Method, device and equipment for preventing maloperation of distance protection and storage medium

Abstract

The application discloses a method, device and equipment for preventing distance protection misoperation and a storage medium. The method comprises the following steps: setting an overload identification criterion as a first criterion when overload blocking protection is started; judging whether a line fault trip occurs outside a to-be-protected line according to a preset discrimination rule; modifying the overload identification criterion as a second criterion when the line fault trip occurs; the stability of the first criterion is greater than the stability of the second criterion; performing overload identification according to the overload identification criterion and phase-to-phase residual voltage to obtain an overload identification result; and adjusting a distance protection III section according to the overload identification result. According to the embodiment of the application, whether a line fault trip occurs outside the to-be-protected line can be identified, different criteria are adaptively used to perform overload identification, and the distance protection III section is adjusted according to the identification result, so that the distance protection misoperation is avoided when a fault occurs outside the line, the fault scale is prevented from being increased, and the system stability is improved.

Description

Technical Field

[0001] This application belongs to the field of relay protection technology, and in particular relates to a method, device, equipment and storage medium for preventing maloperation of distance protection. Background Technology

[0002] In existing power distribution networks, when an external fault occurs on any line, the system is disturbed, which may cause malfunctions in the distance protection devices within that line. Currently, malfunctions of distance protection devices have become a significant factor contributing to the accelerated development and expansion of power outages.

[0003] To improve system stability, reduce system disturbances, and prevent power outages from escalating further, it is necessary to propose a method for preventing maloperation of distance protection when faults occur outside the line. Summary of the Invention

[0004] This application provides a method, apparatus, device, and storage medium for preventing maloperation of distance protection, which can solve the technical problem of maloperation of distance protection when there is an external fault on the line.

[0005] In a first aspect, embodiments of this application provide a method for preventing malfunction of distance protection, applied to the line to be protected, characterized in that the method includes:

[0006] When the overload lockout protection is activated, the overload identification criterion is set as the first criterion;

[0007] Determine whether a line fault trip has occurred outside the line to be protected based on the preset discrimination rules;

[0008] When a line fault trips outside the protected line, the overload identification criterion is modified to a second criterion; the stability of the first criterion is greater than that of the second criterion.

[0009] Overload identification is performed based on overload identification criteria and phase-to-phase cosine voltage to obtain overload identification results;

[0010] Adjust the distance protection stage III based on the overload identification results.

[0011] In some embodiments, determining whether a line fault trip has occurred outside the protected line according to a preset discrimination rule includes:

[0012] Obtain the impedance angle change at the protection position of the line to be protected;

[0013] The circuit breaker is determined based on the change in impedance angle and the first preset condition to determine whether a line fault trip has occurred outside the line to be protected.

[0014] In some embodiments, determining whether a line fault trip has occurred outside the protected line based on the impedance angle change and a first preset condition includes:

[0015] The number of times the change in impedance angle satisfies the first threshold range is counted to obtain the impedance angle count value;

[0016] The impedance angle count and the identification threshold are used to determine whether a line fault trip has occurred outside the protected line.

[0017] In some embodiments, counting the number of times the impedance angle change satisfies a first threshold range to obtain an impedance angle count value includes:

[0018] When the change in impedance angle continues to reach the first threshold range, the impedance angle count is performed.

[0019] In some embodiments, determining whether a line fault trip has occurred outside the protected line according to a preset discrimination rule includes:

[0020] Obtain the negative sequence voltage and zero sequence voltage at the protection position of the line to be protected, and calculate the stable value of the negative sequence voltage to zero sequence voltage ratio;

[0021] Based on the stable value of the negative sequence and zero sequence voltage ratio and the second preset condition, it is determined whether a line fault trip has occurred outside the line to be protected.

[0022] In some embodiments, determining whether a line fault trip has occurred outside the protected line based on the stable value of the negative-sequence and zero-sequence voltage ratios and a second preset condition includes:

[0023] Calculate the ratio of two adjacent negative-sequence zero-sequence voltages to their stable values;

[0024] The ratio and the second threshold are used to determine whether a line fault trip has occurred outside the protected line.

[0025] In some embodiments, obtaining the negative-sequence voltage and zero-sequence voltage at the protection position of the line to be protected, and calculating the stable value of the negative-sequence and zero-sequence voltage ratio, includes:

[0026] Obtain the impedance angle change at the protection position of the line to be protected;

[0027] Determine whether a line fault trip has occurred outside the protected line based on the change in impedance angle and the first preset condition.

[0028] When the change in impedance angle does not meet the first preset condition, the negative sequence voltage and zero sequence voltage of the protected line are obtained, and the stable value of the negative sequence and zero sequence voltage ratio is calculated.

[0029] In some embodiments, overload identification is performed based on overload identification criteria and phase-to-phase cosine voltage to obtain overload identification results, including:

[0030] The overload threshold voltage is determined by multiplying the overload identification criterion and the rated phase-to-phase voltage.

[0031] When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets the second preset condition, the overload identification result is determined to be overload blocking.

[0032] When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets the third preset condition, the overload identification result is determined to be overload open.

[0033] In some embodiments, when the magnitude relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets a second preset condition, determining the overload identification result as overload blocking includes:

[0034] When the phase-to-phase cosine voltage is lower than the overload threshold voltage, the first count value is counted;

[0035] When the first count value reaches the blocking threshold, the overload identification result is determined to be overload blocking;

[0036] When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets the third preset condition, the overload identification result is determined to be overload enabled, including:

[0037] When the phase-to-phase cosine voltage is higher than the overload threshold voltage, the second count value is counted;

[0038] When the second count value reaches the opening threshold, the overload identification result is determined to be overload opening.

[0039] In some embodiments, when the first count value increases, the second count value is reset to zero; when the second count value increases, the first count value is reset to zero.

[0040] In some embodiments, adjusting the distance protection stage III based on the overload identification result includes:

[0041] When the overload identification result indicates overload blocking, the blocking distance protection stage III is activated.

[0042] When the overload identification result indicates overload opening, the distance protection stage III is opened.

[0043] Secondly, embodiments of this application provide a device for preventing malfunction of distance protection, the device comprising:

[0044] The startup module is used to set the overload identification criterion as the first criterion when the overload lockout protection is started.

[0045] The judgment module is used to determine whether a line fault trip has occurred outside the line to be protected, based on preset judgment rules;

[0046] The criterion setting module is used to modify the overload identification criterion to a second criterion when a line fault trip occurs outside the line to be protected; the stability of the first criterion is greater than that of the second criterion.

[0047] The identification module is used to identify overload based on overload identification criteria and phase-to-phase cosine voltage, and obtain the overload identification result.

[0048] The adjustment module is used to adjust the distance protection stage III based on the overload identification results.

[0049] Thirdly, embodiments of this application provide a device for preventing malfunction of distance protection. The device for preventing malfunction of distance protection includes: a processor and a memory storing computer program instructions.

[0050] The processor implements the above method to prevent distance protection from malfunctioning when executing computer program instructions.

[0051] Fourthly, embodiments of this application provide a computer storage medium storing computer program instructions, which, when executed by a processor, implement the above-mentioned method for preventing malfunctions of distance protection.

[0052] Compared with existing technologies, the method, apparatus, device, and storage medium for preventing maloperation of distance protection provided in this application can set the overload identification criterion as the first criterion when overload blocking is initiated, and determine whether a line fault trip has occurred outside the protected line according to a preset discrimination rule. When it is determined that a line fault trip has occurred outside the protected line, the overload identification criterion can be modified from the first criterion to the second criterion. After determining the overload identification criterion, overload identification can be performed based on the determined overload identification criterion and the obtained current phase-to-phase cosine voltage to obtain the overload identification result. Specifically, when no line fault trip has occurred outside the protected line, the system is in a stable state, and overload identification can be performed using the relatively stable first criterion; when a line fault trip has occurred outside the protected line, the system is disturbed and may be in an unstable state. If the first criterion is continued to be used for overload identification, erroneous overload identification results may occur due to system instability. By adjusting the stringent first criterion to a more lenient second criterion, maloperation of protection can be avoided when the system is unstable. When the system is in different states, it can adaptively identify overload based on different criteria, and adjust the distance protection stage III on the protected line according to the overload identification result. The adjustment method can be to block the distance protection stage III or open the distance protection stage III. When a line fault trips outside the protected line, the number of lines in the distribution network system that are overloaded will increase. By judging whether a line fault trip has occurred outside the protected line, different criteria can be adaptively used to perform overload identification based on the judgment result, thereby avoiding maloperation of the distance protection on non-faulty protected lines and preventing disturbances to the system, thus preventing the scale and scope of system faults from further increasing and improving system stability. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a flowchart illustrating a method for preventing malfunction of distance protection according to an embodiment of this application;

[0055] Figure 2 This is a flowchart illustrating a method for preventing malfunction of distance protection according to another embodiment of this application;

[0056] Figure 3 This is a flowchart illustrating a method for preventing malfunction of distance protection according to another embodiment of this application;

[0057] Figure 4 This is a flowchart illustrating a method for preventing malfunction of distance protection according to another embodiment of this application;

[0058] Figure 5 This is a flowchart illustrating a method for preventing malfunction of distance protection according to another embodiment of this application;

[0059] Figure 6 This is a flowchart illustrating a method for preventing malfunction of distance protection according to another embodiment of this application;

[0060] Figure 7 This is a schematic diagram of the angles of measuring voltage and measuring current in one embodiment of this application;

[0061] Figure 8 This is a schematic diagram of the line relationship of the line to be protected in one embodiment of this application;

[0062] Figure 9 This is a circuit diagram of a single-phase short-circuit fault in one embodiment of this application;

[0063] Figure 10 This is a schematic diagram of the negative sequence equivalent network during a single-phase short-circuit fault in one embodiment of this application;

[0064] Figure 11 This is a schematic diagram of the zero-sequence equivalent network during a single-phase short-circuit fault in one embodiment of this application;

[0065] Figure 12 This is a circuit diagram of a single-phase fault tripping in one embodiment of this application;

[0066] Figure 13 This is a schematic diagram of the negative sequence equivalent network during a single-phase fault trip in one embodiment of this application;

[0067] Figure 14 This is a schematic diagram of the zero-sequence equivalent network during a single-phase fault trip in one embodiment of this application;

[0068] Figure 15 A schematic diagram of the structure of a device for preventing malfunction of distance protection provided in an embodiment of this application;

[0069] Figure 16 This is a schematic diagram of the structure of a device for preventing malfunction of distance protection provided in an embodiment of this application. Detailed Implementation

[0070] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples of this application.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0072] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0073] Currently, in power distribution networks, when an external fault occurs on any line, the resulting disturbance can cause malfunctions in the distance protection systems within that line. These malfunctions have become a significant factor contributing to the accelerated development and wider spread of power outages.

[0074] To improve system stability, reduce system disturbances, and prevent power outages from escalating further, it is necessary to determine whether a fault location is within the line when a line fault occurs, and to prevent distance protection from malfunctioning when a fault occurs outside the line.

[0075] To address the aforementioned technical problems, embodiments of this application provide a method, apparatus, device, and storage medium for preventing malfunctions of distance protection. The method for preventing malfunctions of distance protection provided in this application embodiment will be described first below.

[0076] Figure 1 A flowchart illustrating a method for preventing malfunction of distance protection according to an embodiment of this application is shown. The method for preventing malfunction of distance protection includes:

[0077] S110, when the overload lockout protection is activated, the overload identification criterion is set as the first criterion;

[0078] S120 determines whether a line fault trip has occurred outside the protected line according to the preset discrimination rules;

[0079] S130: When a line fault trips outside the protected line, the overload identification criterion is modified to a second criterion; the stability of the first criterion is greater than that of the second criterion.

[0080] S140, overload identification is performed based on the overload identification criteria and the phase-to-phase cosine voltage to obtain the overload identification result;

[0081] S150, adjust the distance protection stage III based on the overload identification results.

[0082] The method for preventing maloperation of distance protection provided in this application embodiment can be applied to a device for preventing maloperation of distance protection. The device can be installed on the line to be protected and adjust the distance protection stage III when a fault trip occurs on other lines outside the line to be protected, so as to avoid maloperation of the protection when a fault occurs outside the line.

[0083] In this embodiment, when the overload blocking is initiated, the device can set the overload identification criterion as the first criterion and determine whether a line fault trip has occurred outside the protected line according to a preset discrimination rule. When the device determines that a line fault trip has occurred outside the protected line, the overload identification criterion can be modified from the first criterion to the second criterion. After determining the overload identification criterion, the device can perform overload identification based on the determined overload identification criterion and the acquired current phase-to-phase cosine voltage to obtain the overload identification result. Specifically, when no line fault trip has occurred outside the protected line, the system is in a stable state, and overload identification can be performed using the relatively stable first criterion. When a line fault trip has occurred outside the protected line, the system experiences disturbances and may be in an unstable state. If the first criterion is continued for overload identification, the system instability may lead to a misjudgment that the protected line is in an overload state. By adjusting the stringent first criterion to a more lenient second criterion, voltage fluctuations can be avoided from being misjudged as an overload state when the system is unstable. When the system is in different states, the device identifies overload based on different criteria. Based on the overload identification result, it can adjust the distance protection stage III on the protected line. The adjustment method can be either blocking or opening the distance protection stage III. For example, if it is determined that the protected line is in an overload state, distance protection stage III can be blocked; if it is determined that the protected line is not in an overload state, distance protection stage III can be opened. When a line fault trips outside the protected line, the number of overloaded lines in the distribution network system will increase. By determining whether a line fault trip has occurred outside the protected line, different criteria can be used to identify overload on the protected line based on the determination result. This avoids misjudging the overload state of non-faulty protected lines and also prevents maloperation of distance protection in overloaded states, thus preventing disturbances to the system, reducing the scale and scope of system faults, and improving system stability.

[0084] In S110, the device can set the overload identification criterion as the first criterion when the overload lockout protection is activated.

[0085] like Figure 7 As shown, the device can measure the voltage and current at the protected location on the circuit to be protected, in order to obtain the measured voltage U at the protected location. M and the current I measured at the protection point M When the system power angle is stable, if the power angle difference of the potentials on both sides of the line to be protected is less than 90°, then the voltage U measured at the protection point will be [value missing]. M and the current I measured at the protection point M The included angle, i.e. the measured impedance angle, must be less than 45°. Based on this, by setting an appropriate margin, the first criterion can be obtained.

[0086] Understandably, since the first criterion is an overload identification criterion used when the system power angle is stable, it cannot be used for overload identification when the system oscillates. However, distance protection is blocked during system oscillation, preventing maloperation of the distance protection. That is, there will be no external fault causing maloperation of the distance protection within the line during system oscillation.

[0087] In one example, the device can set the first criterion as the initial criterion, that is, when the overload blocking protection is not activated or the protection is reset, the first criterion can be set as the default criterion used by the device to identify overload.

[0088] In S120, the device can determine whether a line fault trip has occurred outside the line to be protected according to preset discrimination rules.

[0089] Understandably, when the system power angle is stable, the device can identify overload based on the first criterion. However, when the system experiences disturbances, such as a fault in a line other than the protected line, the system may be in an unstable state. In this case, if the first criterion is continued, the overload state cannot be reliably identified. Therefore, the device needs to determine whether a line fault has occurred outside the protected line, and adjust the overload identification criterion when an external fault is confirmed. In one example, the device can determine whether a line fault has occurred outside the protected line based on the impedance angle change, or it can determine whether a line fault has occurred outside the protected line based on the negative sequence voltage and zero sequence voltage.

[0090] Please refer to Figure 2 As an optional embodiment, the above-described S120 may include:

[0091] S210, obtain the impedance angle change at the protection position of the line to be protected;

[0092] S220 determines whether a line fault trip has occurred outside the protected line based on the change in impedance angle and the first preset condition.

[0093] In this embodiment, the device can acquire the impedance angle change at the protected position on the line to be protected, and determine whether a line fault trip has occurred outside the line to be protected based on whether the impedance angle change meets a first preset condition. When a fault occurs outside the line, the impedance angle detected by the device will suddenly increase; when the fault trips outside the line, the impedance angle detected by the device will decrease back to near the impedance angle when there is no fault. By calculating the impedance angle change, the degree of impedance angle change can be obtained, thereby determining whether a fault trip has occurred outside the line. It can be understood that since the impedance angle will decrease rapidly when a fault trips outside the line, the first preset condition can be that the impedance angle decrease reaches a certain range. That is, the device can determine whether a line fault trip has occurred outside the line to be protected based on whether the decrease in impedance angle reaches a corresponding angle value.

[0094] In S210, the device can obtain the impedance angle of the protection position of the line to be protected at different times and calculate the change in impedance angle between two consecutive times.

[0095] In S220, after calculating the change in impedance angle, the device can determine whether a line fault trip has occurred outside the protected line based on whether the change in impedance angle meets the first preset condition.

[0096] When a line fault occurs outside this line, the impedance angle measured at the protection position within this line will increase to near the line impedance angle. When the line trips due to an external fault, the line will return to a fault-free state, and the impedance angle measured at the protection position within this line will decrease to near the load impedance angle. The first preset condition can be that the device detects a decrease in the impedance angle reaching a certain magnitude. When the device detects that the decrease in the impedance angle meets the first preset condition, it can be determined that a fault has occurred on another line outside the line to be protected, and that faulty line has tripped, thus confirming that a line fault has occurred outside the line to be protected.

[0097] Please refer to Figure 3 As an optional embodiment, the above-described S220 may include:

[0098] S310, count the number of times the impedance angle change satisfies the first threshold range to obtain the impedance angle count value;

[0099] S320 determines whether a line fault trip has occurred outside the protected line based on the impedance angle count value and the identification threshold.

[0100] In this embodiment, the device can count the impedance angle count value each time it is determined that the current impedance angle change meets the first threshold range, and determine that a line fault trip has occurred outside the line to be protected when the impedance angle count value reaches the identification threshold.

[0101] In S310, the first preset condition may be that the device detects that the impedance angle change repeatedly meets a first threshold range. The device may increment the count of the number of times the impedance angle change meets the first threshold range when it detects a decrease in the impedance angle and the decrease reaches the first threshold range. While the impedance angle change continues to meet the first threshold range, multiple counts can be performed to obtain the corresponding impedance angle count value.

[0102] It is understood that the aforementioned first threshold range can be less than -20°, meaning that when the device detects an impedance angle drop exceeding 20°, it can be determined that the impedance angle change meets the first threshold range. Furthermore, the first threshold range can also be determined based on the actual values ​​of the system's line impedance angle and load impedance angle.

[0103] In S320, the device can acquire a pre-set identification threshold and determine whether a line fault trip has occurred outside the protected line based on the relationship between the current impedance angle count value and the identification threshold. For example, the identification threshold can be set to 10. When the device detects that the impedance angle change meets the first threshold range, it starts counting from 1. When the impedance angle count value reaches 10, it can be determined that a line fault trip has occurred outside the protected line.

[0104] As an optional embodiment, the above-described S310 may include:

[0105] When the change in impedance angle continues to reach the first threshold range, the impedance angle count is performed.

[0106] In this embodiment, the impedance angle count value can also be set to count only when the impedance angle change continuously meets the first threshold range. That is, when the device continuously detects that the impedance angle change meets the first threshold range, the device can count according to the number of impedance angle changes. If one of the multiple impedance angle changes does not meet the first threshold range, the impedance angle count value can be cleared to zero, so as to avoid the device misjudging voltage fluctuations as line faults and tripping when the system is unstable, thereby improving the stability and accuracy of the device.

[0107] Please refer to Figure 4 As an optional embodiment, the above-described S120 may include:

[0108] S410: Obtain the negative sequence voltage and zero sequence voltage at the protection position of the line to be protected, and calculate the stable value of the negative sequence voltage to zero sequence voltage ratio.

[0109] S420 determines whether a line fault trip has occurred outside the protected line based on the stable value of the negative sequence and zero sequence voltage ratio and the second preset condition.

[0110] In this embodiment, the device can acquire the negative-sequence voltage and zero-sequence voltage on the line to be protected, and calculate the stable value of the negative-sequence and zero-sequence voltage ratio. Based on whether the stable values ​​of the negative-sequence and zero-sequence voltage ratios before and after the protection meet a second preset condition, the device can determine whether a line fault trip has occurred outside the line to be protected. Since the amplitude ratio of the negative-sequence and zero-sequence voltage ratio between a line short-circuit fault and a line fault trip does not change with the magnitude of the transition resistance of the faulty line, when the device detects a significant change in the stable value of the negative-sequence and zero-sequence voltage ratio, it can determine that a line fault has occurred outside the protected line, and that the faulty line has tripped.

[0111] In S410, the preset discrimination rule can be that the device determines whether a line fault trip has occurred outside the protected line based on the negative-sequence voltage and zero-sequence voltage. When a line fault occurs, the device can acquire the negative-sequence voltage and zero-sequence voltage at multiple different times at the protection position of the protected line, and calculate the ratio of the negative-sequence voltage to the zero-sequence voltage to obtain a stable value for the negative-sequence and zero-sequence voltage ratio at different times. After acquiring the stable values ​​of the negative-sequence and zero-sequence voltage ratio at different times, the device can use these stable values ​​to determine whether a line fault trip has occurred outside the protected line.

[0112] The following is a detailed analysis of determining whether a line fault trip has occurred outside the protected line based on negative sequence voltage and zero sequence voltage:

[0113] like Figure 8 As shown, L PM This is a non-faulty line, i.e., a line to be protected; L MN This refers to the remote backup line for distance protection of the line to be protected, which is also the line where a line fault has occurred.

[0114] i) When a single-phase short-circuit fault occurs on the line, the line diagram is as follows: Figure 9 As shown, the boundary conditions for the short-circuit point are as follows:

[0115]

[0116] Converting it to the boundary conditions under a positive and negative zero-order network is as follows:

[0117]

[0118] A schematic diagram of the negative-order equivalent network is shown below. Figure 10 As shown, Z M Z is the equivalent negative sequence impedance of the system to the left of bus M. L Z represents the negative sequence impedance of the line to the left of the fault. R Z represents the negative sequence impedance of the line to the right of the faulty line. N This is the equivalent negative sequence impedance of the system to the right of bus N.

[0119] UM2 The voltage measurement value of bus M at the left end of the faulty line is given by U. When a fault occurs in the remote backup line of the line to be protected, the negative sequence voltage value of bus M at the opposite end can be calculated using single-end voltage and current measurements and line parameters. M2 U M2 The calculation formula is as follows:

[0120]

[0121] The above parameters are defined as follows:

[0122] Z all =Z M +Z L +Z R +Z N Z Lall =Z M +Z L Z Rall =Z N +Z R ;

[0123] The above U can be M2 The calculation formula is simplified to:

[0124]

[0125] Similarly, a schematic diagram of the zero-order equivalent network is shown below. Figure 11 As shown, Z M0 Z is the equivalent negative sequence impedance of the system to the left of bus M. L0 Z represents the negative sequence impedance of the line to the left of the fault. R0 Z represents the negative sequence impedance of the line to the right of the faulty line. N0 This is the equivalent negative sequence impedance of the system to the right of bus N.

[0126] At this time, the zero-sequence voltage value U of bus M M0 The calculation formula is as follows:

[0127]

[0128] Define Z all0 =Z M0 +Z L0 +Z R0 +Z N0 Z Lall0 =Z M0 +Z L0 Z Rall0 =Z N0 +Z R0 The above formula can be simplified to:

[0129]

[0130] Based on the calculation formulas for negative-sequence voltage and zero-sequence voltage mentioned above, the ratio of the magnitudes of the negative-sequence voltage to the zero-sequence voltage can be determined as follows:

[0131]

[0132] Since the impedance ratio of the PM line and the system back side of bus P does not change with single-phase tripping and single-phase short circuit, the above negative-sequence and zero-sequence voltage amplitude ratio can be converted into the bus voltage amplitude ratio, i.e.:

[0133]

[0134] ii) When a single-phase trip occurs on the line, i.e., a single-phase fault trip, the line diagram is as follows: Figure 12 As shown, the boundary conditions can be expressed as follows:

[0135]

[0136] Converting it to the boundary conditions under a positive and negative zero-order network is as follows:

[0137] U 1M =U 2M =U 0M U 1N =U 2N =U 0N ;

[0138] like Figure 13 As shown, in the negative-sequence equivalent network, the formula for calculating the negative-sequence voltage is as follows:

[0139]

[0140] Similarly, simplifying the above formula yields:

[0141]

[0142] like Figure 14 As shown, in the zero-sequence equivalent network, the formula for calculating the zero-sequence voltage is:

[0143]

[0144] After simplification, we get:

[0145]

[0146] Based on the calculation formulas for negative-sequence voltage and zero-sequence voltage mentioned above, the ratio of the magnitudes of the negative-sequence voltage to the zero-sequence voltage can be determined as follows:

[0147]

[0148] Similar to single-phase short-circuit faults, the above negative-sequence and zero-sequence voltage ratios can be converted into the amplitude ratios of the bus voltages:

[0149]

[0150] Based on the above, comparing the negative-sequence and zero-sequence voltage ratios under single-phase short circuit and single-phase trip conditions, it can be determined that under single-phase short circuit conditions, the negative-sequence and zero-sequence voltage amplitude ratio is smaller than that under single-phase trip conditions, and the magnitude of the amplitude ratio does not change with the resistance value of the transition resistor on the faulty line. According to the calculation formulas for the negative-sequence and zero-sequence amplitude ratios under single-phase short circuit and single-phase trip conditions, the ratio between the two amplitude ratios can be obtained as follows:

[0151]

[0152] Among them, Z Rall Z is the negative sequence impedance of the right-hand side impedance. Rall0 The zero-sequence impedance of the right-side impedance; that is, the ratio of the negative-sequence and zero-sequence amplitudes under a single-phase short circuit to the negative-sequence and zero-sequence amplitudes under a single-phase trip depends on the ratio of the negative-sequence impedance to the zero-sequence impedance of the right-side impedance.

[0153] When the device determines that a line fault has occurred, it can acquire the negative-sequence voltage and zero-sequence voltage at the protected location and calculate the amplitude ratio of the negative-sequence voltage and zero-sequence voltage. Since the amplitude ratio of the negative-sequence voltage and zero-sequence voltage on the protected line is consistent with the amplitude ratio of the negative-sequence voltage and zero-sequence voltage on the bus, the device can also acquire the negative-sequence voltage and zero-sequence voltage on the bus and calculate the amplitude ratio of the negative-sequence and zero-sequence voltages.

[0154] It is understandable that, since the negative sequence and zero sequence voltage amplitude ratios are relatively stable and will not change due to the influence of the Guofu resistor, and the negative sequence and zero sequence voltage amplitude ratios under single-phase short circuit conditions are less than those under single-phase trip conditions, the device can determine that the faulty line has changed from a single-phase short circuit to a single-phase trip when the value of the negative sequence and zero sequence voltage amplitude ratio increases and the increase meets the corresponding conditions.

[0155] The device can calculate the negative-sequence and zero-sequence voltage amplitude ratio based on the acquired negative-sequence and zero-sequence voltages, and then determine at least two stable values ​​for the negative-sequence and zero-sequence voltage ratio. When the latter stable value for the negative-sequence and zero-sequence voltage ratio shows a significant increase compared to the former, the device determines that the corresponding line fault has changed from a short-circuit fault to a line tripping fault. That is, when the device determines that the difference between the two stable values ​​for the negative-sequence and zero-sequence voltage ratios meets a preset condition, it can determine that a single-phase tripping fault has occurred outside the local line.

[0156] In one embodiment, the device can acquire two stable negative-sequence zero-sequence voltage ratios when a system failure occurs, namely, a first stable negative-sequence zero-sequence voltage ratio value. The stable value of the second negative sequence zero sequence voltage ratio exist Furthermore, when the difference between the stable values ​​of the two negative-sequence and zero-sequence voltage ratios is large, the device can determine that a single-phase tripping fault has occurred outside this line.

[0157] In one example, the device can calculate the ratio of two stable negative-sequence and zero-sequence voltage ratios. When this ratio reaches a preset threshold, it determines that a single-phase tripping fault has occurred outside the local line. This preset threshold can be set to 1.05. That is, a single-phase tripping fault outside the local line can be determined when the stable ratios of the two negative-sequence and zero-sequence voltage ratios satisfy the following formula:

[0158]

[0159] It is understandable that the above-mentioned preset threshold can also be based on the negative sequence impedance Z of the right-hand impedance. Rall and zero-sequence impedance Z Rall0 Adjustments will be made.

[0160] Please refer to Figure 5 As an optional embodiment, the above-described S410 may include:

[0161] S510, obtain the impedance angle change at the protection position of the line to be protected;

[0162] S520 determines whether a line fault trip has occurred outside the protected line based on the impedance angle change and the first preset condition.

[0163] S530: When the impedance angle change does not meet the first preset condition, obtain the negative sequence voltage and zero sequence voltage of the protection position of the line to be protected, and calculate the stable value of the negative sequence and zero sequence voltage ratio.

[0164] In this embodiment, when an external line fault occurs, a large transition resistance will result in an insignificant change in impedance angle. Therefore, it is impossible to accurately determine whether a line fault has occurred outside the protected line based solely on the impedance angle change. Thus, the device can combine the impedance angle change determination method with the negative-sequence voltage and zero-sequence voltage determination methods. Using negative-sequence and zero-sequence voltage determination methods is not affected by the size of the transition resistance, thereby improving the accuracy of the device in determining whether a line fault has occurred outside the protected line.

[0165] In S510, the device can obtain the impedance angle of the protection position of the line to be protected at different times and calculate the change of the impedance angle between two consecutive times.

[0166] In S520, after calculating the change in impedance angle, the device can determine whether a line fault trip has occurred outside the protected line based on whether the change in impedance angle meets the first preset condition.

[0167] Similar to the above embodiments, the first preset condition may be that the device detects that the decrease in impedance angle reaches a certain value. When the device detects that the decrease in impedance angle meets the first preset condition, it can be determined that a fault has occurred in other lines besides the line to be protected, and the fault trips, that is, it is determined that a fault has occurred in a line besides the line to be protected.

[0168] However, when a single-phase ground fault occurs outside the line, if the transition resistance is large, the change in impedance angle will not be very significant, and correspondingly, the decrease in impedance angle when the fault outside the line trips will also be small. That is, when a single-phase ground fault occurs outside the line, the device may not detect a change in impedance angle that meets the first preset condition. Therefore, judging by the amount of change in impedance angle may not accurately identify faults outside the line.

[0169] In S530, when the device detects that the impedance angle change does not meet the first preset condition, there may be two scenarios: one is that no fault has occurred outside the line, and the other is that a single-phase ground fault has occurred outside the line, but due to the large transition resistance, the impedance angle change detected by the device is not significant, thus failing to meet the first preset condition. In this case, the device can obtain the negative sequence voltage and zero sequence voltage at the protection position of the line to be protected, and calculate the stable value of the negative sequence and zero sequence voltage ratio. Based on the stable value of the negative sequence and zero sequence voltage ratio, it can determine whether a line fault has occurred outside the line to be protected, causing a trip.

[0170] In S420, the device can determine whether a line fault trip has occurred outside the protected line based on whether the stable values ​​of the negative-sequence and zero-sequence voltage ratios at different times meet a second preset condition. For example, the device can calculate the variation range of the stable values ​​of the negative-sequence and zero-sequence voltage ratios at two consecutive times, where the second preset condition can be that the variation range meets a certain range. That is, when the device calculates that the variation range of the stable values ​​of the negative-sequence and zero-sequence voltage ratios at two times meets the range corresponding to the second preset condition, it can determine whether a line fault trip has occurred outside the protected line.

[0171] It is understandable that in embodiments that combine the impedance angle change judgment method with the negative-sequence voltage and zero-sequence voltage judgment methods, the impedance angle change judgment method can be set first, followed by the negative-sequence voltage and zero-sequence voltage judgment methods, or vice versa. When the device determines that a line fault trip has occurred outside the protected line using the former judgment method, it can directly modify the overload identification criterion to the second criterion and no longer execute the latter judgment method.

[0172] As an optional embodiment, the above-described S420 may include:

[0173] Calculate the ratio of two adjacent negative-sequence zero-sequence voltages to their stable values;

[0174] The ratio and the second threshold are used to determine whether a line fault trip has occurred outside the protected line.

[0175] The device can calculate the ratio of two adjacent negative-sequence and zero-sequence voltage ratio stable values ​​after acquiring the stable values ​​of the negative-sequence and zero-sequence voltage ratios at different times. This ratio can be the ratio of the later negative-sequence and zero-sequence voltage ratio stable value to the earlier negative-sequence and zero-sequence voltage ratio stable value, to represent the magnitude of the change in the stable value of the negative-sequence and zero-sequence voltage ratio.

[0176] After determining the ratio of two adjacent negative-sequence and zero-sequence voltage ratios at the current moment, the device can obtain a preset second threshold and determine whether a line fault trip has occurred outside the protected line based on the relationship between this ratio and the second threshold. In one example, if the ratio is greater than the second threshold, the device can determine that a line fault trip has occurred outside the protected line. The second threshold can be set to 1.05, meaning that if the ratio of two adjacent negative-sequence and zero-sequence voltage ratios is greater than 1.05, a line fault trip outside the protected line can be determined.

[0177] In this embodiment, the device can acquire two consecutive stable negative-sequence and zero-sequence voltage ratios and calculate the ratio of these two stable negative-sequence and zero-sequence voltage ratios. Based on the relationship between this ratio and a second threshold, the device can determine whether a line fault trip has occurred outside the protected line. If the ratio is greater than the second threshold, it indicates a significant change in the stable negative-sequence and zero-sequence voltage ratios, and the device can then determine that the faulty line outside the protected line has changed from a short-circuit fault to a fault trip. When the ratio is less than the second threshold, the device can determine that no line fault trip has occurred outside the protected line.

[0178] In S130, when the device determines that a short-circuit fault has occurred outside the protected line according to preset discrimination rules, it can modify the overload identification criterion to a second criterion. The difference between the first and second criters is that the overload stability of the first criterion is greater than that of the second criterion. For example, under the premise of stable system power angle, using the first criterion for overload identification can determine that the system is in an overload state when the phase-to-phase cosine voltage exceeds the voltage range of the first criterion. However, when a line fault trips outside the protected line, the system is in an unstable state. At this time, the phase-to-phase cosine voltage may exceed the voltage range of the first criterion even when no overload has occurred, causing the device to mistakenly judge that the protected line is in an overload state. By modifying the overload identification criterion from the first to the second criterion when it is determined that a line fault trip has occurred outside the protected line, the voltage range of the overload identification criterion can be increased, making the overload identification criterion more lenient and avoiding the device from mistakenly judging that the protected line is in an overload state when the phase-to-phase cosine voltage exceeds the voltage range of the first criterion in an unstable state.

[0179] In S140, the device can identify overload based on the overload identification criterion and the phase-to-phase cosine voltage. The phase-to-phase cosine voltage can be expressed as:

[0180]

[0181] Where U is the actual phase-to-phase voltage, for a single-phase impedance relay, This is the zero-sequence compensation coefficient; for phase-to-phase impedance relays, Let A be any two distinct phases from the three phases A, B, and C.

[0182] The device can determine the corresponding voltage range based on the overload identification criteria, and determine the corresponding overload identification result based on whether the magnitude of the phase-to-phase cosine voltage exceeds the voltage range.

[0183] Please refer to Figure 6 As an optional embodiment, the above-described S140 may include:

[0184] S610 determines the overload threshold voltage based on the product of the overload identification criterion and the rated phase-to-phase voltage;

[0185] S620, when the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets the second preset condition, the overload identification result is determined to be overload blocking;

[0186] S630, when the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets the third preset condition, determines the overload identification result as overload open.

[0187] In this embodiment, the device can calculate the overload threshold voltage based on the product of the overload visual criterion and the rated phase-to-phase voltage.

[0188] In S610, the device can obtain the rated phase-to-phase voltage and calculate the overload threshold voltage based on the product of the overload identification criterion and the rated phase-to-phase voltage. The overload threshold voltage can be expressed as:

[0189] cosα*pu;

[0190] Where cosα is the overload identification criterion and pu is the rated phase-to-phase voltage.

[0191] It is understandable that when the overload identification criterion is the first criterion α1, the overload threshold voltage is cos(α1)*pu; when the overload identification criterion is the second criterion α2, the overload threshold voltage is cos(α2)*pu.

[0192] In one example, since the angle between the measured voltage and measured current at the protected position, i.e., the measured impedance angle, is necessarily less than 45° when the system power angle is stable, the aforementioned first criterion α1 can be determined by setting a corresponding margin based on 45°. For example, when the margin is set to 15°, the first criterion α1 can be 60°, and the overload threshold voltage is cos(α1)*pu=0.5pu. It can be understood that by adjusting the preset margin, the first criterion α1 can be modified accordingly, thereby adjusting the overload threshold voltage corresponding to the first criterion.

[0193] When the system becomes unstable due to a fault tripping outside the line, the phase-to-phase cosine voltage may fall below the overload threshold voltage under the first criterion, leading to abnormal overload identification results. In this case, the overload identification criterion can be relaxed to prevent the device from misjudging the unstable system state as an overload state. For example, by setting the second criterion α2 to be greater than the first criterion α1, the overload threshold voltage cos(α2)*pu can be reduced, preventing the phase-to-phase cosine voltage from falling below the overload threshold voltage during system instability. In one example, the second criterion α2 can be 70°, then the corresponding overload threshold voltage is cos(α2)*pu = 0.34pu. When the system is unstable, modifying the first criterion to the second criterion can reduce the overload threshold voltage, thus preventing overload blocking due to voltage fluctuations during system instability.

[0194] In S620, the device can compare the magnitudes of the overload threshold voltage and the phase-to-phase cosine voltage, and determine whether the overload identification result is an overload blocking based on whether the relationship between the overload threshold voltage and the phase-to-phase cosine voltage meets a second preset condition. For example, the second preset condition could be that the phase-to-phase cosine voltage is lower than the overload threshold voltage. That is, when the device determines that the current phase-to-phase cosine voltage is less than the overload threshold voltage, it can determine that the overload identification result is an overload blocking.

[0195] It should be noted that even when the system is in a stable power angle state, fluctuations in phase-to-phase voltage may cause the phase-to-phase cosine voltage to fall below the overload threshold voltage. If the second preset condition is only limited to the phase-to-phase cosine voltage being less than the overload threshold voltage, the device will frequently misjudge voltage fluctuations as overloads of the protected line. To avoid misjudgments of overloads, the second preset condition can be further restricted to prevent the device from making misjudgments during voltage fluctuations. For example, the second preset condition could be that the phase-to-phase cosine voltage falls below the overload threshold voltage multiple times within a certain period of time, thereby avoiding the influence of voltage fluctuations on overload identification.

[0196] As an optional embodiment, the above-described S620 may include:

[0197] S621, when the phase-to-phase cosine voltage is lower than the overload threshold voltage, count the first count value;

[0198] S622, when the first count value reaches the blocking threshold, the overload identification result is determined to be overload blocking.

[0199] In this embodiment, the device can count a first count value when the phase-to-phase cosine voltage is lower than the overload threshold voltage, and determine the overload identification result as overload blocking when the first count value reaches the blocking threshold. Based on the determined overload identification result, the device can adjust the distance protection for overload blocking.

[0200] In S621, after calculating the current phase-to-phase cosine voltage, if the phase-to-phase cosine voltage is lower than the overload threshold voltage, the device can count the first count value.

[0201] In S622, after incrementing the first count value by 1, the device can determine whether the first count value has reached the locking threshold. When the first count value reaches the locking threshold, the device can determine that the overload identification result is an overload locking.

[0202] In S630, similar to the second preset condition, the device can also determine whether the overload identification result is an overload blocking based on whether the relationship between the overload threshold voltage and the phase-to-phase cosine voltage satisfies a third preset condition. For example, the third preset condition could be that the phase-to-phase cosine voltage is higher than the overload threshold voltage. That is, when the device determines that the current phase-to-phase cosine voltage is greater than the overload threshold voltage, it can determine that the overload identification result is an overload opening.

[0203] Similarly, when interphase voltage fluctuates, the interphase cosine voltage may exceed the overload threshold voltage. If the third preset condition is only that the interphase cosine voltage is greater than the overload threshold voltage, the device may mistakenly identify the system as stable when it is overloaded. To avoid misjudgment during overload, the third preset condition can be further restricted to prevent misjudgment during voltage fluctuations. For example, the third preset condition could be that the interphase cosine voltage exceeds the overload threshold voltage multiple times within a certain period, thereby preventing misjudgment of the system as stable when it is overloaded.

[0204] As an optional embodiment, the above-described S630 may include:

[0205] S631, when the phase-to-phase cosine voltage is higher than the overload threshold voltage, count the second count value;

[0206] S632, when the second count value reaches the opening threshold, the overload identification result is determined to be overload opening.

[0207] In this embodiment, the device can count the second count value when the phase-to-phase cosine voltage is higher than the overload threshold voltage, and determine the overload identification result as overload open when the second count value reaches the open threshold. Based on the determined overload identification result, the device can adjust the distance protection to open under overload conditions.

[0208] In S631, after calculating the current phase-to-phase cosine voltage, if the phase-to-phase cosine voltage is higher than the overload threshold voltage, the device can count the second count value.

[0209] In S632, after incrementing the second count value by 1, the device can determine whether the second count value has reached the opening threshold. When the second count value reaches the opening threshold, the device can determine that the overload identification result is overload opening.

[0210] As an optional embodiment, when the first count value increases, the second count value is reset to zero; when the second count value increases, the first count value is reset to zero.

[0211] In this embodiment, the device can reset the second count value to zero when the first count value increases. Alternatively, the device can reset the first count value to zero when the second count value increases.

[0212] It is understandable that when interphase voltage fluctuates, the fluctuation range of the interphase cosine voltage may encompass both sides of the overload threshold voltage. That is, the interphase cosine voltage will change between a range greater than and less than the overload threshold voltage during fluctuations. If the device does not use continuous counting during counting, both the first and second count values ​​will continuously accumulate during the fluctuation process, reaching the corresponding blocking or opening threshold, leading to incorrect overload identification results. Therefore, to avoid interphase voltage fluctuations affecting overload identification, the device can increment one of the first and second count values ​​while resetting the other to zero. Thus, during interphase voltage fluctuations, because both count values ​​are continuously reset during the back-and-forth counting process, the count value will not reach the corresponding threshold, preventing the device from generating incorrect overload identification results. When the first count value reaches the blocking threshold, it indicates that the phase-to-phase cosine voltage has been continuously lower than the overload threshold voltage for a certain period of time. At this time, the device can determine that the phase-to-phase cosine voltage being lower than the overload threshold voltage is not the cause of phase-to-phase voltage fluctuations, and determine the overload identification result as overload blocking.

[0213] Similarly, when the second count value reaches the open threshold, it indicates that the phase-to-phase cosine voltage has been continuously higher than the overload threshold voltage for a certain period of time. At this time, the device can eliminate phase-to-phase voltage fluctuations and determine the overload identification result as overload blocking.

[0214] In S150, after determining the overload identification result through overload identification, the device can adjust the distance protection stage III according to the overload identification result.

[0215] Understandably, distance protection typically includes three stages: distance protection stage I, stage II, and stage III. Distance protection stages I and II usually provide relay protection for line faults within the local line, while the protection range of distance protection stage III typically includes a portion of other lines outside the local line. Therefore, when a line fault occurs outside the local line, distance protection stage III often malfunctions, leading to a further expansion of the line fault.

[0216] The device adjusts distance protection stage III based on overload identification results. This adjustment can involve blocking or opening distance protection stage III, or extending its operating time. When the system power angle is stable and no overload occurs, the device can open distance protection stage III to achieve complete distance protection. When the system is unstable and overload occurs, the device can block distance protection stage III to prevent maloperation of distance protection stage III caused by fault tripping of lines outside the local line, thus reducing the disturbance to the system when other lines trip due to faults.

[0217] Understandably, when multiple lines to be protected are overloaded, the devices on each line to be protected can block the distance protection stage III to prevent multiple overloaded lines from malfunctioning, reduce the disturbance impact of these overloaded lines on the system, and prevent the line accident from further developing and expanding.

[0218] In some embodiments, when the system is unstable or overloaded, the device can extend the operating time of the distance protection stage III to allow time for dynamic adjustment of the system. This enables the system to handle fault tripping of other lines through dynamic adjustment, preventing the distance protection stage III from malfunctioning before the system is dynamically adjusted, and reducing the scale of line power outage accidents.

[0219] As an optional embodiment, the above-described S150 may include:

[0220] When the overload identification result indicates overload blocking, the blocking distance protection stage III is activated.

[0221] When the overload identification result indicates overload opening, the distance protection stage III is opened.

[0222] In this embodiment, when the overload identification result is determined to be overload blocking, the device can block distance protection stage III. At this time, under system overload conditions, distance protection stage III will not operate, thus preventing malfunction of distance protection stage III and the resulting expansion of the fault range. When the overload identification result is determined to be overload opening, the device can open distance protection stage III. At this time, the system recovers from the overload state to a stable state, and distance protection stage III can effectively provide distance protection for the protected line.

[0223] This application also provides a device for preventing malfunction of distance protection, such as... Figure 15 As shown, the device includes:

[0224] The starting module 1501 is used to set the overload identification criterion as the first criterion when the overload lockout protection is started;

[0225] The judgment module 1502 is used to determine whether a line fault trip has occurred outside the line to be protected according to the preset judgment rules;

[0226] The criterion setting module 1503 is used to modify the overload identification criterion to a second criterion when a line fault trip occurs outside the line to be protected; the stability of the first criterion is greater than that of the second criterion.

[0227] The identification module 1504 is used to identify overload based on the overload identification criteria and the phase-to-phase cosine voltage, and obtain the overload identification result.

[0228] The adjustment module 1505 is used to adjust the distance protection stage III based on the overload identification results.

[0229] Figure 16 A schematic diagram of the hardware structure of a device for preventing malfunction of distance protection provided in an embodiment of this application is shown.

[0230] Devices that prevent distance protection from malfunctioning may include a processor 1601 and a memory 1602 storing computer program instructions.

[0231] Specifically, the processor 1601 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0232] Memory 1602 may include mass storage for data or instructions. For example, and not limitingly, memory 1602 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where suitable, memory 1602 may include removable or non-removable (or fixed) media. Where suitable, memory 1602 may be internal or external to a device preventing malfunction of distance protection. In a particular embodiment, memory 1602 is a non-volatile solid-state memory.

[0233] In a particular embodiment, memory 1602 may include read-only memory (ROM), random access memory (RAM), disk storage media device, optical storage media device, flash memory device, electrical, optical, or other physical / tangible memory storage device. Thus, generally, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of this disclosure.

[0234] The processor 1601 implements any of the Gamma debugging methods described in the above embodiments by reading and executing computer program instructions stored in the memory 1602.

[0235] In one example, the device for preventing malfunction of the distance protection may further include a communication interface 1603 and a bus 1610. For example, Figure 16 As shown, the processor 1601, memory 1602, and communication interface 1603 are connected through bus 1610 and complete communication with each other.

[0236] The communication interface 1603 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0237] Bus 1610 includes hardware, software, or both, that couples components of a device that prevents distance protection from malfunctioning together. For example, and not as a limitation, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel 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 (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 1610 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0238] Furthermore, in conjunction with the Gamma debugging methods in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the Gamma debugging methods in the above embodiments.

[0239] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0240] The functional blocks shown in the above block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0241] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0242] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0243] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for preventing maloperation of distance protection, applied to the line to be protected, characterized in that, The method includes: When the overload lockout protection is activated, the overload identification criterion is set as the first criterion; Determine whether a line fault trip has occurred outside the line to be protected according to the preset discrimination rules; When a line fault trip occurs outside the line to be protected, the overload identification criterion is modified to a second criterion; the first criterion is determined based on a set margin on the basis of 45°, the second criterion is greater than the first criterion, the cosine value of the first criterion is greater than the cosine value of the second criterion, and the stability of the first criterion is greater than the stability of the second criterion. Overload identification is performed based on the overload identification criteria and the phase-to-phase cosine voltage to obtain the overload identification result. Adjust the distance protection segment III based on the overload identification results.

2. The method for preventing malfunction of distance protection according to claim 1, characterized in that, The step of determining whether a line fault trip has occurred outside the protected line according to a preset discrimination rule includes: Obtain the impedance angle change at the protection position of the line to be protected; Based on the change in impedance angle and the first preset condition, it is determined whether a line fault trip has occurred outside the line to be protected.

3. The method for preventing malfunction of distance protection according to claim 2, characterized in that, The step of determining whether a line fault trip has occurred outside the protected line based on the impedance angle change and the first preset condition includes: The number of times the impedance angle change satisfies the first threshold range is counted to obtain the impedance angle count value; Based on the impedance angle count value and the identification threshold, it is determined whether a line fault trip has occurred outside the line to be protected.

4. The method for preventing malfunction of distance protection according to claim 3, characterized in that, The step of counting the number of times the impedance angle change satisfies the first threshold range to obtain the impedance angle count value includes: When the change in impedance angle continues to reach the first threshold range, the impedance angle count value is counted.

5. The method for preventing malfunction of distance protection according to claim 1, characterized in that, The step of determining whether a line fault trip has occurred outside the protected line according to a preset discrimination rule includes: Obtain the negative sequence voltage and zero sequence voltage at the protection position of the line to be protected, and calculate the stable value of the negative sequence and zero sequence voltage ratio; Based on the stable value of the negative-sequence and zero-sequence voltage ratio and the second preset condition, it is determined whether a line fault trip has occurred outside the line to be protected.

6. The method for preventing malfunction of distance protection according to claim 5, characterized in that, The step of determining whether a line fault trip has occurred outside the protected line based on the stable value of the negative-sequence and zero-sequence voltage ratio and the second preset condition includes: Calculate the ratio of two adjacent negative-sequence zero-sequence voltages to their stable values; Based on the ratio and the second threshold, it is determined whether a line fault trip has occurred outside the line to be protected.

7. The method for preventing malfunction of distance protection according to claim 5, characterized in that, The process of obtaining the negative-sequence voltage and zero-sequence voltage at the protection position of the line to be protected, and calculating the stable value of the negative-sequence and zero-sequence voltage ratio, includes: Obtain the impedance angle change at the protection position of the line to be protected; Based on the change in impedance angle and the first preset condition, determine whether a line fault trip has occurred outside the line to be protected. When the impedance angle change does not meet the first preset condition, the negative sequence voltage and zero sequence voltage of the protection position of the line to be protected are obtained, and the stable value of the negative sequence and zero sequence voltage ratio is calculated.

8. The method for preventing malfunction of distance protection according to claim 1, characterized in that, The overload identification process based on the overload identification criterion and the phase-to-phase cosine voltage, to obtain the overload identification result, includes: The overload threshold voltage is determined by multiplying the overload identification criterion and the rated phase-to-phase voltage. When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage satisfies the second preset condition, the overload identification result is determined to be overload blocking; When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage satisfies a third preset condition, the overload identification result is determined to be overload enabled.

9. The method for preventing malfunction of distance protection according to claim 8, characterized in that, When the relationship between the overload threshold voltage and the phase-to-phase cosine voltage satisfies a second preset condition, determining the overload identification result as overload blocking includes: When the phase-to-phase cosine voltage is lower than the overload threshold voltage, the first count value is counted; When the first count value reaches the locking threshold, the overload identification result is determined to be overload locking; The step of determining the overload identification result as overload enabled when the magnitude relationship between the overload threshold voltage and the phase-to-phase cosine voltage satisfies a third preset condition includes: When the phase-to-phase cosine voltage is higher than the overload threshold voltage, the second count value is counted; When the second count value reaches the opening threshold, the overload identification result is determined to be overload opening.

10. The method for preventing malfunction of distance protection according to claim 9, characterized in that, When the first count value increases, the second count value is reset to zero; when the second count value increases, the first count value is reset to zero.

11. The method for preventing malfunction of distance protection according to claim 8, characterized in that, The adjustment of distance protection stage III based on the overload identification result includes: When the overload identification result indicates overload blocking, the blocking distance protection stage III is activated. When the overload identification result indicates overload opening, the distance protection stage III is opened.

12. A device for preventing maloperation of distance protection, applied to the line to be protected, characterized in that, The device includes: The startup module is used to set the overload identification criterion as the first criterion when the overload lockout protection is started. The judgment module is used to determine whether a line fault trip has occurred outside the line to be protected according to a preset judgment rule; The criterion setting module is used to modify the overload identification criterion to a second criterion when a line fault trip occurs outside the line to be protected; the first criterion is determined based on a set margin on the basis of 45°, the second criterion is greater than the first criterion, the cosine value of the first criterion is greater than the cosine value of the second criterion, and the stability of the first criterion is greater than the stability of the second criterion. The identification module is used to identify overload based on the overload identification criteria and the phase-to-phase cosine voltage, and obtain the overload identification result; The adjustment module is used to adjust the distance protection stage III based on the overload identification results.

13. A device for preventing malfunction of distance protection, characterized in that, The device for preventing malfunction of the distance protection includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the method for preventing malfunction of distance protection as described in any one of claims 1-11.

14. A computer storage medium, characterized in that, The computer storage medium stores computer program instructions, which, when executed by a processor, implement the method for preventing malfunction of distance protection as described in any one of claims 1-11.

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