A method for detecting faults in electrically active systems in a subsea entity and a system for detecting faults in electrically active systems in a subsea entity

Abstract

The disclosure relates to a method for detecting faults in electrically active systems (3) in a subsea entity (1,1'), comprising: providing at least two electrodes (2) being pared to provide at least one electric field sensor arranged in a subsea entity (1,1') for measuring electric fields (3') stemming from faults in electrically active systems (3) in the subsea entity (1,1'), providing a processing means (6) for receiving and processing data from the electric field sensors, measuring the electric fields (3') originating from the subsea entity (1, 1') with the at least one electric field sensor, and determining by the processing means (6) to what extent the electric field (3') deviating from an expected electric field baseline of the subsea entity (1, 1').

Description

[0001] A method for detecting faults in electrically active systems in a subsea entity and a system for detecting faults in electrically active systems in a subsea entity

[0002] Technical field

[0003] The present disclosure relates to a method for detecting faults in electrically active systems in a subsea entity and a system for detecting faults in electrically active systems in a subsea entity. More specifically, the disclosure relates to a method for detecting faults in electrically active systems in a subsea entity and a system for detecting faults in electrically active systems in a subsea entity as defined in the introductory parts of the independent claims.

[0004] Background art

[0005] Subsea is a harsh environment and one significant threat to asset integrity is water ingress. Water ingress can lead to corrosion, reduced structural integrity and very commonly electrical failures. Water ingress is often not detected until the asset presents a critical failure and stops functioning.

[0006] It is a reality that most frequent causes of system failure on subsea vehicles, including AUV's, ROV's or fixed installations, is water ingress into:

[0007] • Pressure vessels

[0008] • Subsea cables

[0009] • Subsea connectors

[0010] • Subsea control systems (thrusters, actuators)

[0011] When seawater ingress occurs in an electrically active subsea system, the following occurs:

[0012] 1. Seawater ingress leads to unintended conductive pathways within the connector or system / module

[0013] 2. Different voltage potentials within the system act as anodes (or cathodes), depending on potential difference a. Causing very aggressive corrosion

[0014] 3. Aggravated galvanic (dissimilar metals) corrosion will occur, as electric fields will enhance the galvanic effect, causing very rapid corrosion of less noble materials a. In particular, solder points and IC points 4. Electrical short circuits

[0015] 5. Mechanical destruction of connectors, PCB's and other exposed metal components

[0016] 6. Potential mechanical weakening of critical load bearing structures

[0017] A problem with the solutions of the prior art is that for Subsea pressure vessels the methods for detecting water ingress usually are humidity sensors, pressure sensors and resistor strips. The main problem with these sensors is that they require to be installed in every pressure vessel or even several for the same vessel. Additionally, they require control circuitry and logic to communicate the readings. For larger systems like, ROVs, AUVs these quickly become costly, complex and difficult to fully integrate for the asset owner.

[0018] However for connector and cable faults none of these methods would work.

[0019] An RCD (Residual current detector), also known as a Ground Fault Circuit Interrupter (GCFI), is the standard method for detecting electrical ground faults.

[0020] However they are not commonly used in subsea systems. The main reason for lack of use, is that "nuisance tripping" can and does occur, which either will give a warning or shut-down an otherwise functional system, often causing more harm than good. The following are some examples of how an RCD can inadvertently trip.

[0021] 1. High frequency electrical noise and transient conditions (sudden changes in a load, especially an inductive load)

[0022] 2. Power supply surges (or drops), can also cause an RCD to trip

[0023] 3. A lightning strike, near the subsea entity

[0024] 4. In subsea DC systems, imbalanced loads are common, making RCD's ineffective a. Example: Module A and module B share common 0V; however have 2 different

[0025] DC inputs e.g. 12V and 24V, or have a 24V supply from 2 different sources b. Land based (industrial and domestic) electrical supplies are installed such that shared (AC) neutral is avoided (and often illegal) i.e. loads are always balanced. However no such rules apply to DC subsea systems.

[0026] 5. Subsea modules, are sometimes powered by an internal battery, with no connection to vehicle power. In which case RCD type protection has no effect.

[0027] Another main problem with residual current devices is that they cannot discriminate between a "legitimate" power consumption and electrolysis / corrosion / degradation of the system due to water ingress. This leaves all subsea systems vulnerable to undetected water ingress.

[0028] Typically, subsea systems like AUV's do not have RCD type devices installed. As such no established strategy exists for detecting subsea faults caused by water ingress.

[0029] There is thus a need for improved method and system for an early warning system detecting faults in electrically active systems in a subsea entity, such as for example caused by water ingress in such underwater assets.

[0030] Summary

[0031] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem. According to a first aspect there is provided a method for detecting faults in electrically active systems in a subsea entity, comprising: providing at least two electrodes being paired to provide at least one electric field sensor arranged in a subsea entity for measuring electric fields stemming from faults in electrically active systems in the subsea entity, providing a processing means for receiving and processing data from the electric field sensors, measuring the electric fields originating from the subsea entity with the at least one electric field sensor, and determining by the processing means to what extent the electric field deviating from an expected electric field baseline of the subsea entity.

[0032] Processing means may typically be implemented as a processor driven controller comprising Hardware and optional Software components, data storage, power and communication modules. The processor driven controller may be either onsite, or offsite communicating either wirelessly or by wire with the electrodes.

[0033] Being able to detect faults in the electrically active modules of a subsea entity decreases fault analysis time and thereby increase up-time. There is thus provided a method saving time and resources.

[0034] According to some embodiments, the method comprises, when more than two electrodes are arranged in the subsea entity: pairing any two of the at least two electrodes to increase the number of pair combinations constituting the electric field sensors.

[0035] This hugely increases the flexibility in the analysis tool provided, and higher granularity in the pin-pointing the origin of the fault. According to some embodiments, the method comprises: providing a pairing schedule for the electrodes to increase sensitivity in segments of interest of the subsea entity, the pairing schedule being predetermined or dynamically defined.

[0036] According to some embodiments, the method comprises: determining the location of a source for the electric field deviating from the expected electric field baseline.

[0037] The advantage is that when servicing the subsea entity it is possible to find the faulty module without wasting any time.

[0038] According to some embodiments, the method comprises: determining if the deviating electric field is caused by water ingress.

[0039] Water ingress is responsible for a vast majority of faults in subsea electrically active systems.

[0040] According to some embodiments, the method comprises: determining the severity and cause of the detected deviation of the electric field based on the magnitude of the deviating electric field.

[0041] By estimating severity of fault, it will be possible to initiate remedial measures at optimal timing.

[0042] According to some embodiments, the method comprises: determining if the deviating electric field is caused by water ingress in an electric connector or cable in the electrically active system.

[0043] The electric connectors and cables are the most vulnerable parts of an electrically active subsea entity.

[0044] According to some embodiments the expected electric field baseline is composed of data measured over a predetermined time sequence where the subsea entity operates fault free.

[0045] Thus present invention may be adapted to any type of subsea entity and any operational environment.

[0046] According to some embodiments the measuring of the electric fields is performed in one or a combination of: a predetermined time schedule, at predetermined time intervals, and in a triggered time interval. According to some embodiments the subsea entity is one of a subsea vehicle, subsea infrastructure or subsea asset.

[0047] According to some embodiments, the method comprises: providing the processing means with Software algorithms, and the Software algorithms are configured for determining the severity and cause of the detected deviation of the electric field.

[0048] According to some embodiments, the method comprises: determining if the cause of the deviating electric field is one of:

[0049] - aggravated galvanic corrosion,

[0050] - electrical short circuits, and

[0051] - mechanical destruction of connectors, PCB's and other exposed metal components.

[0052] According to some embodiments, the method comprises: providing a machine learning module, and inputting the processed data from the electric field sensors to the machine learning module, and the machine learning module outputting data describing a detection and / or location of a fault in the electrically active system.

[0053] According to some embodiments, the method comprises: providing a communication module for communicating electric field data and / or other data provided by the processing means to one of a surface vehicle, or a remote server location.

[0054] According to some embodiments, the method comprises: providing the processing means with data storage means, and storing in the storage means electric field data and / or other data provided by the processing means. Storage means may be composed one of, or a combination of: memory, such as RAM, random Access Memory, and the like, and storage, such as Hard Disc Drive, HDD, Solid-State drives, SSDs, or the like.

[0055] According to some embodiments, the method comprises: arranging the electric field sensor for detection of electric fields originating from electrically active systems inside the subsea entity.

[0056] According to some embodiments, the method comprises: arranging the electrodes in the subsea entity enabling the electric field sensors to discriminate a single source for the detected deviating electric field. According to some embodiments, the method comprises: arranging N electrodes enabling up to fc i k pairing combinations constituting electric field sensors.

[0057] According to some embodiments, the method comprises: determining multiple sources for the deviating electric fields.

[0058] According to a second aspect there is provided a system for detecting faults in electrically active systems in a subsea entity, comprising: a subsea entity comprising one or more electrically active systems, at least two electrodes arranged in the subsea entity, the electrodes, when paired, constituting at least one electric field sensor for measuring electric fields stemming from faults in the electrically active systems, and processing means for processing data from the electric field sensors.

[0059] According to some embodiments, the system comprise N electrodes with up to k pairing combinations, and the electrodes are arranged to enable a spanning of one or more of the electrically active systems comprised in the subsea entity.

[0060] Effects and features of the second aspect are to a large extent analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect.

[0061] The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

[0062] Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps. Terminology

[0063] The term "electric field baseline" is to be interpreted the sum of the electric field stemming from internal, and external, electrically active components and systems when a subsea entity is in normal fault free operation mode.

[0064] The term "electrically active system" shall in present disclosure be understood as any system or component that will output a current in seawater driven by an electrical potential difference coming in contact with the sea-water. Examples of such system or component may include but is not limited to: electric connectors, cables, and passive components / systems becoming active when exposed to sea-water.

[0065] The term subsea entity shall be understood to encompass underwater assets including underwater infrastructure, remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs) or any subsea vehicle, towed equipment behind a subsea or surface vessel or vehicle as well as a fixed subsea assets, or other, used in industries operating underwater such as in oil and gas exploration, offshore power generation, fish farming, mineral exploration etc.

[0066] Brief descriptions of the drawings

[0067] The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and nonlimiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

[0068] Figure 1 shows a side view of the inside of an AUV according to an embodiment of the present disclosure.

[0069] Figure 2 shows a side view of a subsea oil / gas X-mas tree according to an embodiment of the present disclosure.

[0070] Figure 3 shows two connectors being damaged by water ingress.

[0071] Figure 4 shows a block diagram according to an embodiment of the present disclosure.

[0072] Figure 5 shows a sensor matrix of a set of electrodes ranging from 3 to 8 electrodes.

[0073] Figure 6 shows a response from an electromagnetic receiving system indicating a fault in an electrically active systems has occurred. Figure 7 FFT analysis of a clean and a faulty situation before and after a connector fault. EO - E7 is the nomenclature for channels on the fault detection system of present disclosure.

[0074] Figure 8 shows an example demonstrational setup in a cylindrical profile, eg. and AUV profile.

[0075] Figure 9 shows the example demonstrational setup of figure 8, where one pair of electrodes are used to transmit a calibration / reference signal.

[0076] Figure 10 shows an embodiment of an operational environment for an AUV deployed in the sea.

[0077] Detailed description

[0078] The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

[0079] Exploration EM (Electromagnetic) systems are well known, however they are designed to detect large scale EM anomalies that are outside the subsea vehicle. The invention described in present disclosure is designed to detect and locate localized EM anomalies caused by the subsea asset.

[0080] When these anomalies occur, electric fields local to the fault will occur. A very sensitive EF (electric field) detection system as introduced in present disclosure can detect these types of fault, and as will be shown, can also locate where the fault occurred.

[0081] Figure 1 shows the internal layout of an AUV according to an embodiment of the present disclosure, wherein 7 electrodes 2 are shown arranged in a distributed manner throughout the internal of the AUV, wherein at least one pair of electrodes embraces any of the installed electrically active systems 3 arranged in the AUV.

[0082] Figure 2 shows a further embodiment of present disclosure wherein the electrodes are installed on and around an subsea oil and gas X-mas tree, including several electrically active systems 3. Figure 4 shows a block diagram of the main components in a system according to present disclosure comprising electrodes, a processing unit, a storage, and an optional communication module.

[0083] The first aspect of this disclosure shows a method for detecting faults in electrically active systems 3 in a subsea entity 1,1', comprising: providing at least two electrodes 2 being paired to provide at least one electric field sensor arranged in a subsea entity 1,1' for measuring electric fields 3' stemming from faults in electrically active systems 3 in the subsea entity 1,1', providing a processing means 6 for receiving and processing data from the electric field sensors, measuring the electric fields 3' originating from the subsea entity 1,1' with the at least one electric field sensor, and determining by the processing means (6) to what extent the electric field 3' deviating from an expected electric field baseline of the subsea entity 1,1'.

[0084] Figure 6 shows a typical scenario wherein the electric field is measured by an electric field sensor comprised of two electrodes 2, and "Data normal" constitutes the time period prior to a fault happens, and represents expected electric field baseline. A "Connector fault" is representing the electric field measured when a fault is introduced into the electrically active system 3 monitored by the electric field sensor.

[0085] As exemplified in figure 1 and 2 the method comprises, when more than two electrodes are arranged in the subsea entity 1,1' it is an option to pair 4 any two if the at least two electrodes 2 to increase the number of pair 4 combinations constituting the electric field sensors.

[0086] An example of this is shown in the table in figure 5, where for example for 4 electrodes lined up in a subsea entity, a sensor may be made up of paired electrodes 2 number 1+2, 1+3, 1+4, 2+3, 2+4, and 3+4. It is thus possible to use these electrode combinations to localize the source for a detected electric field 3' deviating from the electric field baseline with higher precision. For example if the detected electric field is strongest in the electrode pair 2+3, and weaker and in the pair 1+2 and 3+4, the source for the fault may be determined to be between the second and third electrode.

[0087] Finding and locating a fault in an electrically active module in a subsea entity may be cumbersome, and the source for spending a lot of time and resources. This is one of the main problems that is solved by the method and system of present disclosure: determining the location of a source for the electric field 3' in a subsea entity 1. 1' deviating from the expected electric field baseline. Present disclosure further comprise providing a pairing 4 schedule for the electrodes 2 to increase sensitivity in segments of interest in the subsea entity 1,1', the pairing 4 schedule being predetermined or dynamically defined.

[0088] When dynamically configuring the pairing schedule, this may be influenced by for example one or more of, but not limited to: the detected electric fields 3', geometry of the subsea entity, impact of erroneous electrodes.

[0089] An example of a dynamically altered sensor configuration may be if a fault in an electric active module is detected, a pairing of electrodes covering different geometric plane(s) may be set up to get a more complete measuring of the electric fields. One of the main reasons for faulty electric active subsea systems / modules are water ingress. These types of faults are sometimes very difficult to diagnose and locate / isolate because:

[0090] 1. Water ingress is sometimes gradual a. Physical problems present as infrequent intermittent failures, progressing to total failure. b. A failing sub-system, can often affect other subsystems, making isolating the specific problematic subsystem difficult.

[0091] 2. When the problem is identified (as water ingress), a physical check of the complete system is often required a. Removing and inspecting every subsea connection point b. Inspecting every subsea cable.

[0092] A typical example of subsea water damage 25 is shown in figure 3. As can be seen from the image, the internal pins on this connector 30 are extensively damaged. Finding this type of fault is very difficult, as the connector 30 will visibility look undamaged while mated (connected) i.e. the connector must be unmated for proper inspection.

[0093] Water ingress when it occurs will always lead to:

[0094] • A full system fault o The problem, will typically go from gradual (system "semi-functioning"), to full system disfunction (as the ingress gets worse) • Significant downtime, is typical, in some cases the subsea vehicle needs to be disassembled to locate and inspect all connection points o Inspecting the subsea vehicle o Finding the fault o Repairing the damaged components

[0095] • Significant cost

[0096] Traditional method for detecting water ingress in subsea pressure vessels are humidity sensors, pressure sensors and resistor strips. The main problem with these sensors is that they require to be installed in every pressure vessel or even several for the same vessel. Additionally, they require control circuitry and logic to communicate the readings. For larger systems like, ROVs, AUVs these quickly become costly, complex and difficult to fully integrate for the asset owner. And more importantly, these methods would not work for connector and cable faults.

[0097] An RCD (Residual current detector), also known as a Ground Fault Circuit Interrupter (GCFI), is the standard method for detecting electrical ground faults, but these are also not commonly used in subsea systems. The main reason for lack of use, is that "nuisance tripping" can and does occur, which either will give a warning or shut-down an otherwise functional system, often causing more harm than good. Another main problem with residual current devices is that they cannot discriminate between a "legitimate" power consumption and electrolysis / corrosion / degradation of the system due to water ingress.

[0098] The method of present disclosure comprises determining if the deviating electric field 3' is caused by water ingress 25.

[0099] It is provided a system and method to detect faults on an subsea entity in sea water using measured electric potential differences between electrodes mounted on / in the subsea entity with the aim to detect electric fields originating from electrical active modules of the subsea entity. The electric field may be measured over some period of time and analyzed for such faults. The faults may appear as strong noise over the background field or have other characteristics that indicate that there are faults on the asset where the system is mounted and in use, see figure 6 and 7. The electrical sensor system can for instance be installed in an AUV, and ROV or any subsea vehicle, towed equipment behind a subsea or surface vessel or vehicle as well as a fixed subsea asset. In the analysis of the measured signals, the analysis may look at various features such as not normal strong electric field strength, electrical signals at certain frequencies or frequency bands including zero frequency, to discriminate the electrical signal part that is due to faults on the asset and the parts that is due to external or normal internal electric potential gradients. External generated electrical fields may be detected and dismissed based on that they will, unlike internally generated electric fields, most likely appear with same signal profile and strength simultaneously on several of the electric field sensors. The analysis may also use other deterministic or statistical methods such as machine learning and Al to further draw conclusions on where the fault is located, or on which part on the vehicle or asset the fault seems to be located at, and / or to what type and severity of fault is detected.

[0100] A system with more than two electrodes can enable measurements of more than one component of the electric field. By analyzing the faults appearance on all the measured electrode pairs, the pinpointing of the fault location or which part on the vehicle or asset may be improved can be determined.

[0101] Analysing the measured signal may be used to determine the severity and cause of the detected deviation of the electric field 3' based on the magnitude of the deviating electric field 3'. Typically a fault may be detected before a major breakdown is the happening, such as in the time sector 0405:00 to 04 05:15 of the measurement shown in figure 6.

[0102] The system and method according to present disclosure comprises: determining if the deviating electric field 3' is caused by water ingress 25 in an electric connector 30 or cable in the electrically active system 3.

[0103] The expected electric field baseline is composed of data measured over a predetermined time sequence where the subsea entity 1,1' operates fault free.

[0104] As disclosed in figure 8, proving feasibility, the following is an example according to present disclosure of how an EM Fault Detector is installed in a sub-sea asset (AUV, ROV, fixed installation) and detect and locate a fault in an electrically active systems.

[0105] The example shows an installation in a cylindrical profile, e.g. an AUV profile. However this example can be scaled to suit any subsea profile.

[0106] This example has 4 electrodes, with the potential of pairing 6 unique electric field sensors, increasing the electrode number will greatly increase fault location accuracy, and volume coverage, see figure 5. The following method is shown: 1. When the above system is operating correctly, a nominal background electric field is observed, se figure 6, "Data normal".

[0107] 2. If a fault in an electrically active system occurs, this fault can be observed as an amplitude in the data record, that is much greater in amplitude than the nominal background.

[0108] 3. The location of the fault can be determined by looking at the data record across each electrode pair. a. The fault will be located between the electrode pair showing the greatest amplitude.

[0109] 4. For example: a. A fault in the forward section will result in i. High detection sensitivity between electrodes 1-2 ii. Less sensitivity between electrodes 1-3 & 1-4 iii. Very little sensitivity between electrodes 2-3 & 2-4 iv. No sensitivity between electrodes 3-4 b. A fault in the middle section will result in i. High detection sensitivity between electrodes 2-3, 1-4, 1-3, & 1-4 ii. Little to no sensitivity between electrodes 1-2 & 3-4 c. A fault in the AFT section will result in i. Maximum high detection between electrodes 3-4 ii. Less sensitivity between electrodes 4-1 & 4-2 iii. Very little sensitivity between electrodes 3-2 & 3-1 iv. No sensitivity between electrodes 1-

[0110] The measuring of the electric fields 3' is set up to be performed in one, or a combination, of: a predetermined time schedule, at predetermined time intervals, and in a triggered time interval. Time interval may be varying between fractions of seconds to weeks or months, all dependent on nature of the subsea entity that is to be monitored / surveyed, available power resources, data storage capacity and processing and communication capacities.

[0111] As discussed above and defined in the terminology section: the subsea entity 1,1' is one of a subsea vehicle 1, subsea infrastructure 1' or subsea asset.

[0112] It is further suggested to provide a system and method comprising: providing the processing means with Software algorithms, wherein the Software algorithms are configured for determining the severity and cause of the detected deviation of the electric field 3'. Typically when analysing the sensor data, and also a Fast Fourier Transform, FFT, analysis of the sensor data as exemplified in figure 6 and 7, both in a normal operation situation and in a fault situation will enhance the ability to analyse and determine severity and cause.

[0113] The method comprises to determine if the cause of the deviating electric field 3' is one of, but not limited to:

[0114] - defect cables,

[0115] - aggravated galvanic corrosion,

[0116] - electrical short circuits, and

[0117] - mechanical destruction of connectors 30, PCB's and other exposed metal components.

[0118] In a further embodiment according to present disclosure, the system and method comprise providing a machine learning module, inputting the processed data from the electric field sensors to the machine learning module, and the machine learning module outputting data describing a detection and / or location of a fault in the electrically active system 3.

[0119] In one embodiment a pre-trained machine learning module having being trained, wherein historical sensor data may have been used, the pre-training process comprising inputting the processed historical data from the electric field sensors to the machine learning module for training. The machine learning module may thus be trained to output data for the detection and / or location of a water ingress situation 25 in a connector 30 and / or cable of the electrically active system 3.

[0120] Another option when using a machine learning module is to let the machine learning module be deployed un-trained. When deployed in a fault free environment the machine learning module may be fed with a fault free baseline in order to learn, in-situ, a fault free operation mode. When a fault appear in the electrically active system 3, or any anomaly being measured by the sensors, the machine learning module may react and identify that an anomaly has been detected.

[0121] It is further proposed to use data read from the electric field sensors, the processed data from the processing means 6, and the evaluated result of the degree, severity and cause, of deviation the processed data deviate from an expected electric field baseline, as learning data for further training of the machine learning module. The method further comprises to provide a communication module 8 for communicating electric field data and / or other data received and processed by the processing means to one of a surface vehicle 9, or a remote server location.

[0122] As seen in figure 10, a remote server location, mother ship 9, is on the surface able to receive data produced by the electric field sensor in the subsea entity 1. Remote server location may also be a land based, or platform based, or other subsea entity.

[0123] Data storage means 7 are provided for use by the processing means 6 with data storage means 7, for storing electric field 3' data and / or other data provided by the processing means 6. The data storage means may be arranged in the subsea entity 1, 1', but may also be located on shore, or on a mothership, or in a nearby second subsea entity 1,1'. Communication modules 8 may be implemented with the storage and the processing means 6 to facilitate data communication between the processing means and the storage means 7.

[0124] When it is decided to provide a system and method for the detection of faulty connectors and cables in a subsea entity 1, 1', it is a priority to provide and map the modules and electrical wiring of the subsea entity 1, 1'. Then arranging the electrodes 2 constituting required electric field sensors for detection of electric fields 3' originating from electrically active systems 3 inside the subsea entity 1,1'. The electrode 2 arrangement should be optimized for best possible detection of faults at known vulnerable spots in the subsea entity 1, 1'.

[0125] The goal of arranging the electrodes 2, connecting them to the controller 6 wired or wireless, in the subsea entity 1,1' is to enable the electric field sensors to discriminate a single source 3 for the detected deviating electric field 3'. As discussed above in the example installation it is not necessary to deploy one unique sensor for each electrically active component, but it is important to be able to pinpoint the source of a fault based on a combination of electric field sensors data.

[0126] It is in figure 5 stipulated arranging 3 to 8 electrodes 2 enabling up to 28 pairing 4 combinations constituting electric field sensors. The present disclosure does not limit the number of sensors to these combinations, but any number of electrodes between 2 and an imaginable large number, hundreds or thousands, may be used. The number of possible electrode combinations could be expressed as: number of pairing combinations = k where N is the number of electrodes being 2 or greater.

[0127] It is the size of the subsea entity and the number of electrically active modules and / or connectors and cables that will dictate the number of electrodes 2 necessary to achieve a result with sufficient granularity in the result data.

[0128] The better coverage of multiple electrodes and electric field sensors that is deployed in the subsea entity, the better possibility is it to determine where and to what extent is a fault present. The more sensors that is deployed also provides a system and method for improved possibility of determining if there are multiple faults happening at the same time in the subsea entity 1, 1'. Thereby, it is possible to determining multiple sources 3 for multiple deviating electric fields 3'.

[0129] The second aspect of this disclosure shows a system for detecting faults in electrically active systems 3 in a subsea entity 1,1', comprising: a subsea entity 1,1' comprising one or more electrically active systems 3, at least two electrodes 2 arranged in the subsea entity 1,1', the electrodes 2, when paired 4, constituting at least one electric field sensor for measuring electric fields 3' stemming from faults in the electrically active systems 3, the system further comprising: processing means 6 configured for receiving and processing data from the electric field sensors.

[0130] If the system comprise 2 or more electrodes 2 it is possible to provide k pairing 4 combinations, where N is the number of electrodes. Typically the electrodes will be arranged to enable a spanning of one or more of the electrically active systems 3 comprised in the subsea entity 1,1'.

[0131] As demonstrated in figure 9, showing a subsea entity having 4 electrodes 2 installed, it is possible to use the receiver electrodes for fault detection. The electrodes 2 may additionally be electronically configured to transmit a current into the sea-water and / or between electrodes in an electrode pair. This gives the additional possibility of simulating fault scenarios, and of training the system at install time, or it can be used for calibration of, or periodically recalibrating, the installed system.

[0132] In the example demonstrated in figure 9, the fault detection system transmits a calibration / reference signal between electrode pair 2 & 3. This signal, will place an electric field in seawater as indicated by the field lines highlighted with the arrows. The remaining electric pairs may cycle through each (5 remaining) possible sequence configured in receiving pairs:

[0133] - 1&4

[0134] - 1&2

[0135] - 1&3

[0136] - 2&4

[0137] - 3&4

[0138] Similarly, this concept may be implemented on any electrode 2 configuration on any subsea entity as discussed earlier in present disclosure.

[0139] Each electrode or electrode pair may act as a transmitter electrode / pair in a preconfigured sequence, and for each transmitting configuration the rest of the electrode pairs may be used to measure the electric field in the same manner as described above.

[0140] This method is useful for: training a machine learning module calibrating the system calibrate / testing for ageing electrodes detection of fa u lty- / fa u It grade of- electrodes (faulty electrodes will not transmit an electric field of expected magnitude)

[0141] The transmitted signal used in the training / calibration operations may differ significantly.

[0142] A signal transmitting regime is controlled by the controller. When using the transmitting regime for calibration purposes or supervised / unsupervised training of the machine learning module, it is sufficient that the electrical fields generated by the transmitting electrodes / electrode pairs is detectable by one or more of the receiving electrode pairs. The measured signal is compared with an expected measured signal to verify if the electrodes are capable of operating as expected. Failure to verify this may raise an error state, and may be processed by the processor 6 or transmitted to a remote server for further analysis.

[0143] But, if using the transmitting electrodes / electrode pairs for training the machine learning module to recognize location and quantify severity of fault, it is necessary for the transmitting electrodes / electrode pairs to output a simulation signal copying various signal patterns, optionally mimicking faulty signals with possible variations of severity. The machine learning module can then be supervised to learn how to detect, accurately locate, and quantify severity of a fault in the subsea entity.

[0144] The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.

Claims

AMENDED CLAIMS received by the International Bureau on 16 February 2026 (16.02.2026).

1. A method for detecting faults in electrically active systems (3) inside a subsea entity (1, 1'), the method comprising: arranging at least three electrodes (2) inside the subsea entity (1, 1'), the electrodes being pairable to form a plurality of electric field sensors configured to measure electric fields (3') generated by internal electrically active systems (3) of the subsea entity (1, 1'), providing a processing means (6) configured to receive and process electric fields originating from the internal electrically active systems (3), measuring, by the electric field sensors, and determining, by the processing means (6), whether the measured electric field (3') deviates from an expected internal electric field baseline of the subsea entity (1, 1').

2. The method according to claim 1, further comprising: determining the location of a source for the electric field (3') deviating from the expected internal electric field baseline.

3. The method according to claim 1 or 2, further comprising: determining if the deviating electric field (3') is caused by water ingress (25) based on characteristic internal electric field signatures.

4. The method according to any one of previous claims, further comprising: determining the severity and cause of the detected deviation of the electric field (3') based on the magnitude and spatial distribution of the deviating electric field (3').

5. The method according to any one of previous claims, further comprising: determining if the deviating electric field (3') is caused by water ingress (25) in an electric connector (30) or cable in the electrically active system (3).

6. The method according to any one of previous claims, wherein: expected internal electric field baseline is composed of data measured over a predetermined time sequence where the subsea entity (1, 1') operates fault free.

7. The method according to any one of previous claims, wherein: the measuring of the electric fields (3') is performed in one, or a combination, of: a predetermined time schedule, at predetermined time intervals, and in a triggered time interval.

8. The method according to any one of previous claims, wherein: the subsea entity (1, T) is one of a subsea vehicle (1), subsea infrastructure (1') or subsea asset.

9. The method according to any one of previous claims, further comprising: providing the processing means with Software algorithms, and the Software algorithms are configured for determining the severity and cause of the detected deviation of the electric field (3').

10. The method according to any one of previous claims, further comprising: determining if the cause of the deviating electric field (3') is one of: defect cables, aggravated galvanic corrosion, electrical short circuits, and mechanical destruction of connectors (30), PCB's and other exposed metal components.11.The method according to any one of previous claims, further comprising: providing a machine learning module, inputting the processed data from the electric field sensors to the machine learning module, and the machine learning module outputting data describing a detection and / or location of a fault in the electrically active system (3).12.The method according to any one of previous claims, further comprising: providing a communication module (8) for communicating electric field data and / or other data provided by the processing means to one of a surface vehicle (9), or a remote server location.13.The method according to any one of previous claims, further comprising: providing the processing means (6) with data storage means (7), and storing in the storage means (7) electric field (3') data and / or other data provided by the processing means (6).14.The method according to any one of previous claims, further comprising: arranging the electric field sensors for detection of electric fields (3') originating from electrically active systems (3) inside the subsea entity (1, I').15.The method according to any one of previous claims, further comprising: arranging the electrodes (2) in the subsea entity (1, T) enabling the electric field sensors to discriminate a single source (3) for the detected deviating electric field (3').16.The method according to any one of previous claims, further comprising: arranging N electrodes (2) enabling up to k=i k pairing (4) combinations constituting electric field sensors, wherein N is the number of electrodes (2).17.The method according to any one of previous claims, further comprising: determining multiple sources (3) for the deviating electric fields (3').

18. A system for detecting faults in electrically active systems (3) inside a subsea entity (1, 1'), comprising: a subsea entity (1, T) comprising one or more internal electrically active systems (3), at least three electrodes (2) arranged inside the subsea entity (1, T), the electrodes being pairable to form a plurality of electric field sensors configured to measure electric fields generated by the internal electrically active systems (3), when the at least electrodes (2) are paired (4), they constitute electric field sensors for measuring electric fields (3') originating from internal electrically active systems (3), and processing means (6) configured for: receiving and processing data from the electric field sensors, and determining to what extent the electric field (3') deviating from an expected internal electric field baseline of the subsea entity (1, T).

19. The system according to claim 18, wherein the system: comprise N electrodes (2) with up to Efc=i pairing (4) combinations, and the electrodes are arranged to enable a spanning of one or more of the electrically active systems (3) comprised in the subsea entity (1, I').

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