An Adaptive Reclosing Method, Device, Equipment and Medium

Abstract

The present invention provides an adaptive reclosing method, device, equipment and medium, including: after an interphase fault occurs in a transmission line, turning on a switch module to close the transmission line, detecting the voltage of the transmission line to obtain a first voltage of the switch module; acquiring 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 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, acquiring a second three-phase voltage and a second fault current of the switch module and calculating a second reclosing fault impedance; determining the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance and performing an adaptive reclosing operation. According to the technical solution of this embodiment, the fault type of the transmission line can be accurately judged, and secondary hazards to electrical equipment can be avoided.

Description

Technical Field

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

[0002] The power supply reliability indicators of the distribution network mainly include the average annual power outage time and outage frequency of 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. Currently, drip switches widely adopt the automatic reclosing function, that is, after a fault occurs in the low-voltage line, the switch first trips, and then three-phase automatic reclosing occurs after the set reclosing time arrives. If the line fault has disappeared before the automatic reclosing, that is, the instantaneous fault can quickly resume 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 of power outages and outage time, and bringing secondary hazards to electrical equipment. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides an adaptive reclosing method, device, equipment, and medium, which can accurately judge the line fault and avoid bringing secondary hazards to 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. The power distribution system includes a transmission line, a power distribution module, a load, and a switch module. The transmission line is respectively connected to the power distribution module, the load, and the switch module. The adaptive reclosing method includes:

[0005] After 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 the first voltage of the switch module;

[0006] Obtain the first fault current in the transmission line, confirm the first three-phase voltage of the transmission line according to the first voltage and turn on the switch module, and calculate the first reclosing fault impedance according to the first three-phase voltage and the first fault current;

[0007] When the conduction time of the switch module reaches a preset first time, obtain the second three-phase voltage and the second fault current of the switch module, and calculate the second reclosing fault impedance according to the second three-phase voltage and the second fault current;

[0008] Determine the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance, and perform 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.

[0009] In some embodiments of the present invention, determine the fault voltage of the switch module and the rated voltage preset for the transmission line;

[0010] 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 conduction is a permanent ground fault;

[0011] When the transmission line is a permanent ground fault, lock the switch module.

[0012] 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 arranged in the first phase of the transmission line, the second switch unit is arranged in the second phase of the transmission line, and the third switch unit is arranged in 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 ends of the plurality of first switches are all connected to the power distribution module, and the other ends of the plurality of first switches are all connected to the load. The first thyristor is connected in parallel with the first switch. Determining the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance includes:

[0013] Determine the faulty lines of the first phase, the second phase, and the third phase in the transmission line;

[0014] After the first switch trips the faulty line, send a conduction signal to the first thyristor;

[0015] Collect the first transient current, the second transient current, and the third transient current of the first thyristor of the faulty line when it is in the first phase, the second phase, and the third phase according to a preset sampling frequency;

[0016] Calculate the first transient information of the instantaneous current product between the first transient current and the second transient current, the second transient information of the instantaneous current product between the second transient current and the third transient current, and the third transient information of the instantaneous current product between the first transient current and the third transient current;

[0017] Obtain 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;

[0018] Obtain a fault confirmation value based on the maximum transient information value and the minimum transient information value, and determine the fault type of the transmission line according to the fault confirmation value.

[0019] In some embodiments of the present invention, the determining the fault type of the transmission line according to the fault confirmation value includes:

[0020] Determine the decision value of the fault confirmation value;

[0021] When the fault confirmation value is greater than the decision value, determine that the fault type is an instantaneous fault, and the transmission line uses three-phase automatic reclosing to restore power supply;

[0022] When the fault confirmation value is less than the decision value, determine that the fault type is a permanent fault, and lock the first switch, the second switch, and the third switch.

[0023] 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, and both the fourth switch and the fifth switch are 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 arranged on the first phase of the transmission line, the fifth switch and the eighth switch are arranged on the second phase of the transmission line, and the ninth switch is arranged on the third phase of the transmission line. A first resistor is also connected between the second phase and the third phase of the transmission line. After an interphase fault occurs on the transmission line, the adaptive reclosing operation is performed according to the fault type, including:

[0024] When the fault type between the transmission lines is an interphase fault, determine the fault line of the transmission line;

[0025] Perform a first closing on the fifth switch or the sixth switch of the fault line, and the eighth switch;

[0026] Obtain the zero-sequence voltage and zero-sequence current of the load, and obtain the first reclosing fault impedance at the time of the first closing according to the zero-sequence voltage and the zero-sequence current;

[0027] Obtain the first impedance of the first phase, the second impedance of the second phase, and the resistance value of the first resistor;

[0028] Calculate the first impedance amplitude of the first reclosing fault impedance under the permanent fault at the first closing, and the second impedance amplitude of the first reclosing fault impedance under the transient fault at the first closing according to the first impedance, the second impedance, and the resistance value.

[0029] In some embodiments of the present invention, after obtaining the first reclosing fault impedance at the first closing according to the zero-sequence voltage and the zero-sequence current, the method further includes:

[0030] Perform a second closing on the fifth switch or the sixth switch, and the seventh switch and the eighth switch;

[0031] Obtain the third impedance of the first phase and the fourth impedance of the second phase, and calculate the third impedance amplitude of the second reclosing fault impedance under the permanent fault at the second closing, and the fourth impedance amplitude of the second reclosing fault impedance under the transient fault at the second closing according to the third impedance, the fourth impedance, and the resistance value.

[0032] In some embodiments of the present invention, determining the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance includes:

[0033] Obtain the setting values of the first reclosing fault impedance and the second reclosing fault impedance;

[0034] When the ratio of the first reclosing fault impedance and the second reclosing fault impedance is greater than the setting value, determine that there is a permanent fault in the transmission line.

[0035] In a second aspect, an embodiment of the present invention provides an adaptive reclosing device, including at least one control processor and a memory communicatively connected to 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 to enable the at least one control processor to execute the adaptive reclosing method as described in the first aspect above.

[0036] In a third aspect, an embodiment of the present invention provides an electronic device, including the adaptive reclosing device as described in the second aspect above.

[0037] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, storing computer-executable instructions for executing the adaptive reclosing method as described in the first aspect above.

[0038] The adaptive reclosing method according to the embodiment of the present invention has at least the following beneficial effects:

[0039] When a phase - to - phase fault occurs in the transmission line, the closing switch module closes the transmission line, detects the voltage of the transmission line to obtain the first voltage of the switch module; obtains the first fault current in the transmission line, confirms the first three - phase voltage of the transmission line based on the first voltage and conducts the switch module, and calculates the first reclosing fault impedance based on the first three - phase voltage and the first fault current; when the conduction time of the switch module reaches the preset first time, obtains the second three - phase voltage and the second fault current of the switch module, and calculates the second reclosing fault impedance based on the second three - phase voltage and the second fault current; determines the fault type of the transmission line based on the first reclosing fault impedance and the second reclosing fault impedance, and performs an adaptive reclosing operation 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 an instantaneous phase - to - phase fault, the switch module maintains the reclosing of the transmission line. According to the technical solution of this embodiment, the fault type of the transmission line can be accurately judged. When the transmission line is an instantaneous fault, the switch module automatically recloses. When the transmission line is a permanent fault, the switch module locks, thereby avoiding secondary hazards to electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flowchart of an adaptive reclosing method provided by an embodiment of the present invention;

[0041] Figure 2 is a flowchart after obtaining the first voltage of the switch module in an embodiment of the present invention;

[0042] Figure 3 is a flowchart of determining the fault type of the transmission line based on the first reclosing fault impedance and the second reclosing fault impedance in an embodiment of the present invention;

[0043] Figure 4 is a flowchart of determining the fault type of the transmission line based on the fault confirmation value in an embodiment of the present invention;

[0044] Figure 5 is a flowchart of performing an adaptive reclosing operation according to the fault type in an embodiment of the present invention;

[0045] Figure 6 is a flowchart after obtaining the first reclosing fault impedance at the first closing based on the zero - sequence voltage and the zero - sequence current in an embodiment of the present invention;

[0046] Figure 7 is a flowchart after determining the fault type of the transmission line based on the first reclosing fault impedance and the second reclosing fault impedance in an embodiment of the present invention;

[0047] Figure 8It is the structural diagram of the adaptive reclosing device provided by another embodiment of the present invention;

[0048] Figure 9 It is the structural schematic diagram of the first switch unit, the second switch unit and the third switch unit of the embodiment of the present invention;

[0049] Figure 10 It is the structural schematic diagram of the fourth switch unit and the fifth switch unit of the embodiment of the present invention;

[0050] Figure 11 It is the equivalent circuit diagram of closing one phase for phase - to - ground fault in the embodiment of the present invention;

[0051] Figure 12 It is the schematic diagram of closing one phase of the grounding switch in the embodiment of the present invention;

[0052] Figure 13 It is the simplified equivalent circuit diagram of closing one phase of the grounding switch in the embodiment of the present invention;

[0053] Figure 14 It is the schematic diagram of closing another phase of the grounding switch in the embodiment of the present invention;

[0054] Figure 15 It is the simplified equivalent circuit diagram of closing another phase of the grounding switch in the embodiment of the present invention;

[0055] Figure 16 It is the structural schematic diagram of the distribution network simulation system model in the embodiment of the present invention;

[0056] Figure 17 It is the waveform diagram of closing impedance for permanent fault in the embodiment of the present invention;

[0057] Figure 18 It is the waveform diagram of closing impedance for transient fault in the embodiment of the present invention;

[0058] Figure 19 It is the schematic diagram of the low - voltage distribution network model in the embodiment of the present invention;

[0059] Figure 20 It is the waveform diagram of two - phase transient fault in the embodiment of the present invention;

[0060] Figure 21 It is the waveform diagram of two - phase permanent fault in the embodiment of the present invention. Detailed implementation manners

[0061] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0062] In the description of the present invention, it should be understood that with respect to the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc., it is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0063] In the description of the present invention, the meaning of "a number of" is one or more, the meaning of "a plurality of" is two or more, and understandings such as "greater than", "less than", "exceeding", etc. do not include the recited number, while understandings such as "above", "below", "within", etc. include the recited number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0064] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above terms in the present invention in combination with the specific content of the technical solution.

[0065] An embodiment of the present invention provides an automatic reclosing method, which is applied to a distribution system. Referring to Figure 9 and Figure 10 , the distribution system includes a transmission line, a distribution module, a load, and a switch module. The transmission line is respectively connected to the distribution module, the load, and the switch module. 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 disposed on the first phase of the transmission line, the second switch unit is disposed on the second phase of the transmission line, and the third switch unit is disposed on 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 ends of the plurality of first switches are all connected to the distribution module, and the other ends of the plurality of first switches are all connected to the load. The first thyristor is connected in parallel with the first switch. 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, and both the fourth switch and the fifth switch are 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 disposed on the first phase of the transmission line, the fifth switch and the eighth switch are disposed on the second phase of the transmission line, and the ninth switch is disposed on 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.

[0066] It should be noted that multiple first switches are all low-voltage switches, and the multiple first switches are T1, T2, and T3 respectively. After the multiple first switches trip, a three-phase electronic switch is connected in series in the transmission line, and the driving circuit is controlled through the PWM pin of the single-chip microcomputer, so that multiple first thyristors change from low level to high level, and finally multiple first switches in the switch module are turned on.

[0067] In this embodiment, there is no need to additionally add an AC voltage source. Only by controlling the conduction angle and conduction time of the switch module can a transient current for permanent fault identification be generated. And a switch module of the distribution system that will not cause a secondary impact and its corresponding automatic reclosing strategy. When it is accurately determined that the transmission line is an instantaneous fault, the switch module realizes three-phase automatic reclosing, and when it is a permanent fault, the switch module automatically locks the reclosing.

[0068] Next, based on the accompanying drawings, the control method of the embodiment of the present invention will be further elaborated.

[0069] Refer to Figure 1 , Figure 1 which is a flowchart of an adaptive reclosing method provided by an embodiment of the present invention. The adaptive reclosing method includes but is not limited to the following steps:

[0070] Step S11, when an interphase fault occurs in the transmission line, turn on the switch module to close the transmission line, detect the voltage of the transmission line, and obtain the first voltage of the switch module;

[0071] It should be noted that when an interphase fault occurs in the line, the fourth switch unit of the switch module uses single-phase closing, closes one fault phase A, and then detects the first voltage of the reclosed phase A.

[0072] Step S12, obtain the first fault current in the transmission line, confirm the first three-phase voltage of the transmission line according to the first voltage and turn on the switch module, and calculate the first reclosing fault impedance according to the first three-phase voltage and the first fault current;

[0073] 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. Turn on the fifth switch unit to reclose the second phase of the transmission line, then a jump from high to low of the first-phase voltage and a small fault current flowing through will be detected at the fourth switch unit. At this time, divide the first three-phase voltage of the reclosed first phase at the fourth switch unit by the first fault current to obtain the first reclosing fault impedance.

[0074] Step S13, when the conduction time of the switch module reaches the preset first time, obtain the second three-phase voltage and the second fault current of the switch module, and calculate the second reclosing fault impedance according to the second three-phase voltage and the second fault current;

[0075] It should be noted that when the fourth switch unit recloses the second phase and 100 ms later, the fifth switch unit recloses the third phase, the voltage and current of the first phase will both change at the fourth switch unit. At this time, dividing the second and third phase voltages of the first phase when the fourth switch unit recloses the first phase by the second fault current can obtain the second reclosing fault impedance.

[0076] Step S14: Determine the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance, and perform adaptive reclosing operation 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 an instantaneous phase-to-phase fault, the switch module keeps reclosing the transmission line.

[0077] It should be noted that by obtaining the ratio of the first reclosing fault impedance to the second reclosing fault impedance, when the ratio of the two is greater than 1.75, it can be determined that a permanent phase-to-phase fault has occurred in the transmission line. Then, the fourth switch unit trips and recloses the first phase and locks the automatic reclosing. At this time, after the fifth switch unit detects that the three-phase voltage and the fault current of the transmission line disappear, it trips the reclosed second phase and third phase. 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 an instantaneous phase-to-phase fault has occurred in the transmission line. Then, the fourth switch unit keeps reclosing the first phase. When the fifth switch unit detects that the duration of the low-voltage current exceeds 500 ms, it trips the reclosed first phase and second phase. At this time, the fourth switch unit will detect a jump in the three-phase voltage of the first phase from low to high, and then reclose the remaining two phases to restore power supply to the line.

[0078] It should be noted that through the determination of the fault of the transmission line, the switch module and its corresponding automatic reclosing strategy that prevent the distribution system from generating secondary shocks. When it is accurately determined that the transmission line is an instantaneous fault, the switch module realizes three-phase automatic reclosing. When it is a permanent fault, the switch module automatically locks the reclosing.

[0079] In addition, in one embodiment, referring to Figure 2 , after Figure 1 step S11 of the embodiment shown, it further includes but is not limited to the following steps:

[0080] Step S21: Determine the fault voltage of the switch module and the preset rated voltage of the transmission line;

[0081] Step S22: 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 conduction is a permanent ground fault;

[0082] Step S23: When the transmission line is a permanent ground fault, lock the switch module.

[0083] It should be noted that after an interphase fault occurs in the transmission line, the fourth switch unit performs single-phase closing, closes 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 ground fault has occurred on the reclosed line. At this time, the first phase after reclosing is tripped, and the automatic reclosing is blocked.

[0084] In addition, in one embodiment, referring to Figure 3 , in Figure 1 the step S14 of the embodiment shown, it further includes but is not limited to the following steps:

[0085] Step S31, determining the fault lines of the first phase, the second phase, and the third phase in the transmission line;

[0086] Step S32, when the first switch trips the fault line, sending a conduction signal to the first thyristor;

[0087] Step S33, collecting the first transient current, the second transient current, and the third transient current of the first thyristor in the fault line when it is in the first phase, the second phase, and the third phase according to a preset sampling frequency;

[0088] Step S34, calculating the first transient information of the instantaneous current product between the first transient current and the second transient current, the second transient information of the instantaneous current product between the second transient current and the third transient current, and the third transient information of the instantaneous current product between the first transient current and the third transient current;

[0089] Step S35, obtaining 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;

[0090] 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.

[0091] It should be noted that when an interphase fault occurs in the transmission line, after the switch module performs overcurrent protection and trips the fault line, a delay of 300 ms is used to release the influence of the residual charge of the fault line. Subsequently, the single-chip microcomputer issues a PWM pulse to control the first switch or the second switch or the third switch in the fault phase to conduct for half a power frequency cycle (about 10 ms), and collects the first transient current of the fault phase for half a cycle when the switch module conducts at a sampling frequency of 100 kHz i A (k), the second transient current i B (k) and the third transient current i C(k), where k = 1, 2, 3... N and N = 1000. Then calculate the average values of the first transient current, the second transient current, and the third transient current, and finally obtain the first transient information, the second transient information, and the third transient information.

[0092] Calculate the first transient information, the second transient information, and the third transient information, which are expressed by the following formula:

[0093] ;

[0094] Where, is the first transient information, is the second transient information, is the third transient information.

[0095] 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:

[0096] Where, is the maximum transient information value, is the minimum transient information value, and KR is the fault confirmation value.

[0097]

[0098] In addition, in an embodiment, referring to Figure 4 , in Figure 3 the step S36 of the embodiment shown, it further includes but is not limited to the following steps:

[0099] Step S41, determine the judgment value of the fault confirmation value;

[0100] Step S42, when the fault confirmation value is greater than the judgment value, determine that the fault type is a transient fault, and the transmission line uses three-phase automatic reclosing to restore power supply;

[0101] Step S43, when the fault confirmation value is less than the judgment value, determine that the fault type is a permanent fault, and lock the switch module.

[0102] It should be noted that when the fault confirmation value KR > 300, it is determined that the fault occurring in the distribution system is a transient fault, and at this time, the distribution system can use three-phase automatic reclosing to restore power supply. When KR < 300, it can be confirmed that the fault occurring in the distribution system is a permanent fault, and at this time, the reclosing is locked.

[0103] In addition, in an embodiment, referring to Figure 5 , in Figure 1 the step S11 of the embodiment shown, it further includes but is not limited to the following steps:

[0104] Step S51: When the fault type between transmission lines is an interphase fault, determine the faulty line of the transmission line.

[0105] Step S52: Perform a first closing on the fifth switch or the sixth switch of the faulty line, and the eighth switch.

[0106] Step S53: Obtain the zero-sequence voltage and zero-sequence current of the load, and obtain the first reclosing fault impedance at the first closing based on the zero-sequence voltage and zero-sequence current.

[0107] Step S54: Obtain the first impedance of the first phase, the second impedance of the second phase, and the resistance value of the first resistor.

[0108] Step S55: Calculate the first impedance amplitude of the first reclosing fault impedance under a permanent fault at the first closing, and the second impedance amplitude of the first reclosing fault impedance under a transient fault at the first closing according to the first impedance, the second impedance, and the resistance value.

[0109] It should be noted that the first reclosing fault impedance is the ratio of the zero-sequence voltage of the load side to the zero-sequence current, and is expressed by the following third formula:

[0110]

[0111] is the first reclosing 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.

[0112] Referring to Figure 13 , it can be obtained that , , then the first impedance amplitude when the earthing switch is first closed under a permanent fault is expressed by the following fourth formula:

[0113] ;

[0114] is the first impedance amplitude, is the first impedance, is the resistance value of the first resistor.

[0115] The magnitude of the second impedance of the switching module under transient faults is expressed by the following fifth formula:

[0116]

[0117] is the magnitude of the second impedance.

[0118] In addition, in one embodiment, referring to Figure 6 , after step S53 of the embodiment shown in Figure 5 , the following steps are included but not limited to:

[0119] Step S61, perform a second closing on the fifth switch or the sixth switch and the eighth switch;

[0120] Step S62, obtain the third impedance of the first phase and the fourth impedance of the second phase, and calculate the magnitude of the third impedance of the second reclosing fault impedance under permanent faults and the magnitude of the fourth impedance of the second reclosing fault impedance under transient faults according to the third impedance, the fourth impedance and the resistance value.

[0121] It should be noted that referring to Figure 11 , the eighth switch is an earthing switch. When the fifth switch is closed and then the eighth switch is closed, or when the sixth switch is closed and then the eighth switch is closed, the equivalent circuit is as shown in Figure 15 , and can be obtained.

[0122] Then the magnitude of the third impedance of the earthing switch's second closing under permanent faults in the transmission line is expressed by the following sixth formula:

[0123] ;

[0124] wherein, is the magnitude of the third impedance.

[0125] The magnitude of the fourth impedance of the earthing switch's second closing under transient faults in the transmission line is expressed by the following seventh formula:

[0126] , wherein, is the magnitude of the fourth impedance.

[0127] In addition, in one embodiment, referring to Figure 7 , in step S14 of the embodiment shown in Figure 1 , the following steps are included but not limited to:

[0128] Step S71, obtain the setting values of the first reclosing fault impedance and the second reclosing fault impedance;

[0129] Step S72: When the ratio of the first reclosing fault impedance to the second reclosing fault impedance is greater than the setting value, it is determined that there is a permanent fault on the transmission line.

[0130] It should be noted that the first ratio is obtained based on the first impedance amplitude and the third impedance amplitude of the earthing switch under permanent fault, and is expressed by the following eighth formula:

[0131] ;

[0132] Wherein, is the first ratio.

[0133] The fourth ratio is obtained based on the second impedance amplitude and the fourth impedance amplitude of the earthing switch under transient fault, and is expressed by the following ninth formula:

[0134] ;

[0135] Wherein, is the second ratio.

[0136] In this embodiment, the setting value is set to the mean value of the first ratio and the second ratio (1.75 is taken in this example), that is, when the ratio of the first closing to the second closing of the eighth switch calculated is greater than 1.75, it can be considered that there is a permanent fault on the closing line.

[0137] Simulation example 1:

[0138] Refer to Figures 10 to 15 , a simulation model of a 10 kV system is established in PSCAD / EMTDC, as shown in Figure 10 . The specific parameters of the model are as follows: The lengths of each section are as follows: L1 = 5.1 km, L2 = 3 km, L3 = 10 km, L4 = 2 km, L5 = 2 km, L6 = 7 km, L7 = 2 km, L8 = 3 km, L9 = 5 km, L10 = 5 km, L11 = 5 km, L12 = 4 km, L13 = 4 km. The cable parameters are: r1 = 0.141 Ω / km, x1 = 0.068 Ω / km, b1 = 2.4 MΩ*m, r0 = 0.276 Ω / km, x0 = 0.273 Ω / km, b0 = 3 MΩ*m. The parameters of the overhead insulated line are r1 = 0.243 Ω / km, x1 = 0.3168 Ω / km, b1 = 283.19 MΩ*m, r0 = 0.378 Ω / km, x0 = 0.325 Ω / km, b0 = 1339 MΩ*m. A fault is set at point F1, the fault resistance is 20 Ω, the fault disappearance time under transient fault is set to 0.8 s, the fault setting duration under permanent fault is 1.5, and the entire simulation process duration is 1.5 s.

[0139] 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.

[0140] Simulation Example 2:

[0141] 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.

[0142] Table 1 Low voltage distribution line parameters

[0143]

[0144] by Figure 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. Figure 20 and Figure 21 They are respectively the simulated current waveforms measured at the switch S3 during the thyristor conduction time when an instantaneous fault and a permanent phase-to-phase fault occur in the line.

[0145] During transient faults, the current in phase A is approximately 0 for about 5 ms, while the current in phase B is approximately 0 for about 1 ms. Under permanent faults, a small reverse current appears in the currents of both phases A and B, but the current value is not 0. Therefore, during transient faults, the cumulative sum of the products of the currents in phases B and C within the 10 ms when the thyristor is conducting is very small, while it is larger under permanent faults. The processing data obtained from simulations under different conditions are shown in Tables 1 - 4. Table 2 presents the data analysis for different interphase fault types, Table 3 presents the data analysis for different fault resistances, and Table 4 presents the data analysis for different trigger angles. It can be seen from this that the ratio under transient faults is greater than 600, while it is much less than 600 under permanent faults. The setting threshold of the present invention is taken as 300, providing a large margin.

[0146] Table 2 Simulation Data under Different Fault Types

[0147]

[0148] Table 3 Simulation Results of Permanent Interphase AB Faults under Different Fault Resistances

[0149]

[0150] Table 4 Simulation Results of Permanent Faults under Different Switch Trigger Angles

[0151]

[0152] As Figure 8 shown, Figure 8 is the structural diagram of the adaptive reclosing device provided by an embodiment of the present invention. The present invention also provides an adaptive reclosing device, including:

[0153] A processor 801, which can be implemented in ways such as 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 by the embodiments of the present application;

[0154] 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), etc. The memory 802 can store an operating system and other application programs. When implementing the technical solutions provided in the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 802, and the processor 801 is used to call and execute the adaptive reclosing method of the embodiments of this application;

[0155] The input / output interface 803 is used to implement information input and output;

[0156] The communication interface 804 is used to implement communication and interaction between this device and other devices. Communication can be achieved through a wired method (such as USB, network cable, etc.) or through a wireless method (such as a mobile network, WIFI, Bluetooth, etc.);

[0157] The bus 805 transmits information between the various components of the device (such as the processor 801, the memory 802, the input / output interface 803, and the communication interface 804);

[0158] Among them, the processor 801, the memory 802, the input / output interface 803, and the communication interface 804 achieve communication connections with each other inside the device through the bus 805.

[0159] The embodiments of this application also provide an electronic device, including the above-mentioned adaptive reclosing device.

[0160] The embodiments of this application also provide a storage medium. The storage medium is a computer-readable storage medium. The storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned adaptive reclosing method is implemented.

[0161] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory optionally includes a memory remotely provided relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof. The device embodiments described above are merely illustrative, where the units described as separate components may or may not be physically separated, and can be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0162] Those of ordinary skill in the art can understand that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or can be implemented as hardware, or can be implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill 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 includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVDs) or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, as is well known to those of ordinary skill in the art, a communication medium generally includes computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0163] The above is a specific description of the preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. An adaptive reclosing method, characterized in that, Applied to a power distribution system, the power distribution system includes a transmission line, a power distribution module, a load, and a switch module. The transmission line is respectively connected to the power distribution module, the load, and the switch module. The adaptive reclosing method includes: After an interphase fault occurs on the transmission line, turn on the switch module to close the transmission line, detect the voltage of the transmission line, and obtain the first voltage of the switch module; Obtain the first fault current in the transmission line, confirm the first three-phase voltage of the transmission line according to the first voltage and turn on the switch module, and calculate the 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, obtain the second three-phase voltage and the second fault current of the switch module, and calculate the second reclosing fault impedance according to the second three-phase voltage and the second fault current; Determine the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance, and perform an adaptive reclosing operation according to the fault type. When the fault type is a permanent interphase fault, the switch module trips the fault phase of the transmission line and locks the fault phase. When the fault type is a transient interphase fault, the switch module keeps reclosing the transmission line; The switch module is provided with a first switch unit, a second switch unit, and a third switch unit. The first switch unit is arranged on the first phase of the transmission line, the second switch unit is arranged on the second phase of the transmission line, and the third switch unit is arranged on 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 ends of multiple first switches are all connected to the power distribution module, and the other ends of multiple first switches are all connected to the load. The first thyristor is connected in parallel with the first switch. Determining the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance includes: Determine the fault lines of the first phase, the second phase, and the third phase in the transmission line; After the first switch trips the fault line, send a conduction signal to the first thyristor; Collect the first transient current, the second transient current, and the third transient current of the first thyristor when the fault line is in the first phase, the second phase, and the third phase according to a preset sampling frequency; Calculate the first transient information of the instantaneous current product between the first transient current and the second transient current, the second transient information of the instantaneous current product between the second transient current and the third transient current, and the third transient information of the instantaneous current product between the first transient current and the third transient current; Obtain the maximum transient information value and the minimum transient information value in the first transient information, the second transient information, and the third transient information; A fault confirmation value is obtained based on the maximum transient information value and the minimum transient information value, and the fault type of the transmission line is determined according to the fault confirmation value.

2. The adaptive reclosing method according to claim 1, characterized in that The confirmation of the fault type of the 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, it is determined that the fault type is an instantaneous fault, and the transmission line is restored to power by three-phase automatic reclosing; When the fault confirmation value is less than the determination value, it is determined that the fault type is a permanent fault, and the first switch, the second switch, and the third switch are blocked.

3. The adaptive reclosing method according to claim 2, wherein 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, and both the fourth switch and the fifth switch are 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 arranged on the first phase of the transmission line, the fifth switch and the eighth switch are arranged on the second phase of the transmission line, and the ninth switch is arranged on the third phase of the transmission line. A first resistor is also connected between the second phase and the third phase of the transmission line. When an interphase fault occurs on the transmission line, closing the switch module to close the transmission line includes: When the fault type between the transmission lines is an interphase fault, determining the faulty line of the transmission line; Performing a first closing on the fifth switch or the sixth switch of the faulty line, and the seventh switch and the eighth switch; Obtaining the zero-sequence voltage and zero-sequence current of the load, and obtaining the first reclosing fault impedance at the first closing according to the zero-sequence voltage and the zero-sequence current; Obtaining the first impedance of the first phase, the second impedance of the second phase, and the resistance value of the first resistor; Calculating the amplitude of the first impedance of the first reclosing fault impedance under the permanent fault at the first closing according to the first impedance, the second impedance, and the resistance value, and the amplitude of the second impedance of the first reclosing fault impedance under the instantaneous fault at the first closing.

4. The adaptive reclosing method according to claim 3, wherein After obtaining the first reclosing fault impedance at the first closing according to the zero-sequence voltage and the zero-sequence current, the method further includes: Performing a second closing on the fifth switch or the sixth switch, and the seventh switch and the eighth switch; Obtaining the third impedance of the first phase and the fourth impedance of the second phase, and calculating the amplitude of the third impedance of the second reclosing fault impedance under the permanent fault at the second closing according to the third impedance, the fourth impedance, and the resistance value, and the amplitude of the fourth impedance of the second reclosing fault impedance under the instantaneous fault at the second closing.

5. The adaptive reclosing method according to claim 1, wherein The determination of the fault type of the transmission line according to the first reclosing fault impedance and the second reclosing fault impedance includes: Obtaining the setting values of the first reclosing fault impedance and the second reclosing fault impedance; When the ratio of the first reclosing fault impedance to the second reclosing fault impedance is greater than the setting value, it is determined that the transmission line has a permanent fault.

6. An adaptive autoreclosing device, characterized in that, It includes at least one control processor and a memory for communicatively connecting 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 to enable the at least one control processor to execute the adaptive reclosing method according to any one of claims 1 to 5.

7. An electronic device, characterized in that, It includes the adaptive reclosing device according to claim 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to execute the adaptive reclosing method according to any one of claims 1 to 5.

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