Distribution network section positioning method for matrix transformation and modal analysis of single-core cable

Abstract

The invention belongs to the technical field of relay protection of a power distribution network of a power system, and provides a distribution network section positioning method for matrix transformation and modal analysis of a single-core cable, which comprises the following steps of: 1, optimally deploying point measuring devices; step 2, obtaining a fault identification mode component; step 3, calculating the energy EMi of the voltage sigma mode, and determining an end point of the fault section by using the size of the EMi; according to the method, measuring points are reasonably distributed in combination with the spatial position of a distribution network topological structure, a topological structure measuring point distribution matrix, a current alpha modal polarity matrix and a final criterion matrix are constructed, logic complementation is achieved through information interaction between the matrixes, and then accurate positioning of a fault section is achieved while measuring point distribution is reduced and cost is saved; the final criterion matrix constructed by the method belongs to a sparse matrix with dominant diagonal elements, is small in calculation amount, low in memory storage requirement, less in time consumption and high in timeliness, and has certain engineering value.

Description

Technical Field

[0001] The invention belongs to the technical field of relay protection of power system distribution network, and in particular is a distribution network section positioning method of single-core cable matrix transformation and modal analysis. Background Art

[0002] In recent years, cable lines have been widely developed in urban distribution networks due to their advantages such as light weight, high temperature resistance, high transmission power, and small footprint, and the cableization rate has increased year by year. They are buried deep underground. As the operation time increases, they will be affected by humid environment erosion, mechanical external force damage, long-term overload operation, etc., and the internal insulation will deteriorate and produce defects, which will damage the main insulation, causing the cable core to directly contact the shielding layer and aggravate the damage to the cable outer sheath. And over time, it gradually evolves into a breakdown of the main insulation, thus forming a discharge channel that runs through the cable core of the faulty phase of the cable to the ground, and a cable core-shield single-phase grounding fault occurs.

[0003] Due to the complex topology of the distribution network, short cable length and multiple branches, the fault characteristics of a single-phase grounding fault are weak and changeable. In addition, the structure of the three-phase single-core cable is complex, there is electromagnetic coupling between the metal conductors, and the electrical parameters are asymmetric, which makes it difficult to adapt the existing decoupling method of overhead lines and three-core cables, making it difficult to accurately locate the single-phase grounding fault of the cable in the distribution network.

[0004] To this end, those skilled in the art have proposed a distribution network section positioning method based on single-core cable matrix transformation and modal analysis to solve the problems raised by the background technology. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a distribution network section positioning method of single-core cable matrix transformation and modal analysis to solve the problems in the prior art that the distribution network topology is complex, the cable length is short and there are many branches, and after a single-phase grounding fault occurs, its fault characteristics are weak and changeable. In addition, the three-phase single-core cable has a complex structure, there is electromagnetic coupling between the metal conductors, and the electrical parameters are asymmetric, which makes it difficult to adapt to the existing decoupling method of overhead lines and three-core cables, resulting in difficulties in accurately locating the single-phase grounding fault of the cable in the distribution network.

[0006] A distribution network section positioning method based on single-core cable matrix transformation and modal analysis comprises the following steps:

[0007] Step 1: Optimize the deployment of measuring point devices: Install measuring points at the beginning of each line of the trunk line. When the branch line b of the node where the terminal cable is located is greater than or equal to 2, add b-1 measuring points at the beginning of the branch line connected to the node; and number the measuring points M. i , where i = 1, 2, ..., s, s is the total number of measurement points;

[0008] Step 2, obtaining fault identification modal components: when a fault occurs in the distribution network line, the three-phase current and three-phase voltage collected at the measuring point are transformed into phase modes, and the voltage σ mode and current α mode are obtained through matrix decoupling;

[0009] Step 3: Calculate the energy E of the voltage σ mode Mi , using E M The size of i determines one end point of the fault segment;

[0010] Step 4: Combine the topological structure measurement point distribution matrix X and the current α modal polarity matrix Y to construct the final criterion matrix K nm Determine the faulty section.

[0011] Preferably, the specific process of step 2 is:

[0012] S2.1. When a distribution network line fails, the three-phase current and three-phase voltage collected at the measuring point are calculated based on the single-core cable parameters. The time when the distribution network fails is t. ph and the parallel admittance Y ph ; The formula is as follows:

[0013]

[0014] Among them, z1, z2, z3, z4 are the cable core-shield mutual impedance, shield self-impedance, and phase-to-phase mutual impedance, respectively; y1, y2, y3, y4 are the cable core self-admittance, cable core-shield mutual admittance, shield self-admittance, and phase-to-phase mutual admittance, respectively;

[0015] Calculate the energy Z ph Y ph and Y ph Z ph The transformation matrix T of similar diagonalization V and T I , using the transformation matrix T V and T I Voltage V ph and current I ph Phase mode transformation is performed to achieve decoupling of the three-phase system; the formula involved is as follows:

[0016] [V ph ]=[T V ][V M ]

[0017] [I ph ]=[T I ][I M ]

[0018] Among them, T V is the voltage transformation matrix, T Iis the current transformation matrix, V ph and I ph is the voltage and current matrix in the phase domain, V M and I M are the voltage and current matrices in the modal domain;

[0019] In the voltage matrix, six modal signals are obtained after decoupling and are recorded as: u α (t),u β (t),u γ (t),u η (t),u θ (t) and u σ (t); in the current matrix, six modal signals are obtained after decoupling and are recorded as: i α (t), i β (t), i γ (t), i η (t), i θ (t) and i σ (t), obtain the voltage σ modal u σ (t) and current α mode i α (t) is used as the modal component for fault identification.

[0020] Preferably, the specific process of step 3 is:

[0021] Assume that the time when the distribution network fails is t, and the acquisition time window is (t, t+0.03)s, a total of 3ms u σ (t) signal, where t = 1, 2, ..., n, n is the sampling point; the measurement point M in the time window i Energy E Mi The calculation formula is:

[0022]

[0023] Compare the energy values ​​of all measuring points, the maximum energy Corresponding node N max The fault section S F An endpoint of .

[0024] Preferably, the specific process of step 4 is:

[0025] 4.1. Determine an endpoint N of the faulty segment according to step 3 max Then, according to endpoint N max The topological structure of the connected lines and the distribution matrix of measuring points X:

[0026] According to the distribution of measurement points in the topological space, if the node is equipped with measurement points, it is 1, otherwise it is 0; the matrix X formula is as follows:

[0027]

[0028] Among them, N n Represents the endpoint N max Connect each node;

[0029] 4.2. Construct the current α modal polarity matrix Y:

[0030] Determine the polarity of the current α mode, define the direction from the line to the fault point as the positive direction, and the direction from the fault point to the line as the reverse direction; the polarity is recorded as 1 in the positive direction, -1 in the reverse direction, and 0 when there is no measuring point: The matrix Y formula is as follows:

[0031]

[0032] Among them, R m is the mode i of the current α at each node α (t) polarity;

[0033] 4.3. Construct the final criterion matrix K nm :Combining the topological structure measurement point distribution matrix X with the current α mode polarity matrix Y, the final criterion matrix K is obtained nm =X T Y; among them,

[0034]

[0035] When the following equation is satisfied, it is determined that the ground fault occurs in the fault section S F In, L nm Represents the segment composed of nodes n and m: where L nm :

[0036] L nm =Logical(n n r m =-n m r n )·L nm

[0037] S F =min(L nm ).

[0038] A distribution network section positioning device for single-core cable matrix transformation and modal analysis, comprising:

[0039] The data acquisition module is responsible for collecting three-phase current and three-phase voltage signals from each measuring point in the distribution network in real time;

[0040] The signal processing module pre-processes and transforms the collected three-phase current and voltage signals to achieve decoupling of the three-phase system.

[0041] Fault feature extraction module, calculates the energy E of the voltage σ mode Mi , use the energy size to preliminarily determine one end point of the fault section;

[0042] The fault criterion construction module constructs the final criterion matrix Knm according to the distribution of topological structure measurement points and the polarity of current α mode to achieve accurate positioning of the fault section;

[0043] Display and control module, which displays the fault location results and provides a user interaction interface;

[0044] Communication interface module enables communication between the device and the host computer or remote monitoring center.

[0045] A processor is configured to execute the above-mentioned distribution network section positioning method of single-core cable matrix transformation and modal analysis.

[0046] A machine-readable storage medium stores instructions, which, when executed by a processor, configure the processor to execute the distribution network section positioning method of single-core cable matrix transformation and modal analysis.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The present invention considers the multi-conductor coupling structure of a single-core cable and proposes a matrix transformation method suitable for the grounding mode of two ends of a three-phase single-core cable in a distribution network; it realizes the complete decoupling of the system, screens the fault characteristic mode, fully reflects the changes in transient characteristics before and after the fault, and lays the foundation for the accurate positioning of the fault section;

[0049] 2. The present invention reasonably distributes measuring points in combination with the spatial position of the distribution network topology structure, constructs a topology structure measuring point distribution matrix, a current α modal polarity matrix and a final criterion matrix, and uses information interaction between matrices to achieve logical complementarity, thereby reducing the distribution of measuring points and saving costs while achieving accurate positioning of the fault section; the final criterion matrix constructed by this method is a sparse matrix dominated by diagonal elements, with small computational complexity, low storage memory requirements, low time consumption, high timeliness, and certain engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A flow chart of a distribution network section positioning method of single-core cable matrix transformation and modal analysis according to the present invention;

[0051] Figure 2 The current path diagrams of each mode after phase mode transformation decoupling of the present invention; wherein, (a) is the coaxial mode; (b) is the sheath inter-mode; (c) is the grounding mode;

[0052] Figure 3Graph showing the changes of the three-phase voltage, current and decoupled current before and after the α modal fault in an embodiment of the present invention;

[0053] Figure 4 This is a diagram showing the changes of each voltage modal fault before and after decoupling in an embodiment of the present invention;

[0054] Figure 5 is a current loop diagram of a single-phase grounding fault in an embodiment of the present invention;

[0055] Figure 6 This is a topological structure diagram of a 10kV cable distribution network in an embodiment of the present invention;

[0056] Figure 7 is the current α modal polarity diagram and the final criterion matrix K in the embodiment of the present invention nm picture. DETAILED DESCRIPTION

[0057] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0058] Embodiment 1: The present invention provides a distribution network section positioning method based on single-core cable matrix transformation and modal analysis, comprising the following steps:

[0059] Step 1: Optimize the deployment of measuring point devices: Install measuring points at the beginning of each line of the trunk line. When the branch line b of the node where the terminal cable is located is greater than or equal to 2, add b-1 measuring points at the beginning of the branch line connected to the node; and number the measuring points M. i , where i = 1, 2, ..., s, s is the total number of measurement points;

[0060] Step 2, obtaining fault identification modal components: When a fault occurs in the distribution network line, the three-phase current and three-phase voltage collected at the measuring point are transformed into phase modes, and the voltage σ mode and current α mode are obtained through matrix decoupling; the specific process of step 2 is:

[0061] S2.1. When a distribution network line fails, the three-phase current and three-phase voltage collected at the measuring point are calculated based on the single-core cable parameters. The time when the distribution network fails is t. ph and the parallel admittance Y ph ; The formula is as follows:

[0062]

[0063] Among them, z1, z2, z3, z4 are the cable core-shield mutual impedance, shield self-impedance, and phase-to-phase mutual impedance, respectively; y1, y2, y3, y4 are the cable core self-admittance, cable core-shield mutual admittance, shield self-admittance, and phase-to-phase mutual admittance, respectively;

[0064] Calculate the energy Z ph Y ph and Y ph Z ph The transformation matrix T of similar diagonalization V and T I , using the transformation matrix T V and T I Voltage V ph and current I ph Phase mode transformation is performed to achieve decoupling of the three-phase system; the formula involved is as follows:

[0065] [V ph ]=[T V ][V M ]

[0066] [I ph ]=[T I ][I M ]

[0067] Among them, T V is the voltage transformation matrix, T I is the current transformation matrix, V ph and I ph is the voltage and current matrix in the phase domain, V M and I M are the voltage and current matrices in the modal domain;

[0068] In the voltage matrix, six modal signals are obtained after decoupling and are recorded as: u α (t),u β (t),u γ (t),u η (t),u θ (t) and u σ (t); in the current matrix, six modal signals are obtained after decoupling and are recorded as: i α (t), i β (t), i γ (t), i η (t), i θ (t) and i σ (t), obtain the voltage σ modal u σ (t) and current α mode i α (t) as the fault identification modal component;

[0069] Step 3: Calculate the energy E of the voltage σ mode Mi , using E M The size of i determines an end point of the fault section; the specific process of step 3 is:

[0070] Assume that the time when the distribution network fails is t, and the acquisition time window is (t, t+0.03)s, a total of 3ms u σ (t) signal, where t = 1, 2, ..., n, n is the sampling point; the measurement point M in the time window i Energy E Mi The calculation formula is:

[0071]

[0072] Compare the energy values ​​of all measuring points, the maximum energy Corresponding node N max The fault section S F An endpoint of

[0073] Step 4: Combine the topological structure measurement point distribution matrix X and the current α modal polarity matrix Y to construct the final criterion matrix K nm Determine the fault section; the specific process of step 4 is:

[0074] 4.1. Determine an endpoint N of the faulty segment according to step 3 max Then, according to endpoint N max The topological structure of the connected lines and the distribution matrix of measuring points X:

[0075] According to the distribution of measurement points in the topological space, if the node is equipped with measurement points, it is 1, otherwise it is 0; the matrix X formula is as follows:

[0076]

[0077] Among them, N n Represents the endpoint N max Connect each node;

[0078] 4.2. Construct the current α modal polarity matrix Y:

[0079] Determine the polarity of the current α mode, define the direction from the line to the fault point as the positive direction, and the direction from the fault point to the line as the reverse direction; the polarity is recorded as 1 in the positive direction, -1 in the reverse direction, and 0 when there is no measuring point: The matrix Y formula is as follows:

[0080]

[0081] Among them, R m is the mode i of the current α at each node α (t) polarity;

[0082] 4.3. Construct the final criterion matrix K nm :Combining the topological structure measurement point distribution matrix X with the current α mode polarity matrix Y, the final criterion matrix K is obtained nm =X T Y; among them,

[0083]

[0084] When the following equation is satisfied, it is determined that the ground fault occurs in the fault section S F In, L nm Represents the segment composed of nodes n and m: where L nm :

[0085] L nm =Logical(n n r m =-n m r n )·L nm

[0086] S F =min(L nm ).

[0087] The working principle of the distribution network section positioning method of the single-core cable matrix transformation and modal analysis of the present invention is:

[0088] 1. Three-phase single-core cable decoupling

[0089] Taking the commonly used cable model YJV-8.7 / 10kV-1×300 of 10kV urban distribution network as an example, the decoupling of three-phase single-core cable is carried out. Table 1 shows the parameters of YJV-8.7 / 10kV-1×300 cable. The specific steps are as follows:

[0090] Table 1

[0091]

[0092]

[0093] Substitute the test cable technical parameters shown in Table 1 into the corresponding impedance matrix Z ph And the admittance matrix Y ph :

[0094]

[0095]

[0096] Among them, z1, z2, z3, z4 are the cable core-shield mutual impedance, shield self-impedance, and phase-to-phase mutual impedance, respectively; y1, y2, y3, y4 are the cable core self-admittance, cable core-shield mutual admittance, shield self-admittance, and phase-to-phase mutual admittance, respectively;

[0097] Swap the order of the matrix column vectors to cable core A-cable core B-cable core C-shield A-shield B-shield C, and calculate the matrix Z ph and the matrix Yph The product matrix Z ph Y ph :

[0098]

[0099] Calculate the matrix Z ph Y ph The eigenvalues ​​and eigenvectors of exist a fixed matrix T such that T -1 Z ph Y ph T=TY ph Z ph T -1 = diagonal matrix D; by calculation, the voltage transformation matrix T V and the current transformation matrix T I as follows:

[0100]

[0101]

[0102] 2. Modal analysis after system decoupling

[0103] After analyzing the physical meaning of the six propagation modes after system decoupling, the transmission modes of the three-phase single-core cable can be divided into: 3 coaxial modes, 2 sheath inter-modes and 1 grounding mode. Figure 2 are the current paths of each mode after decoupling.

[0104] Figure 2 (a) The coaxial mode corresponds to the cable core-shield loop, where the core current returns completely in the shield of the same cable; Figure 2 (b) The inter-sheath mode corresponds to the shield-shield loop, where the current flowing in the shield returns from the shield of the other cable; the grounding mode between the sheath and the earth, Figure 2 (c) The ground mode corresponds to the shield-earth loop and is a zero-sequence mode. The same current is injected into all three shields and returns from the earth. Through the characteristics of these modes, another classification method can be summarized: ① Zero-sequence mode: the same current is injected into all three phases; ② Inter-conductor mode: current is injected into one phase and returns through the other two phases; ③ Conductor mode: current is injected into one phase and returns from another phase.

[0105] 2. Screening fault characteristic modes

[0106] During normal operation, the voltage between the three-phase cable core and the ground is symmetrical and the sum is zero. In general, the cable lines in the 10kV urban distribution network are often grounded at both ends, so the voltage η modulus and the current α modulus contain some weak signal components on the grounding line. When a cable fault occurs, the voltage of the fault conductor suddenly changes and the voltage is no longer symmetrical. At this time, it is equivalent to superimposing a reverse power supply at the fault point. The voltage signal propagates along the cable to both ends, causing the three-phase cable core voltage to ground and the three-phase cable core current to change, which in turn causes the voltage and current modes to suddenly change after decoupling. Among the six modes of current, except for the current α mode, the other modes cannot be calculated through the measured signal. Before and after the single-phase grounding fault occurs, the changes in the three-phase voltage, current and decoupled current α mode of the single-core cable are shown in the following figure. Figure 3 As shown in Figure 2, the changes of each voltage mode after decoupling are as follows: Figure 4 shown by Figure 3 and Figure 4 It can be seen that when a single-phase grounding fault occurs, the distribution network structure is complex or when the impedance is large, the changes in the three-phase voltage and current are not obvious, and the decoupled current α mode, voltage α mode, voltage γ mode and voltage σ mode are almost zero before the fault, and mutations occur after the fault, especially the voltage σ mode belonging to the grounding mode, which has a sharp mutation and is easy to identify; in contrast, the amplitude of the voltage γ mode is small and difficult to measure, and the polarity change trend of the current α mode is obvious; therefore, for the single-phase grounding fault of the cable distribution network, the energy of the voltage σ mode and the polarity of the current α mode are selected as the fault characteristic modes.

[0107] 3. Energy of voltage σ mode

[0108] Figure 5 This is the current loop of a single-phase grounding fault. Since it is connected to the fault phase at the end of the cable, the current of the grounding cables at both ends returns through the earth, the fault phase semiconductor shielding layer and the normal phase shielding layer. In the figure, Z cp_x , Z sp_x Respectively represent the impedance of the p-phase cable core and the shielding layer, Z g_x represents the common ground impedance of the shield layer, x represents the beginning or the end; the calculation formula for the ground mode and conductor mode amplitude is:

[0109]

[0110] Among them, M c is the conductor modal amplitude, M g is the grounding modal amplitude; ΔV p Indicates the modal change of the p-phase voltage, ΔV pq Indicates the modal change of the p and q phase voltages; ΔV A The amplitude is about lp.u., and ΔV B and ΔV CThe size of depends on the system structure and is less than 1p.u., so the amplitude of the grounding mode is greater than that of the conductor mode;

[0111] The grounding mode corresponds to the voltage σ mode. Therefore, the energy of the voltage σ mode can be used to determine an end point of the fault section. The voltage σ mode energy is calculated as follows:

[0112] E σ =U σ 2 =M g 2

[0113] Among them, E σ is the voltage σ modal energy, U σ is the modal voltage value of σ.

[0114] Example 2

[0115] In order to verify the effectiveness and reliability of the proposed method, the following Figure 6 The 10kV cable distribution network model shown in the figure adopts a three-phase single-core cable model arranged in a finished product shape according to the frequency characteristics. The cable model is YJV-8.7 / 10kV-1×300; the arc suppression coil adopts an overcompensation setting of 8%, and the grounding resistance R g is 10Ω; the simulation frequency is 10kHz, the simulation time is 0.2s; the measurement points are optimized and deployed; the feeder l AB Taking a 200Ω grounding fault as an example, the grounding method is small resistance grounding, and the initial phase angle is 90°; the voltage and current phase mode transformation of each measuring point is decoupled to obtain the voltage σ mode and the current α mode, and the energy of the voltage σ mode is further calculated; Table 2 shows the energy of the voltage σ mode at each measuring point;

[0116] Table 2

[0117]

[0118] From Table 2, we can see that the voltage σ modulus energy of nodes corresponding to different measuring points is different, and the modulus energy of nodes closer to the fault location is relatively large; among them, the energy of node A corresponding to measuring point M2 is the largest, which is 2.26kV 2 ; Thus, one end point of the fault section is determined as point A; then the current α modal polarity is calculated, the topological structure measurement point distribution matrix X and the current α modal polarity matrix Y are constructed, and the final criterion matrix K is determined nm Conduct fault location. Figure 7 is the current α modal polar diagram and the final criterion matrix K nm ; It can be obtained that XB=-BX, AB=-BA, and min(XB, AB)=AB, so the fault section is determined to be AB, and the result is consistent with the set fault condition.

[0119] In order to verify the fault section positioning of the method proposed in the present invention under different fault conditions, the cable core shielding single-phase grounding fault is set under different fault positions and different transition resistance conditions. Table 3 shows the positioning results under different conditions;

[0120] Table 3

[0121]

[0122] It can be seen from Table 3 that when the system transition resistance R g As increases, the energy of the voltage σ mode gradually decreases, while the polarity of the current α mode is basically not affected by the fault position, fault distance and transition resistance; therefore, this method is fully capable of realizing the section positioning under the cable core shielding grounding fault.

[0123] As can be seen from the above, the present invention proposes a matrix transformation method suitable for the grounding mode of the two ends of the three-phase single-core cable in the distribution network by considering the multi-conductor coupling structure of the single-core cable; realizes the complete decoupling of the system, screens the fault characteristic mode, fully reflects the changes in transient characteristics before and after the fault, and lays the foundation for the accurate positioning of the fault section; at the same time, by combining the spatial position of the distribution network topology structure to reasonably distribute the measuring points, construct the topology structure measuring point distribution matrix, the current α modal polarity matrix and the final criterion matrix, and utilizes the information interaction between the matrices to realize logical complementarity, thereby reducing the distribution of measuring points and saving costs while realizing the accurate positioning of the fault section; the final criterion matrix constructed by this method is a sparse matrix dominated by diagonal elements, which has a small amount of calculation, low storage memory requirements, low time consumption, high timeliness, and has certain engineering value.

[0124] A distribution network section positioning device for single-core cable matrix transformation and modal analysis, characterized in that it includes a data acquisition module, a signal processing module, a fault feature extraction module, a fault criterion construction module, a display and control module and a communication interface module, wherein the data acquisition module, the signal processing module, the fault feature extraction module, the fault criterion construction module, the display and control module and the communication interface module are electrically connected in sequence:

[0125] The data acquisition module is responsible for collecting three-phase current and three-phase voltage signals from each measuring point in the distribution network in real time;

[0126] The signal processing module performs preprocessing and phase mode conversion on the collected three-phase current and voltage signals;

[0127] Fault feature extraction module, calculates the energy E of the voltage σ mode Mi , use the energy size to preliminarily determine one end point of the fault section;

[0128] The fault criterion construction module constructs the final criterion matrix Knm according to the topological structure measurement point distribution and the current α mode polarity;

[0129] Display and control module, which displays the fault location results and provides a user interaction interface;

[0130] Communication interface module enables communication between the device and the host computer or remote monitoring center.

[0131] In this embodiment, the distribution network section positioning device of single-core cable matrix transformation and modal analysis includes a processor and a memory, and the processor includes a kernel, and the kernel calls the corresponding program unit from the memory. One or more kernels can be set, and the distribution network section positioning method of single-core cable matrix transformation and modal analysis is implemented by adjusting kernel parameters.

[0132] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0133] An embodiment of the present application provides a processor configured to execute the above-mentioned distribution network section positioning method of single-core cable matrix transformation and modal analysis.

[0134] An embodiment of the present application provides a machine-readable storage medium having instructions stored thereon, which, when executed by a processor, configures the processor to execute the distribution network section positioning method of the above-mentioned single-core cable matrix transformation and modal analysis.

[0135] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0136] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0137] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0138] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0139] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0140] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0141] Computer readable media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0142] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0143] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0144] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A distribution network section positioning method based on single-core cable matrix transformation and modal analysis, characterized in that: The following steps are involved: Step 1: Optimize the deployment of measuring point devices: Install measuring points at the head end of each line of the trunk line. When the branch line b of the node where the terminal cable is located is greater than or equal to 2, add b-1 measuring points at the head end of the branch line connected to the node. And number the measuring points M i , where i = 1, 2, ..., s, s is the total number of measurement points; Step 2, obtaining fault identification modal components: when a fault occurs in the distribution network line, the three-phase current and three-phase voltage collected at the measuring point are transformed into phase modes, and the voltage σ mode and current α mode are obtained through matrix decoupling; Step 3: Calculate the energy E of the voltage σ mode Mi , using E M The size of i determines one end point of the fault segment; Step 4: Combine the topological structure measurement point distribution matrix X and the current α modal polarity matrix Y to construct the final criterion matrix K nm Determine the faulty section.

2. A distribution network section positioning method based on single-core cable matrix transformation and modal analysis as claimed in claim 1, characterized in that: The specific process of step 2 is as follows: S2.

1. When a distribution network line fails, the three-phase current and three-phase voltage collected at the measuring point are assumed to be the time when the distribution network fails. According to the parameters of the single-core cable, the 6×6-order series impedance matrix Z is calculated. ph and the parallel admittance Y ph ; The formula is as follows: Among them, z1, z2, z3, z4 are the cable core-shield mutual impedance, shield self-impedance, and phase-to-phase mutual impedance, respectively; y1, y2, y3, y4 are the cable core self-admittance, cable core-shield mutual admittance, shield self-admittance, and phase-to-phase mutual admittance, respectively; Calculate the energy Z ph Y ph and Y ph Z ph The transformation matrix T of similar diagonalization V and T I , using the transformation matrix T V and T I Voltage V ph and current I ph Perform phase mode transformation to achieve decoupling of the three-phase system; In the voltage matrix, six modal signals are obtained after decoupling and are recorded as: u α (t),u β (t),u γ (t),u η (t),u θ (t) and u σ (t); in the current matrix, six modal signals are obtained after decoupling and are recorded as: i α (t), i β (t), i γ (t), i η (t), i θ (t) and i σ (t), obtain the voltage σ modal u σ (t) and current α mode i α (t) is used as the modal component for fault identification.

3. A distribution network section positioning method based on single-core cable matrix transformation and modal analysis as claimed in claim 1, characterized in that: The specific process of step 3 is: Assume that the time when the distribution network fails is t, and the acquisition time window is (t, t+0.03)s, a total of 3ms u σ (t) signal, where t = 1, 2, ..., n, and n is a sampling point.

4. A distribution network section positioning method based on single-core cable matrix transformation and modal analysis as claimed in claim 1, characterized in that: The specific process of step 4 is as follows: S4.

1. Determine an endpoint N of the faulty segment according to step 3. max Then, according to endpoint N max The topological structure of the connected lines and the distribution matrix of measuring points X: According to the distribution of measurement points in the topological space, if the node is equipped with measurement points, it is 1, otherwise it is 0; S4.

2. Construct the current α modal polarity matrix Y: Determine the polarity of the current α mode, define the direction from the line to the fault point as the positive direction, and the direction from the fault point to the line as the reverse direction; the polarity is recorded as 1 for the positive direction, -1 for the reverse direction, and 0 when there is no measuring point: S4.

3. Construct the final criterion matrix K nm :Combining the topological structure measurement point distribution matrix X with the current α mode polarity matrix Y, the final criterion matrix K is obtained nm =X T Y; S4.

4. Finally determine that the ground fault occurs in the fault section S F In, L nm Represents the segment composed of nodes n and m.

5. A distribution network section positioning device for single-core cable matrix transformation and modal analysis as described in any one of claims 1 to 4, characterized in that: include: The data acquisition module is responsible for collecting three-phase current and three-phase voltage signals from each measuring point in the distribution network in real time; The signal processing module performs preprocessing and phase mode conversion on the collected three-phase current and voltage signals; Fault feature extraction module, calculates the energy E of the voltage σ mode Mi , use the energy size to preliminarily determine one end point of the fault section; The fault criterion construction module constructs the final criterion matrix Knm according to the topological structure measurement point distribution and the current α mode polarity; Display and control module, which displays the fault location results and provides a user interaction interface; Communication interface module enables communication between the device and the host computer or remote monitoring center.

6. A processor, characterized in that: A distribution network section positioning method configured to perform single-core cable matrix transformation and modal analysis according to any one of claims 1 to 4.

7. A machine-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor is configured to execute the distribution network section positioning method based on single-core cable matrix transformation and modal analysis according to any one of claims 1 to 4.

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