Looped network line fault positioning method and device of power distribution network

Abstract

The invention relates to the technical field of fault positioning and protection of a power distribution network, and particularly provides a looped network line fault positioning method and device of the power distribution network, and the method comprises the steps: obtaining a correlation coefficient between a current waveform after a looped network line fault of the power distribution network and a current waveform after a series-parallel flexible interconnection device actively controls a power grid to reach a steady state; and based on the correlation coefficient, carrying out fault positioning on the power distribution network looped network line. According to the technical scheme provided by the invention, the communication requirement is low, data synchronization is not needed, the accuracy of positioning the fault section of the power distribution network is improved, and a technical method with engineering value is provided for the fault positioning method of the power distribution network accessed by the series-parallel flexible interconnection equipment; the method lays a theoretical foundation for further analysis of fault characteristics of the series-parallel flexible interconnection equipment, and has guiding significance in engineering application and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of fault location and protection of a distribution network, and in particular to a method and a device for locating a ring network line fault of a distribution network. Background Art

[0002] With the progress of power and information technology, the distribution network has entered a stage of rapid development. The share of power supply is increasing, and electricity has replaced the widespread popularity of social production, people's lives, transportation electrification and other fields. The diversity of technical elements and requirements contained in the circulation network has brought many challenges. In the face of future demand for distribution networks, how to use innovative technologies such as electrical equipment and adaptive processes to effectively support the acquisition and consumption of clean energy, provide various energy services to end customers, and meet the interaction between distribution networks and social production in many areas of life has become an important issue at present. In recent years, with the large-scale access of distributed generation (DG), the flow in the medium-voltage distribution network has flowed in both directions, and the uneven line load has become increasingly serious. The flexible interconnection technology of the distribution network can fully tap the power supply potential of the distribution network, improve the reliability of power supply, and improve the quality of power by connecting flexible interconnection equipment to the distribution network, and is an important measure to solve the problem of high-proportion consumption of distributed generation in the distribution network.

[0003] Existing flexible interconnection equipment is mainly a multi-port power electronic device represented by a back-to-back voltage source converter, which realizes flexible interconnection of multiple AC feeders, also known as an intelligent soft switch (soft open point, SOP), but its cost is relatively high. Series-parallel flexible interconnection equipment can achieve independent regulation of active and reactive power through discrete compensation voltage, and has the advantages of good economy, small footprint, and low loss, making it an ideal flexible interconnection equipment. However, its impact on the automation of distribution network feeders after access and the corresponding solutions need to be studied urgently.

[0004] In order to solve the problem of insufficient reliability of the ring network line fault location method of the traditional distribution network in the scenario of series-parallel flexible interconnected equipment access line, it is necessary to propose a ring network line fault location method for the distribution network accessed by series-parallel flexible interconnected equipment. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present invention proposes a method and device for locating a ring network line fault of a distribution network.

[0006] In a first aspect, a method for locating a ring network line fault of a distribution network is provided, the method for locating a ring network line fault of the distribution network comprising:

[0007] Obtain the correlation coefficient between the current waveform after the distribution network ring network line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state;

[0008] Based on the correlation coefficient, fault location is performed on the distribution network ring network line.

[0009] Preferably, the correlation coefficient between the current waveform after the distribution network ring network line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows:

[0010]

[0011] In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the grid to reach a steady state, φ i is the fault phase difference, △i φi,before is the fault phase difference after the distribution network ring line fails i Current waveform, △i φi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the fault phase difference φ is reached after the power grid reaches a steady state i The current waveform, P(△i φi,before ,△i φi,after ) is △i φi,before and △i φi,after The Pearson correlation coefficient between them, n is the number of fault phases.

[0012] Preferably, the fault location of the distribution network ring network line based on the correlation coefficient includes:

[0013] Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line;

[0014] If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

[0015] Further, after locating the fault of the distribution network ring network line based on the correlation coefficient, the method further comprises:

[0016] When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped;

[0017] Reclose the substation outlet circuit breaker of the distribution network.

[0018] Preferably, the series-parallel flexible interconnection equipment is actively controlled until the power grid reaches a steady state, including:

[0019] The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

[0020] Furthermore, the characteristic voltage is an equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0021] Furthermore, the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows:

[0022]

[0023] In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0024] Furthermore, n1, n2, and n3 are as follows:

[0025]

[0026] In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

[0027] In a second aspect, a ring network line fault locating device for a distribution network is provided, the ring network line fault locating device for the distribution network comprising:

[0028] An acquisition module is used to obtain the current waveform after the distribution network ring network line fails, and the correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state;

[0029] The analysis module is used to locate the fault of the distribution network ring network line based on the correlation coefficient.

[0030] Preferably, the correlation coefficient between the current waveform after the distribution network ring network line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows:

[0031]

[0032] In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the grid to reach a steady state, φ i is the fault phase difference, △i φi,before is the fault phase difference after the distribution network ring line fails i Current waveform, △i φi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the fault phase difference φ is reached after the power grid reaches a steady state i The current waveform, P(△i φi,before ,△i φi,after ) is △i φi,before and △i φi,after The Pearson correlation coefficient between them, n is the number of fault phases.

[0033] Preferably, the analysis module is specifically used for:

[0034] Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line;

[0035] If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

[0036] Furthermore, the device includes: a fault isolation module, which is used to:

[0037] When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped;

[0038] Reclose the substation outlet circuit breaker of the distribution network.

[0039] Preferably, the series-parallel flexible interconnection equipment is actively controlled until the power grid reaches a steady state, including:

[0040] The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

[0041] Furthermore, the characteristic voltage is an equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0042] Furthermore, the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows:

[0043]

[0044] In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0045] Furthermore, n1, n2, and n3 are as follows:

[0046]

[0047] In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

[0048] In a third aspect, a computer device is provided, comprising: one or more processors;

[0049] The processor is configured to execute one or more programs;

[0050] When the one or more programs are executed by the one or more processors, the method for locating a ring network line fault in a distribution network is implemented.

[0051] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed, the method for locating a ring network line fault of the distribution network is implemented.

[0052] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0053] The present invention provides a method and device for locating a ring network line fault of a distribution network, including: obtaining a current waveform after a distribution network ring network line fault, and a correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state; based on the correlation coefficient, locating the fault of the distribution network ring network line. The technical solution provided by the present invention has low communication requirements and does not require data synchronization, improves the accuracy of locating the fault section of the distribution network, provides a technical method with engineering value for the distribution network fault locating method connected to the series-parallel flexible interconnection equipment, lays a theoretical foundation for further analyzing the fault characteristics of the series-parallel flexible interconnection equipment, and has guiding significance for its engineering application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic flow chart of main steps of a method for locating a ring network line fault in a distribution network according to an embodiment of the present invention;

[0055] Figure 2 is a topological structure diagram of a series-parallel flexible interconnection device according to an embodiment of the present invention;

[0056] Figure 3 This is a structural diagram of a distribution network including series-parallel flexible interconnection equipment connected in an embodiment of the present invention;

[0057] Figure 4 is an equivalent positive and negative sequence model diagram of the series-parallel flexible interconnection equipment of an embodiment of the present invention;

[0058] Figure 5 This is a fault additional network diagram before active control of the series-parallel flexible interconnection equipment of an embodiment of the present invention;

[0059] Figure 6 This is a fault additional network diagram after active control of the series-parallel flexible interconnection equipment according to an embodiment of the present invention;

[0060] Figure 7 It is an action timing diagram of the fault location solution of an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0062] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] As disclosed in the background technology, with the progress of power and information technology, the distribution network has entered a stage of rapid development. The share of power supply continues to increase, and electricity has replaced the widespread popularity of social production, people's lives, transportation electrification and other fields. The diversity of technical elements and requirements contained in the circulation network has brought many challenges. In the face of future demand for distribution networks, how to use innovative technologies such as electrical equipment and adaptive processes to effectively support the acquisition and consumption of clean energy, provide various energy services to end customers, and meet the interaction between distribution networks and social production in many areas of life has become an important issue at present. In recent years, with the large-scale access of distributed generation (DG), the flow in the medium-voltage distribution network has flowed in both directions, and the phenomenon of uneven line load has become increasingly serious. The flexible interconnection technology of the distribution network can fully tap the power supply potential of the distribution network, improve the reliability of power supply, and improve the quality of power, etc. by connecting the flexible interconnection equipment to the distribution network, and changing the open-loop distribution network into a closed-loop operation. It is an important measure to solve the problem of high-proportion consumption of distributed generation in the distribution network.

[0064] Existing flexible interconnection equipment is mainly a multi-port power electronic device represented by a back-to-back voltage source converter, which realizes flexible interconnection of multiple AC feeders, also known as an intelligent soft switch (soft open point, SOP), but its cost is relatively high. Series-parallel flexible interconnection equipment can achieve independent regulation of active and reactive power through discrete compensation voltage, and has the advantages of good economy, small footprint, and low loss, making it an ideal flexible interconnection equipment. However, its impact on the automation of distribution network feeders after access and the corresponding solutions need to be studied urgently.

[0065] In order to solve the problem of insufficient reliability of the ring network line fault location method of the traditional distribution network in the scenario of series-parallel flexible interconnected equipment access line, it is necessary to propose a ring network line fault location method for the distribution network accessed by series-parallel flexible interconnected equipment.

[0066] In order to improve the above problems, the present invention provides a method and device for locating the fault of the ring network line of the distribution network, including: obtaining the current waveform after the fault of the ring network line of the distribution network, and the correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state; based on the correlation coefficient, locating the fault of the ring network line of the distribution network. The technical solution provided by the present invention has low communication requirements and does not require data synchronization, improves the accuracy of locating the fault section of the distribution network, and provides a technical method with engineering value for the fault location method of the distribution network connected to the series-parallel flexible interconnection equipment, laying a theoretical foundation for further analyzing the fault characteristics of the series-parallel flexible interconnection equipment, and has guiding significance for its engineering application and promotion.

[0067] The above scheme is described in detail below.

[0068] Example 1

[0069] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of a method for locating a ring line fault in a distribution network according to an embodiment of the present invention. Figure 1 As shown, the method for locating a ring network line fault of a distribution network in an embodiment of the present invention mainly includes the following steps:

[0070] Step S101: obtaining a current waveform after a distribution network ring network line fault occurs, and a correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state;

[0071] Step S102: Based on the correlation coefficient, fault location is performed on the distribution network ring network line.

[0072] In a specific embodiment, Figure 2 As shown in Figure 1, the topological structure of the series-parallel flexible interconnection equipment consists of a three-phase four-winding transformer. The primary winding A of the four-winding transformer E , B E , C E Star connection forms an excitation unit; the three secondary windings of the four-winding transformer are all tapped, among which the A-phase secondary windings are a1, a2, and a3; the B-phase secondary windings are b1, b2, and b3; the C-phase secondary windings are c1, c2, and c3. The secondary windings are connected in series in the three-phase circuit to form a series voltage regulation unit, among which the windings a1, b3, and c2 are connected in series in the A-phase circuit to form an A-phase series voltage regulation unit, and its output voltage is Similarly, windings a2, b1, and c3 form a B-phase series voltage regulating unit; windings a3, b2, and c1 form a C-phase series voltage regulating unit. By adjusting the gear position of the series voltage regulating unit, four-quadrant regulation of the series compensation voltage can be achieved.

[0073] The typical structure of the distribution network with ST access to series-parallel flexible interconnection equipment is as follows: Figure 3 As shown in the figure, QF1-QF4 are circuit breakers; QL11-QL63 are section switches; S1 and S2 are the upper power supplies on both sides of the distribution network; S Lx (x=1,2,3,…6) is the load outgoing line of each ring main unit; M, N, O, P are the four nodes of the distribution network; A, B, C, D, E, F are the six load outgoing line nodes of the ring main unit. Smart Terminal Unit (STU) is installed at each switch for neighborhood information exchange.

[0074] The following will analyze the impact of the access of series-parallel flexible interconnection equipment on the original distribution network fault location solution from different fault locations.

[0075] (1) A fault occurs at ring network line f1

[0076] When a fault occurs at the ring network line f1, system power supply 1 provides short-circuit current to the short-circuit point through QF2, QL11, and QL12, and system power supply 2 also provides short-circuit current to the short-circuit point through the series-parallel flexible interconnection equipment, causing the fault current to flow through QL21, QL22, QL31, and QL32. At this time, each STU communicates with the adjacent STU. Since all STUs detect the fault current, each STU determines that the fault current is a through-current, resulting in fault location error.

[0077] (2) A fault occurs at the outgoing line f2

[0078] When a fault occurs at the outgoing line f2, the system power supply 1 provides short-circuit current to the short-circuit point through QF1, QL11, and QL13, and the system power supply 2 also provides short-circuit current to the short-circuit point through the series-parallel flexible interconnection equipment. Since only the forward fault current flows through QL23, it will not cause fault location errors, that is, the original fault location plan can still be applied to the fault at the outgoing line.

[0079] The positive and negative sequence equivalent model of series-parallel flexible interconnection equipment is as follows Figure 4 As shown, They are respectively the positive sequence primary and secondary voltages and currents of the series-parallel flexible interconnection equipment, Z m is the magnetizing reactance, Z T1 is the equivalent positive sequence leakage reactance, Z T2 is the equivalent negative sequence leakage reactance; They are respectively the negative sequence primary and secondary voltages and currents of the series-parallel flexible interconnection equipment, and are the equivalent positive sequence voltage and current transformation ratio, and They are the equivalent negative sequence voltage and current transformation ratios, as follows:

[0080]

[0081] The control of the gear position of the series-parallel flexible interconnected equipment is actually a change in its equivalent transformation ratio. Therefore, by changing the control strategy, the phase of the equivalent transformation ratio can be adjusted after a fault occurs, thereby injecting a phase-related characteristic signal to achieve accurate positioning of the flexible interconnected distribution network fault.

[0082] It can be seen from the above formula that the adjustment range of the equivalent transformation ratio of the series-parallel flexible interconnection equipment is determined by the transformation ratios n1, n2, and n3, among which the positive sequence voltage transformation ratio The vector diagram of changes with n1, n2, and n3 is as follows Figure 6 As shown, taking the range of n1, n2, and n3 as [-0.2, 0.2] as an example, at this time The phase change range is -23°~+23°. When the phase angle is adjusted too small, the characteristic signal may not be obvious due to the influence of current transformer sampling error, noise, etc.; when the phase angle is adjusted too large, the impact on the system will also increase. Therefore, considering all factors, the equivalent ratio adjustment angle of the series-parallel flexible interconnection equipment is set to 5°.

[0083] Therefore, in this embodiment, the series-parallel flexible interconnection equipment actively controls until the power grid reaches a steady state, including:

[0084] The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

[0085] In one embodiment, the characteristic voltage is an equivalent positive sequence voltage of series-parallel flexible interconnection equipment.

[0086] In one embodiment, the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows:

[0087]

[0088] In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0089] In one embodiment, n1, n2, and n3 are as follows:

[0090]

[0091] In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

[0092] The research object of this invention is the phase-to-phase short circuit fault of the distribution network. Figure 3 The three-phase short circuit fault at point f1 is taken as an example for analysis.

[0093] when Figure 3 When a three-phase short circuit fault occurs at f1 of the flexible interconnected distribution network with series-parallel flexible interconnected equipment, the fault additional network is as follows: Figure 5 As shown. Wherein, the first equivalent impedance Z1=Z S1 +Z MA +Z Af1 , the second equivalent impedance Z2=Z f1B +Z BC +Z CP , the third equivalent impedance Z3=Z S2 +Z ND +Z DE +Z EF +Z FO . Z MA , Z BC , Z CP , Z ND , Z DE , Z EF , Z FO are the impedances between the corresponding nodes; Z Af1 , Z f1B is the line impedance between the fault point f1 and nodes A and B respectively; Z S1 , Z S2 are the equivalent impedances of the two systems, is the equivalent voltage source of the fault additional network, R f is the transition resistance, is the fault component of the current upstream of the fault point, is the fault component of the current downstream of the fault point, and T is the equivalent transformation ratio amplitude of the series-parallel flexible interconnection equipment.

[0094] The fault additional network after the series-parallel flexible interconnection equipment actively adjusts the equivalent transformation ratio is as follows Figure 6 As shown. Among them, They are respectively the upstream and downstream current fault components of the fault point after active phase adjustment control of the series-parallel flexible interconnection equipment, The original equivalent transformation ratio phase angle of the series-parallel flexible interconnection equipment, It is the equivalent transformation ratio phase angle after active phase adjustment control of series-parallel flexible interconnection equipment. It is the original equivalent potential of series-parallel flexible interconnection equipment.

[0095] Depend on Figure 5 and Figure 6 It can be seen that when the series-parallel flexible interconnection equipment adopts the active phase adjustment control strategy, the current phase on the line will change. The phase changes of the current fault component measured by the STUs on both sides of the non-fault line are the same, while the phase changes of the current fault component measured by the STUs on both sides of the fault line will be different. Therefore, the difference in the phase changes of the current fault component on both sides of the fault line can be used to construct the corresponding judgment criteria to identify the corresponding fault section.

[0096] The fault current after a distribution network fault mainly consists of a periodic component and an attenuated DC component. In order to reduce the influence of the DC component on the Pearson correlation coefficient, a differential operation is used to increase the periodic component content and reduce the non-periodic component content.

[0097] At the same time, in order to reduce the influence of the measurement error of the current transformer and highlight the phase difference of the current before and after the phase adjustment of the series-parallel flexible interconnection equipment, this paper takes the inverse cosine of the Pearson correlation coefficient of the fault phase current before and after the adjustment of the series-parallel flexible interconnection equipment, and then subtracts it from the current phase difference when the series-parallel flexible interconnection equipment is not adjusted, and finally takes the average value, that is, the correlation coefficient between the current waveform after the distribution network ring network line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows:

[0098]

[0099] In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the grid to reach a steady state, φ i is the fault phase difference, △i φi,before is the fault phase difference after the distribution network ring line fails i Current waveform, △i φi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the fault phase difference φ is reached after the power grid reaches a steady state i The current waveform, P(△i φi,before ,△i φi,after ) is △i φi,before and △i φi,after The Pearson correlation coefficient between them, n is the number of fault phases.

[0100] In this embodiment, the fault location of the distribution network ring network line based on the correlation coefficient includes:

[0101] Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line;

[0102] If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

[0103] In one embodiment, after locating the fault of the distribution network ring network line based on the correlation coefficient, the method includes:

[0104] When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped;

[0105] Reclose the substation outlet circuit breaker of the distribution network.

[0106] In a specific embodiment, Figure 7 As shown, including:

[0107] (1) Assume that a fault occurs in the distribution network to which the series-parallel flexible interconnection equipment is connected at time t0.

[0108] (2) From t0 to t1, the distributed protection terminal collects the first current waveform.

[0109] (3) At time t2, the series-parallel flexible interconnected equipment is actively controlled to reach a steady state.

[0110] (4) From t2 to t3, the distributed protection terminal collects the second current waveform and calculates the ratio of the autocorrelation coefficients of the current waveform, and determines the fault section according to the preset process.

[0111] (5) At time t4, the substation outlet circuit breaker operates.

[0112] (6) At t5, the section switches at both ends of the fault section are tripped, and the outlet circuit breakers are reclosed, completing the fault isolation.

[0113] The specific process of the fault location improvement solution is as follows:

[0114] (1) After a fault occurs, the distributed protection terminal uses the current mutation quantity to start and select the fault phase using the current mutation quantity to determine the fault type.

[0115] (2) After a fault is detected, the series-parallel flexible interconnection equipment collects the first current waveform (data window length 10ms) at the distributed protection terminal, and then starts active control to adjust its equivalent transformation ratio. After the series-parallel flexible interconnection equipment reaches a steady state, it collects the second current waveform (data window length 10ms).

[0116] (3) Communicate with adjacent intelligent terminals and calculate the ratio of the autocorrelation coefficients of the current waveforms on both sides of the ring network line. If the ratio exceeds a threshold value, a fault occurs in the section from one end point of the distribution network ring network line to an end point adjacent to the one end point of the distribution network ring network line. Otherwise, no fault occurs in the section from one end point of the distribution network ring network line to an end point adjacent to the one end point of the distribution network ring network line.

[0117] Example 2

[0118] Based on the same inventive concept, the present invention also provides a ring network line fault locating device for a distribution network, the ring network line fault locating device for the distribution network comprising:

[0119] An acquisition module is used to obtain the current waveform after the distribution network ring network line fails, and the correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state;

[0120] The analysis module is used to locate the fault of the distribution network ring network line based on the correlation coefficient.

[0121] Preferably, the correlation coefficient between the current waveform after the distribution network ring network line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows:

[0122]

[0123] In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the grid to reach a steady state, φ i is the fault phase difference, △i φi,before is the fault phase difference after the distribution network ring line fails i Current waveform, △i φi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the fault phase difference φ is reached after the power grid reaches a steady state i The current waveform, P(△i φi,before ,△i φi,after ) is △i φi,before and △i φi,afterThe Pearson correlation coefficient between them, n is the number of fault phases.

[0124] Preferably, the analysis module is specifically used for:

[0125] Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line;

[0126] If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

[0127] Furthermore, the device includes: a fault isolation module, which is used to:

[0128] When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped;

[0129] Reclose the substation outlet circuit breaker of the distribution network.

[0130] Preferably, the series-parallel flexible interconnection equipment is actively controlled until the power grid reaches a steady state, including:

[0131] The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

[0132] Furthermore, the characteristic voltage is an equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0133] Furthermore, the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows:

[0134]

[0135] In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

[0136] Furthermore, n1, n2, and n3 are as follows:

[0137]

[0138] In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

[0139] Example 3

[0140] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a computer storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of a method for locating a ring network line fault of a distribution network in the above embodiment.

[0141] Example 4

[0142] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of a method for locating a ring network line fault of a distribution network in the above embodiment.

[0143] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0144] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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 produce 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.

[0145] 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.

[0146] 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 A step that specifies a function in one or more boxes.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for locating a ring line fault in a distribution network, characterized in that: The method comprises: Obtain the correlation coefficient between the current waveform after the distribution network ring network line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state; Based on the correlation coefficient, fault location is performed on the distribution network ring network line.

2. The method according to claim 1, characterized in that The correlation coefficient between the current waveform after the distribution network ring network line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows: In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state, and f i is the fault phase difference, △i fi,before is the fault phase difference f after the distribution network ring line fails i Current waveform, △i fi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the power grid reaches a steady state. i The current waveform, P(△if i,before ,△if i,after ) is △if i,before and △if i,after The Pearson correlation coefficient between them, n is the number of fault phases.

3. The method according to claim 1, characterized in that The method of locating a fault on the distribution network ring line based on the correlation coefficient includes: Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line; If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

4. The method according to claim 3, characterized in that After locating the fault of the distribution network ring network line based on the correlation coefficient, the method includes: When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped; Reclose the substation outlet circuit breaker of the distribution network.

5. The method according to claim 1, characterized in that The series-parallel flexible interconnection equipment actively controls until the power grid reaches a steady state, including: The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

6. The method according to claim 5, characterized in that The characteristic voltage is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

7. The method according to claim 6, characterized in that The equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows: In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

8. The method according to claim 7, characterized in that The n1, n2, and n3 are as follows: In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

9. A ring network line fault locating device for a distribution network, characterized in that: The device comprises: An acquisition module is used to obtain the current waveform after the distribution network ring network line fails, and the correlation coefficient between the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state; The analysis module is used to locate the fault of the distribution network ring network line based on the correlation coefficient.

10. The device according to claim 9, characterized in that The correlation coefficient between the current waveform after the distribution network ring network line fault and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state is as follows: In the above formula, r is the correlation coefficient between the current waveform after the distribution network ring line fails and the current waveform after the series-parallel flexible interconnection equipment actively controls the power grid to reach a steady state, and f i is the fault phase difference, △i fi,before is the fault phase difference f after the distribution network ring line fails i Current waveform, △i fi,after Actively control the series-parallel flexible interconnection equipment of the distribution network ring network until the power grid reaches a steady state. i The current waveform, P(△if i,before ,△if i,after ) is △if i,before and △if i,after The Pearson correlation coefficient between them, n is the number of fault phases.

11. The device according to claim 9, characterized in that The analysis module is specifically used for: Obtaining a ratio between the correlation coefficient corresponding to an end point of a distribution network ring network line and the correlation coefficient corresponding to an adjacent end point of the distribution network ring network line; If the ratio exceeds the threshold, a fault occurs in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line; otherwise, a fault does not occur in the section from one end point of the distribution network ring network line to the adjacent end point of the distribution network ring network line.

12. The device according to claim 11, characterized in that The device comprises: a fault isolation module, which is used for: When a fault occurs in the section from one end point of the distribution network ring network line to the end point adjacent to the one end point of the distribution network ring network line, after disconnecting the substation outlet circuit breaker of the distribution network, the section switches at one end point of the distribution network ring network line and at the end point adjacent to the one end point of the distribution network ring network line are tripped; Reclose the substation outlet circuit breaker of the distribution network.

13. The device according to claim 9, characterized in that The series-parallel flexible interconnection equipment actively controls until the power grid reaches a steady state, including: The gear position of the series-parallel flexible interconnection equipment is adjusted so that the phase angle of the characteristic voltage injected into the power grid increases by 5 degrees until the power grid reaches a steady state.

14. The device according to claim 13, characterized in that The characteristic voltage is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

15. The device according to claim 14, characterized in that The equivalent positive sequence voltage of the series-parallel flexible interconnection equipment is as follows: In the above formula, is the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, n1 is the first transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n2 is the second transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, n3 is the third transformation ratio of the series-side voltage regulating unit and the parallel-side excitation unit of the series-parallel flexible interconnection equipment, j is the imaginary unit, |T U1 | is the amplitude of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment, It is the phase angle of the equivalent positive sequence voltage of the series-parallel flexible interconnection equipment.

16. The device according to claim 15, characterized in that The n1, n2, and n3 are as follows: In the above formula, They are the three-phase voltages of the parallel side excitation unit of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the A phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the voltage regulating unit on the B phase series side of the series-parallel flexible interconnection equipment, The voltage of each winding of the C-phase series side voltage regulating unit is equipped for series-parallel flexible interconnection.

17. A computer device, characterized in that: include: one or more processors; The processor is configured to execute one or more programs; When the one or more programs are executed by the one or more processors, the method for locating a ring network line fault in a distribution network as described in any one of claims 1 to 8 is implemented.

18. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, the method for locating a ring network line fault of a distribution network as claimed in any one of claims 1 to 8 is implemented.

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