Self-adaptive reclosing method, device, equipment and medium

Abstract

The invention provides a self-adaptive reclosing method, device, equipment and medium, and the method comprises the steps: switching on a switch module to switch on a power transmission line after an inter-phase fault occurs in the power transmission line, and detecting the voltage of the power transmission line to obtain a first voltage of the switch module; obtaining a first fault current in the power transmission line, determining a first three-phase voltage of the power transmission line according to the first voltage, conducting a switch module, and calculating a first reclosing fault impedance according to the first three-phase voltage and the first fault current; when the conduction time of the switch module reaches a preset first time, obtaining a second three-phase voltage and a second fault current of the switch module, and calculating a second reclosing fault impedance; and determining the fault type of the power transmission line according to the first reclosing fault impedance and the second reclosing fault impedance, and carrying out self-adaptive reclosing operation. According to the technical scheme of the embodiment, the fault type of the power transmission line can be accurately judged, and secondary damage to electric equipment is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution networks, and in particular to an adaptive reclosing method, device, electronic equipment, and storage medium. Background Art

[0002] The power supply reliability index of the distribution network mainly includes the average annual power outage time and frequency of power outages for users. As a key link directly facing users, the fault handling level of the low-voltage distribution network directly affects the power supply quality of users. At present, the automatic reclosing function is widely used in drip switches, that is, after a low-voltage line fault, the switch will first trip, and then automatically reclose after the set reclosing time. If the line fault has disappeared before the automatic reclosing, that is, the instantaneous fault can quickly restore power supply, but if it is a permanent fault, a short-circuit current will be generated again after closing, and the protection will trip again, increasing the number and duration of power outages, causing secondary damage to electrical equipment. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an adaptive reclosing method, device, equipment and medium, which can avoid accurately judging the fault of the line and avoid secondary harm to the electrical equipment.

[0004] In a first aspect, an embodiment of the present invention provides an adaptive reclosing method, which is applied to a power distribution system, wherein the power distribution system includes a transmission line, a power distribution module, a load, and a switch module, wherein the transmission line is connected to the power distribution module, the load, and the switch module, respectively, and the adaptive reclosing method includes: When an interphase fault occurs in the power transmission line, the switch module is turned on to close the power transmission line, and the voltage of the power transmission line is detected to obtain a first voltage of the switch module; Acquire a first fault current in the transmission line, confirm a first three-phase voltage of the transmission line according to the first voltage and turn on the switch module, and calculate a first coincidence fault impedance according to the first three-phase voltage and the first fault current; When the on-time of the switch module reaches a preset first time, obtaining a second three-phase voltage and a second fault current of the switch module, and calculating a second coincident fault impedance according to the second three-phase voltage and the second fault current; The fault type of the transmission line is determined according to the first reclosing fault impedance and the second reclosing fault impedance, and an adaptive reclosing operation is performed according to the fault type. When the fault type is a permanent phase-to-phase fault, the switch module trips the fault phase of the transmission circuit and locks the fault phase. When the fault type is a transient phase-to-phase fault, the switch module keeps reclosing the transmission line.

[0005] In some embodiments of the present invention, a fault voltage of the switch module and a preset rated voltage of the transmission line are determined; When the fault voltage is less than 80% of the rated voltage, it is determined that the transmission line where the switch module is located after being turned on is a permanent ground fault; When the power transmission line has a permanent ground fault, the switch module is locked.

[0006] In some embodiments of the present invention, the switch module is provided with a first switch unit, a second switch unit and a third switch unit, the first switch unit is provided at the first phase of the transmission line, the second switch unit is provided at the second phase of the transmission line, the third switch unit is provided at the third phase of the transmission line, the first switch unit, the second switch unit and the third switch unit are all provided with a first switch and a first thyristor, one end of a plurality of the first switches is connected to the power distribution module, the other end of a plurality of the first switches is connected to the load, the first thyristor is connected in parallel to the first switch, and the determining of the fault type of the transmission line according to the first coincident fault impedance and the second coincident fault impedance includes: Determining fault lines of a first phase, a second phase, and a third phase in the transmission line; When the first switch trips the fault line, a conduction signal is sent to the first thyristor; collecting, according to a preset sampling frequency, a first transient current, a second transient current, and a third transient current when the first thyristor of the fault line is in the first phase, the second phase, and the third phase; Calculating first transient information of an instantaneous current product between the first transient current and the second transient current, second transient information of an instantaneous current product between the second transient current and the third transient current, and third transient information of an instantaneous current product between the first transient current and the third transient current; Obtaining a maximum transient information value and a minimum transient information value among the first transient information, the second transient information, and the third transient information; A fault confirmation value is obtained according to the maximum transient information value and the minimum transient information value, and a fault type of the power transmission line is determined according to the fault confirmation value.

[0007] In some embodiments of the present invention, the confirming the fault type of the power transmission line according to the fault confirmation value includes: Determining a determination value of the fault confirmation value; When the fault confirmation value is greater than the determination value, the fault type is determined to be a transient fault, and the transmission line uses three-phase automatic reclosing to restore power supply; When the fault confirmation value is less than the determination value, the fault type is determined to be a permanent fault, and the first switch, the second switch, and the third switch are locked.

[0008] In some embodiments of the present invention, the switch module is further provided with a fifth switch unit and a sixth switch unit, the fifth switch unit is provided with a fourth switch and a fifth switch, the fourth switch and the fifth switch are both connected to the power distribution module, the sixth switch unit is provided with a seventh switch, an eighth switch and a ninth switch, the fourth switch and the seventh switch are provided at the first phase of the transmission line, the fifth switch and the eighth switch are provided at the second phase of the transmission line, the ninth switch is provided at the third phase of the transmission line, and a first resistor is further connected between the second phase and the third phase of the transmission line, and when a phase-to-phase fault occurs in the transmission line, an adaptive reclosing operation is performed according to the fault type, including: When the fault type between the transmission lines is a phase-to-phase fault, determining a faulty line of the transmission lines; Performing a first closing operation on the fifth switch or the sixth switch, and the eighth switch of the faulty line; Acquire a zero-sequence voltage and a zero-sequence current of the load, and obtain the first coincidence fault impedance when the first switch is closed according to the zero-sequence voltage and the zero-sequence current; Obtaining a first impedance of the first phase, a second impedance of the second phase, and a resistance value of the first resistor; A first impedance amplitude of the first coincident fault impedance under the permanent fault at the time of the first closing is calculated according to the first impedance, the second impedance and the resistance value, and a second impedance amplitude of the first coincident fault impedance under the transient fault at the time of the first closing is calculated.

[0009] In some embodiments of the present invention, after obtaining the first coincidence fault impedance at the time of the first closing according to the zero-sequence voltage and the zero-sequence current, the method further includes: Performing a second closing operation on the fifth switch or the sixth switch, and the seventh switch and the eighth switch; Obtain a third impedance of the first phase and a fourth impedance of the second phase, and calculate a third impedance amplitude of the second coincident fault impedance under the permanent fault when the second circuit is closed according to the third impedance, the fourth impedance and the resistance value, and a fourth impedance amplitude of the second coincident fault impedance under the transient fault when the second circuit is closed.

[0010] In some embodiments of the present invention, determining the fault type of the transmission line according to the first coincident fault impedance and the second coincident fault impedance includes: Obtaining setting values ​​of the first coincident fault impedance and the second coincident fault impedance; When the ratio of the first coincident fault impedance to the second coincident fault impedance is greater than the set value, it is determined that a permanent fault exists in the transmission line.

[0011] In a second aspect, an embodiment of the present invention provides an adaptive reclosing device, comprising at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor so that the at least one control processor can execute the adaptive reclosing method as described in the first aspect above.

[0012] In a third aspect, an embodiment of the present invention provides an electronic device, comprising the adaptive reclosing device as described in the second aspect above.

[0013] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the adaptive reclosing method as described in the first aspect above.

[0014] The adaptive reclosing method according to the embodiment of the present invention has at least the following beneficial effects: When a phase-to-phase fault occurs in the transmission line, the switch module is turned on to close the transmission line, and the voltage of the transmission line is detected to obtain a first voltage of the switch module; the first fault current in the transmission line is obtained, the first three-phase voltage of the transmission line is confirmed according to the first voltage, and the switch module is turned on, and the first reclosing fault impedance is calculated according to the first three-phase voltage and the first fault current; when the on-time of the switch module reaches the preset first time, the second three-phase voltage and the second fault current of the switch module are obtained, and the second reclosing fault impedance is calculated according to the second three-phase voltage and the second fault current; the fault type of the transmission line is determined according to the first reclosing fault impedance and the second reclosing fault impedance, and an adaptive reclosing operation is performed according to the fault type. When the fault type is a permanent phase-to-phase fault, the switch module trips the fault phase of the transmission circuit and locks the fault phase. When the fault type is a transient phase-to-phase fault, the switch module keeps reclosing the transmission line. According to the technical solution of this embodiment, the fault type of the transmission line can be accurately determined. When the transmission line has a transient fault, the switch module automatically recloses. When the transmission line has a permanent fault, the switch module is locked, thereby avoiding secondary harm to electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of an adaptive reclosing method provided by an embodiment of the present invention; Figure 2 is a flow chart after obtaining the first voltage of the switch module according to an embodiment of the present invention; Figure 3 is a flow chart of determining the fault type of a power transmission line according to a first coincident fault impedance and a second coincident fault impedance according to an embodiment of the present invention; Figure 4 is a flow chart of confirming the fault type of a power transmission line according to a fault confirmation value according to an embodiment of the present invention; Figure 5 is a flow chart of an adaptive reclosing operation according to a fault type according to an embodiment of the present invention; Figure 6 This is a flow chart after obtaining the first reclosing fault impedance at the first closing time according to the zero-sequence voltage and the zero-sequence current in an embodiment of the present invention; Figure 7 is a flow chart after determining the fault type of the transmission line according to the first coincident fault impedance and the second coincident fault impedance according to an embodiment of the present invention; Figure 8 is a structural diagram of an adaptive reclosing device provided by another embodiment of the present invention; Fig. 9 is a schematic structural diagram of a first switch unit, a second switch unit and a third switch unit in an embodiment of the present invention; Fig.10 is a schematic structural diagram of a fourth switch unit and a fifth switch unit in an embodiment of the present invention; Fig.11 is an equivalent circuit diagram of closing one phase in case of a phase-to-phase ground fault according to an embodiment of the present invention; Fig.12 is a schematic diagram of closing one phase of the grounding switch according to an embodiment of the present invention; Fig.13 is a simplified equivalent circuit diagram of one phase of the grounding switch in the embodiment of the present invention; Fig.14 is a schematic diagram of another phase of the grounding switch of the embodiment of the present invention being closed; Fig.15 is a simplified equivalent circuit diagram of another phase of the grounding switch of an embodiment of the present invention when the grounding switch is closed; Fig.16 is a schematic diagram of the structure of a distribution network simulation system model according to an embodiment of the present invention; Fig.17 is a permanent fault closing impedance waveform diagram of an embodiment of the present invention; Fig.18 is a waveform diagram of instantaneous fault closing impedance according to an embodiment of the present invention; Fig.19is a schematic diagram of a low-voltage distribution network model according to an embodiment of the present invention; Fig. 20 is a two-phase instantaneous fault waveform diagram of an embodiment of the present invention; Fig.21 It is a two-phase permanent fault waveform diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0017] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0018] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0019] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0020] The embodiment of the present invention provides an automatic reclosing method, which is applied to a power distribution system. Fig. 9 and Fig.10The power distribution system includes a transmission line, a distribution module, a load and a switch module, and the transmission line is connected to the distribution module, the load and the switch module respectively. Further, the switch module is provided with a first switch unit, a second switch unit and a third switch unit, the first switch unit is provided at the first phase of the transmission line, the second switch unit is provided at the second phase of the transmission line, and the third switch unit is provided at the third phase of the transmission line. The first switch unit, the second switch unit and the third switch unit are all provided with a first switch and a first thyristor, one end of the plurality of first switches are all connected to the distribution module, the other end of the plurality of first switches are all connected to the load, the first thyristor is connected in parallel to the first switch, the switch module is also provided with a fifth switch unit and a sixth switch unit, the fifth switch unit is provided with a fourth switch and a fifth switch, the fourth switch and the fifth switch are both connected to the distribution module, the sixth switch unit is provided with a seventh switch, an eighth switch and a ninth switch, the fourth switch and the seventh switch are provided at the first phase of the transmission line, the fifth switch and the eighth switch are provided at the second phase of the transmission line, the ninth switch is provided at the third phase of the transmission line, and a first resistor is also connected between the second phase and the third phase of the transmission line.

[0021] It should be noted that the multiple first switches are all low-voltage switches, and the multiple first switches are T1, T2 and T3 respectively. When the multiple first switches are tripped, the three-phase electronic switch is connected in series in the transmission line, and the drive circuit is controlled by the PWM pin of the microcontroller to make the multiple first thyristors change from a low level to a high level, and finally the multiple first switches in the switch module are turned on.

[0022] In this embodiment, there is no need to add an additional AC voltage source. It is only necessary to control the conduction angle and conduction time of the switch module to generate a transient current that can be used for permanent fault identification. In addition, the power distribution system does not generate a switch module with secondary impact and its corresponding automatic reclosing strategy. When the transmission line is accurately determined to be a transient fault, the switch module realizes three-phase automatic reclosing. In the case of a permanent fault, the switch module automatically locks the reclosing.

[0023] The control method of the embodiment of the present invention is further described below based on the accompanying drawings.

[0024] Reference Figure 1 , Figure 1 A flowchart of an adaptive reclosing method provided in an embodiment of the present invention, the adaptive reclosing method includes but is not limited to the following steps: Step S11, when an interphase fault occurs in the transmission line, the switch module is turned on to close the transmission line, and the voltage of the transmission line is detected to obtain a first voltage of the switch module; It should be noted that when a phase-to-phase fault occurs in the line, the fourth switch unit of the conduction switch module adopts single-phase closing to close a faulty phase A, and then detects the first voltage of the reclosing phase A.

[0025] Step S12, obtaining a first fault current in the transmission line, confirming a first three-phase voltage of the transmission line according to the first voltage and turning on the switch module, and calculating a first coincidence fault impedance according to the first three-phase voltage and the first fault current; It should be noted that when the first voltage is the rated voltage, the fifth switch unit can also detect the first three-phase voltage close to the rated voltage. When the fifth switch unit is turned on to overlap the second phase of the transmission line, the fourth switch unit will detect the jump of the first phase voltage from high to low and a small fault current will flow through. At this time, the first three-phase voltage of the first phase overlapped at the fourth switch unit is divided by the first fault current to obtain the first overlapping fault impedance.

[0026] Step S13, when the conduction time of the switch module reaches the preset first time, obtaining the second three-phase voltage and the second fault current of the switch module, and calculating the second coincidence fault impedance according to the second three-phase voltage and the second fault current; It should be noted that when the fifth switch unit recloses the third phase 100ms after the fourth switch unit recloses the second phase, the fourth switch unit will detect that both the voltage and current of the first phase have changed. At this time, the second three-phase voltage of the first phase reclosed by the fourth switch unit is divided by the second fault current to obtain the second reclosing fault impedance.

[0027] Step S14, determining the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance, and performing adaptive reclosing operation according to the fault type. When the fault type is a permanent phase-to-phase fault, the switch module trips the faulty phase of the transmission circuit and locks the faulty phase. When the fault type is a transient phase-to-phase fault, the switch module keeps reclosing the transmission line.

[0028] It should be noted that the ratio of the first reclosing fault impedance to the second reclosing fault impedance is obtained. When the ratio of the two is greater than 1.75, it can be determined that a permanent phase-to-phase fault occurs in the transmission line, and the fourth switch unit will trip the first phase and lock the automatic reclosing switch. At this time, after the fifth switch unit detects that the three-phase voltage and fault current of the transmission line disappear, it will trip the second and third phases that have been reclosed. When the ratio of the first reclosing fault impedance to the second reclosing fault impedance is less than 1.75, it can be determined that a transient phase-to-phase fault occurs in the transmission line, and the fourth switch unit will keep reclosing the first phase. When the fifth switch unit detects that the low voltage and current last for more than 500ms, it will trip the first and second phases that are reclosed. At this time, the fourth switch unit will detect the jump from low to high in the three-phase voltage of the first phase, and then reclose the remaining two phases to restore the line power supply.

[0029] It should be noted that the switch module and its corresponding automatic reclosing strategy are used to determine the fault of the transmission line so that the distribution system will not produce secondary impact. When it is accurately determined that the transmission line has a transient fault, the switch module realizes three-phase automatic reclosing. In the case of a permanent fault, the switch module automatically locks the reclosing.

[0030] In addition, in one embodiment, referring to Figure 2 ,exist Figure 1 After step S11 of the illustrated embodiment, the following steps are also included but not limited to: Step S21, determining the fault voltage of the switch module and the preset rated voltage of the transmission line; Step S22, when the fault voltage is less than 80% of the rated voltage, it is determined that the transmission line where the switched-on switch module is located is a permanent ground fault; Step S23: When the power transmission line has a permanent ground fault, the switch module is locked.

[0031] It should be noted that when a phase-to-phase fault occurs in the transmission line, the fourth switch unit uses single-phase closing to close the first phase after the fault, and then detects the fault voltage of the first phase after reclosing. When the fault voltage is less than 80% of the rated voltage, it can be determined that a permanent grounding fault has occurred in the reclosing line. At this time, the first phase after reclosing is tripped and the automatic reclosing is locked.

[0032] In addition, in one embodiment, referring to Figure 3 ,exist Figure 1 Step S14 of the illustrated embodiment also includes but is not limited to the following steps: Step S31, determining the fault lines of the first phase, the second phase and the third phase in the transmission line; Step S32, after the first switch trips the fault line, a conduction signal is sent to the first thyristor; Step S33, collecting a first transient current, a second transient current and a third transient current when the first thyristor of the fault line is in the first phase, the second phase and the third phase according to a preset sampling frequency; Step S34, calculating first transient information of the instantaneous current product between the first transient current and the second transient current, second transient information of the instantaneous current product between the second transient current and the third transient current, and third transient information of the instantaneous current product between the first transient current and the third transient current; Step S35, obtaining a maximum transient information value and a minimum transient information value among the first transient information, the second transient information, and the third transient information; Step S36, obtaining a fault confirmation value according to the maximum transient information value and the minimum transient information value, and determining the fault type of the transmission line according to the fault confirmation value.

[0033] It should be noted that when a phase-to-phase fault occurs in the transmission line, after the switch module executes the overcurrent protection to trip the fault line, a delay of 300ms is used to release the influence of the residual charge of the fault line. Then the single-chip microcomputer sends a PWM pulse to control the first switch, the second switch or the third switch in the fault phase to turn on half of the power frequency cycle (about 10ms), and the first transient current of the fault phase in half a cycle when the switch module is turned on is collected at a sampling frequency of 100kHz. i A (k), the second transient current i B (k) and the third transient current i C (k), where k = 1, 2, 3 ... N, N = 1000. Then the average values ​​of the first transient current, the second transient current and the third transient current are calculated, and finally the first transient information, the second transient information and the third transient information are obtained.

[0034] The first transient information, the second transient information and the third transient information are calculated and expressed by the following formula: ; in, is the first transient information, is the second transient information, It is the third transient information.

[0035] Find the maximum transient information value and the minimum transient information value among the first transient information, the second transient information, and the third transient information, and obtain the fault confirmation value according to the maximum transient information value and the minimum transient information value, which is expressed by the following second formula: in, is the maximum transient information value, is the minimum transient information value, and KR is the fault confirmation value.

[0036]

[0037] In addition, in one embodiment, referring to Figure 4 ,exist Figure 3 Step S36 of the illustrated embodiment also includes but is not limited to the following steps: Step S41, determining a determination value of a fault confirmation value; Step S42, when the fault confirmation value is greater than the determination value, the fault type is determined to be a transient fault, and the transmission line adopts three-phase automatic reclosing to restore power supply; Step S43: when the fault confirmation value is less than the determination value, the fault type is determined to be a permanent fault, and the switch module is locked.

[0038] It should be noted that when the fault confirmation value KR>300, the fault in the distribution system is determined to be a transient fault, and the distribution system can use three-phase automatic reclosing to restore power supply. When KR<300, it can be confirmed that the fault in the distribution system is a permanent fault, and the reclosing switch is locked.

[0039] In addition, in one embodiment, referring to Figure 5 ,exist Figure 1 Step S11 of the illustrated embodiment also includes but is not limited to the following steps: Step S51, when the fault type between the transmission lines is a phase-to-phase fault, determining the fault line of the transmission line; Step S52, performing a first closing operation on the fifth switch or the sixth switch and the eighth switch of the faulty line; Step S53, obtaining the zero-sequence voltage and zero-sequence current of the load, and obtaining the first coincidence fault impedance at the time of the first closing according to the zero-sequence voltage and zero-sequence current; Step S54, obtaining a first impedance of the first phase, a second impedance of the second phase, and a resistance value of the first resistor; Step S55, calculating a first impedance amplitude of the first coincident fault impedance under a permanent fault at the first closing according to the first impedance, the second impedance and the resistance, and a second impedance amplitude of the first coincident fault impedance under a transient fault at the first closing.

[0040] It should be noted that the first coincident fault impedance is the ratio of the zero-sequence voltage to the zero-sequence current on the load side, which is expressed by the following third formula:

[0041] is the first coincident fault impedance, A is the voltage of the first phase, B is the voltage of the second phase, C is the voltage of the first phase, A is the current of the first phase, B is the current of the second phase, C is the current of the first phase.

[0042] Reference Fig.13 , it can be concluded that , , then the first impedance amplitude of the grounding switch when it is closed for the first time under a permanent fault is expressed by the following fourth formula: ; is the first impedance amplitude, is the first impedance, is the resistance value of the first resistor.

[0043] The second impedance amplitude of the switch module under the instantaneous fault is expressed by the following fifth formula:

[0044] is the second impedance amplitude.

[0045] In addition, in one embodiment, referring to Figure 6 ,exist Figure 5 After step S53 in the illustrated embodiment, the following steps are also included but not limited to: Step S61, performing a second closing operation on the fifth switch or the sixth switch and the eighth switch; Step S62, obtaining the third impedance of the first phase and the fourth impedance of the second phase, and calculating the third impedance amplitude of the second coincident fault impedance under a permanent fault when the second circuit is closed according to the third impedance, the fourth impedance and the resistance value, and the fourth impedance amplitude of the second coincident fault impedance under a transient fault when the second circuit is closed.

[0046] It should be noted that, refer to Fig.11 , the eighth switch is a grounding switch. When the fifth switch is closed, the eighth switch is closed again, or, after the sixth switch is closed, the eighth switch is closed again. The equivalent circuit at this time is as follows: Fig.15 As shown, we can get .

[0047] Then the third impedance amplitude of the second closing of the grounding switch under the permanent fault of the transmission line is expressed by the following sixth formula: ; in, is the third impedance amplitude.

[0048] The fourth impedance amplitude of the second closing of the grounding switch under the instantaneous fault of the transmission line is expressed by the following seventh formula: ,in, is the fourth impedance amplitude.

[0049] In addition, in one embodiment, referring to Figure 7 ,exist Figure 1 Step S14 of the illustrated embodiment also includes but is not limited to the following steps: Step S71, obtaining setting values ​​of the first coincident fault impedance and the second coincident fault impedance; Step S72: When the ratio of the first coincident fault impedance to the second coincident fault impedance is greater than a set value, it is determined that a permanent fault exists in the transmission line.

[0050] It should be noted that the first ratio is obtained according to the first impedance amplitude and the third impedance amplitude of the grounding switch under the permanent fault, and is expressed by the following eighth formula: ; in, is the first ratio.

[0051] The fourth ratio is calculated according to the second impedance amplitude and the fourth impedance amplitude of the grounding switch of the instantaneous fault, and is expressed by the following ninth formula: ; in, is the second ratio.

[0052] In this embodiment, the setting value is set to the average of the first ratio and the second ratio (1.75 in this example). That is, when the ratio of the first closing of the eighth switch to the second closing is calculated to be greater than 1.75, it can be considered that a permanent fault exists in the closing line.

[0053] Simulation Example 1: Reference Figures 10 to 15 , a simulation model of a 10kV system is established in PSCAD / EMTDC, such as Fig.10 The specific parameters of the model are as follows: The length of each section is as follows: L1=5.1km, L2=3km, L3=10km, L4=2km, L5=2km, L6=7km, L7=2km, L8=3km, L9=5km, L10=5km, L11=5km, L12=4km, L13=4km. The cable parameters are: r1=0.141Ω / km, x1=0.068Ω / km, b1=2.4MΩ*m, r0=0.276Ω / km, x0=0.273Ω / km, b0=3MΩ*m. The parameters of the overhead insulated line are r1=0.243Ω / km, x1=0.3168Ω / km, b1=283.19MΩ*m, r0=0.378Ω / km, x0=0.325Ω / km, b0=1339MΩ*m. A fault is set at point F1, the fault resistance is 20Ω, the fault disappearance time is set to 0.8s for transient faults, and the fault duration is set to 1.5 for permanent faults. The entire simulation process lasts for 1.5s.

[0054] The simulation is set to close the B phase of the grounding switch at t=1.1s, and the C phase at t=1.3s. The simulation results show that the closing impedances calculated for the two closings under different fault properties are as follows: Figure 6 and Figure 7 As shown in the figure, it can be seen that under permanent fault, the first closing impedance calculation value is 35.9Ω; the second closing impedance calculation value is 24.3Ω, and the ratio between them is 1.477, which is very close to the theoretical analysis value; under transient fault, the first closing impedance calculation value is 377.2Ω; the second closing impedance calculation value is 189.3Ω, and the ratio between them is 1.992, which is basically consistent with the theoretical analysis value 2. Therefore, the threshold of 1.75 can be used to distinguish whether there is a permanent fault in the closing line.

[0055] Simulation Example 2: Reference Figures 16 to 21 , using PSCAD / EMTDC to build a 0.4kV low-voltage distribution network model. Among them, the base-state distribution capacity is 315kVA, the user scale is 73 households, of which 68 are single-phase meters and 5 are three-phase meters. The power supply radius of the substation is 1000 meters. The busbar uses BLV-150×4 cable conductors, the single-phase branch line uses BLV-50×2 cable conductors, and the three-phase branch line uses BLV-50×4 cable conductors. The parameters of the low-voltage distribution line are shown in Table 1.

[0056] Table 1 Low voltage distribution line parameters

[0057] by Fig. 9 The location shown occurs For example, the AB phase fault of the simulation, the fault occurs at 0.6s, the circuit breaker K1 is disconnected at 0.9s, and multiple first thyristors are put into use at 1s. The trigger angle of the first thyristor is 0°, and the conduction time of the first thyristor is 10ms. The duration of the transient fault is 0.3s, and the permanent fault lasts until the end of the simulation. Fig. 20 and Fig.21 The simulated current waveforms are measured at the switch S3 in the figure during the thyristor conduction time when instantaneous faults and permanent faults occur in the line and the phase-to-phase faults occur respectively.

[0058] Under a transient fault, the current of phase A is equal to 0 for about 5ms, and the current of phase B is equal to 0 for about 1ms; under a permanent fault, a small reverse current appears in the currents of phases AB, but the current value is not 0. Therefore, under a transient fault, the cumulative sum of the multiplication and addition of the current values ​​of phases B and C within 10ms of the thyristor being turned on is very small, while it is larger under a permanent fault. The processed data obtained by simulating different situations are shown in Tables 1-4. Table 2 gives the data analysis under different interphase fault types, Table 2 gives the data analysis under different fault resistances, and Table 4 gives the data analysis under different trigger angles; it can be seen that the ratio under a transient fault is greater than 600, while it is much less than 600 under a permanent fault. The setting threshold of the present invention is taken as 300, which has a large margin.

[0059] Table 2 Simulation data under different fault types

[0060] Table 3 Simulation results of permanent AB phase fault under different fault resistances

[0061] Table 4 Permanent fault simulation results under different switch trigger angles

[0062] like Figure 8 As shown, Figure 8 : is a structural diagram of an adaptive reclosing device provided by an embodiment of the present invention. The present invention also provides an adaptive reclosing device, comprising: The processor 801 may be implemented by a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application; The memory 802 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 802 can store an operating system and other application programs. When the technical solution provided in the embodiment of this specification is implemented by software or firmware, the relevant program code is stored in the memory 802, and the processor 801 is called to execute the adaptive reclosing method of the embodiment of the present application; Input / output interface 803, used to implement information input and output; The communication interface 804 is used to realize the communication interaction between the present apparatus and other devices. The communication can be realized through a wired manner (such as USB, network cable, etc.) or a wireless manner (such as mobile network, WIFI, Bluetooth, etc.); A bus 805 that transmits information between various components of the device (e.g., the processor 801, the memory 802, the input / output interface 803, and the communication interface 804); The processor 801 , the memory 802 , the input / output interface 803 and the communication interface 804 are connected to each other in communication within the device via a bus 805 .

[0063] An embodiment of the present application also provides an electronic device, comprising the adaptive reclosing device as described above.

[0064] An embodiment of the present application further provides a storage medium, which is a computer-readable storage medium and stores a computer program. When the computer program is executed by a processor, the above-mentioned adaptive reclosing method is implemented.

[0065] As a non-transient computer-readable storage medium, the memory can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and are implemented to be located in one place, or may also be distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0066] It will be appreciated by those skilled in the art that all or some of the steps and systems in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transient medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically include computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0067] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions under the shared conditions without violating the spirit of the present invention. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. An adaptive reclosing method, characterized in that: Applied in a power distribution system, the power distribution system comprises a power transmission line, a power distribution module, a load and a switch module, the power transmission line is respectively connected to the power distribution module, the load and the switch module, and the adaptive reclosing method comprises: When an interphase fault occurs in the power transmission line, the switch module is turned on to close the power transmission line, and the voltage of the power transmission line is detected to obtain a first voltage of the switch module; Acquire a first fault current in the transmission line, confirm a first three-phase voltage of the transmission line according to the first voltage and turn on the switch module, and calculate a first coincidence fault impedance according to the first three-phase voltage and the first fault current; When the on-time of the switch module reaches a preset first time, obtaining a second three-phase voltage and a second fault current of the switch module, and calculating a second coincident fault impedance according to the second three-phase voltage and the second fault current; The fault type of the transmission line is determined according to the first reclosing fault impedance and the second reclosing fault impedance, and an adaptive reclosing operation is performed according to the fault type. When the fault type is a permanent phase-to-phase fault, the switch module trips the fault phase of the transmission circuit and locks the fault phase. When the fault type is a transient phase-to-phase fault, the switch module keeps reclosing the transmission line.

2. The adaptive reclosing method according to claim 1, characterized in that: After obtaining the first voltage of the switch, the method further includes: Determining the fault voltage of the switch module and the preset rated voltage of the transmission line; When the fault voltage is less than 80% of the rated voltage, it is determined that the transmission line where the switch module is located after being turned on is a permanent ground fault; When the power transmission line has a permanent ground fault, the switch module is locked.

3. The adaptive reclosing method according to claim 1, characterized in that: The switch module is provided with a first switch unit, a second switch unit and a third switch unit, the first switch unit is provided at the first phase of the transmission line, the second switch unit is provided at the second phase of the transmission line, and the third switch unit is provided at the third phase of the transmission line, the first switch unit, the second switch unit and the third switch unit are all provided with a first switch and a first thyristor, one end of a plurality of the first switches are connected to the power distribution module, the other end of a plurality of the first switches are connected to the load, the first thyristor is connected in parallel to the first switch, and the determining of the fault type of the transmission line according to the first coincidence fault impedance and the second coincidence fault impedance includes: Determining fault lines of a first phase, a second phase, and a third phase in the transmission line; When the first switch trips the fault line, a conduction signal is sent to the first thyristor; collecting, according to a preset sampling frequency, a first transient current, a second transient current, and a third transient current when the first thyristor of the fault line is in the first phase, the second phase, and the third phase; Calculating first transient information of an instantaneous current product between the first transient current and the second transient current, second transient information of an instantaneous current product between the second transient current and the third transient current, and third transient information of an instantaneous current product between the first transient current and the third transient current; Obtaining a maximum transient information value and a minimum transient information value among the first transient information, the second transient information, and the third transient information; A fault confirmation value is obtained according to the maximum transient information value and the minimum transient information value, and a fault type of the power transmission line is determined according to the fault confirmation value.

4. The adaptive reclosing method according to claim 3, characterized in that: The confirming the fault type of the power transmission line according to the fault confirmation value includes: Determining a determination value of the fault confirmation value; When the fault confirmation value is greater than the determination value, the fault type is determined to be a transient fault, and the transmission line uses three-phase automatic reclosing to restore power supply; When the fault confirmation value is less than the determination value, the fault type is determined to be a permanent fault, and the first switch, the second switch, and the third switch are locked.

5. The adaptive reclosing method according to claim 1, characterized in that: The switch module is further provided with a fifth switch unit and a sixth switch unit, the fifth switch unit is provided with a fourth switch and a fifth switch, the fourth switch and the fifth switch are both connected to the power distribution module, the sixth switch unit is provided with a seventh switch, an eighth switch and a ninth switch, the fourth switch and the seventh switch are provided at the first phase of the transmission line, the fifth switch and the eighth switch are provided at the second phase of the transmission line, the ninth switch is provided at the third phase of the transmission line, a first resistor is further connected between the second phase and the third phase of the transmission line, and when an interphase fault occurs in the transmission line, the switch module is turned on to close the transmission line, comprising: When the fault type between the transmission lines is a phase-to-phase fault, determining a faulty line of the transmission lines; Performing a first closing operation on the fifth switch or the sixth switch, and the seventh switch and the eighth switch of the faulty line; Acquire a zero-sequence voltage and a zero-sequence current of the load, and obtain the first coincidence fault impedance when the first switch is closed according to the zero-sequence voltage and the zero-sequence current; Obtaining a first impedance of the first phase, a second impedance of the second phase, and a resistance value of the first resistor; A first impedance amplitude of the first coincident fault impedance under the permanent fault at the time of the first closing is calculated according to the first impedance, the second impedance and the resistance value, and a second impedance amplitude of the first coincident fault impedance under the transient fault at the time of the first closing is calculated.

6. The adaptive reclosing method according to claim 5, characterized in that: After obtaining the first coincidence fault impedance at the time of the first closing according to the zero-sequence voltage and the zero-sequence current, the method further includes: Performing a second closing operation on the fifth switch or the sixth switch, and the seventh switch and the eighth switch; Obtain a third impedance of the first phase and a fourth impedance of the second phase, and calculate a third impedance amplitude of the second coincident fault impedance under the permanent fault when the second circuit is closed according to the third impedance, the fourth impedance and the resistance value, and a fourth impedance amplitude of the second coincident fault impedance under the transient fault when the second circuit is closed.

7. The adaptive reclosing method according to claim 1, characterized in that: The determining the fault type of the transmission line according to the first coincident fault impedance and the second coincident fault impedance comprises: Obtaining setting values ​​of the first coincident fault impedance and the second coincident fault impedance; When the ratio of the first coincident fault impedance to the second coincident fault impedance is greater than the set value, it is determined that a permanent fault exists in the transmission line.

8. An adaptive reclosing device, characterized in that: It includes at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions that can be executed by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor to execute the adaptive reclosing method as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: Including the adaptive reclosing device as described in claim 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the adaptive reclosing method according to any one of claims 1 to 7.

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