CN118604530B - A DC fault location method and system - Google Patents

Abstract

The invention provides a direct current fault positioning method and a system, wherein the method comprises the steps of acquiring a first voltage and current signal of a direct current circuit in real time; respectively acquiring an anode current signal and a cathode current signal of the direct current circuit, calculating the current between the anode and the cathode of the direct current circuit based on the anode current signal and the cathode current signal by utilizing a component formula, acquiring a second voltage current signal of the direct current circuit in a preset time period, sequentially connecting all the second voltage current signals in the preset time period, and performing curve fitting on the formed lines to form a fitting line; and selecting a third voltage current signal corresponding to the two random time points of the fitting line, selecting a corresponding matrix formula based on the type of the fault signal, and calculating the position of the direct current line fault based on the value of the current between the positive electrode and the negative electrode of the direct current line, the voltage matrix and the current matrix by using a distance calculation formula so as to realize rapid and accurate fault positioning.

Description

A DC fault location method and system

Technical Field

The present invention belongs to the technical field of power system fault protection, and in particular relates to a direct current fault locating method and system.

Background Art

With the advancement of power electronics technology, flexible DC systems based on voltage source converters (VSCs) have been widely used in recent years. Flexible DC grids are an attractive option for long-distance power transmission and renewable energy grid connection. However, the lack of mature DC fault protection technology is an important issue that restricts its widespread application.

In the case of a DC side fault in a flexible DC grid, the discharge of the DC side voltage stabilizing capacitor will generate severe fault transient current. Since the power electronic devices of the converter, especially the freewheeling diode, are easily damaged by excessive fault current, compared with the AC system and the traditional DC system based on the current source converter (VSC), the flexible DC grid based on the voltage source converter requires fast fault detection and protection technology to ensure the safe and reliable operation of the system.

When a permanent fault occurs in a flexible DC system, accurately estimating the fault location is of great significance for reducing system downtime, reducing maintenance costs, and accelerating system recovery. Therefore, developing a fast and accurate fault location method is of great significance for solving the DC short-circuit fault protection problem of the flexible DC system.

Summary of the invention

In order to solve the above technical problems, the present invention provides a DC fault location method and system, which are used to solve the technical problems in the prior art.

In a first aspect, the invention provides the following technical solution, a DC fault location method, the method comprising:

Acquire a first voltage and current signal of a DC line in real time, and determine whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal;

then respectively obtaining a positive current signal and a negative current signal of the DC line, and calculating the current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and judging the type of the fault signal based on the value of the current between the positive and negative poles of the DC line;

Acquire the second voltage and current signal of the DC line within a preset time period, sequentially connect all the second voltage and current signals within the preset time period, and perform curve fitting on the formed line to form a fitting line;

Selecting a third voltage and current signal corresponding to two random time points of the fitting line, and selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signal using the selected matrix formula;

The position of the DC line fault is calculated using a distance calculation formula based on the value of the current between the positive and negative poles of the DC line, the voltage matrix, and the current matrix.

Compared with the prior art, the beneficial effects of the present application are as follows: by determining the type of the fault signal based on the value of the current between the positive and negative poles of the DC line, the type of the fault signal can be distinguished; by calculating the position of the DC line fault based on the value of the current between the positive and negative poles of the DC line, the voltage matrix and the current matrix using a distance calculation formula, fast and accurate fault location can be achieved.

Furthermore, the component formula includes:

;

In the formula, Describes the current between the DC line and the ground. Describes the current between the positive and negative electrodes. and They are the positive and negative current signals of the DC line respectively.

Furthermore, the step of selecting a corresponding matrix formula based on the type of the fault signal includes:

If the type of the fault signal is the first fault type, the matrix formula is a first matrix formula, and the first matrix formula includes:

;

If the type of the fault signal is the second fault type, the matrix formula is a second matrix formula, and the second matrix formula includes:

;

in, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, , , and are the voltage and current corresponding to two random time points respectively, For The time derivative of the current at that moment, For The time derivative of the current at that moment, and Indicates the line current and line voltage near the fault point, and are two random time points, represents the differential of the line current, Represents the differential of time.

Furthermore, the voltage matrix and current matrix formed by the first matrix formula are:

, ;

The voltage matrix and current matrix formed by the second matrix formula are the same as the voltage matrix and current matrix of the first matrix formula;

in, , They are represented as voltage matrix and current matrix respectively.

Further, if the type of the fault signal is the first fault type, the distance calculation formula includes:

;

If the type of the fault signal is the second fault type, the distance calculation formula includes:

;

in, is the distance from the fault point to the detection point, Expressed as a correction factor, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance.

Further, the step of judging the type of the fault signal based on the value of the current between the positive pole and the negative pole of the DC line includes:

Determine whether the current between the positive pole and the negative pole of the DC line is less than a threshold value, if the current between the positive pole and the negative pole of the DC line is less than the threshold value, the type of the fault signal is a first fault type;

If the current between the positive pole and the negative pole of the DC line is greater than or equal to a threshold, the type of the fault signal is a second fault type.

Furthermore, after the step of if the first voltage and current signal is a fault signal, the method further includes:

Determine whether the fault signal is a high impedance fault. If the fault signal is a high impedance fault, the matrix formula is a third matrix formula, and the third matrix formula includes:

;

in, , preset time point and For order Two equal time points, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, , , and are the voltage and current corresponding to two random time points respectively, For The time derivative of the current at that moment, For The time derivative of the current at that moment, and Indicates the line current and line voltage near the fault point, and are two random time points, represents the differential of the line current, represents the time differential, is the line current at the far end of the fault point.

In a second aspect, the invention provides the following technical solution: a DC fault location system, the system comprising:

A judgment module is used to obtain a first voltage and current signal of a DC line in real time, and judge whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal;

A calculation module, configured to respectively obtain a positive current signal and a negative current signal of the DC line, calculate a current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and determine a type of the fault signal based on a value of the current between the positive and negative poles of the DC line;

A fitting module, used for acquiring the second voltage and current signal of the DC line within a preset time period, sequentially connecting all the second voltage and current signals within the preset time period, and performing curve fitting on the formed line to form a fitting line;

A matrix module, used for selecting the third voltage and current signals corresponding to two random time points of the fitting line, selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signal using the selected matrix formula;

The positioning module is used to calculate the position of the DC line fault based on the value of the current between the positive pole and the negative pole of the DC line, the voltage matrix and the current matrix by using a distance calculation formula.

In a third aspect, the invention provides the following technical solution: a computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the DC fault location method as described above when executing the computer program.

In a fourth aspect, the invention provides the following technical solution: a storage medium having a computer program stored thereon, wherein the computer program implements the DC fault locating method as described above when executed by a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a diagram showing current paths in a pole-ground (PG) fault and a pole-pole (PP) fault provided by a first embodiment of the present invention;

FIG2 is a PP fault current diagram in a distributed parameter model provided in the first embodiment of the present invention;

FIG3 is a PG fault current diagram in a distributed parameter model provided in the first embodiment of the present invention;

FIG4 is a flow chart of a DC fault locating method provided by a first embodiment of the present invention;

FIG5 is a structural block diagram of a DC fault location system provided by a second embodiment of the present invention;

FIG. 6 is a schematic diagram of the hardware structure of a computer provided in the third embodiment of the present invention.

The embodiments of the present invention will be further described below with reference to the accompanying drawings.

DETAILED DESCRIPTION

Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout are the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

Embodiment 1

In the first embodiment of the present invention, referring to FIG. 1 to FIG. 4 , a DC fault location method includes the following steps S01 to S05:

S01, acquiring a first voltage and current signal of a DC line in real time, and determining whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal;

Specifically, a monitoring device equipped with a fault detection algorithm is used to process the DC line signal in real time, and when a fault signal is identified, the voltage and current signals are stored for subsequent analysis.

S02, respectively acquiring a positive current signal and a negative current signal of the DC line, and calculating the current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and determining the type of the fault signal based on the value of the current between the positive and negative poles of the DC line;

Specifically, the component formula includes:

;

In the formula, Describes the current between the DC line and the ground. Describes the current between the positive and negative electrodes. and They are the positive and negative current signals of the DC line respectively.

Specifically, the step of judging the type of the fault signal based on the value of the current between the positive pole and the negative pole of the DC line includes:

Determine whether the current between the positive pole and the negative pole of the DC line is less than a threshold value, if the current between the positive pole and the negative pole of the DC line is less than the threshold value, the type of the fault signal is a first fault type;

If the current between the positive pole and the negative pole of the DC line is greater than or equal to a threshold, the type of the fault signal is a second fault type.

In this embodiment, the positive and negative current signals of the DC line are selected and , the 1-mode component of the DC current is calculated according to the following formula ;

;

in, Describes the current between the DC line and the ground. Describes the current between the positive and negative poles of the DC line. Close to 0, PG failure The value is larger. A (threshold), the fault is regarded as a PP fault (the first fault type), otherwise the fault is regarded as a PG fault (the second fault type).

S03, obtaining the second voltage and current signals of the DC line within a preset time period, sequentially connecting all the second voltage and current signals within the preset time period, and performing curve fitting on the formed line to form a fitting line;

In this embodiment, in order to eliminate the current ripple introduced into the line current by the discharge of the distributed capacitor of the DC line, a cubic spline curve fitting is used to eliminate the influence of the current ripple of the second voltage and current signal.

S04, selecting the third voltage and current signals corresponding to two random time points of the fitting line, and selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signals by using the selected matrix formula;

Specifically, the step of selecting a corresponding matrix formula based on the type of the fault signal includes:

If the type of the fault signal is the first fault type, the matrix formula is a first matrix formula, and the first matrix formula includes:

;

Specifically, the voltage matrix and current matrix formed by the first matrix formula are:

, ;

In this embodiment, the DC fault is located by estimating the distance from the fault point to the DC line terminal by estimating the line inductance. As shown in (a) PG fault in FIG1 , when a PG DC fault occurs in the transmission line, the DC fault is located at the end point. The PG voltage measured at can be expressed as:

;

in is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, is the short-circuit current at the fault point, is the line current near the fault point, is the line current at the far end of the fault point. When is small, we can define:

;

Therefore, the above formula can be rewritten as:

;

By measuring the fault and Time point and ,get , the matrix equation can be established as follows:

;

If we define the matrix and matrix as follows:

, ;

Specifically, if the type of the fault signal is the second fault type, the matrix formula is a second matrix formula, and the second matrix formula includes:

;

in, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, , , and are the voltage and current corresponding to two random time points respectively, For The derivative of the current with respect to time at the moment is calculated as follows for discrete signals: , For The derivative of the current with respect to time at the moment is calculated as follows for discrete signals: , represents the time difference, and Indicates the line current and line voltage near the fault point, and are two random time points, represents the differential of the line current, Represents the differential of time.

The voltage matrix and current matrix formed by the second matrix formula are:

, ;

in, , They are represented as voltage matrix and current matrix respectively.

In this embodiment, as shown in FIG1 (b) PP fault, when a PP DC fault occurs in the transmission line, due to the extreme voltage , the matrix equation can be established as follows:

;

If we define the matrix and matrix as follows:

, .

S05, calculating the position of the DC line fault by using a distance calculation formula based on the value of the current between the positive pole and the negative pole of the DC line, the voltage matrix and the current matrix.

Specifically, if the type of the fault signal is the first fault type, the distance calculation formula is the first calculation formula, and the first calculation formula includes:

;

Specifically, if the type of the fault signal is the second fault type, the distance calculation formula is the second calculation formula, and the second calculation formula includes:

;

in, is the distance from the fault point to the detection point, Expressed as a correction factor.

In this embodiment, the fault point to endpoint The distance can be calculated by the following formula:

;

It is worth noting that, since the inductance estimation term is the same as the first calculation formula, the same positioning method can be used for PP fault and PG fault.

In order to improve the ranging accuracy of the positioning method, the following method needs to be used to correct the DC line voltage and current waveforms.

For PP fault, the DC line current not affected by distributed capacitance is defined as , the DC line current affected by the distributed capacitance is In order to accurately estimate the voltage drop in the line inductance, the ripple effect caused by the distributed capacitance in the DC line current should be excluded. As shown in Figure 2 (a) before the PP fault current curve is fitted, the cubic spline curve is used to fit The reconstructed signal can be obtained As shown in Figure 2 (b) after fitting the PP fault current curve, the reconstructed signal and Therefore, the DC line current affected by the distributed capacitance can be obtained by cubic spline curve fitting. Directly obtain DC line current without the influence of distributed capacitance .

In addition, since the positioning method proposed in this patent only requires a small number of sampling points after the fault starts, it is not necessary to increase the order of the fitting function to reconstruct the entire current waveform. This patent uses the fault current signal within 20 sampling cycles after the fault starts for curve fitting.

For PG faults, incomplete discharge of distributed capacitors will not only introduce ripples in the DC line current, but also cause current waveform amplitude distortion as shown in Figure 3 (a) before PG fault current curve fitting. Therefore, it is necessary to introduce a correction factor in the first calculation formula: , the distorted signal is corrected as shown in (b) of FIG3 after the PG fault current curve is fitted, and the improved fault location method is obtained as follows:

;

In practical applications, Set to 2.8.

Specifically, after the step of if the first voltage and current signal is a fault signal, the method further includes:

Determine whether the fault signal is a high impedance fault. If the fault signal is a high impedance fault, the matrix formula is a third matrix formula, and the third matrix formula includes:

;

in, , preset time point and For order Two equal time points, is the line current at the far end of the fault point. For a sampling frequency of 10kHz, and The 5th and 12th sampling points after the fault occurs are usually used.

In this embodiment, for a high impedance fault, The term cannot be ignored, so the DC line terminal voltage can be expressed as follows:

;

if exist and If the values at the time are equal, then The high impedance fault distance can be estimated by the following matrix equation:

;

When the sampling frequency is 10 kHz, The values at the 5th sampling point and the 12th sampling point are basically the same. Therefore, if and By using the 5th and 12th sampling moments after the fault occurs respectively, the fault distance can be estimated more accurately through the above formula.

In this embodiment, in order to reduce the terminal voltage oscillation effect based on the energy exchange of LC elements caused by the current limiting inductor being directly installed on the DC line, an energy release circuit is connected in parallel to both ends of the current limiting inductor to obtain a smooth terminal voltage curve and reduce the influence of LC oscillation in the DC line on the positioning accuracy. As the distance from the fault point to the end point increases, the current ripple introduced by the distributed capacitor discharge also gradually increases. In order to eliminate the current ripple effect, using more sampling points in the cubic spline curve fitting can improve the fitting effect. In practical applications, a fault distance of 50 km requires 20 sampling points to achieve sufficient positioning accuracy.

It is worth noting that the distance from the fault point to the DC line terminal is estimated by estimating the line inductance; it is named L positioning here. Since the fault impedance is dominated by the resistance parameters, the proposed L positioning is less affected by the change of fault impedance. In addition, in DC systems where the distributed capacitance has a greater impact on the DC line, when the proposed L positioning is used to locate the end-to-end (pole-pole, PP) fault, in order to eliminate the ripple effect caused by the discharge of the distributed capacitor, the current signal should be filtered out by the least squares method and the cubic spline curve fitting method; when locating the pole-to-ground (pole-ground, PG) fault, in addition to reconstructing the current signal by cubic spline curve fitting, a correction factor should be introduced into the fault distance equation. ; In order to eliminate the terminal voltage oscillation effect caused by the current limiting inductor, a smooth terminal voltage curve is obtained by connecting an energy release circuit in parallel at both ends of the current limiting inductor. For high-resistance faults, the fault distance matrix equation is constructed by using the voltage and current signals at specific sampling points to achieve accurate positioning of high-resistance faults;

Usually, PP fault and PG fault can be To distinguish, and accordingly apply the distance-based formula to achieve fault location. For high impedance faults, when the sampling frequency is 10 kHz, the 5th and 12th sampling points should be used to construct matrix A and matrix B respectively. In practical applications, the unit inductance should be combined to achieve fault distance measurement by measuring the DC line inductance. Since this new fault location method achieves fault distance measurement by estimating the DC line inductance, it is named L location.

In summary, by sampling the DC line current and voltage waveforms at two time points, constructing matrices A and B, the DC line inductance is estimated, and fault distance measurement is achieved. In terms of data processing, the DC fault is identified through the fault detection method, and the fault type is determined by calculating the line mode component of the DC line to determine whether the DC fault type is a PP fault or a PG fault, and whether to introduce a correction factor . In terms of current waveform processing, the influence of current ripple introduced by the discharge of distributed capacitors is eliminated by fitting the cubic spline curve for the DC line current waveform. In terms of voltage waveform processing, by connecting the energy release circuit in parallel at both ends of the current limiting inductor, for PG faults, the influence of current ripple and amplitude deformation introduced by insufficient discharge of distributed capacitors is eliminated by fitting the cubic spline curve for the DC line current waveform and amplitude correction. The matrix A and matrix B are constructed using the corrected voltage and current signals, and substituted into the matrix equation for estimating the line inductance of the fault loop to achieve fast and accurate fault location.

Embodiment 2

As shown in FIG5 , a second embodiment of the present invention provides a DC fault location system, the system comprising:

The judgment module 10 is used to obtain the first voltage and current signal of the DC line in real time, and judge whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal;

A calculation module 20 is used to respectively obtain a positive current signal and a negative current signal of the DC line, and calculate the current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and determine the type of the fault signal based on the value of the current between the positive and negative poles of the DC line;

A fitting module 30, configured to obtain a second voltage and current signal of the DC line within a preset time period, sequentially connect all the second voltage and current signals within the preset time period, and perform curve fitting on the formed line to form a fitting line;

A matrix module 40, for selecting a third voltage and current signal corresponding to two random time points of the fitting line, and selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signal using the selected matrix formula;

The positioning module 50 is used to calculate the position of the DC line fault by using a distance calculation formula based on the value of the current between the positive pole and the negative pole of the DC line, the voltage matrix and the current matrix.

The DC fault location system provided in the embodiment of the present invention has the same implementation principle and technical effects as those of the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the system embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

Embodiment 3

As shown in FIG6 , in a third embodiment of the present invention, the embodiment of the present invention provides the following technical solution: a computer, comprising a memory 202, a processor 201, and a computer program stored in the memory 202 and executable on the processor 201; the processor 201 implements the DC fault location method as described above when executing the computer program.

Specifically, the processor 201 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

Among them, the memory 202 may include a large-capacity memory for data or instructions. For example, but not limitation, the memory 202 may include a hard disk drive (HDD), a floppy disk drive, a solid state drive (SSD), a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 202 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 202 may be inside or outside the data processing device. In a specific embodiment, the memory 202 is a non-volatile memory. In a specific embodiment, the memory 202 includes a read-only memory (ROM) and a random access memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically alterable ROM (EAROM) or a flash memory (FLASH), or a combination of two or more of these. Under appropriate circumstances, the RAM can be a static random access memory (SRAM) or a dynamic random access memory (DRAM), wherein the DRAM can be a fast page mode dynamic random access memory (FPMDRAM), an extended data output dynamic random access memory (EDODRAM), a synchronous dynamic random access memory (SDRAM), etc.

The memory 202 may be used to store or cache various data files that need to be processed and/or used for communication, as well as possible computer program instructions executed by the processor 201 .

The processor 201 implements the above DC fault location method by reading and executing computer program instructions stored in the memory 202 .

In some embodiments, the computer may further include a communication interface 203 and a bus 200. As shown in Fig. 6, the processor 201, the memory 202, and the communication interface 203 are connected via the bus 200 and communicate with each other.

The communication interface 203 is used to implement communication between the modules, devices, units and/or equipment in the embodiment of the present application. The communication interface 203 can also implement data communication with other components such as: external devices, image/data acquisition equipment, databases, external storage, and image/data processing workstations.

The bus 200 includes hardware, software or both, and couples the components of the computer to each other. The bus 200 includes but is not limited to at least one of the following: a data bus, an address bus, a control bus, an expansion bus, and a local bus. By way of example and not limitation, bus 200 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, bus 200 may include one or more buses. Although embodiments of the present application describe and illustrate a particular bus, the present application contemplates any suitable bus or interconnect.

Embodiment 4

In a fourth embodiment of the present invention, in combination with the above-mentioned DC fault locating method, the embodiment of the present invention provides the following technical solution: a storage medium having a computer program stored thereon, and the computer program implements the above-mentioned DC fault locating method when executed by a processor.

Those skilled in the art will appreciate that the logic and/or steps described in the flowchart as data or in other ways herein, for example, can be considered as a sequenced data table of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses.

More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or a combination thereof: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims (5)

1. A DC fault location method, characterized in that the method comprises: Acquire a first voltage and current signal of the DC line in real time, and determine whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal, then respectively obtaining a positive current signal and a negative current signal of the DC line, and calculating the current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and judging the type of the fault signal based on the value of the current between the positive and negative poles of the DC line; Acquire the second voltage and current signal of the DC line within a preset time period, sequentially connect all the second voltage and current signals within the preset time period, and perform curve fitting on the formed line to form a fitting line; Selecting a third voltage and current signal corresponding to two random time points of the fitting line, and selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signal using the selected matrix formula; Calculate the position of the DC line fault using a distance calculation formula based on the value of the current between the positive and negative poles of the DC line, the voltage matrix and the current matrix; The component formulas include: In the formula, Describes the current between the DC line and the ground. Describes the current between the positive and negative electrodes. and They are respectively the positive and negative current signals of the DC line; The step of selecting a corresponding matrix formula based on the type of the fault signal comprises: If the type of the fault signal is a first fault type, that is, an end-to-end fault, the matrix formula is a first matrix formula, and the first matrix formula includes: If the type of the fault signal is the second fault type, that is, an end-to-ground fault, the matrix formula is a second matrix formula, and the second matrix formula includes: in, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, , , and are the voltage and current corresponding to two random time points respectively, For The time derivative of the current at that moment, For The time derivative of the current at that moment, and Indicates the line current and line voltage near the fault point, and are two random time points, represents the differential of the line current, Represents the differential of time; The voltage matrix and current matrix formed by the first matrix formula are: , The voltage matrix and current matrix formed by the second matrix formula are the same as the voltage matrix and current matrix of the first matrix formula; in, , Represented as voltage matrix and current matrix respectively; If the type of the fault signal is the first fault type, the distance calculation formula includes: If the type of the fault signal is the second fault type, the distance calculation formula includes: in, is the distance from the fault point to the detection point, Expressed as a correction factor, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance; For high impedance faults, Items cannot be ignored, so , the high impedance fault distance is estimated by the following matrix equation: in, , preset time point and For order Two equal time points, is the fault resistance, is the fault distance, is the unit resistance, is the unit inductance, , , and are the voltage and current corresponding to two random time points respectively, For The time derivative of the current at that moment, For The time derivative of the current at that moment, and Indicates the line current and line voltage near the fault point, is the line current far from the fault point, and are two random time points, represents the differential of the line current, Represents the differential of time. 2. The DC fault location method according to claim 1, characterized in that the step of judging the type of the fault signal based on the value of the current between the positive pole and the negative pole of the DC line comprises: Determine whether the current between the positive pole and the negative pole of the DC line is less than a threshold value, if the current between the positive pole and the negative pole of the DC line is less than the threshold value, the type of the fault signal is a first fault type; If the current between the positive pole and the negative pole of the DC line is greater than or equal to a threshold, the type of the fault signal is a second fault type. 3. A DC fault locating system, applicable to the DC fault locating method according to claim 1, characterized in that the system comprises: A judgment module is used to obtain a first voltage and current signal of a DC line in real time, and judge whether the first voltage and current signal is a fault signal. If the first voltage and current signal is a fault signal; A calculation module, configured to respectively obtain a positive current signal and a negative current signal of the DC line, calculate a current between the positive and negative poles of the DC line based on the positive current signal and the negative current signal using a component formula, and determine a type of the fault signal based on a value of the current between the positive and negative poles of the DC line; A fitting module, used for acquiring the second voltage and current signal of the DC line within a preset time period, sequentially connecting all the second voltage and current signals within the preset time period, and performing curve fitting on the formed line to form a fitting line; A matrix module, used for selecting the third voltage and current signals corresponding to two random time points of the fitting line, selecting a corresponding matrix formula based on the type of the fault signal, and constructing a voltage matrix and a current matrix of the third voltage and current signal using the selected matrix formula; The positioning module is used to calculate the position of the DC line fault based on the value of the current between the positive pole and the negative pole of the DC line, the voltage matrix and the current matrix by using a distance calculation formula. 4. A computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the DC fault location method according to any one of claims 1 to 2 when executing the computer program. 5. A storage medium, characterized in that a computer program is stored on the storage medium, and when the computer program is executed by a processor, the DC fault location method according to any one of claims 1 to 2 is implemented.