Power transmission line disconnection fault protection method, device and equipment and storage medium

Abstract

The invention relates to a power transmission line disconnection fault protection method, device and equipment and a storage medium, and the method comprises the steps: collecting a phase voltage value, a zero sequence voltage value and two groups of phase current values of a power transmission line in real time, carrying out the real-time monitoring of a circuit breaker, and obtaining a position state signal; according to the phase current value and the position state signal, whether the current transformer has a disconnection fault is judged in real time, and when the current transformer has the disconnection fault, a CT disconnection signal is output; obtaining a current break variable of the transmission line, calculating a self-produced zero-sequence current according to the phase current value, judging whether the self-produced zero-sequence current, the zero-sequence voltage value or the current break variable meets a preset condition or not, and if yes, outputting a disconnection protection starting signal; and after disconnection protection is started, judging whether the power transmission line has a disconnection fault or not according to the phase voltage value, the phase current value, the position state signal and the CT disconnection signal, and if the judgment result is yes, outputting a circuit breaker tripping outlet and a starting failure outlet.

Description

Technical Field

[0001] The present application relates to the technical field of power system protection, and in particular to a method, device, equipment and storage medium for protecting a power transmission line from a line break fault. Background Art

[0002] For a long time, because the probability of power system line break failure is very low, and after the line break failure occurs, the longitudinal zero sequence generated can cause the zero-sequence overcurrent protection to operate, so for the transmission line line break failure, various protection manufacturers have not configured dedicated protection or devices.

[0003] In recent years, with the completion of the flexibility transformation of thermal power units and the large-scale access to the grid of new energy, most thermal power units have been operating at 20% or 30% load for a long time. The zero-sequence overcurrent protection III stage of the current system transmission line is often set to an empirical value of 300A. When the unit is running at low load, if a line break occurs, the zero-sequence current will not reach the protection setting value, the protection cannot be activated, and the fault cannot be removed in time. The power frequency overvoltage and negative sequence voltage generated by the line break endanger equipment and personal safety. Therefore, it is very necessary to configure a dedicated line break protection for the power plant transmission line. Summary of the invention

[0004] The embodiments of the present application provide a method, device, equipment and storage medium for protecting a power transmission line from a line break fault, so as to at least solve the problem in the related art that protection cannot be activated when a line break fault occurs under low load conditions of the unit.

[0005] In a first aspect, an embodiment of the present application provides a transmission line disconnection fault protection method, which is applied to a transmission line in a power system, comprising:

[0006] The phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line are collected in real time, the circuit breaker in the transmission line is monitored in real time, and the position state signal representing the contact state of each phase in the three phases of the circuit breaker is obtained; wherein the two sets of phase current values ​​are collected at the same line position through different current transformer secondary windings;

[0007] Determine in real time whether a current transformer has a disconnection fault according to the phase current value and the position status signal, and output a CT disconnection signal when a current transformer has a disconnection fault;

[0008] Obtain the current mutation amount of the transmission line, and calculate the self-generated zero-sequence current according to the phase current value, and determine whether the self-generated zero-sequence current, zero-sequence voltage value or current mutation amount meets the preset conditions. If yes, output a line break protection start signal;

[0009] After the line break protection is started, it is determined whether a line break fault occurs in the transmission line according to the phase voltage value, phase current value, position status signal and CT line break signal. If the judgment result is yes, the circuit breaker tripping output and the starting failure output are output.

[0010] In one embodiment, the determining whether the self-generated zero-sequence current, zero-sequence voltage value or current mutation amount meets a preset condition includes:

[0011] Calculate a first threshold value and a second threshold value respectively according to the zero-sequence voltage value and the self-generated zero-sequence current;

[0012] Obtaining a minimum load current of a single unit in the power system, and calculating a third threshold value according to the minimum load current;

[0013] The self-generated zero-sequence current, zero-sequence voltage value and current mutation amount are judged, and a line break protection start signal is output when the preset conditions are met; wherein the preset conditions include one or more of the zero-sequence voltage value being greater than a first threshold value, the self-generated zero-sequence current being greater than a second threshold value, or the current mutation amount being greater than a third threshold value.

[0014] In one embodiment, assuming that two sets of phase current values ​​are I1 and I2 respectively, the real-time determination of whether a current transformer has a disconnection fault according to the phase current values ​​and the position status signal includes:

[0015] Calculate the current discrimination coefficient based on the two sets of phase current values ​​I1 and I2;

[0016] When the absolute value of I1 is not equal to the absolute value of I2, the absolute value of the difference between I1 and I2 is greater than the current discrimination coefficient and the position state signal indicates that the circuit breaker is in the closed position, it is determined that the current transformer has a disconnection fault.

[0017] In one embodiment, judging whether a power transmission line has a disconnection fault according to the phase voltage value, the phase current value, the position status signal and the CT disconnection signal includes:

[0018] In the absence of a current transformer disconnection signal, when the phase voltage is greater than the voltage low setting value and less than the voltage high setting value, the phase current is less than the current setting value, at least one of the other two phases has current, the circuit breaker has not changed position within a preset time, and the circuit breaker is in a closed state, it is determined that a transmission line disconnection fault has occurred.

[0019] In a second aspect, an embodiment of the present application provides a power transmission line disconnection fault protection device, including a signal acquisition unit, a first logic judgment unit, a second logic judgment unit and a third logic judgment unit, wherein:

[0020] The signal acquisition unit is used to collect the phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line in real time, monitor the circuit breaker in the transmission line in real time, and obtain the position status information representing the contact status of each phase in the three phases of the circuit breaker; wherein the two sets of phase current values ​​are collected at the same line position through different current transformer secondary windings;

[0021] The first logic judgment unit is used to judge in real time whether a current transformer has a disconnection fault according to the phase current value and the position state signal, and output a CT disconnection signal when a current transformer has a disconnection fault;

[0022] The second logic judgment unit is used to obtain the current mutation amount of the transmission line, and calculate the self-generated zero-sequence current according to the phase current value, and judge whether the self-generated zero-sequence current, zero-sequence voltage value and current mutation amount meet the preset conditions, and if so, output the line break protection start signal;

[0023] The third logic judgment unit is used to judge whether a line break fault occurs in the transmission line according to the phase voltage value, phase current value, position status signal and CT line break signal after the line break protection is started. If the judgment result is yes, the circuit breaker tripping output and the starting failure output are output.

[0024] In one embodiment, the first logic judgment unit includes a first logic AND gate, a first current judgment unit, and a second current judgment unit, wherein a first input end of the first logic AND gate is connected to the first current judgment unit, a second input end of the first logic AND gate is connected to the position state signal, and a third input end of the first logic AND gate is connected to the second current judgment unit;

[0025] The first current judgment unit is used to judge whether the two sets of phase current values ​​meet the first preset rule; the second current judgment unit is used to judge whether the two sets of phase current values ​​meet the second preset rule;

[0026] When the determination results of the first current determination unit and the second current determination unit are yes, and the position state signal indicates that the circuit breaker is in the closed position, the first logic determination unit outputs a CT disconnection signal.

[0027] In one embodiment, the second logic judgment unit includes a second logic OR gate, a first comparison module, a second comparison module and a third comparison module, wherein the second logic OR gate includes three input terminals, which are respectively connected to the first comparison module, the second comparison module and the third comparison module;

[0028] The first comparison module is used to determine whether the zero-sequence voltage value is greater than a first threshold value, the second comparison module is used to determine whether the self-generated zero-sequence current value is greater than a second threshold value, and the third comparison module is used to determine whether the sudden change amount of the phase current is greater than a third threshold value;

[0029] When the determination result of any one of the first comparison module, the second comparison module and the third comparison module is yes, the second logic OR gate outputs a line break protection start signal.

[0030] In one embodiment, the third logic judgment unit includes a third logic AND gate, a first NOT gate, a second NOT gate, a voltage comparison module, a current comparison module, a current monitoring module, and a circuit breaker position monitoring module, wherein:

[0031] The first input end of the third logic AND gate is connected to the voltage comparison module, the second input end of the third logic AND gate is connected to the output end of the first logic judgment unit through the first NOT gate, the third input end of the third logic AND gate is connected to the position state signal, the fourth input end of the third logic AND gate is connected to the current comparison module, the fifth input end of the third logic AND gate is connected to the current monitoring module, and the sixth input end of the third logic AND gate is connected to the circuit breaker position change monitoring module through the second NOT gate;

[0032] The voltage comparison module is used to determine whether the phase voltage is greater than the low voltage setting value and less than the high voltage setting value; the current comparison module is used to determine whether the phase current is less than the current setting value; the current monitoring module is used to determine whether any phase of the other two phases has current; the circuit breaker position monitoring module is used to determine whether the circuit breaker has been displaced within a preset time length;

[0033] When the determination results of the voltage comparison module, the current comparison module, the current monitoring module and the circuit breaker position monitoring module are yes, the circuit breaker is in the closed state, and no current transformer disconnection signal is received, the third logic AND gate outputs the circuit breaker trip output and the start failure output.

[0034] In a third aspect, an embodiment of the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the transmission line disconnection fault protection method as described in the first aspect above is implemented.

[0035] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the power transmission line disconnection fault protection method as described in the first aspect above.

[0036] The power transmission line disconnection fault protection method, device, equipment and storage medium provided by the embodiments of the present application have at least the following technical effects:

[0037] By using the comprehensive logic judgment of characteristic electrical quantities when the line is disconnected, the disconnected phase can be accurately judged and the disconnection fault can be removed. The present invention also solves the problem that the current zero-sequence overcurrent protection fails during low-load operation, and at the same time provides a setting scheme for disconnection protection, ensuring the reliability, selectivity and sensitivity of the protection, and having a certain degree of rapidity.

[0038] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0040] Figure 1 is a flow chart of a power transmission line disconnection fault protection method in one embodiment of the present application;

[0041] Figure 2 It is a structural block diagram of a power transmission line disconnection fault protection device in one embodiment of the present application;

[0042] Figure 3 yes Figure 2 A logic principle diagram of the first logic judgment unit in the embodiment;

[0043] Figure 4 yes Figure 2 A logic principle diagram of the second logic judgment unit in the embodiment;

[0044] Figure 5 yes Figure 2 Logic principle diagram of the third logic judgment unit in the embodiment;

[0045] Figure 6 is a logic principle diagram of a third logic judgment unit in another embodiment of the present application;

[0046] Figure 7 It is a structural block diagram of an electronic device in one embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0048] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0049] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0050] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0051] Through power system calculation and analysis, when a single-phase line is disconnected, the calculation method of each sequence current is as follows:

[0052]

[0053] When two phases are disconnected, the calculation method of each sequence current is as follows:

[0054]

[0055] In the above formula, I L is the load current before disconnection, Z 1Σ is the system positive sequence impedance, Z 2Σ is the system negative sequence impedance, Z 0Σ is the system zero-sequence impedance, is the positive sequence current when the single-phase line is broken, is the negative sequence current when a single-phase line is broken, is the zero-sequence current when a single-phase line is broken, is the positive sequence current when two phases are disconnected, is the negative sequence current when two phases are disconnected, It is the zero-sequence current when two phases are disconnected. It can be seen that the sequence current after the disconnection fault occurs is not only related to the positive sequence, negative sequence and zero sequence impedance parameters of the power system, but also directly depends on the load current before the disconnection.

[0056] Based on the above situation, the embodiments of the present application provide a method, device, equipment and storage medium for protecting a power transmission line from a disconnection fault.

[0057] In a first aspect, an embodiment of the present application provides a transmission line disconnection fault protection method, which is applied to a transmission line in a power system. Figure 1 is a flowchart of this method, refer to Figure 1 The power transmission line disconnection fault protection method of the present application is implemented by the following steps.

[0058] Step S1, real-time acquisition of the phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line, real-time monitoring of the circuit breaker in the transmission line, and acquisition of the position status signal of each phase contact in the three phases of the circuit breaker; wherein the two sets of phase current values ​​are acquired at the same line position through different current transformer secondary windings.

[0059] Step S2: determining in real time whether a current transformer has a disconnection fault according to the phase current value and the position status signal, and outputting a CT disconnection signal when a current transformer has a disconnection fault. Figure 3 , Figure 3 Taking the two groups of currents of phase A as an example, the two groups of current values ​​are collected by the first group of CT and the second group of CT respectively. Assuming that the two groups of phase current values ​​are I1 and I2 respectively, when judging whether the current transformer has a disconnection fault in real time according to the phase current values ​​and the position status signal, the current discrimination coefficient is first calculated according to the two groups of phase current values ​​I1 and I2; when the absolute value of I1 is less than the absolute value of I2, the absolute value of the difference between I1 and I2 is greater than the current discrimination coefficient, the position status signal HW A When the circuit breaker is in the closed position, it is determined that the first group of current transformers of phase A has a disconnection fault; on the contrary, when the absolute value of I2 is less than the absolute value of I1, the absolute value of the difference between I1 and I2 is greater than the current discrimination coefficient, the position state signal HW A When the circuit breaker is in the closed position, it is determined that the second current transformer of phase A has a disconnection fault. Similarly, the judgment process of whether the CT of phase B and phase C is disconnected is the same as that of reference Figure 2 The judgment method is the same as that of FIG. 1 , except that the current signal at the corresponding position is collected. Therefore, this embodiment will not be described in detail here.

[0060] Step S3, obtaining the current mutation of the transmission line, and calculating the self-generated zero-sequence current I0 according to the phase current value, and determining the self-generated zero-sequence current I0 and the zero-sequence voltage value U L Or whether the current mutation ΔI meets the preset conditions. If so, the line break protection start signal is output. For the specific judgment process, refer to Figure 4, respectively calculate a first threshold value and a second threshold value according to the zero-sequence voltage value and the self-produced zero-sequence current; obtain the minimum load current of a single unit in the power system, and calculate a third threshold value according to the minimum load current; judge the size of the self-produced zero-sequence current, the zero-sequence voltage value and the current mutation amount, and output a line break protection start signal when the preset conditions are met; wherein the preset conditions include one or more of the zero-sequence voltage value being greater than the first threshold value, the self-produced zero-sequence current being greater than the second threshold value, or the current mutation amount being greater than the third threshold value.

[0061] Step S4, after the disconnection protection is started, determine whether the transmission line has a disconnection fault according to the phase voltage value, phase current value, position state signal and CT disconnection signal. If the judgment result is yes, output the circuit breaker trip output and the start failure output. For the specific judgment process, refer to Figure 5 , when no current transformer disconnection signal is received, when the phase voltage is greater than the voltage low setting value and less than the voltage high setting value, the phase current is less than the current setting value, at least one of the other two phases has current, the circuit breaker does not change position within the preset time, and the circuit breaker is in the closed state, it is determined that a transmission line disconnection fault has occurred.

[0062] In summary, the power transmission line disconnection fault protection method provided by the embodiment of the present application can accurately determine the disconnection phase and remove the disconnection fault by using the comprehensive logic judgment of the characteristic electrical quantity when the line is disconnected. The problem that the current zero-sequence overcurrent protection fails during low-load operation is solved. The present invention also provides a setting scheme for disconnection protection, which ensures the reliability, selectivity and sensitivity of the protection and has a certain degree of rapidity.

[0063] In a second aspect, the present application provides a power transmission line disconnection fault protection device, referring to Figure 2 , including a signal acquisition unit, a first logic judgment unit, a second logic judgment unit and a third logic judgment unit. The signal acquisition unit is used to collect the phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line in real time, monitor the circuit breaker in the transmission line in real time, and obtain the position state signal representing the contact status of each phase in the three phases of the circuit breaker; wherein the two sets of phase current values ​​are collected at the same line position through different current transformer secondary windings.

[0064] In the device of this embodiment, the first logic judgment unit is used to judge in real time whether the current transformer has a line break fault according to the phase current value and the position status signal, and output a CT line break signal when the current transformer has a line break fault; the second logic judgment unit is used to obtain the current mutation amount of the transmission line, and calculate the self-generated zero-sequence current according to the phase current value, and judge whether the self-generated zero-sequence current, zero-sequence voltage value and current mutation amount meet the preset conditions, and if so, output a line break protection start signal; the third logic judgment unit is used to judge whether the transmission line has a line break fault according to the phase voltage value, phase current value, position status signal and CT line break signal after the line break protection is started, and if the judgment result is yes, output the circuit breaker tripping output and the starting failure output.

[0065] Specifically refer to Figure 3 The first logic judgment unit includes a first logic AND gate, a first current judgment unit and a second current judgment unit, wherein the first input end of the first logic AND gate is connected to the first current judgment unit, the second input end of the first logic AND gate is connected to the position state signal, and the third input end of the first logic AND gate is connected to the second current judgment unit; the first current judgment unit is used to judge whether the two sets of phase current values ​​meet the first preset rule; the second current judgment unit is used to judge whether the two sets of phase current values ​​meet the second preset rule. When the judgment results of the first current judgment unit and the second current judgment unit are yes, and the position state signal indicates that the circuit breaker is in the closed position, the first logic judgment unit outputs a current transformer (CT) disconnection signal.

[0066] In the embodiment of the present application, the first preset rule is: The second preset rule is to compare the values ​​of I1 and I2, and the group of CTs with the smaller value is judged as broken, where I1 and I2 are the phase current values ​​collected by the first and second groups of current transformers in phase A, B or C. In addition, Figure 3 Middle I A1 and I A2 Indicates the phase current value of phase A, that is Figure 3 The CT disconnection process is schematically illustrated using the current of phase A. The judgment process of phases B and C is similar.

[0067] refer to Figure 4 The second logic judgment unit includes a second logic OR gate, a first comparison module, a second comparison module and a third comparison module, wherein the second logic OR gate includes three input terminals, which are respectively connected to the first comparison module, the second comparison module and the third comparison module; the first comparison module is used to judge the zero-sequence voltage value U LThe second comparison module is used to determine whether the self-generated zero-sequence current value I0 is greater than the second threshold value, and the third comparison module is used to determine whether the sudden change amount ΔI of the phase current is greater than the third threshold value. When the determination result of any one of the first comparison module, the second comparison module and the third comparison module is yes, the second logic OR gate outputs a line break protection start signal.

[0068] refer to Figure 5 The third logic judgment unit includes a third logic AND gate, a first NOT gate, a second NOT gate, a voltage comparison module, a current comparison module, a current monitoring module, and a circuit breaker position change monitoring module. The first input end of the third logic AND gate is connected to the voltage comparison module, the second input end of the third logic AND gate is connected to the output end of the first logic judgment unit through the first NOT gate, the third input end of the third logic AND gate is connected to the position state signal, the fourth input end of the third logic AND gate is connected to the current comparison module, the fifth input end of the third logic AND gate is connected to the current monitoring module, and the sixth input end of the third logic AND gate is connected to the circuit breaker position change monitoring module through the second NOT gate.

[0069] The voltage comparison module is used to determine whether the phase voltage is greater than the voltage low setting value U zdL And less than the voltage high setting value U zdh The present application embodiment takes the phase voltage of phase A as an example, and its judgment condition is U zdL A zdh The current comparison module is used to determine whether the phase current is less than the current setting value I zd ; The current monitoring module is used to determine whether there is current in any of the other two phases; the circuit breaker position change monitoring module is used to determine whether the circuit breaker changes position within a preset time (such as 100ms). In this embodiment, when the judgment results of the voltage comparison module, the current comparison module, the current monitoring module and the circuit breaker position change monitoring module are yes and the circuit breaker is in the closed state (i.e., HW A / B / C =1,) and when no current transformer disconnection signal is received, the third logic AND gate outputs a circuit breaker tripping output and a starting failure output.

[0070] In one embodiment, this embodiment refers to Figure 3 , Figure 4 and Figure 6 The power transmission line disconnection fault protection method and device proposed in this application are described in detail.

[0071] Specifically, the protection device of the present application collects a group of line three-phase voltage analog quantities U A U B U C U N (U​​N The protection device of this application collects a group of line zero-sequence voltage analog quantity U L U N The protection device in this application collects 2 sets of line three-phase current analog values ​​I A1 I B1 I C1 and I A2 I B2 I C2 , respectively provided by different current transformer secondary windings (the acquisition position is the same, and the two sets of parameters can be used at will). The protection device of this application acquires the closing position HW of each phase of the three-phase circuit breaker A , HW B , HW C .

[0072] Then pass Figure 3 The first logic judgment unit compares the two sets of three-phase current analog quantities to form a CT disconnection judgment logic, and the CT disconnection locks the disconnection protection to avoid malfunction of the disconnection protection when the CT is disconnected. Figure 4 To judge the protection start, the line zero-sequence voltage analog value U L Or the line self-generated zero-sequence current I0 is greater than the threshold value, which is used for protection startup. The protection device calculates and generates the self-generated zero-sequence current I0 based on the collected current analog quantity. The sudden change amount △I of any phase current is greater than the threshold value, which is used for protection startup. In this application, the calculation of the sudden change amount requires the collection of currents at least two times, and the time interval between the two currents can be determined according to the hardware configuration or determined by the user.

[0073] Last passed Figure 6 The logic unit judges the disconnection fault. Specifically, a phase of the circuit breaker is in the closed position and the current of the phase is less than the current setting value I zd , used to determine whether the phase is broken. Among them, the current constant I zd The setting is based on half of the load current flowing through the line when the unit is running at the lowest load in the minimum operation mode. The circuit breaker position has not changed, which is used to distinguish it from the line misoperation with load power transmission. The misoperation impact current is large, causing the protection to malfunction (normal operation is no-load power transmission, and then load is added after a period of time). There is current in any of the other two phases, which is used to distinguish it from the line no-load operation. The three-phase voltage is greater than the voltage low setting value U zdl And both are less than the high voltage setting value U zdh , used to distinguish it from short-circuit fault. Among them, the voltage constant U zdl When the unit is running at the minimum load under the minimum operation mode and a line break occurs, the setting is made when the voltage is less than the minimum value of the three-phase line voltage, i.e., U zdl =min(U A , U B , U C) / K rel , K rel The reliability coefficient is 1.1. zdh The setting is based on the maximum load under the maximum operation mode when the unit is running at the maximum load and the line failure occurs, which is greater than the maximum value of the three-phase line voltage, that is, U zdh =K rel ×max(U A , U B , U C ), K rel The reliability coefficient is 1.1. After the above conditions are met, the protection device provides a tripping output and a starting failure output. In addition, in the embodiment, the line break protection is set with a delay t1 to cooperate with other protections. Among them, the line break protection delay t1 is coordinated with the longest delay of the line backup protection to avoid empty line and short circuit fault conditions, that is, t1 = t max +△t.t max is the maximum delay of line backup protection; △t is the coordination difference, which is 0.3s.

[0074] exist Figure 6 In the embodiment of the present invention, the judgment logic of the present embodiment can judge the disconnection fault of phases A, B and C at the same time, and the phase voltage judgment result (U zdL A zdh , U zdL B zdh , U zdL C zdh ) is input into a logic AND gate. When the three-phase voltages meet the conditions, the AND gate outputs the judgment result "1". Then, three logic AND gates are used to determine whether phases A, B and C have a line break fault, and then the line break fault is sent to the same OR gate. As long as any phase has a line break fault, the OR gate outputs a line break fault signal, and after extending the t1 time, it outputs the circuit breaker trip output and the start failure output.

[0075] In summary, the power system transmission line disconnection fault protection device of the present application collects electrical quantities such as line voltage, line current, and line circuit breaker position to form a disconnection protection judgment logic. After the logic determines that a disconnection fault occurs in the line, the line circuit breaker is tripped and the circuit breaker failure protection is started through the tripping outlet and the failure start outlet provided by the device. Using the circuit breaker position, line current, line voltage, and the absence of CT disconnection and other conditions, the line disconnection fault is judged by comprehensive logic, and the fault is removed to ensure system safety. In addition, the present application provides a calculation method for current constants, voltage constants, and delay constants, which ensures the selectivity and sensitivity of the protection while taking into account reliability and speed. ​​​​​​

[0076] In a third aspect, an embodiment of the present application provides an electronic device, Figure 7 FIG. 1 is a block diagram of an electronic device according to an exemplary embodiment. Figure 7 As shown, the electronic device may include a processor 11 and a memory 12 storing computer program instructions.

[0077] Specifically, the processor 11 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0078] Among them, the memory 12 may include a large-capacity memory for data or instructions. By way of example and not limitation, the memory 12 may include a hard disk drive (HDD), a floppy disk drive, a solid-state drive (SSD), a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory 12 may include a removable or non-removable (or fixed) medium. Where appropriate, the memory 12 may be inside or outside a data processing device. In a specific embodiment, the memory 12 is a non-volatile memory. In a specific embodiment, the memory 12 includes a read-only memory (ROM) and a random access memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (Programmable Read-Only Memory, PROM for short), an erasable PROM (Erasable ProgrammableRead-Only Memory, EPROM for short), an electrically erasable PROM (Electrically Erasable ProgrammableRead-Only Memory, EEPROM for short), an electrically alterable ROM (Electrically Alterable Read-Only Memory, EAROM for short) or a flash memory (FLASH) or a combination of two or more of these. Under appropriate circumstances, the RAM can be a static random access memory (SRAM) or a dynamic random access memory (DRAM), wherein the DRAM can be a fast page mode dynamic random access memory (FPMDRAM), an extended data output dynamic random access memory (EDODRAM), a synchronous dynamic random access memory (SDRAM), etc.

[0079] The memory 12 may be used to store or cache various data files that need to be processed and / or used for communication, as well as possible computer program instructions executed by the processor 11 .

[0080] The processor 11 reads and executes computer program instructions stored in the memory 12 to implement any one of the power transmission line disconnection fault protection methods in the above embodiments.

[0081] In one embodiment, the electronic device may further include a communication interface 13 and a bus 10. Figure 7 As shown, the processor 11, the memory 12, and the communication interface 13 are connected via a bus 10 and communicate with each other.

[0082] The communication interface 13 is used to realize the communication between the modules, devices, units and / or equipment in the embodiment of the present application. The communication port 13 can also realize data communication with other components such as: external devices, image / data acquisition equipment, databases, external storage and image / data processing workstations.

[0083] The bus 10 includes hardware, software or both, and couples the components of the electronic device to each other. The bus 10 includes but is not limited to at least one of the following: a data bus, an address bus, a control bus, an expansion bus, and a local bus. By way of example and not limitation, bus 10 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, bus 10 may include one or more buses. Although embodiments of the present application describe and illustrate a particular bus, the present application contemplates any suitable bus or interconnect.

[0084] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a program stored thereon, and when the program is executed by a processor, the power transmission line disconnection fault protection method provided in the first aspect is implemented.

[0085] The readable storage medium may include but is not limited to: a portable disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical storage device, a magnetic storage device or any suitable combination of the above.

[0086] In a possible implementation, the present invention can also be implemented in the form of a program product, which includes program code. When the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps of the transmission line disconnection fault protection method provided in the first aspect.

[0087] The program code for executing the present invention may be written in any combination of one or more programming languages, and may be executed entirely on a user device, partially on a user device, as an independent software package, partially on a user device and partially on a remote device, or entirely on a remote device.

[0088] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0089] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for protecting a power transmission line from disconnection fault, characterized in that: Applications in power transmission lines of power systems include: The phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line are collected in real time, the circuit breaker in the transmission line is monitored in real time, and the position state signal representing the contact state of each phase in the three phases of the circuit breaker is obtained; wherein the two sets of phase current values ​​are collected at the same line position through different current transformer secondary windings; Determine in real time whether a current transformer has a disconnection fault according to the phase current value and the position status signal, and output a CT disconnection signal when a current transformer has a disconnection fault; Obtain the current mutation amount of the transmission line, and calculate the self-generated zero-sequence current according to the phase current value, and determine whether the self-generated zero-sequence current, zero-sequence voltage value or current mutation amount meets the preset conditions. If yes, output a line break protection start signal; After the line break protection is started, it is determined whether a line break fault occurs in the transmission line according to the phase voltage value, phase current value, position status signal and CT line break signal. If the judgment result is yes, the circuit breaker tripping output and the starting failure output are output.

2. The power transmission line disconnection fault protection method according to claim 1, characterized in that: The determining whether the self-generated zero-sequence current, zero-sequence voltage value or current mutation amount meets the preset conditions includes: Calculate a first threshold value and a second threshold value respectively according to the zero-sequence voltage value and the self-generated zero-sequence current; Obtaining a minimum load current of a single unit in the power system, and calculating a third threshold value according to the minimum load current; The self-generated zero-sequence current, zero-sequence voltage value and current mutation amount are judged, and a line break protection start signal is output when the preset conditions are met; wherein the preset conditions include one or more of the zero-sequence voltage value being greater than a first threshold value, the self-generated zero-sequence current being greater than a second threshold value, or the current mutation amount being greater than a third threshold value.

3. The power transmission line disconnection fault protection method according to claim 1, characterized in that: Assuming that two groups of phase current values ​​are I1 and I2 respectively, the method of judging in real time whether a current transformer has a disconnection fault according to the phase current values ​​and the position status signal includes: Calculate the current discrimination coefficient based on the two sets of phase current values ​​I1 and I2; When the absolute value of I1 is not equal to the absolute value of I2, the absolute value of the difference between I1 and I2 is greater than the current discrimination coefficient, and the position status signal indicates that the circuit breaker is in the closed position, it is determined that the current transformer has a disconnection fault.

4. The power transmission line disconnection fault protection method according to claim 1, characterized in that: The determining whether a power transmission line has a disconnection fault according to the phase voltage value, the phase current value, the position status signal and the CT disconnection signal comprises: In the absence of a current transformer disconnection signal, when the phase voltage is greater than the voltage low setting value and less than the voltage high setting value, the phase current is less than the current setting value, at least one of the other two phases has current, the circuit breaker has not changed position within a preset time, and the circuit breaker is in a closed state, it is determined that a transmission line disconnection fault has occurred.

5. A power transmission line disconnection fault protection device, characterized in that: It includes a signal acquisition unit, a first logic judgment unit, a second logic judgment unit and a third logic judgment unit, wherein: The signal acquisition unit is used to collect the phase voltage value, zero-sequence voltage value and two sets of phase current values ​​of the transmission line in real time, monitor the circuit breaker in the transmission line in real time, and obtain the position state signal representing the contact status of each phase in the three phases of the circuit breaker; wherein the two sets of phase current values ​​are collected at the same line position through different current transformer secondary windings; The first logic judgment unit is used to judge in real time whether a current transformer has a disconnection fault according to the phase current value and the position state signal, and output a CT disconnection signal when a current transformer has a disconnection fault; The second logic judgment unit is used to obtain the current mutation amount of the transmission line, and calculate the self-generated zero-sequence current according to the phase current value, and judge whether the self-generated zero-sequence current, zero-sequence voltage value and current mutation amount meet the preset conditions, and if so, output the line break protection start signal; The third logic judgment unit is used to judge whether a line break fault occurs in the transmission line according to the phase voltage value, phase current value, position status signal and CT line break signal after the line break protection is started. If the judgment result is yes, the circuit breaker tripping output and the starting failure output are output.

6. The power transmission line disconnection fault protection device according to claim 5, characterized in that: The first logic judgment unit includes a first logic AND gate, a first current judgment unit and a second current judgment unit, wherein the first input end of the first logic AND gate is connected to the first current judgment unit, the second input end of the first logic AND gate is connected to the position state signal, and the third input end of the first logic AND gate is connected to the second current judgment unit; The first current judgment unit is used to judge whether the two sets of phase current values ​​meet the first preset rule; the second current judgment unit is used to judge whether the two sets of phase current values ​​meet the second preset rule; When the determination results of the first current determination unit and the second current determination unit are yes, and the position state signal indicates that the circuit breaker is in the closed position, the first logic determination unit outputs a CT disconnection signal.

7. The power transmission line disconnection fault protection device according to claim 5, characterized in that: The second logic judgment unit includes a second logic OR gate, a first comparison module, a second comparison module and a third comparison module, wherein the second logic OR gate includes three input terminals, which are respectively connected to the first comparison module, the second comparison module and the third comparison module; The first comparison module is used to determine whether the zero-sequence voltage value is greater than a first threshold value, the second comparison module is used to determine whether the self-generated zero-sequence current value is greater than a second threshold value, and the third comparison module is used to determine whether the sudden change amount of the phase current is greater than a third threshold value; When the determination result of any one of the first comparison module, the second comparison module and the third comparison module is yes, the second logic OR gate outputs a line break protection start signal.

8. The power transmission line disconnection fault protection device according to claim 5, characterized in that: The third logic judgment unit includes a third logic AND gate, a first NOT gate, a second NOT gate, a voltage comparison module, a current comparison module, a current monitoring module, and a circuit breaker position change monitoring module, wherein: The first input end of the third logic AND gate is connected to the voltage comparison module, the second input end of the third logic AND gate is connected to the output end of the first logic judgment unit through the first NOT gate, the third input end of the third logic AND gate is connected to the position state signal, the fourth input end of the third logic AND gate is connected to the current comparison module, the fifth input end of the third logic AND gate is connected to the current monitoring module, and the sixth input end of the third logic AND gate is connected to the circuit breaker position change monitoring module through the second NOT gate; The voltage comparison module is used to determine whether the phase voltage is greater than the low voltage setting value and less than the high voltage setting value; the current comparison module is used to determine whether the phase current is less than the current setting value; the current monitoring module is used to determine whether any phase of the other two phases has current; the circuit breaker position monitoring module is used to determine whether the circuit breaker has been displaced within a preset time length; When the determination results of the voltage comparison module, the current comparison module, the current monitoring module and the circuit breaker position monitoring module are yes, the circuit breaker is in the closed state, and no current transformer disconnection signal is received, the third logic AND gate outputs the circuit breaker trip output and the start failure output.

9. An electronic device, characterized in that: It comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the power transmission line disconnection fault protection method as claimed in any one of claims 1 to 4 when executing the computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, a power transmission line disconnection fault protection method according to any one of claims 1 to 4 is implemented.

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