Active fault property discrimination method based on injection disturbance current response characteristics

Abstract

The invention belongs to the technical field of power system power distribution network relay protection, and provides an active fault property discrimination method based on injection disturbance current response characteristics, which comprises the following steps: step 1, when an inter-phase fault occurs in a system, three-phase tripping of a fault line outlet circuit breaker occurs, and according to three-phase current and voltage change conditions before and after the fault, determining whether the fault occurs or not; determining two phases with increased line current and reduced voltage as fault phases; 2, delaying for 200ms after the circuit breaker trips, and controlling the action of a split-phase switch; according to the method, disturbance current signals are injected through an external power supply, the disturbance signals have obvious difference in response characteristics during permanent faults and instantaneous faults, the reliability and superiority of the method under different working conditions are verified through simulation, the method makes up for the defects of an active injection type method during fault property recognition processing, and the method has the advantages of high reliability and high reliability. The method is not influenced by injection time and fault duration, fault property discrimination can be realized only through one-time injection, and the method is simple in operation, small in calculation amount and high in reliability.

Description

Technical Field

[0001] The invention belongs to the technical field of relay protection of power system distribution network, and in particular to an active fault property identification method based on injection disturbance current response characteristics. Background Art

[0002] In recent years, with the development of new distribution networks, distributed power sources, active inverters and other devices are continuously connected to the distribution network. Active signal injection increases fault identification information, providing new ideas for the study of adaptive reclosing.

[0003] At present, in order to improve the reliability of power supply in the distribution network, a three-phase reclosing device is usually configured at the outlet of the substation to achieve rapid power restoration of instantaneous faults. However, the reclosing device usually does not have the function of fault nature identification. When a permanent fault occurs in the system, blindly performing the reclosing operation may cause the system to suffer from overcurrent shock, which puts the equipment at risk of damage and affects the safe and stable operation of the distribution network. It can be seen that before the reclosing device is activated, it is particularly important to add a fault nature identification link. According to the identification results of the fault nature, formulating a fault recovery strategy is a prerequisite for ensuring that the distribution network is protected from the secondary impact of the short-circuit current and the safe and stable operation of the system. Since the circuit breaker trips after the line short-circuit fault, there is a lack of available information for fault nature identification, which brings difficulties to the research on adaptive reclosing.

[0004] To this end, those skilled in the art have proposed an active fault property identification method based on the response characteristics of the injected disturbance current to solve the problems raised by the background technology. Summary of the invention

[0005] The purpose of the present invention is to provide an active fault nature identification method based on the response characteristics of injected disturbance current, so as to solve the problem of lack of effective electrical quantity information in the line after the circuit breaker trips when the passive adaptive reclosing strategy is adopted in the current traditional distribution line; 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 nature.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] The active fault property identification method based on the injection disturbance current response characteristics includes the following steps:

[0008] Step 1: When a phase-to-phase fault occurs in the system, the three-phase circuit breaker at the fault line outlet trips. According to the changes in the three-phase current and voltage before and after the fault, the two phases with increased line current and reduced voltage are determined to be the faulty phases;

[0009] Step 2: After the circuit breaker trips, the time delay is 200ms, and the phase switch is controlled to operate. A disturbance current signal I0(t) with an amplitude of 20A and a frequency of 20Hz is injected into the fault phase using a single-phase inverter power supply. The injection duration is set to 1.2s, and the disturbance voltage U0(t) between the fault phases is recorded by the voltage transformer at the head end of the fault line.

[0010] 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) injection, and time window T2 is from 1.0s to 1.2s after I0(t) injection. Calculate the energy relative entropy value H of the two disturbance voltage waveform time windows. u , set the threshold like Determine it as a transient fault; otherwise, go to step 4;

[0011] Step 4: Use fast Fourier transform to perform frequency domain analysis on the disturbance voltage waveform in time window T1 and set the threshold Define the amplitude of the 20Hz frequency component as A. If If the fault is positive, it is judged as a permanent fault; otherwise, it is judged that the fault has disappeared when the signal is injected.

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

[0013] Step 2.1, S1, S2, S3, S4 are switch devices for controlling the injection of disturbance current between fault phases, and are connected between the three phases A, B, and C of the fault line; wherein S1 connects the A phase with the single-phase inverter power supply; S2 connects the B phase with one side of the single-phase inverter power supply; S3 connects the B phase with the other side of the single-phase inverter power supply; S4 connects the C phase with 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 identify the fault nature. The specific operation is as follows:

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

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

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

[0018] Preferably, in step 3, the relative entropy H u The specific calculation process is:

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

[0020]

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

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

[0023]

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

[0025]

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

[0027] H u =H u_T1T2 +H u_T2T1

[0028] According to the relative entropy of energy H u The result of the calculation is equal to the threshold in step 3 For comparison, If , it is determined that a transient short circuit fault occurs; otherwise, continue to execute step 4.

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

[0030] An active fault property identification device based on the response characteristics of the injected disturbance current includes:

[0031] The fault detection module is used to monitor the electrical parameters in the distribution network in real time, including three-phase current and voltage. Once a phase-to-phase fault is detected, the three-phase tripping operation of the circuit breaker at the fault line outlet is immediately triggered to isolate the fault area and prevent the fault from expanding.

[0032] 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;

[0033] The data recording module includes a plurality of phase-splitting switches (such as S1, S2, S3, and S4), which intelligently controls the closing of corresponding switches according to the fault phase position determined by the fault detection module, and accurately injects the disturbance current signal into the fault phase;

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

[0035] The control decision module intelligently outputs control signals based on the comprehensive judgment results of the data processing module.

[0036] A processor is configured to execute the above-mentioned active fault property determination method based on injection disturbance current response characteristics.

[0037] A machine-readable storage medium stores instructions, which, when executed by a processor, configure the processor to execute the above-mentioned active fault property determination method based on injected disturbance current response characteristics.

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

[0039] Aiming at the lack of useful fault information in the traditional passive AC adaptive reclosing of distribution network, this active fault nature identification method for phase-to-phase fault based on the response characteristics of injected disturbance current proposes to inject disturbance current signal through an external power supply. There are obvious differences in the response characteristics of disturbance signal in permanent fault and transient fault. The difference is used to complete the fault nature identification, and the reliability and superiority of this method under different working conditions are verified by simulation. This method makes up for the shortcomings of active injection method in dealing with fault nature identification, and is not affected by injection time and fault duration. Only one injection is needed to realize fault nature identification, and the operation is simple, the calculation amount is small, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flow chart of the active fault property identification method based on the injection disturbance current response characteristics of the present invention;

[0041] Figure 2 Schematic diagram of an equivalent circuit for injecting a disturbance signal in the present invention;

[0042] Figure 3 This is a simplified circuit diagram of the fault continuation stage in the present invention;

[0043] Figure 4 It is a schematic diagram of an equivalent circuit in a fault-free stage of the present invention;

[0044] Figure 5It is a simplified circuit diagram of the fault-free stage in the present invention;

[0045] Figure 6 This is a schematic diagram of a fault property discrimination simulation model for actively injecting disturbance signals into a 10kV distribution network according to an embodiment of the present invention;

[0046] Figure 7 A schematic diagram of a phase-splitting switch control strategy of an injection device according to an embodiment of the present invention;

[0047] Figure 8 It is a schematic diagram of the disturbance voltage waveform of the fault phase under transient fault and permanent fault obtained by measurement after the disturbance current is injected in the embodiment of the present invention;

[0048] Fig. 9 Schematic diagram of the disturbance voltage waveform and time window selection of the fault phase during an instantaneous fault in an embodiment of the present invention;

[0049] Fig.10 Schematic diagram of the disturbance voltage waveform and time window selection of the fault phase during a permanent fault in an embodiment of the present invention;

[0050] Fig.11 Schematic diagram of the time domain and frequency domain waveforms of the fault phase disturbance voltage during a permanent fault in an embodiment of the present invention;

[0051] Fig.12 It is a schematic diagram of the time domain and frequency domain waveforms of the fault phase disturbance voltage when the fault disappears when the signal is injected in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0053] Embodiment: The present invention provides an active fault property determination method based on the injection disturbance current response characteristics, and the active fault property determination method based on the injection disturbance current response characteristics comprises the following steps:

[0054] Step 1: When a phase-to-phase fault occurs in the system, the three-phase circuit breaker at the fault line outlet trips. According to the changes in the three-phase current and voltage before and after the fault, the two phases with increased line current and reduced voltage are determined to be the faulty phases;

[0055] Step 2: After the circuit breaker trips, the time delay is 200ms, and the phase switch is controlled to operate. A disturbance current signal I0(t) with an amplitude of 20A and a frequency of 20Hz is injected into the fault phase using a single-phase inverter power supply. The injection duration is set to 1.2s, and the disturbance voltage U0(t) between the fault phases is recorded by the voltage transformer at the head end of the fault line.

[0056] In step 2, the phase switches of the phase switch include S1, S2, S3, and 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, and are connected between the three phases A, B, and C of the fault line; wherein S1 connects the A phase with the single-phase inverter power supply; S2 connects the B phase with one side of the single-phase inverter power supply; S3 connects the B phase with the other side of the single-phase inverter power supply; S4 connects the C phase with the single-phase inverter power supply;

[0058] Step 2.2: Based on the specific situation of the fault phase, inject the disturbance current I0(t) to identify the fault nature. The specific operation is as follows:

[0059] If the fault occurs between phases A and B, close S1 and S3 to inject I0(t) between phases A and B;

[0060] If the fault occurs between phases B and C, close S2 and S4 to inject I0(t) between phases B and C;

[0061] If the fault occurs between phases C and A, close S1 and S4 to inject I0(t) between phases C and A.

[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) injection, and time window T2 is from 1.0s to 1.2s after I0(t) injection. Calculate the energy relative entropy value H of the two disturbance voltage waveform time windows. u , set the threshold like Determine it as a transient fault; otherwise, go to the next step 4;

[0063] In step 3, the relative entropy H u The specific calculation process is:

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

[0065]

[0066]

[0067] Where U0(t) is the measured fault phase-to-phase disturbance voltage, and I0(t) is the injected disturbance current;

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

[0069]

[0070] The relative entropy H of the waveform energy in time window T2 relative to the waveform energy in time window T1 u_T2T1 for:

[0071]

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

[0073] H u =H u_T1T2 +H u_T2T1

[0074] According to the relative entropy of energy H u The result of the calculation is equal to the threshold in step 3 For comparison, If the fault is detected, it is determined that a transient short circuit fault has occurred; otherwise, continue to execute the contents of step 4;

[0075] Step 4: Use fast Fourier transform to perform frequency domain analysis on the disturbance voltage waveform in time window T1 and set the threshold Define the amplitude of the 20Hz frequency component as A. If If the fault is positive, it is determined to be a permanent fault; 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] Furthermore, the working principle of the active fault property identification method based on the injection disturbance current response characteristics of the present invention is:

[0077] 1. Fault feature analysis

[0078] Taking the interphase short circuit fault of phase AB as an example, the equivalent network topology of the fault line after the disturbance current signal is injected is derived, and the difference in the response characteristics of the injected disturbance current during transient faults and permanent faults is analyzed. Figure 2 Equivalent circuit for disturbance signal injection after tripping of the faulty line breaker.

[0079] Figure 2 In the example, the circuit breaker trips, and the fault line is equivalent to a linear passive two-port network. The fault phase is selected to analyze its port response characteristics; where i(t) is the equivalent constant current source of the single-phase inverter, and the disturbance current signal is injected; R A , R B , R C is the line resistance, L A , L B , L C is the line inductance, and R A=R B =R C , L A =L B =L C ; μ is the ratio of the distance from the line head end to the fault point to the length of the entire 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 phase-to-phase fault resistance.

[0080] 1.1 Fault Existence Stage

[0081] like Figure 2 As shown in the figure, after a short circuit fault occurs between phases A and B, due to the transition resistance R AB Due to the existence of the original parameters and structure of the line, different responses will be generated by injecting disturbance current through the constant current source connected to the line outlet. Figure 2 The A and B phase fault duration stage is equivalent to Figure 3 , Figure 3 Simplify the circuit for the fault persistence phase.

[0082] Depend on Figure 3 It can be seen that after the disturbance current is injected, during the fault continuation stage, the equivalent impedance Z between the fault phases A and B is 1eq for:

[0083]

[0084] Furthermore, the disturbance voltage generated by the disturbance current between the AB fault phases can be calculated. for:

[0085]

[0086] 1.2 Fault disappearance stage

[0087] Depend on Figure 3 It can be seen that if a transient fault occurs, the equivalent circuit between phases A and B after the fault disappears can be expressed as Figure 4 Equivalent circuit of the fault-free stage; at this time, the disturbance current is injected from phases A and B, and the voltage disturbance response generated between phases A and B is obviously different from that during the fault.

[0088] Further Figure 5 The simplified circuit for the fault-free phase is shown:

[0089] Depend on Figure 5 It is known that after the fault disappears, the equivalent impedance Z of the phase-to-phase circuit 2eq :

[0090] Z 2eq =2[RL +L L +R load +jω(L T +L load )] (3)

[0091] At this time, the phase-to-phase voltage at the output of the lower line is injected into the disturbance current. for:

[0092]

[0093] It can be seen from equations (1) and (3) that when a phase-to-phase short circuit fault occurs, due to the existence of transition resistance, the phase-to-phase equivalent impedance of the permanent fault is significantly different from the phase-to-phase impedance in the fault-free stage; at this time, when the same disturbance current signal is applied to the phase-to-phase circuit, the disturbance voltage presents different response characteristics, and the results are shown in equations (2) and (4); therefore, a method for distinguishing the nature of the phase-to-phase fault can be constructed based on the difference in disturbance voltage.

[0094] 2. Feature selection of injection signal

[0095] 1) Amplitude

[0096] The selection of the injection signal amplitude is mainly based on 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 nature judgment. The greater the injection signal strength, the more obvious the phase-to-phase voltage characteristics in the fault continuation stage and the fault-free stage, which is more conducive to the application of the fault nature judgment method. However, on the one hand, the larger the injection current, the larger the required single-phase inverter output power and the higher the cost. On the other hand, infinitely increasing the injection current amplitude may cause phase-to-phase insulation breakdown, causing transient faults to develop into permanent faults. Taking all factors into consideration, the injection signal current amplitude is selected to be 20A to meet the requirements of transformer measurement accuracy and single-phase inverter output power.

[0097] 2) Frequency

[0098] When the distribution network operates normally, the line is equivalent to a capacitor model. However, when a phase-to-phase short circuit occurs, the line no longer conforms to the capacitor model due to the presence of transition resistance. Under the capacitor model, the disturbance voltage U d The expression is:

[0099]

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

[0101] The magnitude of the disturbance voltage is affected by the magnitude 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 phase-to-phase disturbance voltage response is, and the more conducive it is to the fault nature judgment. The amplitude of the injected disturbance current is limited by the output power of the injection device and should not be too large. In order to reduce costs, the frequency of the injected disturbance current can be reduced to improve the phase-to-phase disturbance voltage response. On the other hand, if the frequency of the disturbance current signal is too low, the disturbance voltage cycle is too long, and the required signal sampling time is longer, which is not conducive to the rapid restoration of power supply. Therefore, the selected injection disturbance signal frequency is a low frequency of 20Hz.

[0102] 3. Energy relative entropy

[0103] Energy relative entropy is used to characterize the similarity of energy spectra between different signals. The results are accurate, reliable, clear and understandable. The larger the energy relative entropy value, the greater the energy difference between the two waveforms. The smaller the result, the higher the similarity between the two waveforms. In particular, when the energy relative entropy of two waveforms is 0, it means that the two waveforms are exactly the same.

[0104] From the definition of energy, we can know that after the disturbance current is injected, the energy expression of the steady-state part of the disturbance voltage generated is E u (t) is:

[0105]

[0106] Where u0(τ) is the measured fault phase-to-phase voltage, and i0(τ) is the measured injection current value.

[0107] Example

[0108] In order to verify the reliability of the method proposed in the present invention, a Figure 6 The fault nature identification simulation model of the 10kV distribution network actively injecting disturbance signals is shown in the figure. The phase switch control strategy is as follows Figure 7 As shown, the specific parameter settings of the system are shown in Table 1; take the RAB=1Ω short-circuit fault at 11km of the l5 overhead line as an example for explanation; the fault occurs at 0.1s, and the line l5 circuit breaker trips after the fault. Since there is still a large amount of residual electricity 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, the permanent fault exists in the entire simulation process, and the signal injection time is 0.3s; the disturbance voltage waveform between the AB phases under the transient fault and permanent fault is as follows Figure 8 .

[0109] Table 1 System parameter settings

[0110]

[0111] The disturbance voltage waveform between phases AB during transient faults and permanent faults is as follows: Fig. 9 and Fig.10 As shown; two time windows are intercepted in the steady-state waveform of the AB phase disturbance voltage, and the energy relative entropy algorithm is used for calculation; time window 1 is 0.4s~0.6s, and time window T2 is 1.0s~1.2s; the energy relative entropy calculation results of the disturbance voltage of transient fault and permanent fault are shown in Table 2 and Table 3;

[0112] Table 2 Calculation results of relative entropy of energy during transient faults

[0113]

[0114] Table 3 Calculation results of relative entropy of energy in case of permanent fault

[0115]

[0116] It can be seen from the simulation results of Table 2 and Table 3 that, in the case of instantaneous faults, the relative entropy of energy is large at different positions and different transition resistances, and the difference between the two waveforms is large, that is, under the instantaneous fault, the two disturbance voltage waveforms have a large difference, and this feature is less affected by the fault position and transition resistance; in the case of permanent faults, the relative entropy of energy is close to 0 at different positions and different transition resistances, indicating that the two waveforms are almost the same, that is: under permanent faults, there is no obvious difference between the two disturbance voltage waveforms, and this feature is less affected by the fault position and transition resistance; therefore, according to Criterion 1 combined with the simulation results of Table 2 and Table 3, a transient fault can be preliminarily judged.

[0117] When the active injection method is used to identify the nature of the fault, there may be a situation where the fault has disappeared before the signal is injected. In this case, it is difficult to distinguish it from the permanent fault condition. According to the different frequency domain responses of the disturbance voltage in the two cases, it is considered to add a supplementary criterion of using fast Fourier transform to process the disturbance voltage waveform and observe the difference between the two voltage disturbance waveforms in the frequency domain. The fast Fourier transform results of the two cases of permanent fault and the disappeared fault are shown in Fig.11 and Fig.12 shown.

[0118] Depend on Fig.11 , Fig.12 It can be seen that under the same disturbance current, the time domain waveforms of the disturbance voltage are similar under the two conditions of permanent fault and the disappearance of the fault before the injection signal. The spectrum analysis results show that in the case of permanent fault, the amplitude of the 20Hz frequency component in the disturbance voltage waveform is 0.179; when the fault disappears, the 20Hz frequency component in the disturbance voltage waveform reaches 1.561, which is close to 9 times that of the permanent fault. Therefore, according to the difference in the frequency domain distribution of the disturbance voltage waveform, the judgment criteria are used to judge the permanent fault and the disappearance of the fault before the injection signal.

[0119] In summary, the present invention proposes an active fault property discrimination method for phase-to-phase faults based on the response characteristics of injected disturbance current, and proposes to inject disturbance current signals through an external power supply. There are obvious differences in the response characteristics of the disturbance signals when there are permanent faults and transient faults. The difference is used to complete the fault property identification, and the reliability and superiority of the method in this paper under different working conditions are verified through simulation. This method makes up for the shortcomings of the active injection method in dealing with fault property identification, and is not affected by the injection time and fault duration. Only one injection is required to realize the fault property discrimination, and the operation is simple, the calculation amount is small, and the reliability is high.

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

[0121] The fault detection module is used to monitor the electrical parameters in the distribution network in real time, including three-phase current and voltage. Once a phase-to-phase fault is detected, the three-phase tripping operation of the circuit breaker at the fault line outlet is immediately triggered 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 phase-splitting switches (such as S1, S2, S3, and S4), which intelligently controls the closing of corresponding switches 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 within two preset 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 control signals based on the comprehensive judgment results of the data processing module.

[0126] The processor includes a kernel, and the kernel retrieves the corresponding program unit from the memory. One or more kernels can be provided, and the above-mentioned active fault property identification method based on the injection disturbance current response characteristics is implemented by adjusting kernel parameters.

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

[0128] An embodiment of the present application provides a processor configured to execute the above-mentioned active fault property determination method based on the injected disturbance current response characteristics.

[0129] An embodiment of the present application provides a machine-readable storage medium having instructions stored thereon. When the instructions are executed by a processor, the processor is configured to execute the above-mentioned active fault property determination method based on the injected disturbance current response characteristics.

[0130] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0131] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0132] 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.

[0133] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

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

[0135] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0136] Computer readable media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0137] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device that includes the elements.

[0138] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An active fault property identification method based on the response characteristics of the injected disturbance current, characterized in that: The following steps are involved: Step 1: When a phase-to-phase fault occurs in the system, the three-phase circuit breaker at the fault line outlet trips. According to the changes in the three-phase current and voltage before and after the fault, the two phases with increased line current and reduced voltage are determined to be the fault phases; Step 2: After the circuit breaker trips, delay 200ms to control the phase switch to operate, and use the single-phase inverter power supply to inject a disturbance current signal with an amplitude of 20A and a frequency of 20Hz into the fault phase. I 0(t), the injection duration is set to 1.2s, and the disturbance voltage between the fault phases is recorded by the voltage transformer at the head end of the fault line U 0(t); Step 3: From U 0(t), time window T1 and time window T2 are extracted. Time window T1 is I From 0.4s to 0.6s after 0(t) injection, the time window T2 is I0 (t) From 1.0s to 1.2s after injection, calculate the energy relative entropy value of the two disturbance voltage waveform time windows Hu , set the threshold like Determine it as a transient fault; otherwise, proceed to the next step; Step 4: Use fast Fourier transform to perform frequency domain analysis on the disturbance voltage waveform in time window T1 and set the threshold Define the amplitude of the 20Hz frequency component as A. If If the fault is positive, it is judged as a permanent fault; otherwise, it is judged that the fault has disappeared when the signal is injected.

2. The active fault property identification method based on the injection disturbance current response characteristics as claimed in claim 1, characterized in that: In step 2, the control strategy of the phase switch includes the following specific steps: Step 2.1, S1, S2, S3, S4 are switch devices for controlling the injection of disturbance current between fault phases, and are connected between the three phases A, B, and C of the fault line; Step 2.2: Inject disturbance current based on the specific situation of the fault phase I0 (t) In order to identify the nature of the fault, the specific operations are as follows: If the fault occurs between phases A and B, close S1 and S3 to I 0(t) is injected between phases A and B; If the fault occurs between phases B and C, close S2 and S4 to I0 (t) injected between phases B and C; If the fault occurs between phases C and A, close S1 and S4 to I 0(t) is injected between phases C and A.

3. The active fault property identification method based on the injection disturbance current response characteristics as claimed in claim 1, characterized in that: In step three, the energy relative entropy Hu The specific calculation process is: Step 3.1, calculate the disturbance voltage in time windows T1 and T2 respectively U Steady-state energy at 0(t) E u1 , E u2 , to obtain the relative entropy of energy in two time windows Hu ; Step 3.2, then according to the energy relative entropy H u The calculation result and the threshold in step 3 For comparison, If it is, it is determined that a transient short circuit fault occurs; otherwise, proceed to the next step.

4. The active fault property identification method based on the injection disturbance current response characteristics as claimed in claim 1, characterized in that: In step 4, the fast Fourier decomposition frequency is set to 10 kHz.

5. An active fault property identification device for active fault property identification based on injection disturbance current response characteristics using the active fault property identification method based on injection disturbance current response characteristics according to any one of claims 1 to 4, characterized in that: include: The fault detection module is used to monitor the electrical parameters in the distribution network in real time, including three-phase current and voltage. Once a phase-to-phase fault is detected, the three-phase tripping operation of the circuit breaker at the fault line outlet is immediately triggered to isolate the fault area and prevent the fault from expanding. 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; The data recording module includes a plurality of phase-splitting switches, which intelligently controls the closing of corresponding switches according to the fault phase position determined by the fault detection module, and accurately injects the disturbance current signal into the fault phase; The data processing module records the disturbance voltage U0 (t) accurately extracts the disturbance voltage waveform data within the two preset time windows T1 and T2 in order to analyze the response characteristics of the disturbance voltage; The control decision module intelligently outputs control signals based on the comprehensive judgment results of the data processing module.

6. A processor, characterized in that: The method is configured to execute the active fault property determination method based on injected disturbance current response characteristics according to any one of claims 1 to 4.

7. A machine-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor is configured to execute the active fault property determination method based on injected disturbance current response characteristics according to any one of claims 1 to 4.

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