Active fault nature discrimination method based on injected disturbance current response characteristics

Abstract

The application belongs to the technical field of power system distribution network relay protection, and provides an active fault nature discrimination method based on injected disturbance current response characteristics, which comprises the following steps: step one, when a phase-to-phase fault occurs in the system, the three-phase breaker at the outlet of the fault line trips, and according to the changes of three-phase current and voltage before and after the fault, the two phases with increased current and reduced voltage are determined as the fault phases; step two, after the breaker trips, the control split-phase switch operates after a delay of 200 ms; the application injects a disturbance current signal through an external power source, and the response characteristics of the disturbance signal are obviously different between permanent faults and transient faults, and simulation verifies the reliability and superiority of the method under different working conditions; the method makes up for the shortcomings of the active injection method in handling fault nature identification, is not affected by the injection time and fault duration, can realize fault nature discrimination only once, is simple to operate, has small calculation amount, and is highly reliable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power system distribution network relay protection, and particularly relates to an active fault property discrimination method based on injected disturbance current response characteristics. BACKGROUND

[0002] In recent years, with the development of new distribution networks, distributed power sources, active inverters and other devices are continuously connected to distribution networks, which provides a new idea for adaptive reclosing research by actively injecting signals to increase fault identification information.

[0003] At present, in order to improve the power supply reliability of distribution networks, three-phase reclosing devices are usually configured at the outlet position of substations to realize the rapid recovery of power supply for transient faults. However, the reclosing devices usually do not have fault property discrimination functions, and when a permanent fault occurs in the system, blind reclosing operation may cause the system to suffer from overcurrent impact, which may cause the equipment to be damaged and affect the safe and stable operation of the distribution network. Therefore, it is particularly important to add a fault property discrimination link before the reclosing device operates, and to develop a fault recovery strategy according to the identification result of the fault property, which is a prerequisite for ensuring that the distribution network is not subjected to secondary impact of short-circuit current and the system is safe and stable. Since the circuit breaker is tripped after a line short-circuit fault, there is a lack of available information for fault property discrimination, which brings difficulties to adaptive reclosing research.

[0004] Therefore, the active fault property discrimination method based on injected disturbance current response characteristics is proposed by the person skilled in the art to solve the problems in the background art. SUMMARY

[0005] The application aims to provide an active fault property discrimination method based on injected disturbance current response characteristics to solve the problem that passive adaptive reclosing strategies are used in traditional distribution lines, and there is a lack of effective electrical quantity information in the line after the circuit breaker is tripped; the electrical quantity information is increased by active injection, and the response characteristics of the injected signal between the fault phases are used to further identify the fault property.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] The active fault property discrimination method based on injected disturbance current response characteristics comprises the following steps:

[0008] Step 1: when a phase-to-phase fault occurs in the system, the three-phase circuit breaker at the outlet of the fault line is tripped, and according to the changes of three-phase current and voltage before and after the fault, the two phases with increased current and reduced voltage are determined as the fault phases;

[0009] Step 2: After the circuit breaker trips for 200 ms, control the split-phase switch to act, inject a disturbance current signal I0(t) with an amplitude of 20 A and a frequency of 20 Hz into the fault phase interval using a single-phase inverter power supply, and set the injection duration to 1.2 s. Record the disturbance voltage U0(t) in the fault phase interval from the fault line head voltage transformer;

[0010] Step 3: Extract time window T1 and time window T2 from U0(t), time window T1 is from 0.4 s to 0.6 s after I0(t) injection, and time window T2 is from 1.0 s to 1.2 s after I0(t) injection. Calculate the energy relative entropy value H u of the two disturbance voltage waveforms in the time window, and set the threshold value If determine that it is a transient fault; otherwise, perform step 4;

[0011] Step 4: Perform frequency domain analysis on the disturbance voltage waveform in time window T1 using fast Fourier transform, and set the threshold value Define the amplitude of the 20 Hz frequency component as A, if then determine that it is a permanent fault; otherwise, determine that the fault has disappeared when the injection signal is injected.

[0012] Preferably, in step 2, the split-phase switch of the split-phase switch includes S1, S2, S3, and S4, and the control strategy is specifically:

[0013] Step 2.1, S1, S2, S3, and S4 are switch devices for controlling the injection of disturbance current between the fault phases, connected between the A, B, and C phases of the fault line; wherein S1 is connected to the A phase and the single-phase inverter power supply; S2 is connected to one side of the B phase and the single-phase inverter power supply; S3 is connected to the other side of the B phase and the single-phase inverter power supply; and S4 is connected to the C phase and the single-phase inverter power supply;

[0014] Step 2.2, based on the specific situation of the fault phase, inject the disturbance current I0(t) to distinguish the fault nature, and the specific operation is as follows:

[0015] If the fault occurs between A and B phases, close S1 and S3, and inject I0(t) between A and B phases;

[0016] If the fault occurs between B and C phases, close S2 and S4, and inject I0(t) between B and C phases;

[0017] If the fault occurs between C and A phases, close S1 and S4, and inject I0(t) between C and A phases.

[0018] Preferably, in step 3, the calculation process of the energy relative entropy H u is specifically:

[0019] The steady-state energy E of the disturbance voltage U0(t) in the time window T1 and T2 is calculated respectively u1 u2 The calculation formula is as follows:

[0020]

[0021] In the formula, U0(t) is the measured fault phase disturbance voltage, and I0(t) is the injected disturbance current;

[0022] The energy relative entropy H of the waveform energy of the time window T1 relative to the waveform energy of the time window T2 u_T1T2 is:

[0023]

[0024] The energy relative entropy H of the waveform energy of the time window T2 relative to the waveform energy of the time window T1 u_T2T1 is:

[0025]

[0026] Therefore, the energy relative entropy H of the two time windows u is:

[0027] H u = H u_T1T2 + H u_T2T1

[0028] The calculation result of the energy relative entropy H u is compared with the threshold value in step 3, when , it is determined that the instantaneous short-circuit fault occurs; otherwise, the content of step 4 is continued to be executed.

[0029] Preferably, in step 4, the fast Fourier decomposition frequency is set to 10 kHz.

[0030] The active fault nature discrimination device based on the injected disturbance current response characteristics comprises:

[0031] A fault detection module is used to monitor the electrical parameters in the power distribution network in real time, including three-phase current and voltage, and once the occurrence of phase-to-phase fault is detected, the three-phase tripping operation of the fault line outlet breaker is triggered immediately to isolate the fault area and prevent the fault from expanding;

[0032] A disturbance signal injection module intelligently controls the closing of the corresponding switch according to the fault phase position determined by the fault detection module, and accurately injects the disturbance current signal into the fault phase;

[0033] ​A data recording module includes a plurality of split-phase switches (e.g., S1, S2, S3, S4), which intelligently control the closing of the corresponding switches according to the fault phase position determined by the fault detection module, so as to accurately inject the disturbance current signal into the fault phase;

[0034] A data processing module accurately extracts the disturbance voltage waveform data in the preset two time windows T1 and T2 from the recorded disturbance voltage U0(t), so as to analyze the response characteristics of the disturbance voltage;

[0035] A control decision module intelligently outputs a control signal according to the comprehensive judgment result of the data processing module.

[0036] A processor is configured to perform the active fault nature discrimination method based on the response characteristics of the injected disturbance current.

[0037] A machine-readable storage medium has instructions stored thereon, which, when executed by a processor, cause the processor to be configured to perform the active fault nature discrimination method based on the response characteristics of the injected disturbance current.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] In view of the fact that the traditional passive AC adaptive reclosing of the power distribution network lacks useful fault information, the active fault nature discrimination method based on the response characteristics of the injected disturbance current proposes to inject a disturbance current signal through an external power source, and the response characteristics of the disturbance signal are obviously different between permanent faults and transient faults. The difference is used to identify the fault nature, and the reliability and superiority of the method under different working conditions are verified through simulation. The method makes up for the shortcomings of the active injection method in handling fault nature identification, is not affected by the injection time and fault duration, and can realize fault nature discrimination only once, is simple to operate, has small calculation amount, and is highly reliable. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart of the active fault nature discrimination method based on the response characteristics of the injected disturbance current of the present application;

[0041] Figure 2 An equivalent circuit schematic diagram of the disturbance signal injection in the present application;

[0042] Figure 3 A simplified circuit schematic diagram of the fault duration stage in the present application;

[0043] Figure 4 An equivalent circuit schematic diagram of the fault duration stage in the present application;

[0044] Figure 5Simplified circuit diagram for non-fault stage in the application;

[0045] Figure 6 Simplified circuit diagram for fault nature discrimination simulation model of 10kV distribution network active disturbance signal injection in the embodiment of the application;

[0046] Figure 7 Simplified diagram of phase separation switch control strategy of injection device in the embodiment of the application;

[0047] Figure 8 Simplified diagram of disturbance voltage waveform of fault phase under instantaneous fault and permanent fault after injection of disturbance current in the embodiment of the application;

[0048] Figure 9 Simplified diagram of disturbance voltage waveform of fault phase under instantaneous fault and time window selection in the embodiment of the application;

[0049] Figure 10 Simplified diagram of disturbance voltage waveform of fault phase under permanent fault and time window selection in the embodiment of the application;

[0050] Figure 11 Simplified diagram of time domain and frequency domain waveforms of disturbance voltage of fault phase under permanent fault in the embodiment of the application;

[0051] Figure 12 Simplified diagram of time domain and frequency domain waveforms of disturbance voltage of fault phase under fault disappearance after injection of signal in the embodiment of the application. DETAILED DESCRIPTION

[0052] The embodiments of the application will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are used to illustrate the application, but cannot be used to limit the scope of the application.

[0053] Embodiment: The application provides an active fault nature discrimination method based on injection of disturbance current response characteristics, which comprises the following steps:

[0054] Step 1: The system has an inter-phase fault, and the three-phase breaker at the outlet of the fault line is tripped. According to the changes of three-phase current and voltage before and after the fault, the two phases with increased line current and reduced voltage are determined as fault phases.

[0055] Step 2: After the breaker is tripped for 200ms, the phase separation switch is controlled to act, and a single-phase inverter power supply is used to inject a disturbance current signal I0(t) with an amplitude of 20A and a frequency of 20Hz into the fault phase, and the injection duration is set to 1.2s. The disturbance voltage U0(t) of the fault phase is recorded by the voltage transformer at the head of the fault line.

[0056] In step 2, the split-phase switch of the split-phase switch includes S1, S2, S3, S4, and the control strategy is specifically as follows:

[0057] Step 2.1, S1, S2, S3, S4 are switch devices for controlling the injection of disturbance current between fault phases, connected between A, B, C three phases of the fault line; wherein, S1 connects A phase and single-phase inverter power supply; S2 connects one side of B phase and single-phase inverter power supply; S3 connects the other side of B phase and single-phase inverter power supply; S4 connects C phase and single-phase inverter power supply;

[0058] Step 2.2, based on the specific situation of the fault phase, the disturbance current I0(t) is injected to distinguish the fault nature, and the specific operation is as follows:

[0059] If the fault occurs between A and B phases, S1 and S3 are closed, and I0(t) is injected between A and B phases;

[0060] If the fault occurs between B and C phases, S2 and S4 are closed, and I0(t) is injected between B and C phases;

[0061] If the fault occurs between C and A phases, S1 and S4 are closed, and I0(t) is injected between C and A phases

[0062] Step 3: Extract time window T1 and time window T2 from U0(t), time window T1 is from 0.4s to 0.6s after I0(t) is injected, time window T2 is from 1.0s to 1.2s after I0(t) is injected, and the energy relative entropy value H of the two disturbance voltage waveforms in the time window is calculated u , set threshold If determine that it is transient fault; otherwise, execute the next step 4;

[0063] In step 3, the calculation process of energy relative entropy H u is as follows:

[0064] The steady-state energy E u1 , E u2 of disturbance voltage U0(t) in time window T1 and T2 is calculated respectively, and the calculation formula is as follows:

[0065]

[0066]

[0067] In the formula, U0(t) is the measured disturbance voltage between fault phases, and I0(t) is the injected disturbance current;

[0068] The energy relative entropy H u_T1T2 of time window T1 waveform energy relative to time window T2 waveform energy is:

[0069]

[0070] Energy relative entropy H of time window T2 waveform energy relative to time window T1 waveform energy u_T2T1 is:

[0071]

[0072] Therefore, the energy relative entropy H of two time windows u is:

[0073] H u = H u_T1T2 + H u_T2T1

[0074] According to the energy relative entropy H u , the calculation result is compared with the threshold value in step 3 , when , it is determined that a transient short-circuit fault occurs; otherwise, the content of step 4 is continued to be executed;

[0075] Step 4: frequency domain analysis is performed on the disturbance voltage waveform in the time window T1 by using fast Fourier transform, and a threshold value is set; the amplitude of the 20Hz frequency component is defined as A, if , it is determined that a permanent fault occurs; otherwise, it is determined that the fault has disappeared when the signal is injected; in step 4, the fast Fourier decomposition frequency is set to 10kHz.

[0076] Further, the working principle of the active fault nature discrimination method based on the injected disturbance current response characteristics is as follows:

[0077] 1. Fault characteristic analysis

[0078] Taking the phase-to-phase short-circuit fault of the AB phase as an example, the equivalent network topology of the fault line after the injection of the disturbance current signal is derived, and the response characteristic difference of the injected disturbance current between the transient fault and the permanent fault is analyzed. Figure 2 is the equivalent circuit of the disturbance signal injection after the breaker of the fault line is tripped.

[0079] Figure 2 In the equivalent circuit, the breaker is tripped, and the fault line is equivalent to a linear passive two-port network, and the port response characteristics of the fault phase are analyzed; wherein i(t) is a single-phase inverter equivalent constant current source, and the disturbance current signal is injected; R A , R B , R C are line resistances, L A , L B , L C are line inductances, and R A= R B = R C , L A = L B = L C ; μ is the ratio of the distance from the line head to the fault point to the length of the whole line; L T is the equivalent inductance of the distribution transformer; R load , L load is the equivalent resistance and inductance of the distribution line load; R AB is the inter-phase fault resistance.

[0080] 1.1 Fault existing stage

[0081] As shown in FIG. 1, after the short-circuit fault between the A and B phases occurs, due to the existence of the transition resistance R AB , the original parameters and structure of the line change, and the response of the injected disturbance current through the constant current source connected at the outlet of the line is also different; in order to facilitate analysis, the fault duration stage between the A and B phases shown in FIG. 2 is equivalent to Figure 2 , Figure 2 , Figure 3 , Figure 3 is the simplified circuit of the fault duration stage.

[0082] As shown in FIG. 3, after the disturbance current is injected, in the fault duration stage, the equivalent impedance Z 1eq between the A and B fault phases is: Figure 3

[0083]

[0084] Further, the disturbance voltage generated by the disturbance current between the A and B fault phases can be calculated as:

[0085]

[0086] 1.2 Fault disappearing stage

[0087] As shown in FIG. 4, if a transient fault occurs, the equivalent circuit between the A and B phases after the fault disappears can be represented as the equivalent circuit of the no-fault stage of the line shown in FIG. 5; at this time, the disturbance current is injected from the A and B phases, and the voltage disturbance response generated between the A and B phases is obviously different from that when the fault exists. Figure 3 Figure 4 Further, the simplified circuit of the no-fault stage shown in FIG. 6 is obtained:

[0088] As shown in FIG. 7, the equivalent impedance Z 2eq between the A and B phases after the fault disappears is: Figure 5

[0089] As shown in FIG. 8, the equivalent impedance Z 2eq between the A and B phases after the fault disappears is: Figure 5 Z L = 2[R​​​​L +L L +R load +jω(L T +L load )] (3)

[0091] At this time, the disturbance current injection line outlet phase-to-phase voltage is:

[0092]

[0093] From equation (1) and equation (3), when the phase-to-phase short circuit fault occurs, the permanent fault due to the existence of transition resistance, the phase-to-phase equivalent impedance and the phase-to-phase impedance in the fault-free stage exist obvious difference; At this time, the same disturbance current signal is applied to the phase-to-phase circuit, and the disturbance voltage presents different response characteristics, and the results are as shown in equation (2) and equation (4); Therefore, the discrimination method of phase-to-phase fault property can be constructed based on the difference of disturbance voltage.

[0094] 2, the selection of the characteristics of the injection signal

[0095] 1) amplitude

[0096] The selection of the injection signal amplitude mainly considers the measurement accuracy of the distribution line voltage transformer and the output power of the injection device; If the injection signal amplitude is too small, the transformer cannot measure the injection signal, which affects the fault property discrimination; The greater the injection current, the more obvious the phase-to-phase voltage characteristics in the fault duration stage and the fault-free stage, which is more conducive to the application of fault property discrimination method; On the one hand, the greater the injection current, the greater the output power of the single-phase inverter required, and the higher the cost; On the other hand, unlimited increase of the injection current amplitude may cause phase-to-phase insulation breakdown, which makes the transient fault develop into permanent fault; Comprehensive consideration, the injection signal current amplitude is selected as 20A, which meets the requirements of transformer measurement accuracy and single-phase inverter output power.

[0097] 2) frequency

[0098] When the distribution network is in normal operation, the line is equivalent to a capacitor model, and when the phase-to-phase short circuit fault occurs, due to the existence of transition resistance, the line no longer meets the capacitor model; Under the capacitor model, the disturbance voltage U d The expression is:

[0099]

[0100] In the formula, I d is the size of the injected disturbance current, ω d is the angular frequency of the injection signal, and C is the equivalent capacitance between the phases of the fault line.

[0101] The size of the disturbance voltage is affected by the size and frequency of the injected disturbance current. The larger the amplitude of the injected disturbance current and the smaller the frequency, the more obvious the inter-phase disturbance voltage response, which is more conducive to fault property discrimination. However, the amplitude of the injected disturbance current is limited by the output power of the injection device, and it is not appropriate to be too large. In order to reduce the cost, the frequency of the injected disturbance current can be reduced to improve the inter-phase disturbance voltage response. On the other hand, if the frequency of the disturbance current signal is too low, the disturbance voltage period is too long, and the required signal sampling time is longer, which is not conducive to fast power restoration. Therefore, the selected injected disturbance signal frequency is 20Hz.

[0102] 3. Energy relative entropy

[0103] Energy relative entropy is used to represent the similarity of energy spectrum between different signals. The result is accurate, reliable, clear and concise. The greater the energy relative entropy value, the greater the energy difference between the two waveforms. The smaller the result, the higher the similarity of the two waveforms. In particular, when the energy relative entropy of the two waveforms is 0, it means that the two waveforms are completely identical.

[0104] From the definition of energy, after injecting the disturbance current, the energy expression E of the steady-state part of the disturbance voltage is u (t) is:

[0105]

[0106] In the formula, u0(τ) is the measured fault inter-phase voltage, and i0(τ) is the measured injected current value.

[0107] Embodiment

[0108] In order to verify the reliability of the method proposed in the application, a 10kV distribution network active injection disturbance signal fault property discrimination simulation model is built as shown in Figure 6 , the phase switch control strategy is as shown in Figure 7 , the system parameter settings are shown in Table 1; taking the RAB=1Ω short circuit fault at the 11km of the l5 overhead line as an example for illustration; the fault occurs at 0.1s, and the line l5 circuit breaker trips after the fault. Since there is still a large amount of electricity remaining in the distribution line, the residual current is released after a delay of 200ms, and then the disturbance current is injected between the AB phases; the duration of the transient fault is set to 0.7s, and the permanent fault exists throughout the simulation process, and the signal injection time is 0.3s; the AB inter-phase disturbance voltage waveforms under transient fault and permanent fault are as shown in Figure 8 .

[0109] Table 1 System parameter settings

[0110]

[0111] The AB inter-phase disturbance voltage waveforms under transient fault and permanent fault are as shown inFigure 9 and Figure 10 The energy relative entropy of the two time windows of the AB phase disturbance voltage steady-state waveform is calculated by using the energy relative entropy algorithm. The time window 1 is 0.4 s to 0.6 s, and the time window T2 is 1.0 s to 1.2 s. The energy relative entropy calculation results of the transient fault and the permanent fault are shown in Table 2 and Table 3.

[0112] Table 2 Energy relative entropy calculation results in transient fault

[0113]

[0114] Table 3 Energy relative entropy calculation results in permanent fault

[0115]

[0116] It can be seen from the simulation results in Table 2 and Table 3 that in the transient fault, the energy relative entropy values are large in different positions and different transition resistances, and the difference between the two waveforms is large, that is, the two disturbance voltage waveforms have large difference under the transient fault, and the feature is less affected by the fault position and the transition resistance. In the permanent fault, the energy relative entropy values are close to 0 in different positions and different transition resistances, which indicates that the two waveforms are almost the same, that is, the two disturbance voltage waveforms have no obvious difference under the permanent fault, and the feature is less affected by the fault position and the transition resistance. Therefore, according to criterion 1 and the simulation results in Table 2 and Table 3, the transient fault can be preliminarily judged.

[0117] When the active injection method is used to identify the fault property, the fault may disappear before the injection signal, and in this case, it is difficult to distinguish the permanent fault. According to the difference between the disturbance voltage waveforms in the frequency domain under the two conditions, a supplementary criterion for processing the disturbance voltage waveform by using the fast Fourier transform is considered. The fast Fourier transform results under the permanent fault and the fault disappearance are shown in Figure 11 and Figure 12 .

[0118] It can be seen from Figure 11 , Figure 12 that under the same disturbance current, the disturbance voltage time-domain waveforms under the permanent fault and the fault disappearance are similar. The frequency spectrum analysis results show that the amplitude of the 20 Hz frequency component in the disturbance voltage waveform under the permanent fault is 0.179, and when the fault disappears, the amplitude of the 20 Hz frequency component in the disturbance voltage waveform reaches 1.561, which is close to 9 times of that under the permanent fault. Therefore, according to the difference between the frequency domain distributions of the disturbance voltage waveforms, the criterion is used to judge the permanent fault and the fault disappearance before the injection signal.

[0119] In summary, the application proposes an inter-phase fault active fault nature discrimination method based on injected disturbance current response characteristics, proposes injecting a disturbance current signal through an external power supply, and the disturbance signal has obvious differences in response characteristics when permanent faults and transient faults occur, and the differences are used to complete fault nature identification, and simulation verifies the reliability and superiority of the method under different working conditions, the method makes up for the shortcomings of the active injection method in handling fault nature identification, is not affected by the injection time and fault duration, and can realize fault nature discrimination only once, is simple to operate, has small calculation amount, and is highly reliable.

[0120] In this embodiment, the active fault nature discrimination device based on injected disturbance current response characteristics includes a processor and a memory, and the fault detection module, the disturbance signal injection module, the data recording module, the data processing module and the control decision module are electrically connected in sequence:

[0121] The fault detection module is used for monitoring electrical parameters in the power distribution network in real time, including three-phase currents and voltages, and once the occurrence of an inter-phase fault is detected, the three-phase tripping operation of the fault line outlet circuit breaker is triggered immediately to isolate the fault area and prevent the fault from expanding.

[0122] The disturbance signal injection module intelligently controls the closing of the corresponding switch according to the fault phase position determined by the fault detection module, and accurately injects the disturbance current signal into the fault phase.

[0123] The data recording module includes a plurality of split-phase switches (such as S1, S2, S3 and S4), intelligently controls the closing of the corresponding switch according to the fault phase position determined by the fault detection module, and accurately injects the disturbance current signal into the fault phase.

[0124] The data processing module accurately extracts the disturbance voltage waveform data in the preset two time windows T1 and T2 from the recorded disturbance voltage U0(t) so as to analyze the response characteristics of the disturbance voltage.

[0125] The control decision module intelligently outputs a control signal according to the comprehensive judgment result of the data processing module.

[0126] The processor contains a core, and the core retrieves the corresponding program unit from the memory. The core can be set to one or more, and the above-mentioned active fault nature discrimination method based on injected disturbance current response characteristics can be realized by adjusting the core parameters.

[0127] The memory can include a non-permanent memory in a computer readable medium, a random access memory (RAM) and / or a non-volatile memory such as a read-only memory (ROM) or a flash memory (flash RAM), and the memory includes at least one memory chip.

[0128] The embodiment of the present application provides a processor configured to execute the active fault property discrimination method based on the injected disturbance current response characteristic.

[0129] The embodiment of the present application provides a machine readable storage medium, which stores instructions, and the instructions make the processor configured to execute the active fault property discrimination method based on the injected disturbance current response characteristic when executed by the processor.

[0130] Those skilled in the art should understand that the embodiment of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can adopt 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 codes.

[0131] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to the embodiment of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams and the combination of the flows and / or blocks can be implemented by computer program instructions. These computer program instructions can be provided to 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 computer or other programmable data processing device produce a device implemented in the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The function specified in one or more flows and / or blocks

[0132] These computer program instructions can also be stored in a computer readable storage medium capable of guiding the computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer readable storage medium produce a product including instruction devices, which implement the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The function specified in one or more flows and / or blocks

[0133] These computer program instructions can also be loaded into the computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide a process for implementing the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The function specified in one or more flows and / or blocks

[0134] In one typical arrangement, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0135] Memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can read instructions. Memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), programmable read only memory (PROM), or flash memory, about which the processor can read instructions. Memory is an example of computer readable storage media.

[0136] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as 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 programmable read only memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassette, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory media, such as modulated data signals and carrier waves.

[0137] It should also be noted that the terms "comprising", "comprises", "including", "includes" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0138] The embodiments of the present application are given for the purpose of illustration and description, although the embodiments of the present application have been shown and described above, it will be understood by those skilled in the art that the above-mentioned embodiments are exemplary, and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. An active fault nature discrimination method based on injection disturbance current response characteristics, characterized in that: Comprising the following steps: Step one, the system occurs phase-to-phase fault, the fault line outlet breaker tripping, according to the change of three-phase current, voltage before and after the fault, determine the line current increases, the two-phase voltage reduction as fault phase; Step two, after the circuit breaker trips, delay 200ms, control the action of the split-phase switch, inject a disturbance current signal with an amplitude of 20A and a frequency of 20Hz into the fault phase using a single-phase inverter power supply I 0(t), the injection duration is set to 1.2s, and the disturbance voltage in the fault phase is recorded by the fault line head voltage transformer U 0(t); Step three, extracting time window T1 and time window T2 from U 0(t), time window T1 is the 0.4s to 0.6s after the injection of I 0(t), time window T2 is the 1.0s to 1.2s after the injection of I0 (t), and calculating the energy relative entropy value of the two perturbation voltage waveform time windows Hu , setting threshold value If determining as transient fault; otherwise, executing next step; Step four, frequency domain analysis of the disturbance voltage waveform in time window T1 is performed using fast Fourier transform, and a threshold is set Define the amplitude of 20Hz frequency component as A, if permanent fault is determined; otherwise, it is determined that the fault has disappeared when the injection signal is injected.

2. The method of claim 1, wherein the method is characterized by: In step two, the control strategy of the split-phase switch is specifically as follows: Step 2.1, S1, S2, S3, S4 are switch devices for controlling the injection of disturbance current between fault phases, connected between A, B, C three phases of the fault line; Step 2.

2. Depending on the specific case of the faulty phase, inject a disturbance current I0 (t) in order to perform the fault nature discrimination, as follows: If a fault occurs between phases A and B, S1 and S3 are closed, and I 0(t) is injected between phases A and B. If a fault occurs between the B, C phases, S2 and S4 are closed, and I0 (t) injected between the B, C phases; If a fault occurs between the C, A phases, S1 and S4 are closed, and I 0(t) is injected between the C, A phases.

3. The method of claim 1, wherein the method is characterized by: In step three, the calculation of the energy relative entropy Hu is given by: Step 3.1, Calculate the disturbance voltage under time window T1, T2 respectively U The steady state energy of 0(t) E u1 , E u2 To get the energy relative entropy of two time windows Hu ; Step 3.2, then according to energy relative entropy H u The calculation result is compared with the threshold value in step three When , it is determined that the transient short circuit fault occurs; otherwise, the next step is continued.

4. The method of claim 1, wherein the method is characterized by: In step four, the fast Fourier decomposition frequency is set to 10 kHz.

5. An active fault property discrimination device for injecting a disturbance current response feature for active fault property discrimination, using the method of any one of claims 1 to 4 for injecting a disturbance current response feature for active fault property discrimination, characterized by: Comprising: Fault detection module, for real-time monitoring of electrical parameters in power distribution network, including three-phase current and voltage, once the occurrence of phase-to-phase fault is detected, immediately trigger the three-phase tripping operation of the fault line outlet breaker, isolate the fault area, prevent the expansion of the fault; Disturbance signal injection module, according to the fault phase position determined by the fault detection module, intelligent control of the closing of the corresponding switch, accurate injection of disturbance current signal between fault phases; Data recording module, including a plurality of split-phase switches, according to the fault phase position determined by the fault detection module, intelligent control of the closing of the corresponding switch, accurate injection of disturbance current signal between fault phases; The data processing module extracts the perturbation voltage waveform data within the preset two time windows T1 and T2 accurately from the recorded perturbation voltage U0 (t) accurately extracts the perturbation voltage waveform data within the preset two time windows T1 and T2 in order to analyze the response characteristics of the perturbation voltage; Control decision module, according to the comprehensive judgment result of the data processing module, intelligent output control signal.

6. A processor, comprising: The method is configured to perform the active fault nature discrimination method based on the injection of disturbance current response characteristics according to any one of claims 1 to 4.

7. A machine-readable storage medium having stored thereon instructions, the instructions being executable by a machine to cause the machine to perform operations comprising: The instruction, when executed by the processor, causes the processor to be configured to perform the active fault nature discrimination method based on the injection of disturbance current response characteristics according to any one of claims 1 to 4.

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