47 results about "Sheath current" patented technology

A device for use with coaxial cable to attenuate sheath currents associated therewith. The device is adapted to be coupled to incoming and outgoing coaxial cables and includes a ferrite core configured as a first hollow cylinder mounted coaxially within a housing configured as a second hollow cylinder. A conductor within the housing has opposite ends positioned for electrical contact with the incoming and outgoing coaxial cables and an intermediate portion passing through the ferrite core longitudinally at least twice, being passed back over the outside surface of the core between passes therethrough. The elements are so dimensioned that the outside diameter of the housing is less than one inch, thereby allowing side-by-side mounting of a plurality of the devices on industry-standard, multi-port taps which have center-to-center spacings of one inch.

The present invention provides a semi-coaxial resonator and a filter device, which can restrain resonance frequency variation caused by temperature variation without Q value reduction. A resonator (3) which has a gradually reducing diameter from a base to a top part opposite with a cover (8) and is provided with a sphere at the top is provided at a bottom surface of a housing that is closed by the cover (8). An electric wave is transmitted from an input connector (4) to the resonator (3) through a coupling plate (5). The electric wave excited by the resonator (3) is output from a coupling plate (7) and an output connector (6). The linear expansion coefficients of the housing (1) and the cover (8) are larger than that of the resonator (3). A sheath current of the resonator (3) is same from bottom to top so the Q value does not reduce. Because of the sphere at the top, even when a clearance between the cover (8) and the top of the resonator (3) reduces by temperature variation, the top capacitance does not increase. Therefore the resonance frequency variation caused by temperature variation can be restrained.

The invention discloses a method for reducing the loss of sheaths in the submarine cable engineering. The method is characterized by concretely comprising the following steps that a wire core distribution model is built, a submarine cable wire core is equally divided into n sections, and each section is equivalent to a Pi model, wherein n is greater than 5 but is smaller than 15; the induced electromotive force of submarine cable sheaths is calculated according to an equivalent model; the induced current of the submarine cable sheaths is calculated according to the induced electromotive force of the submarine cable sheaths; and the type of sheath current limiting loss reduction equipment is selected according to the induced current obtained through calculation. When the method is adopted, calculation and evaluation measures and tools can be provided for the design of the sheath loss reduction scheme in future.

Disclosed is an apparatus for evaluating underground electric power cables. In order to evaluate, in real time, the conductor temperature and allowable current of an underground electric power cable, and thus, to efficiently calculate the transmission capacity of the electric power cable, the apparatus includes a cable current measuring means (3), a sheath current measuring means (4), a cable temperature measuring means (5), a cable surrounding temperature measuring means (6), and a communication means (7) for connecting all the measuring means to a main computer (9). The main computer (9) calculates, in real time, the transmission capacity of the cable, based on data received from all measuring means via the communication means. The main computer (9) informs a line operator of the calculated transmission capacity and conductor temperature, and sends an alarm to the line operator when an abnormality in the power transmission of the cable occurs.

The invention relates to a 10kV cable online distance measurement method based on sheath current traveling wave time-frequency composite analysis, and belongs to the technical field of force system relay protection. The method comprises the following steps: firstly, extracting three-phase sheath current and Isigma after phase-mode transformation of an extended Clarke matrix as fault distance measurement signals; secondly, performing frequency spectrum transformation on the fault distance measurement signal Isigma through an FFT-MUSIC algorithm, extracting each frequency component in the traveling wave signal, and calculating a fault rough measurement distance x by utilizing a frequency difference method formula; and finally, performing time domain analysis on the signal according to the fault initial position obtained by the frequency domain analysis method in combination with an improved lumped empirical mode decomposition algorithm, accurately judging the arrival time of the secondary reflection wave head of the fault line, and further realizing accurate fault distance measurement by utilizing the time difference among the fault point reflection wave, the opposite end reflectionwave and the initial wave head. The electromagnetic effect of a cable sheath is fully considered, the sheath current is used as the fault characteristic quantity, and the feasibility of online distance measurement is improved.

The invention discloses an electric power tunnel cable monitoring system with self-check and hot swap functions. The system comprises a cable sheath current monitoring unit, a tunnel environment monitoring control unit, a well cover monitoring control unit, a tunnel inlet monitoring control unit and a fire door monitoring control unit. The state monitoring and equipment control units are independently installed on a mainboard in an acquisition box respectively in an insertion mode, and hot swap is supported; and data transmission is GMS / CDMA transmission or CAN-BUSS bus transmission. At the same time, the mainboard is also provided with a humidity detection device for detecting the environment inside the acquisition box at any time and sending correlation detection data to a substation monitoring center. The system is provided with a state self-check device for performing self-check on the working state of each unit at any time so that once a fault occurs in the system or in an individual unit or in an individual detector, working personnel can clearly and rapidly position a fault position.

The invention discloses a current fault detection device of a three-phase crossover cable. The current fault detection device comprises six current sensors. Each current sensor is used for monitoringthe sheath current value of a sheath connecting line in a crossing connection grounding case, and the six current sensors are corresponding to the six sheath connecting lines in the crossing connection grounding case in a one-to-one manner. The current fault detection device also comprises a processor, which is connected to the six current sensors, and is used for determining whether the sheath fault occurs based on the comparison result of the six sheath current values and the operation current value. The invention resolves the technical problem of the prior art that whether the fault of thethree-phase cross-over cable occurs cannot be detected.

The invention relates to the high voltage power cable detection field and especially relates to a high-voltage power cable sheath current sensor broken line identification method and device. Through detecting the three-phase sheath current of a high-voltage power cable, and simultaneously detecting a load current, logic determination is performed according to the conditions of whether the sheath current is zero and whether the load current is zero so as to acquire whether a sheath current sensor on the high-voltage power cable has a broken line. The sheath current is transversely compared, a relation between the sheath current and the load current is combined to determine, and the discrimination function of a single-phase broken line, two-phase broken line and three-phase broken line is possessed so that the hidden danger of cable sheath current loop disconnection is solved. Hardware cost does not need to be increased, control logic is simple and realization is easy.

The invention discloses NB-IOT-based high-voltage cable low-power-consumption online monitoring equipment. The NB-IOT-based low-power-consumption online monitoring equipment comprises a current sensor, an AD conversion module, a main control chip, a PC terminal, an upper computer, an NB-IOT wireless communication module, a sensor group and a power management module. According to the invention, the main control chip carries out priority classification on various required data through equipment working modes, sheath current data and fault recording data are set as a first priority, and the data of the level need to be transmitted in all working modes. Data such as temperature, vibration and equipment information are set as a second priority, and the data of the level can be transmitted only in a normal working mode. In the data transmission process, through the limitation of the sizes of the data packets, the data packets with the too large data size are removed, uploading of invalid data is reduced, in different working modes, the frequency of data communication and the transmission amount of data communication can also be correspondingly changed, communication power consumption is reduced, and normal operation of equipment is also guaranteed.

The invention discloses a cable sheath defect identification method, device and equipment and a readable storage medium. The method comprises the steps of obtaining a circuit diagram of a to-be-identified cable cross interconnection structure; determining an equivalent impedance parameter equation matched with the circuit diagram of the cable cross interconnection structure according to a preset circuit parameter mapping table; obtaining a resistance value of each grounding resistor of the cable cross interconnection structure, a main insulation admittance value of each phase, an operation current value and a sheath current value; according to the equivalent impedance parameter equation, the resistance value of each grounding resistor, the main insulation admittance value of each phase, the operation current value and the sheath current value, calculating an equivalent impedance value of the cable cross interconnection structure; and determining the defect condition of a metal sheath according to the equivalent impedance value. According to the invention, the equivalent impedance of the metal sheath is calculated by measuring the operation current value and the sheath current value, so that whether the metal sheath of the cable has defects or not is judged, and the sheath defect problem is quickly identified.

The invention discloses a high-voltage cable fault on-line monitoring method for constructing a novel criterion based on sheath current. The method comprises the following steps of measuring the amplitude and phase of grounding current of a metal sheath in a direct grounding box at the head and tail ends of a crossed and interconnected main section of a cable, and constructing a new characteristic quantity according to the ratio of the amplitude and phase of the grounding current at the head and tail ends of the same metal sheath loop and the absolute value of the phase difference of the grounding current at the head and tail ends of different metal sheath loops, establishing a characteristic quantity matrix corresponding to a fault criterion according to multi-dimensional characteristic fusion, and adjusting corresponding parameters in the characteristic quantity matrix by using historical data of various faults of a certain high-voltage cable so as to provide a set of fault diagnosis and positioning standards suitable for the high-voltage cable.

The invention discloses a protective layer grounding fault detection method, a positioning method, a detection system and a positioning system. The protective layer grounding fault detection method method comprises the following steps: acquiring a reference current waveform; acquiring a head end current waveform and a tail end current waveform of each section; taking the reference current wave as a zero phase, and based on the head-end current waveform and the tail-end current waveform, obtaining a first phase difference between the head-end sheath current and the reference current and a second phase difference between the tail-end sheath current and the reference current; adopting a fast Fourier transform method to obtain a current vector of a head-end protective layer and a current vector of a tail-end protective layer; and performing difference calculation on the current vector of the head-end protective layer and the current vector of the tail-end protective layer, and if the difference is greater than a preset threshold value, judging that the section has defects. The method has the beneficial effects that the fault can be identified at the first time when the protective layer fault occurs, and the fault position can be accurately positioned; the circulating current monitoring method is mature, the troubleshooting time of the sheath of the high-voltage transmission cable is effectively shortened, and the safety and stability of line operation are improved.

The invention discloses an automatic defect identification method and device for a high-voltage cable grounding system. The method comprises the following steps: collecting current construction sample data of a plurality of cable line sheaths; dividing the sample data into a training set and a test set; training the constructed automatic defect identification model of the high-voltage cable grounding system by adopting the training set; inputting a test sample in a test set into the trained model, comparing a state number output by the model with an actual state number of the test sample, and judging the performance of the defect automatic identification model; acquiring the sheath current of the cable line to be detected; and inputting the sheath current of the cable line to be detected into the trained defect automatic identification model to obtain a state number identification result corresponding to the sheath current of the cable line to be detected. The technical problems that the defect identification and diagnosis process of an existing high-voltage cable grounding system highly depends on experience of inspection personnel, and automatic identification of the defects of the cable grounding system is not achieved are solved.

The invention discloses a single-core power cable fault positioning structure based on a double-ended power system and ring current measurement and a fault positioning method thereof. For cables in mutual connection between two transformer substations, a sheath current is measured by means of cross-connected sheath grounding. Ring current data, obtained by collection, of a sheath current transformer are compared with a cable core fault current measured at a fault phase, so that a fault position is determined and located. According to the invention, the disclosed fault positioning method is simple and is easy to implement; the needed measuring device is simple and the computing load is small; and rapid positioning is realized. The single-core power cable fault positioning structure and thefault positioning method have the actual guidance significance in main insulation fault positioning of a power cable.

The invention belongs to the technical field of cable monitoring, and discloses a cable fault and operation state comprehensive monitoring method and system, and the method comprises the steps: collecting the amplitude and phase information of a metal sheath current at different frequencies, carrying out the calculation of a cable fault point, and analyzing whether a cable has a fault or not; according to the judged fault, carrying out fault type judgment, and carrying out cable fault positioning; and sending the acquired cable fault point data, the fault type and the fault positioning point information to a background. The invention provides a method for judging the fault type of a cable by monitoring the current information of a metal sheath of the cable, and overcomes the defect that the conventional current monitoring device for the metal sheath of the cable only measures the current and cannot judge the fault information of the cable. The invention provides a method for positioning a cable fault point by monitoring current information of a metal sheath of a cable, and overcomes the defects that the conventional offline cable fault positioning work amount is large and the operation is complicated.

The invention discloses an XLPE cable sheath current on-line monitoring and fault diagnosis system which is composed of a current sensor and an on-line monitoring device. The current sensor is installed on a grounding wire of a cable cross interconnection box to be detected, the current sensor is connected with the online monitoring device through a high-shielding coaxial cable, and the online monitoring device can upload a monitoring result to an upper system platform in a network port or optical port mode. Different on-line monitoring devices can run from a looped network, and the device has an edge calculation function, is internally provided with a fault diagnosis algorithm, and can realize information processing, fault diagnosis, alarm and the like on site. According to the method, whether the insulation of the XLPE cable in operation is broken down or not can be accurately and effectively judged, the cable sheath current is used as a characteristic signal, signal characteristic extraction and fault identification are carried out, and a corresponding criterion is given to represent the insulation performance of the power cable.

The invention discloses a power loss calculation method for a power cable sheath. An equivalent admittance matrix of a cable is derived according to basic parameters of the cable and the structure of the cable; the current of a cable sending end is calculated and determined according to the equivalent admittance matrix of the cable and boundary conditions of a cable system; the sheath current of each point of each section along the cable is determined according to the current of the cable sending end, and therefore the loss of the cable sheath is determined. Compared with the prior art, the power loss calculation method is short in consumed time and high in precision, the precise distribution condition of voltage and current along the cable can be calculated, the sheath loss of each section of the cable is determined, and a theoretical basis is provided for subsequent cable loss reducing strategies.

The invention relates to a method for calculating the sheath current of a single-core cable, aiming at accurately calculating the sheath current of the single-core cable and providing guidance for reasonably configuring the sheath current and reactive power for laying and transformation of the cable. The method comprises the following steps: (1) determining the radius a of a cable core, the outerradius b of an insulating layer, the relative dielectric constant Epsilon, the relative permeability [mu]0 of the insulating layer, the resistance Rt of a cable sheath and the conductivity gamma of the insulating layer according to cable parameters; (2) determining a cable length l, a power supply voltage level Us, a power supply frequency f, a power supply voltage level Us and a cable grounding end grounding resistor Rd according to cable operation conditions; 3, calculating capacitive current IC of the single-core cable sheath; (4) calculating the inductive current IL of the single-core cable sheath; 5, calculating the resistive current of the single-core cable sheath; 6, calculating single-core cable sheath current through the following formula I: I =-j (IC+IL)+IR.

The invention relates to a high-voltage line fault detection technology, in particular to a high-voltage cable protector fault on-line detection method based on a sheath current angle difference, which comprises the following steps: establishing a three-phase nine-section crossed and interconnected high-voltage cable equivalent model; current sensors installed at the head end and the tail end of the crossed interconnection cable line are used for measuring sheath current; establishing a transfer function of fault impedance and sheath current difference of the sheath protector; and performing fault diagnosis on the sheath protector by taking the current difference phase angle as a characteristic quantity. And in the process of formulating the diagnosis criterion, the influence of the size of the cable core current, the working voltage fluctuation, the ground impedance, the length of a small section of cable and the fault degree of the sheath protector on the sheath current is considered. According to the detection method, the maintenance efficiency and the fault diagnosis accuracy of the sheath protector at the present stage are improved.

A flexible tube (7) made of a metal bellows made of austenitic stainless steel with a high-flexibility coating applied thereto is employed as gas tubing sections (6a), (6b) connected with sealed containers (1a) to (3b). The flexible tube (7) is provided at both ends with freely rotatable flanges (7b). Using these flanges (7b), the gas tubing is connected with gas ports (8) of the sealed containers. The resistance of the stainless steel flexible tube is high in comparison with copper tubing, and the sheath current can thus be reduced. High-flexibility coating is applied to the outside of the flexible tube. Bending processing of the flexible tube is possible even after coating and weatherability is thereby improved. The support interval of the gas tubing is at least 1 m. Resonance of the gas tubing caused by the frequency of the mains power system thus cannot occur.

The invention discloses a power cable line cross interconnection box fault positioning method and device. The method comprises the following steps: judging whether a cross interconnection box has a ground fault or not and judging the fault type of the cross interconnection box according to the current amplitude change of sheaths at the head end and the tail end of a power cable line; selecting a cable line of a corresponding phase based on the fault type of the cross interconnection box, and calculating the current amplitude ratio of sheaths at the head and tail ends of the cable line of the selected phase; and performing fault positioning on the cross interconnection box based on the ratio. The positioning method is simple and direct, and is suitable for fault positioning of most power cable line cross interconnection boxes.

The invention relates to the technical field of high-voltage cable lines, in particular to a fault diagnosis and positioning method for a cross-connected high-voltage cable sheath protector. The faultdiagnosis and positioning method for the cross-connected high-voltage cable sheath protector comprises the following steps: 1, obtaining a current signal of a high-voltage cable sheath; and 2, carrying out fault diagnosis and positioning on the sheath protector according to a preset standard and a diagnosis method. According to the invention, in high-voltage cable sheath current inspection, detection current data can be effectively utilized, and faults of the sheath protector can be found and positioned in time such that subsequent replacement of the fault protector is facilitated, the safetyof the high-voltage cable sheath and insulation is effectively protected, and the safe operation of a cable line is ensured. According to the technical scheme, the difficulty of data application in protector fault diagnosis in current sheath current detection is overcome, and the problem that current sheath protector fault detection depends on manual observation and offline detection is solved.

The embodiment of the invention provides a high-voltage cable line fault positioning method and system and a readable storage medium, and the method comprises the steps: obtaining the sheath current generated at a plurality of preset sampling points in a same cable channel, and enabling the sheath current to be higher than the sheath current generated at a plurality of preset sampling points in the same cable channel, each sampling point comprises a grounding terminal and a crossed and interconnected intermediate joint; constructing a corresponding high-dimensional data matrix according to the plurality of sheath currents obtained by sampling; clustering analysis is carried out based on the mutual reachable distance between the data objects in the high-dimensional data matrix so as to ensure the overall stability of clustering to the maximum extent, and a most stable target data class is output; and finding out target feature cluster points of the two branch clusters with the minimum density level from the target data class, and carrying out fault positioning according to the time labels corresponding to the target feature cluster points. The implementation of the method can realize more accurate fault location of the high-voltage cable line.

The invention relates to a cable current-carrying capacity optimization method and device, computer equipment and a storage medium. The method comprises the following steps: processing the current current-carrying capacity by adopting a cable line system model, and obtaining the current of a cable metal sheath and the armoring current; Obtaining a current loss factor according to the current carrying capacity, the current of the cable metal sheath and the armoring current; Processing the current loss factor by adopting a cable current-carrying capacity model to obtain a current correction amount; Obtaining an absolute value of a difference value between the current correction amount and the current carrying capacity; When the absolute value is smaller than or equal to a preset value; confirming the current correction quantity as the current-carrying capacity of the cable; Therefore, the influence of the metal sheath and armoring of the submarine cable on the current-carrying capacity is fully considered; The current-carrying capacity of the submarine cable can be accurately acquired by taking the correction value as the current-carrying capacity of the submarine cable only when thecurrent correction value meets the condition, so that the current-carrying capacity of the submarine cable can be accurately acquired, and the safe and economic operation of the submarine cable can be ensured.

The embodiment of the invention provides a high-voltage cable induction parameter estimation method and system and a readable storage medium, and the method comprises the steps: obtaining a sheath current generated at a preset detection point for a long-distance high-voltage cable line composed of a plurality of three-phase nine-section crossed interconnection cable basic units, the detection points comprise direct grounding points arranged at the left end and the right end of the high-voltage cable line. According to the superposition calculation relation between the sheath current and the capacitance current generated at each section of the cable, the induction current generated in the line loop is calculated; under the condition that multiple non-ideal conditions in actual working conditions are considered, induction parameters are estimated according to the induction current, and the induction parameters comprise the self-inductance of the protection layer, the mutual inductance of the A-phase conductor to the B-phase protection layer, the mutual inductance of the A-phase conductor to the C-phase protection layer and the mutual inductance of the B-phase conductor to the C-phase protection layer.

The invention relates to a cross-interconnected high-voltage cable sheath current off-line detection time synchronization method and system, and the method comprises the steps: inputting the voltage of a high-voltage cable core, and respectively measuring the sheath current between two corresponding cross-interconnected grounding points; calculating a capacitance current component of each phase of sheath current according to the sheath circuit; and calculating a capacitance current residual error according to the capacitance current component of each phase of sheath current, calculating the optimal time offset of the capacitance current residual error, and correcting the initial detection time error according to the optimal time offset so as to complete the time synchronization of the plurality of sheath grounding current detection points. According to the method, the capacitive current component and the capacitive current residual error in each phase of sheath current are calculated through the sheath current to determine the optimal time bias, so that the sampling initial time deviation of the power supply side and the load side is corrected, the time synchronization of a plurality of sheath grounding current monitoring points is realized, the sheath current vector can be accurately extracted, and the detection accuracy is improved. And the diagnosis of the grounding fault of the crossed and interconnected high-voltage cable sheath is guided.

The invention relates to an on-line ranging method for a 10kV cable based on the time-frequency composite analysis of the traveling wave of the sheath current, and belongs to the technical field of force system relay protection. First, extract the three-phase sheath current and I ∑ As a fault location signal; secondly, through the FFT-MUSIC algorithm to the fault location signal I ∑ Spectrum transformation is carried out to extract each frequency component in the traveling wave signal, and the rough measurement distance x of the fault is calculated by using the formula of the frequency difference method; finally, the preliminary location of the fault obtained by the frequency domain analysis method combined with the improved lumped empirical mode decomposition algorithm is used to analyze the signal Carry out time-domain analysis to accurately determine the arrival time of the second reflected wave head of the fault line, and then use the time difference between the reflected wave at the fault point, the reflected wave at the opposite end, and the initial wave head to achieve accurate fault location. The invention fully considers the electromagnetic effect of the cable sheath, uses the sheath current as the fault feature quantity, and improves the feasibility of online distance measurement.

The invention provides a power taking device and method of a cable sheath grounding system. The power taking device is arranged at the grounding position of a cable sheath or the cross interconnectionposition of the cable sheath and is far away from the cable in operation, so that damage to the cable, such as compression deformation and the like, can be avoided; when the power taking device is connected to the grounding position of the cable sheath in series, the capacitor current of a cable metal sheath is acquired by the power taking device, and stable current output can be obtained; when the power taking device is connected to the cross interconnection position of the cable sheath in series, sheath capacitance currents and sheath induction currents between different phases are acquired; and due to the fact that the angle differences of the capacitance currents and the induction currents of the cable metal sheaths in different phases are all 120 degrees, sufficient electric energy output can be obtained. According to the cable sheath grounding system, the power taking device takes the sheath current, so that stable electric energy can be obtained, and the device is convenient toinstall.

The invention discloses an electric power tunnel cable monitoring system with self-check and hot swap functions. The system comprises a cable sheath current monitoring unit, a tunnel environment monitoring control unit, a well cover monitoring control unit, a tunnel inlet monitoring control unit and a fire door monitoring control unit. The state monitoring and equipment control units are independently installed on a mainboard in an acquisition box respectively in an insertion mode, and hot swap is supported; and data transmission is GMS / CDMA transmission or CAN-BUSS bus transmission. At the same time, the mainboard is also provided with a humidity detection device for detecting the environment inside the acquisition box at any time and sending correlation detection data to a substation monitoring center. The system is provided with a state self-check device for performing self-check on the working state of each unit at any time so that once a fault occurs in the system or in an individual unit or in an individual detector, working personnel can clearly and rapidly position a fault position.