissimilar metal couple structure to be monitored gi / Δt={ΔU i1 / Δt、ΔU i2 / Δt、ΔU i3 / Δt……ΔU im / Δt}, where ΔU i1 , ΔU i2 , ΔU i3 ……ΔU i4m Indicates the voltage change of each insulation fault in the sampling time interval Δt; During actual monitoring, the insulation fault voltage and insulation fault voltage change rate of each adjacent dissimilar metal couple structure to be monitored are monitored in real time, and compared with the insulation fault voltage feature set and the insulation fault voltage change rate feature set, and the insulation fault is located based on the comparison result.

9. The monitoring method according to claim 8, characterized in that: Construct the insulation fault voltage feature set U of each adjacent dissimilar metal couple structure to be monitored gi = {U i1 , U i2 , U i3 ...U im }Specific steps include: Calculate the average equivalent internal resistance r of each adjacent dissimilar metal couple structure to be monitored 0pj1 、r 0pj2 、r 0pj3 ……r 0pjm ; Set the analog resistance r 01 <r 0pj1 、r 02 <r 0pj2 、r 03 <r 0pj3 ……r 0m <r 0pjm In the initial state where no insulation failure occurs in the heterogeneous metal couple structure, the simulated resistance r 01 、r 02 、r 03 ……r 0m Connect the corresponding dissimilar metal couple structures to be monitored to simulate the insulation damage failure state; Under the simulated insulation damage failure state, measure and record each insulation fault voltage U i1 , U i2 , U i3 , U im , to obtain the insulation fault voltage characteristic set U gi = {U i1 , U i2 , U i3 ...U im }.

10. The monitoring method according to claim 6, characterized in that: When there is no seawater or the seawater pipeline is not filled with seawater, the monitoring method comprises the steps of: Applying an AC excitation signal to each dissimilar metal couple structure to be monitored to measure its AC impedance; The measured AC impedance is compared with the set insulation fault resistance threshold to determine whether an insulation fault has occurred.

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