Distribution network zero-sequence impedance sudden change protection method, device, equipment and medium

Abstract

The present invention discloses a distribution network zero-sequence impedance mutation protection method, device, equipment and medium, comprising: after detecting the presence of a single-phase grounding fault in the distribution network, calculating the zero-sequence impedance at the location of each zero-sequence impedance mutation protection device in real time; dynamically adjusting the neutral point zero-sequence impedance of the distribution network; after completing the adjustment, calculating the zero-sequence impedance mutation at the location of each zero-sequence impedance mutation protection device; taking a zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value as a target protection device, and starting the preset delays of all target protection devices; when any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, controlling the connected circuit breaker to trip by the target protection device that has currently reached the delay.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network grounding fault protection, and in particular to a distribution network zero-sequence impedance sudden change protection method, device, equipment and medium. Background Art

[0002] The zero-sequence current protection of feeder circuit breakers in distribution networks has poor sensitivity and selectivity and is greatly affected by the neutral point grounding method. However, there is currently no highly selective and sensitive zero-sequence current protection method for feeder circuit breakers. With the advancement of the construction of new distribution systems, higher requirements are placed on the rapid and accurate isolation of ground faults, and the above-mentioned problems have become increasingly prominent. Summary of the Invention

[0003] Based on this, it is necessary to provide a distribution network zero-sequence impedance mutation protection method, device, equipment and medium to address the above problems, so as to solve the problem that there is currently no highly selective and sensitive feeder circuit breaker zero-sequence current protection method.

[0004] A method for protecting a distribution network from a sudden change in zero-sequence impedance, wherein the distribution network includes at least one line, each line is provided with a plurality of spaced circuit breakers, and both ends of each circuit breaker are connected to a zero-sequence impedance sudden change protection device. The method includes:

[0005] After detecting a single-phase grounding fault in the distribution network, the zero-sequence impedance at each zero-sequence impedance mutation protection device is calculated in real time;

[0006] Dynamically adjusting the neutral point zero-sequence impedance of the distribution network;

[0007] After the adjustment is completed, the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device is calculated; wherein the zero-sequence impedance mutation amount is calculated based on the zero-sequence impedance calculated in real time;

[0008] A zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value is selected as a target protection device, and preset delays of all target protection devices are activated; wherein the preset delay of a zero-sequence impedance mutation protection device close to a busbar of the distribution network is greater than the preset delay of a zero-sequence impedance mutation protection device far from the busbar of the distribution network;

[0009] When any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that currently reaches the delay controls the connected circuit breaker to trip.

[0010] In one embodiment, the real-time calculation of the zero-sequence impedance at each zero-sequence impedance mutation protection device location includes:

[0011] In real time, a zero-sequence voltage at a target zero-sequence impedance mutation protection device is collected as a target zero-sequence voltage, and a three-phase zero-sequence current is collected as a target three-phase zero-sequence current; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices;

[0012] The ratio of the target zero-sequence voltage to the target three-phase zero-sequence current is calculated, and the modulus of the ratio is taken to obtain the zero-sequence impedance.

[0013] In one embodiment, the calculating of the zero-sequence impedance mutation at each zero-sequence impedance mutation protection device location includes:

[0014] Obtaining a target zero-sequence impedance mutation protection device, a first zero-sequence impedance at an initial moment and a second zero-sequence impedance at an end moment within a preset time period; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices;

[0015] The difference between the first zero-sequence impedance and the second zero-sequence impedance is calculated, and the difference is used as the zero-sequence impedance sudden change amount of the target zero-sequence impedance sudden change amount protection device.

[0016] In one embodiment, the calculating of the zero-sequence impedance mutation at each zero-sequence impedance mutation protection device location includes:

[0017] Obtaining a maximum zero-sequence impedance and a minimum zero-sequence impedance of a target zero-sequence impedance mutation protection device within a preset time period; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices;

[0018] The difference between the maximum zero-sequence impedance and the minimum zero-sequence impedance is calculated, and the difference is used as the zero-sequence impedance sudden change amount of the target zero-sequence impedance sudden change amount protection device.

[0019] In one embodiment, each zero-sequence impedance sudden change protection device detects zero-sequence voltage through a voltage transformer and detects zero-sequence current through a current transformer, and the method further includes:

[0020] Obtaining the zero-sequence impedance to ground, the maximum value of the neutral point zero-sequence impedance, and the minimum value of the neutral point zero-sequence impedance of all lines in the distribution network, and calculating the adjustment range of the neutral point zero-sequence impedance based on the zero-sequence impedance to ground, the maximum value of the neutral point zero-sequence impedance, and the minimum value of the neutral point zero-sequence impedance;

[0021] Obtain the maximum positive deviation of the zero-sequence voltage measurement of the voltage transformer, the maximum negative deviation of the zero-sequence current measurement of the current transformer, and the number of adjustments from the maximum value of the neutral point zero-sequence impedance to the minimum value of the neutral point zero-sequence impedance, and calculate the zero-sequence impedance mutation setting value based on the maximum positive deviation of the zero-sequence voltage measurement, the maximum negative deviation of the zero-sequence current measurement, the number of adjustments, and the adjustment range.

[0022] In one embodiment, the method further comprises:

[0023] The zero-sequence impedance sudden change setting value is calculated based on the detection sensitivity and safety factor of the distribution network to the ground fault.

[0024] In one embodiment, controlling the tripping of the connected circuit breaker by the target protection device with the current arrival delay includes:

[0025] When the amplitude of the zero-sequence voltage at the set position of the target protection device that currently reaches the delay is greater than the preset ground fault detection starting value, the connected circuit breaker is controlled to trip.

[0026] A zero-sequence impedance sudden change protection device for a distribution network, comprising: a zero-sequence voltage sensing module, a zero-sequence current sensing module, and a control and protection module; wherein:

[0027] The zero-sequence voltage sensing module is used to detect the zero-sequence voltage at the installation location of the circuit breaker;

[0028] The zero-sequence current sensing module is used to detect the three-phase zero-sequence current at the installation location of the circuit breaker;

[0029] The control and protection module is used to collect the zero-sequence voltage and three-phase zero-sequence current at the installation location of the circuit breaker and apply the method according to claim 1.

[0030] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor executes the steps of the above-mentioned distribution network zero-sequence impedance sudden change protection method.

[0031] A distribution network zero-sequence impedance mutation protection device comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the distribution network zero-sequence impedance mutation protection method.

[0032] The present invention provides a method, device, equipment, and medium for zero-sequence impedance mutation protection in a distribution network. Upon detecting a single-phase grounding fault in the distribution network, the method calculates the zero-sequence impedance at each zero-sequence impedance mutation protection device in real time. The method then adjusts the zero-sequence impedance at the neutral point of the distribution network, and after the adjustment is complete, calculates the zero-sequence impedance mutation at each zero-sequence impedance mutation protection device. The method then selects zero-sequence impedance mutation protection devices in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value as target protection devices, and activates preset delays for all target protection devices. The preset delay for zero-sequence impedance mutation protection devices located closer to the busbar of the distribution network is greater than the preset delay for zero-sequence impedance mutation protection devices located farther from the busbar. Finally, when any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that has reached the delay controls the connected circuit breaker to trip. Thus, the present invention implements dynamic zero-sequence impedance mutation protection. The dynamic zero-sequence impedance mutation protection of the present invention has a wide range of applications and is suitable for systems with any neutral point grounding method, such as ungrounded, arc suppression coil grounded, resistor grounded, and voltage source flexible grounded. The dynamic zero-sequence impedance mutation protection is also suitable for distribution line feeder circuit breakers and distribution automation intelligent circuit breaker protection, and has high accuracy and sensitivity. At the same time, the dynamic zero-sequence impedance mutation protection is not affected by the power direction of the line, accurately determines the location of the ground fault, and quickly isolates the fault point. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] in:

[0035] Figure 1 1 is a flow chart of a method for protecting a distribution network zero-sequence impedance sudden change according to an embodiment;

[0036] Figure 2 Simplified diagram of electrical connections for distribution network related equipment;

[0037] Figure 3 It is the timing diagram of ground fault and related equipment operation in the distribution network;

[0038] Figure 4 Simplified principle circuit of zero-sequence impedance mutation;

[0039] Figure 5 Schematic diagram of the structure of a zero-sequence impedance sudden change protection device for a distribution network according to an embodiment;

[0040] Figure 6 This is a schematic diagram of the structure of a control and protection module in one embodiment;

[0041] Figure 7 FIG. 1 is a structural block diagram of a distribution network zero-sequence impedance sudden change protection device in one embodiment. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] like Figure 1 As shown, Figure 1 FIG. 1 is a flow chart of a method for protecting a zero-sequence impedance sudden change in a distribution network according to an embodiment of the present invention. Figure 2 To explain, Figure 2 This is a simplified diagram of the electrical connections of the distribution network related equipment. The distribution network includes at least one line, consisting of a busbar, line 1, line 2... line n, and an adjustable neutral point zero sequence impedance Z N DL1, DL2, and DL3 are circuit breakers installed at each line interval. The number of circuit breakers is unlimited and can be greater. CT is a zero-sequence current transformer, used to detect zero-sequence current; PT is a zero-sequence voltage transformer, used to detect zero-sequence voltage. Zero-sequence impedance surge protection devices are connected at both ends of each circuit breaker to implement dynamic zero-sequence impedance surge protection.

[0044] Specifically, the method for protecting the distribution network zero-sequence impedance sudden change in this embodiment includes the following steps:

[0045] Step 102 : After a single-phase grounding fault is detected in the distribution network, the zero-sequence impedance at each zero-sequence impedance mutation protection device is calculated in real time.

[0046] In order to further illustrate the present invention, the following is also combined with Figure 3 This embodiment is described. Figure 3 This is a timing diagram of ground faults in the distribution network and the operation of related equipment.

[0047] See also Figure 3 , a single-phase grounding fault occurs at time T1, corresponding to Figure 2At the location of the fault point f, the fault point f is between DL2 and DL3 of line n. At this time, all zero-sequence impedance sudden change protection devices on line 1-n are activated and the zero-sequence impedance calculation begins, corresponding to Figure 2 The T1-T2 time period.

[0048] In a specific embodiment, for the target zero-sequence impedance sudden change protection device ( Figure 2 For any one of the multiple zero-sequence impedance mutation protection devices), the real-time calculation process of the zero-sequence impedance is as follows: real-time acquisition of the zero-sequence voltage at the position of the target zero-sequence impedance mutation protection device as the target zero-sequence voltage And collect three-phase zero-sequence current as target three-phase zero-sequence current Then calculate the ratio of the target zero-sequence voltage and the target three-phase zero-sequence current, and take the modulus of the ratio. The calculation formula is expressed as:

[0049]

[0050] Where Mod() is a function that takes the modulus of zero-sequence impedance. This allows for real-time calculation of the zero-sequence impedance at the location of each zero-sequence impedance sudden change protection device.

[0051] Step 104: Dynamically adjust the neutral point zero-sequence impedance of the distribution network.

[0052] Among them, the neutral point zero sequence impedance is Figure 2 Z in N , the Z N is any impedance among the inductive L, capacitive C and resistive R. Figure 4 It is a simplified principle circuit of zero-sequence impedance mutation. is the zero-sequence voltage when a ground fault occurs, is the zero sequence current when a ground fault occurs, Z c is the zero-sequence impedance of the line in the distribution network, Z N is the adjustable neutral point zero sequence impedance. As can be seen from the figure, changing Z N The zero-sequence impedance of the fault line can be changed.

[0053] like Figure 3 As shown, after a certain adjustment delay (i.e. T1-T2), the neutral point zero-sequence impedance Z of the distribution network is dynamically adjusted. N In specific application scenarios, the adjustment delay is generally set to 10ms to 5s after the ground fault is detected. The specific setting value needs to take into account the time requirements of other protection coordination and fault clearing.

[0054] See also Figure 3 , adjust the neutral point zero sequence impedance Z at time T2 N, which can be increased or decreased. Adjustment methods include: 1. Directly connecting or disconnecting through a mechanical switch. 2. Controlling the output impedance by adjusting the conduction angle through power electronic equipment.

[0055] Neutral point zero sequence impedance Z N After the change, the zero-sequence current I0 also changes, thereby changing the zero-sequence impedance at the location of the zero-sequence impedance sudden change protection device. Figure 3 , adjust the neutral point zero sequence impedance Z N The time is T2-T3, and at T3 the neutral point impedance is adjusted and returns to the initial state.

[0056] Step 106: After the adjustment is completed, the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device location is calculated.

[0057] The zero-sequence impedance mutation amount is calculated based on the real-time zero-sequence impedance. Figure 3 As shown, T3-T4 is the time for calculating the zero-sequence impedance mutation ΔZ0, which is the inherent time of the protection device.

[0058] In one specific embodiment, the process of calculating the zero-sequence impedance mutation ΔZ0 is as follows: obtaining the target zero-sequence impedance mutation protection device ( Figure 2 any one of the multiple zero-sequence impedance mutation protection devices), a first zero-sequence impedance Z1 at the initial moment and a second zero-sequence impedance Z2 at the end moment within a preset time period T; then calculating the difference between the first zero-sequence impedance and the second zero-sequence impedance, and taking the difference as the zero-sequence impedance mutation of the target zero-sequence impedance mutation protection device, that is:

[0059] ΔZ0=Z1-Z2

[0060] In another specific embodiment, the process of calculating the zero-sequence impedance mutation ΔZ0 is as follows: obtaining the target zero-sequence impedance mutation protection device ( Figure 2 Any one of the multiple zero-sequence impedance sudden change protection devices), the maximum zero-sequence impedance Z within the preset time period T max and minimum zero-sequence impedance Z min ; Then calculate the difference between the maximum zero-sequence impedance and the minimum zero-sequence impedance, and use the difference as the target zero-sequence impedance mutation amount of the zero-sequence impedance mutation amount protection device, that is:

[0061] ΔZ0=Z max -Z min

[0062] Of course, the calculation method of the zero-sequence impedance sudden change ΔZ0 can be selected according to actual needs and is not limited here.

[0063] exist Figure 2In the illustrated embodiment, the single-phase ground fault occurs only at fault point f, which is between DL2 and DL3 on line n, while DL1 and DL2 are closer to the busbar. Therefore, the zero-sequence impedance sudden change protection devices connected to DL1 and DL2 upstream of fault point f both detect the zero-sequence impedance sudden change ΔZ0. However, the zero-sequence impedance sudden change protection device connected to DL3 downstream of fault point f cannot detect ΔZ0, nor can the zero-sequence impedance sudden change protection devices on other lines.

[0064] Step 108 : select the zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than the preset zero-sequence impedance mutation setting value as the target protection device, and start the preset delay of all target protection devices.

[0065] Furthermore, in the zero-sequence impedance mutation protection device that detects the zero-sequence impedance mutation, it is also necessary to determine which ones need to start the delay. In this embodiment, the preset zero-sequence impedance mutation setting value is used as the judgment basis.

[0066] In a specific embodiment, the zero-sequence impedance sudden change setting value is calculated as follows: first, the zero-sequence impedance Z of all lines in the distribution network to ground is obtained. c , the maximum value of the neutral point zero sequence impedance Z` 01 And the minimum value of neutral point zero sequence impedance Z` 02 , and then according to the zero-sequence impedance Z to ground c , the maximum value of the neutral point zero sequence impedance Z` 01 And the minimum value of neutral point zero sequence impedance Z` 02 The adjustment range ΔZ of the neutral point zero-sequence impedance is calculated based on the following formula: N :

[0067]

[0068] Next, obtain the maximum positive deviation of the zero-sequence voltage measurement of the voltage transformer Maximum negative deviation of zero-sequence current measurement of current transformer And the maximum value of the neutral point zero sequence impedance Adjust to the minimum value of neutral point zero sequence impedance Z` 02 The number of adjustments n B , and finally measure the maximum positive deviation based on the zero-sequence voltage Maximum negative deviation of zero-sequence current measurement Adjustment times n B and adjustment range ΔZ N The zero-sequence impedance sudden change setting value is calculated based on the following formula:

[0069]

[0070] In another specific embodiment, the zero-sequence impedance sudden change setting value is calculated as follows: based on the detection sensitivity of the distribution network to ground faults (usually 0.001-50Ω) and the safety factor k (k can be between 1-1.8). The specific calculation formula is: ΔZ zd =Detection sensitivity × safety factor k.

[0071] In other specific embodiments, the calculation method of the zero-sequence impedance sudden change setting value can also be set to a characteristic quantity such as the impedance change rate that represents the continuous change of impedance over a period of time according to user needs.

[0072] Of course, any of the above-mentioned calculation methods for the zero-sequence impedance sudden change setting value can be selected and is not specifically limited here.

[0073] After setting ΔZ zd Then, ΔZ0>ΔZ zd The zero-sequence impedance sudden change protection device is used as the target protection device. In this embodiment, the zero-sequence impedance sudden change protection devices connected to DL1 and DL2 both meet this condition.

[0074] At the same time, in this embodiment, the delay preset for the zero-sequence impedance sudden change protection device close to the busbar of the distribution network is set to be greater than the delay preset for the zero-sequence impedance sudden change protection device far from the busbar of the distribution network. Therefore, taking line n as an example, the delay preset for the zero-sequence impedance sudden change protection device connected to DL1, DL2, and DL3 decreases in sequence. Figure 3 The T4-T5 delay is the delay preset for the zero-sequence impedance sudden change protection device connected to the circuit breaker DL2, and the T4-T6 delay is the delay preset for the zero-sequence impedance sudden change protection device connected to the circuit breaker DL1. At the same time, the delay preset for the target protection device connected to DL1 and DL2 is started.

[0075] Step 110: When any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that has reached the delay is used to control the connected circuit breaker to trip.

[0076] Specifically, since T4-T5 is smaller than T4-T6, Figure 2 The target protection device connected to DL2 reaches the corresponding preset delay first, and the single-phase grounding fault still exists at this time. Therefore, at time T5, the target protection device connected to DL2 controls the output action instruction to control the circuit breaker DL2 to trip, thereby clearing the fault. At this time, all zero-sequence impedance mutation protection devices return to the initial operation state.

[0077] For circuit breaker DL1 on line n, the fault to its connected protection device is cleared before the delay T4-T6 expires. Therefore, the target protection device returns to its initial state early, eliminating the need for tripping of circuit breaker DL1 on line n. Fault point f is effectively isolated. In actual operation, the time from fault detection to isolation is typically 0.1s to 50s, achieving rapid fault clearing.

[0078] In a specific embodiment, when the current reaches the delayed target protection device, the amplitude of the zero sequence voltage U0 at the set position is greater than the preset ground fault detection starting value U 0q In actual scenarios, the set U 0q Greater than 8V. This can effectively avoid false responses.

[0079] The above-mentioned distribution network zero-sequence impedance mutation protection method calculates the zero-sequence impedance at the location of each zero-sequence impedance mutation protection device in real time after detecting a single-phase grounding fault in the distribution network. The zero-sequence impedance at the neutral point of the distribution network is then adjusted, and after the adjustment is completed, the zero-sequence impedance mutation at the location of each zero-sequence impedance mutation protection device is calculated. The zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value is then selected as a target protection device, and the preset delays of all target protection devices are activated. The preset delay of a zero-sequence impedance mutation protection device closer to the distribution network busbar is greater than the preset delay of a zero-sequence impedance mutation protection device farther from the distribution network busbar. Finally, when any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that has reached the delay is used to control the connected circuit breaker to trip. In this way, the present invention can achieve dynamic zero-sequence impedance mutation protection. The dynamic zero-sequence impedance mutation protection of the present invention has a wide range of applications and is suitable for systems with any neutral point grounding method, such as ungrounded, arc suppression coil grounded, resistor grounded, and voltage source flexible grounded. The dynamic zero-sequence impedance mutation protection is also suitable for distribution line feeder circuit breakers and distribution automation intelligent circuit breaker protection, and has high accuracy and sensitivity. At the same time, the dynamic zero-sequence impedance mutation protection is not affected by the power direction of the line, accurately determines the location of the ground fault, and quickly isolates the fault point.

[0080] In one embodiment, Figure 5 As shown, a distribution network zero-sequence impedance mutation protection device is proposed, which includes: a zero-sequence voltage sensing module 1, a zero-sequence current sensing module 2, and a control protection module 3; wherein,

[0081] Zero-sequence voltage sensing module 1, used to detect the zero-sequence voltage at the circuit breaker installation location;

[0082] Zero-sequence current sensing module 2, used to detect the three-phase zero-sequence current at the circuit breaker installation location;

[0083] The control and protection module 3 is used to collect the zero-sequence voltage and three-phase zero-sequence current at the installation location of the circuit breaker, and apply the above-mentioned distribution network zero-sequence impedance sudden change protection method.

[0084] In a specific embodiment, Figure 6 As shown, the control and protection module includes a sampling unit 31, a calculation unit 32, and a tripping unit 33; wherein,

[0085] Sampling unit 31, used for collecting zero-sequence voltage and three-phase zero-sequence current at the installation location of the circuit breaker;

[0086] The calculation unit 32 is used to calculate the zero-sequence impedance at each zero-sequence impedance mutation protection device in real time after detecting a single-phase grounding fault in the distribution network;

[0087] Dynamically adjust the neutral point zero-sequence impedance of the distribution network;

[0088] After the adjustment is completed, the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device is calculated; wherein the zero-sequence impedance mutation amount is calculated based on the zero-sequence impedance calculated in real time;

[0089] The zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than the preset zero-sequence impedance mutation setting value is used as the target protection device, and the preset delays of all target protection devices are activated; wherein, the preset delay of the zero-sequence impedance mutation protection device close to the busbar of the distribution network is greater than the preset delay of the zero-sequence impedance mutation protection device far from the busbar of the distribution network;

[0090] When any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, a control instruction is output to the trip unit 33;

[0091] The trip unit 33 is used to respond to the control instruction and control the connected circuit breaker to trip.

[0092] Figure 7 FIG. 1 shows an internal structure diagram of a zero-sequence impedance sudden change protection device for a distribution network in one embodiment. Figure 7As shown, the distribution network zero-sequence impedance mutation protection device includes a processor, a memory, and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the distribution network zero-sequence impedance mutation protection device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the distribution network zero-sequence impedance mutation protection method. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the distribution network zero-sequence impedance mutation protection method. Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present application, and does not constitute a limitation on the distribution network zero-sequence impedance mutation protection device to which the scheme of the present application is applied. The specific distribution network zero-sequence impedance mutation protection device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0093] A distribution network zero-sequence impedance mutation protection device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented: after detecting the presence of a single-phase grounding fault in the distribution network, the zero-sequence impedance at the location of each zero-sequence impedance mutation protection device is calculated in real time; the neutral point zero-sequence impedance of the distribution network is dynamically adjusted; after the adjustment is completed, the zero-sequence impedance mutation at the location of each zero-sequence impedance mutation protection device is calculated; a zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value is selected as a target protection device, and preset delays of all target protection devices are activated; when any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that has currently reached the delay is used to control the connected circuit breaker to trip.

[0094] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps: after detecting the presence of a single-phase grounding fault in a distribution network, calculating the zero-sequence impedance at the location of each zero-sequence impedance mutation protection device in real time; dynamically adjusting the zero-sequence impedance at the neutral point of the distribution network; after completing the adjustment, calculating the zero-sequence impedance mutation at the location of each zero-sequence impedance mutation protection device; taking a zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value as a target protection device, and initiating preset delays for all target protection devices; and when any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, controlling the connected circuit breaker to trip via the target protection device that has currently reached the delay.

[0095] It should be noted that the above-mentioned distribution network zero-sequence impedance mutation protection method, device, equipment and computer-readable storage medium belong to a general inventive concept, and the contents of the distribution network zero-sequence impedance mutation protection method, device, equipment and computer-readable storage medium embodiments are applicable to each other.

[0096] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, which can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0097] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for protecting a distribution network zero-sequence impedance sudden change, characterized in that: The distribution network includes at least one line, each line is provided with a plurality of spaced circuit breakers, and both ends of each circuit breaker are connected to a zero-sequence impedance sudden change protection device. The method includes: After detecting a single-phase grounding fault in the distribution network, the zero-sequence impedance at each zero-sequence impedance mutation protection device is calculated in real time; Dynamically adjusting the neutral point zero-sequence impedance of the distribution network; After the adjustment is completed, the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device is calculated; wherein the zero-sequence impedance mutation amount is calculated based on the zero-sequence impedance calculated in real time; A zero-sequence impedance mutation protection device in the distribution network whose corresponding zero-sequence impedance mutation is greater than a preset zero-sequence impedance mutation setting value is selected as a target protection device, and preset delays of all target protection devices are activated; wherein the preset delay of a zero-sequence impedance mutation protection device close to a busbar of the distribution network is greater than the preset delay of a zero-sequence impedance mutation protection device far from the busbar of the distribution network; When any target protection device reaches the corresponding preset delay and the single-phase grounding fault still exists, the target protection device that currently reaches the delay controls the connected circuit breaker to trip.

2. The method according to claim 1, characterized in that The real-time calculation of the zero-sequence impedance at each zero-sequence impedance mutation protection device location includes: In real time, a zero-sequence voltage at a target zero-sequence impedance mutation protection device is collected as a target zero-sequence voltage, and a three-phase zero-sequence current is collected as a target three-phase zero-sequence current; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices; The ratio of the target zero-sequence voltage to the target three-phase zero-sequence current is calculated, and the modulus of the ratio is taken to obtain the zero-sequence impedance.

3. The method according to claim 1, characterized in that The calculating of the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device location includes: Obtaining a target zero-sequence impedance mutation protection device, a first zero-sequence impedance at an initial moment and a second zero-sequence impedance at an end moment within a preset time period; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices; The difference between the first zero-sequence impedance and the second zero-sequence impedance is calculated, and the difference is used as the zero-sequence impedance sudden change amount of the target zero-sequence impedance sudden change amount protection device.

4. The method according to claim 1, wherein The calculating of the zero-sequence impedance mutation amount at each zero-sequence impedance mutation amount protection device location includes: Obtaining a maximum zero-sequence impedance and a minimum zero-sequence impedance of a target zero-sequence impedance mutation protection device within a preset time period; wherein the target zero-sequence impedance mutation protection device is any one of a plurality of zero-sequence impedance mutation protection devices; The difference between the maximum zero-sequence impedance and the minimum zero-sequence impedance is calculated, and the difference is used as the zero-sequence impedance sudden change amount of the target zero-sequence impedance sudden change amount protection device.

5. The method according to claim 1, wherein Each zero-sequence impedance mutation protection device detects zero-sequence voltage through a voltage transformer and detects zero-sequence current through a current transformer. The method further includes: Obtaining the zero-sequence impedance to ground, the maximum value of the neutral point zero-sequence impedance, and the minimum value of the neutral point zero-sequence impedance of all lines in the distribution network, and calculating the adjustment range of the neutral point zero-sequence impedance based on the zero-sequence impedance to ground, the maximum value of the neutral point zero-sequence impedance, and the minimum value of the neutral point zero-sequence impedance; Obtain the maximum positive deviation of the zero-sequence voltage measurement of the voltage transformer, the maximum negative deviation of the zero-sequence current measurement of the current transformer, and the number of adjustments from the maximum value of the neutral point zero-sequence impedance to the minimum value of the neutral point zero-sequence impedance, and calculate the zero-sequence impedance mutation setting value based on the maximum positive deviation of the zero-sequence voltage measurement, the maximum negative deviation of the zero-sequence current measurement, the number of adjustments, and the adjustment range.

6. The method according to claim 1, characterized in that The method further comprises: The zero-sequence impedance sudden change setting value is calculated based on the detection sensitivity and safety factor of the distribution network to the ground fault.

7. The method according to claim 1, characterized in that The method of controlling the connected circuit breaker to trip by the target protection device with the current arrival delay comprises: When the amplitude of the zero-sequence voltage at the set position of the target protection device that currently reaches the delay is greater than the preset ground fault detection starting value, the connected circuit breaker is controlled to trip.

8. A zero-sequence impedance sudden change protection device for a distribution network, characterized in that: The device includes: a zero-sequence voltage sensing module, a zero-sequence current sensing module, and a control and protection module; wherein, The zero-sequence voltage sensing module is used to detect the zero-sequence voltage at the installation location of the circuit breaker; The zero-sequence current sensing module is used to detect the three-phase zero-sequence current at the installation location of the circuit breaker; The control and protection module is used to collect the zero-sequence voltage and three-phase zero-sequence current at the installation location of the circuit breaker and apply the method according to claim 1.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. A distribution network zero-sequence impedance sudden change protection device, comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

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