Power transmission line single-phase disconnection fault detection method and system

Abstract

The invention relates to the technical field of power transmission line fault detection, in particular to a power transmission line single-phase disconnection fault detection method and system, and the method comprises the steps: obtaining the three-phase voltage, phase difference, three-phase current and negative-sequence current of each detection point of a power transmission line; analyzing the voltage distribution fluctuation degree of each phase at each detection point of the power transmission line and the discrete condition of the phase difference at each detection point, and obtaining the voltage disconnection index of each detection point of the power transmission line by combining the correlation between any two phases of voltage; detecting the fluctuation amplitude of each phase of current according to the balance characteristics of the three-phase current of the power transmission line and the sudden change condition of the negative-sequence current to obtain a three-phase abnormal index of each detection point of the power transmission line; and the single-phase disconnection confidence of each detection point of the power transmission line is obtained, so that the single-phase disconnection fault of the power transmission line can be detected. According to the invention, the precision of single-phase broken line fault detection of the power transmission line can be improved.

Description

Technical Field

[0001] This application relates to the field of power transmission line fault detection technology, specifically to a method and system for detecting single-phase open-circuit faults in power transmission lines. Background Technology

[0002] As the application of overhead insulated transmission lines in the power grid continues to increase, the probability of transmission line open circuits is also gradually increasing. Open circuits can affect the transmission stability and safety of power transmission lines, and in severe cases, may even endanger personal safety.

[0003] Because a single-phase open-circuit fault causes three-phase imbalance within the transmission line, resulting in a negative-sequence current, current technologies typically detect single-phase open-circuit faults using negative-sequence current protection. However, these technologies do not fully consider that in the case of a single-phase open-circuit fault without grounding, the impedance of the negative-sequence current flow path increases, leading to less significant fluctuations in the negative-sequence current. Furthermore, since many factors contribute to three-phase imbalance in transmission systems, relying solely on negative-sequence current for open-circuit fault detection may introduce substantial errors, thus affecting the accuracy of transmission line open-circuit fault detection and resulting in poor detection effectiveness. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method and system for detecting single-phase open-circuit faults in transmission lines. The specific technical solution adopted is as follows: This application provides a method for detecting single-phase open-circuit faults in transmission lines, including the following steps: Acquire the three-phase voltage, phase difference between any two phase voltages, three-phase current, and negative sequence current at each detection point on the transmission line; The amplitude distribution and fluctuation of each phase voltage at each detection point of the transmission line are analyzed, as well as the dispersion of the phase difference between any two phase voltages at each detection point. Combined with the correlation between any two phase voltages, the voltage disconnection index at each detection point of the transmission line is obtained. Based on the balance characteristics of the three-phase current of the transmission line, and by detecting the fluctuation amplitude of the current of each phase through the sudden change of the negative sequence current, and then combining the voltage disconnection index, the three-phase abnormality index of each detection point of the transmission line is obtained. By measuring the differences in the three-phase anomaly index between adjacent detection points on the transmission line and combining the three-phase anomaly index of each detection point, the confidence level of single-phase open circuit at each detection point of the transmission line can be obtained to detect single-phase open circuit faults in the transmission line.

[0005] Preferably, the three-phase voltages, BA phase difference, CB phase difference and AC phase difference of each detection point are arranged in time sequence to form the phase voltage sequence, BA phase difference sequence, CB phase difference sequence and AC phase difference sequence of each detection point. The phase voltage sequence includes the A phase, B phase and C phase voltage sequences. The peak and valley values ​​in each phase voltage sequence are extracted, and the average value of the dispersion of the peak and valley values ​​in each phase voltage sequence is calculated and denoted as the first mean. The sum of the first mean values ​​calculated for each phase voltage sequence is denoted as the first sum value for each detection point.

[0006] Preferably, the mean of the elements of the three phase difference sequences is calculated separately and denoted as . ,Will The degree of dispersion between them is denoted as the first discrete value of each detection point; Obtain the voltage sequences of phase A and phase B with lag values ​​respectively. The cross-correlation value of phase B and phase C voltage sequences with lag value The cross-correlation value of phase C voltage and phase A voltage sequence with lag value The cross-correlation values ​​of the three points are used to calculate the mean of the three cross-correlation values, which is then recorded as the second mean of each detection point.

[0007] Preferably, the voltage disconnection index at each detection point of the transmission line is further obtained as follows: In the formula, Let be the voltage disconnection index at the i-th detection point. Let i be the first sum value of the detection point; Let i be the first discrete value of the detection point i; The second mean of detection point i; To avoid constants with a denominator of 0.

[0008] Preferably, the acquisition of the three-phase anomaly index at each detection point of the transmission line is further described as follows: In the formula, Let i be the three-phase anomaly index at the i-th detection point. Let N be the second sum value of detection point i, where the sum of the three-phase currents A, B, and C at detection point i at the same moment is calculated, and the cumulative sum of the three-phase currents at all moments is recorded as the second sum value of detection point i; N is the number of abrupt change points in the negative sequence current sequence. It is the first product of the detection point i.

[0009] Preferably, the phase currents and negative sequence currents at each detection point are arranged according to time sequence to form the phase current sequence and negative sequence current sequence at each detection point. Each abrupt change point in the negative sequence current sequence is extracted, and the abrupt change point with the smallest position is taken as the starting abrupt change point. According to the position of the starting abrupt change point in the negative sequence current sequence, each phase current sequence is divided into two sub-sequences. Each phase current sequence includes the A-phase current sequence, the B-phase current sequence, and the C-phase current sequence.

[0010] Preferably, the absolute difference between the ranges of the two subsequences of each phase current sequence is taken as the first difference of each phase current sequence. The number of non-zero first differences among all phase current sequences is counted. The sum of the first differences of all phase current sequences and the product of the count are taken as the first product of each detection point.

[0011] Preferably, the acquisition of the single-phase open circuit confidence level at each detection point of the transmission line further comprises: In the formula, Let i be the confidence level of a single-phase open circuit at the i-th detection point. It is the ratio of the three-phase anomaly index of the adjacent preceding detection point to the three-phase anomaly index of the i-th detection point.

[0012] Preferably, the confidence level of single-phase open circuit at each detection point is obtained, and 3... According to statistical principles, when the confidence level of a single-phase open circuit at a test point does not belong to 3... If the signal is within the specified range, a single-phase open circuit fault occurs at the corresponding detection point; otherwise, no single-phase open circuit fault occurs at the corresponding detection point.

[0013] This application also provides a single-phase open-circuit fault detection system for transmission lines, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described methods for detecting single-phase open-circuit faults in transmission lines.

[0014] As can be seen from the above, the method and system for detecting single-phase open-circuit faults in transmission lines provided in this application have at least the following beneficial effects: This application constructs a voltage disconnection index to reflect whether the three-phase voltage at the detection point has an abnormality; it further obtains a three-phase anomaly index to reflect whether the changes in three-phase current and three-phase voltage conform to the characteristics of a single-phase disconnection fault, thereby distinguishing between power fluctuations and actual faults; based on the single-phase disconnection confidence level, this application can combine the line data of adjacent detection points to further analyze whether the changes in power data at the detection points conform to the characteristics of a disconnection fault. In summary, this application addresses the problem that existing technologies do not fully consider the relatively weak negative sequence current amplitude after a single-phase open-circuit fault, which can easily lead to false detections. By constructing a single-phase open-circuit confidence level, this application can accurately analyze whether the data characteristics collected at the detection point match the characteristics of a single-phase open-circuit fault, thereby improving the accuracy of single-phase open-circuit fault detection in transmission lines and ensuring the power supply stability of transmission lines. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0016] Figure 1 A flowchart of the steps for a single-phase open-circuit fault detection method for transmission lines provided in this application; Figure 2 A block diagram of a single-phase open-circuit fault detection system for power transmission lines provided in an embodiment of this application. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a single-phase open-circuit fault detection method and system for transmission lines proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] The following description, in conjunction with the accompanying drawings, details the specific scheme of the single-phase open-circuit fault detection method and system for transmission lines provided in this application.

[0020] Please see Figure 1 The document illustrates a flowchart of a method for detecting a single-phase open circuit fault in a transmission line according to an embodiment of this application, including the following steps: Step 1: Obtain the three-phase voltage, phase difference between any two phase voltages, three-phase current, and negative sequence current at each detection point of the transmission line.

[0021] In this embodiment, multiple detection points are deployed along the transmission line to collect power data. The distance between each detection point is 5 km. At each detection point, the voltages of phases A, B, and C, the phase difference between the three phase voltages, the three-phase current, and the negative sequence current are collected using a three-phase voltage sensor, a phase meter, a three-phase current sensor, and a negative sequence current transformer. All data are collected synchronously at a frequency of 1 kHz, with each collection cycle lasting 10 seconds. It should be noted that, considering the large amount of data during analysis and to accurately detect single-phase open-circuit faults in the transmission line, in this embodiment, the preferred time interval between two adjacent collection cycles is 24 hours.

[0022] In this embodiment, the i-th detection point in the current acquisition cycle is taken as an example to analyze whether a single-phase open-circuit fault has occurred at its location. For the data collected at the i-th detection point, the following sequences are constructed in chronological order: phase A voltage sequence, phase B voltage sequence, phase C voltage sequence, BA phase difference sequence, CB phase difference sequence, AC phase difference sequence, phase A current sequence, phase B current sequence, phase C current sequence, and negative sequence current sequence for the i-th detection point.

[0023] Preferably, in this embodiment, in order to eliminate the influence of dimensions between data, all data are normalized. The normalization methods include Z-score, maximum value normalization, and maximum and minimum value normalization. In actual application scenarios, implementers can choose the normalization method themselves. This embodiment does not impose any special restrictions on this. Preferably, this embodiment uses maximum and minimum value normalization. The specific normalization process is existing technology and will not be described in detail in this embodiment.

[0024] Step 2: Analyze the amplitude distribution and fluctuation of each phase voltage at each detection point of the transmission line, as well as the dispersion of the phase difference between any two phase voltages at each detection point, and combine the correlation between any two phase voltages to obtain the voltage disconnection index at each detection point of the transmission line.

[0025] When a phase of a transmission line experiences a break in its conductor but is not grounded, the power transmission system abruptly changes from a balanced to an unbalanced three-phase voltage state. At the moment of the break, the generation of an electric arc or the separation of the conductor at the break point causes an electromagnetic transient process, leading to a momentary change in the voltage of the broken phase. Subsequently, after the transient process decays and the system enters a steady-state operation, the broken phase conductor is disconnected from the power supply. Although a certain voltage may still be maintained due to the electric field coupling effect between the power supply and the load side, the voltage will show a significant change. Therefore, by analyzing the degree and differences in the three-phase voltage changes at various detection points, a preliminary analysis can be made to determine whether a break in the conductor has occurred.

[0026] Because the three-phase voltage of the transmission current undergoes a significant abrupt change when a line break occurs, and the voltage of the broken phase decreases after the fault, the voltage amplitude of the phase experiencing the line break will show a large variation. Since the three-phase voltage waveform is a sine wave, it inherently has significant initial fluctuations. Therefore, in this embodiment, the amplitude of the three-phase voltage is analyzed to reflect whether a three-phase voltage fault has occurred.

[0027] In this embodiment, the A-phase voltage sequence at the i-th detection point is used as an example for analysis and explanation. All peak and valley values ​​in the A-phase voltage sequence are obtained through an extreme point detection algorithm. Then, the dispersion between all peak values ​​and the dispersion between all valley values ​​are calculated. The average of these two dispersions is recorded as the first mean of the A-phase voltage sequence at detection point i. The first mean reflects the fluctuation of the A-phase voltage amplitude at the i-th detection point; the larger the value, the greater the probability of a line breakage fault. It should be noted that the calculation of dispersion is not limited to variance, coefficient of variation, and standard deviation; this embodiment uses the coefficient of variation for calculation.

[0028] Accordingly, the first mean of the voltage sequences of phase B and phase C is calculated using the process described above in this embodiment, and the sum of all the first means is recorded as the first sum at detection point i. The first sum can reflect whether abnormal fluctuations have occurred in the three-phase voltage at the i-th detection point. The larger the value, the more inconsistent the voltage amplitude, and the more likely a wire breakage fault may have occurred.

[0029] Furthermore, if no open circuit fault occurs, the waveforms and phase differences between the three-phase voltages will be consistent.

[0030] In this embodiment, taking the BA phase difference sequence as an example, each element of the BA phase difference sequence can reflect the time lag of the B-phase voltage relative to the A-phase voltage at each moment. If a break occurs in the A-phase or B-phase of the three-phase voltage, the phase difference between the A-phase and B-phase after the break will change and will no longer be consistent with the phase difference between the other phases. Moreover, as time goes by, the phase difference difference between the three phase difference sequences will also increase.

[0031] Therefore, in this embodiment, the mean values ​​of the BA phase difference sequence, CB phase difference sequence, and AC phase difference sequence are calculated respectively. and will The degree of dispersion between the three phases is denoted as the first discrete value of detection point i. The first discrete value reflects the consistency of the phase difference between the three phases. The larger the first discrete value, the greater the possibility that the three-phase voltage does not conform to the standard voltage.

[0032] Because there is a phase difference between the three-phase voltages, directly calculating the similarity of the voltage waveforms will introduce errors. Therefore, to accurately analyze the similarity between the voltage waveforms of different phases, this embodiment will analyze the cross-correlation values ​​of any two-phase voltage sequences under different lag values. Specifically, in this embodiment, the cross-correlation values ​​of phase A and phase B voltage sequences under different lag values ​​are obtained respectively. The cross-correlation value of phase B and phase C voltage sequences with lag value The cross-correlation value of phase C voltage and phase A voltage sequence with lag value The cross-correlation values ​​of the three phases at detection point i are calculated, and the average of these three cross-correlation values ​​is recorded as the second average value. The second average value reflects the waveform differences between the three phase voltages at detection point i; the smaller the value, the greater the waveform difference between the voltages. It should be noted that the calculation process for the cross-correlation values ​​of different phase voltage sequences under different hysteresis values ​​is existing technology, and this embodiment does not impose any special restrictions on it, nor will it be elaborated upon here.

[0033] Therefore, in this embodiment, the voltage disconnection index of the i-th detection point is constructed based on the first dispersion and the second mean of each detection point. Preferably, in this embodiment, the specific calculation relationship is as follows: In the formula, Let i be the first sum value of the detection point; Let i be the first discrete value of the detection point i; The second mean of detection point i; To avoid constants with a denominator of 0, the value range is (0.005, 0.01). The value has little impact on the calculation and can be ignored. In this embodiment, 0.008 is used.

[0034] As can be understood from the above process, the voltage disconnection index can reflect whether abnormal fluctuations have occurred in the three-phase voltage at the i-th detection point; the larger the value, the greater the possibility that a certain phase of the three-phase voltage is abnormal, and thus the greater the possibility that a single-phase disconnection and ungrounded fault has occurred in the transmission line at the i-th detection point.

[0035] Step 3: Based on the balance characteristics of the three-phase current of the transmission line, and by detecting the fluctuation amplitude of the current of each phase through the sudden change of the negative sequence current, and then combining the voltage disconnection index, the three-phase abnormality index of each detection point of the transmission line is obtained.

[0036] Furthermore, considering that changes in the transmission power on the power supply side may cause voltage fluctuations in the transmission line, resulting in a larger voltage breakage index, assessing whether a transmission line has experienced a breakage fault solely based on three-phase voltage may be inaccurate and requires further analysis.

[0037] When a line break occurs, not only will the three-phase voltage fluctuate abnormally, but the three-phase current will also change accordingly: the current of the broken phase will drop to 0 or close to 0, while the current of the other two phases will also change. Moreover, after the fault occurs, the three-phase current will no longer be balanced and will generate negative sequence current.

[0038] Since voltage fluctuations caused by changes in transmission power do not affect the three-phase current balance, the sum of the three-phase currents (phases A, B, and C) at detection point i at the same moment is calculated separately. The sum of the three-phase currents obtained at all moments is then recorded as the second sum at detection point i for ease of understanding and description. The sum of the three-phase currents at each moment reflects whether the current still possesses the characteristic of three-phase current balance at each moment. The second sum reflects the overall imbalance of the three-phase current in the transmission line at the i-th detection point; a larger value indicates a greater degree of imbalance in the three-phase current, thus reflecting a greater likelihood that the fluctuations in the three-phase voltage are due to a line break fault rather than the influence of transmission power.

[0039] Furthermore, since a line breakage fault will simultaneously cause changes in the three-phase current sequence and generate a negative sequence current, the timing of the fault can be located by analyzing the negative sequence current, and the possibility of the fault can be further analyzed by analyzing the difference in the three-phase current before and after the fault.

[0040] All mutation points in the negative sequence current sequence are obtained through a mutation point detection algorithm, and the mutation point with the smallest position is recorded as the starting mutation point.

[0041] In this embodiment, taking the B-phase current sequence as an example, the B-phase current sequence is divided into two sub-sequences according to the position of the initial abrupt change point in the negative sequence current. The range of the two sub-sequences is calculated separately, and the absolute difference between the two ranges is recorded as the first difference of the B-phase current sequence. The first difference reflects whether the maximum fluctuation amplitude of the B-phase current before and after the initial abrupt change point is consistent. The larger the value, the greater the fluctuation change of the B-phase current, which is more consistent with the characteristics of a wire break fault.

[0042] Accordingly, according to the above process in this embodiment, the first difference values ​​of the current sequences of phase A and phase C can be obtained respectively, and the number z of non-zero values ​​among all the first differences can be counted. Then, the product of the number z and the sum of the three first differences is recorded as the first product of detection point i. The first product can reflect the overall degree of abnormality in the three-phase current at the i-th detection point; the larger the value, the more phases with abnormal fluctuations in the three-phase current are reflected, and the greater the degree of abnormality, which is more consistent with the characteristics of a wire breakage fault.

[0043] Furthermore, in this embodiment, based on the second sum and the first product of each detection point, and combined with the voltage disconnection index of each detection point, the three-phase anomaly index of the i-th detection point is constructed. Preferably, in this embodiment, the specific calculation relationship is as follows: In the formula, is the second sum value of detection point i; N is the number of abrupt change points in the negative sequence current sequence, where N=0 indicates that no negative sequence current is generated; It is the first product of the detection point i.

[0044] As can be understood from the above process, the three-phase anomaly index can not only reflect whether the changes in the three-phase current and three-phase voltage at the i-th detection point conform to the characteristics of a line break fault; the larger the value, the more the changes in the three-phase current and three-phase voltage at the i-th detection point conform to the characteristics of a single-phase line break without grounding fault, and the greater the possibility of a line break fault occurring in the transmission line at the i-th detection point.

[0045] Step 4: By measuring the differences in the three-phase anomaly index between adjacent detection points on the transmission line and combining the three-phase anomaly index of each detection point, the confidence level of single-phase open circuit at each detection point of the transmission line is obtained, so as to detect single-phase open circuit faults in the transmission line.

[0046] Furthermore, when a single-phase open-circuit fault occurs, the detection points closer to the power supply side before the break point are less affected, so the collected data at these points do not change significantly. However, the detection points farther from the power supply side after the break point are more significantly affected by the open-circuit fault. Therefore, further detection can be performed by combining the data from adjacent detection points of the i-th detection point.

[0047] Furthermore, in this embodiment, for ease of understanding and description, the ratio of the three-phase anomaly index of the preceding detection point adjacent to the i-th detection point to the three-phase anomaly index of the i-th detection point is recorded as the first ratio of the i-th detection point. Preferably, in this embodiment, all detection points are sorted from closest to farthest from the power source side of the transmission line, and the three-phase anomaly index of the preceding detection point adjacent to the i-th detection point is obtained. ,Will and The ratio is denoted as the first ratio at the i-th detection point, where, The purpose of this is to avoid the numerator and denominator being zero during the ratio calculation process; in this embodiment, the value is taken as 0.008.

[0048] It is understandable that the first ratio reflects the difference in the transmission line condition between detection point i and its previous adjacent detection point; the smaller the value, the greater the difference in line condition, and the greater the probability that a single-phase open-circuit fault has occurred at the i-th detection point. It should be noted that both the numerator and denominator are... Summation is performed to avoid the computational risk that the numerator and denominator may both be 0 under normal circuit conditions. If the i-th detection point is the first detection point, the first ratio is set to 1, indicating that fault detection is not performed through the upstream detection point.

[0049] Therefore, in this embodiment, the single-phase disconnection confidence level of the i-th detection point is constructed based on the differences in the three-phase anomaly indices of adjacent detection points and the three-phase anomaly indices of each detection point. Preferably, in this embodiment, the specific calculation relationship is as follows: In the formula, The ratio of the three-phase anomaly index of the adjacent preceding detection point to the three-phase anomaly index of the i-th detection point is also known as the first ratio of the i-th detection point. The single-phase open-circuit confidence score, combined with the inconsistent impact of a single-phase open-circuit fault on upstream and downstream areas, further reflects the probability of an open-circuit fault occurring at the i-th detection point. A higher score indicates a greater probability of an open-circuit fault.

[0050] It should be noted that the larger the three-phase anomaly index of the i-th detection point, the higher the confidence level of the single-phase open circuit at the i-th detection point. At the same time, the smaller the first ratio of the i-th detection point, the greater the probability of a single-phase open circuit fault occurring at the i-th detection point. Therefore, the confidence level of the single-phase open circuit at the i-th detection point is higher. In this embodiment, the purpose of dividing the three-phase anomaly index of the i-th detection point by the first ratio in the calculation of the confidence level of the single-phase open circuit at the i-th detection point is to further highlight the probability of a single-phase open circuit fault occurring at the i-th detection point, so as to better highlight the confidence level of a single-phase open circuit fault occurring at the i-th detection point.

[0051] Furthermore, according to the above process in this embodiment, the single-phase open circuit confidence level of the i-th detection point in the current cycle is calculated using the method for calculating the single-phase open circuit confidence level of each detection point, and then 3... The statistical principles and specific statistical processes are existing technologies known to those skilled in the art, and will not be elaborated upon in this embodiment.

[0052] Specifically, when the confidence level of a single-phase open circuit at the i-th detection point does not belong to 3... If the confidence level of the single-phase open circuit at the i-th detection point of the transmission line is within the specified range, it is determined that a single-phase open circuit and ungrounded fault has occurred. In this case, the transmission line needs to be repaired in a timely manner to ensure the stability of power transmission. If the confidence level of the single-phase open circuit at the i-th detection point is within 3... If the range is defined, it is determined that no single-phase open-circuit fault occurred at the i-th detection point, and the power supply stability of the transmission line is good. Correspondingly, all detection points of the transmission line are tested in the same way to achieve testing of the entire transmission line. It should be noted that, to improve the accuracy of single-phase open-circuit fault detection, the relevant operators need to re-test the detection points identified as having single-phase open-circuit faults to ensure the accuracy of single-phase open-circuit fault detection.

[0053] Based on the same inventive concept as the above method, this application embodiment also provides a single-phase open-circuit fault detection system for transmission lines, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described methods for detecting single-phase open-circuit faults in transmission lines.

[0054] Preferably, in this embodiment, the single-phase open-circuit fault detection system for transmission lines includes a transmission line data acquisition module, a transmission line voltage open-circuit detection module, a transmission line three-phase anomaly detection module, and a transmission line single-phase open-circuit assessment module, wherein: The transmission line data acquisition module acquires the three-phase voltage, phase difference between any two phase voltages, three-phase current, and negative sequence current at each detection point on the transmission line. The transmission line voltage disconnection detection module analyzes the amplitude distribution and fluctuation of each phase voltage at each detection point, as well as the dispersion of the phase difference between any two phase voltages at each detection point. It then combines this with the correlation between any two phase voltages to obtain the voltage disconnection index at each detection point. The transmission line three-phase anomaly detection module detects the fluctuation amplitude of each phase current based on the balance characteristics of the three-phase current and the sudden changes in negative sequence current. It then combines this with the voltage disconnection index to obtain the three-phase anomaly index at each detection point. The transmission line single-phase disconnection assessment module assesses the single-phase disconnection confidence level at each detection point by combining the difference in the three-phase anomaly index between adjacent detection points on the transmission line and the three-phase anomaly index at each detection point. This allows for the detection of single-phase disconnection faults on the transmission line.

[0055] Specifically, the block diagram of the single-phase open-circuit fault detection system for transmission lines in this embodiment is as follows: Figure 2 As shown.

[0056] It is understood that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0057] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0058] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for detecting single-phase open-circuit faults in transmission lines, characterized in that, Includes the following steps: Acquire the three-phase voltage, phase difference between any two phase voltages, three-phase current, and negative sequence current at each detection point on the transmission line; The amplitude distribution and fluctuation of each phase voltage at each detection point of the transmission line are analyzed, as well as the dispersion of the phase difference between any two phase voltages at each detection point. Combined with the correlation between any two phase voltages, the voltage disconnection index at each detection point of the transmission line is obtained. Based on the balance characteristics of the three-phase current of the transmission line, and by detecting the fluctuation amplitude of the current of each phase through the sudden change of the negative sequence current, and then combining the voltage disconnection index, the three-phase abnormality index of each detection point of the transmission line is obtained. By measuring the differences in the three-phase anomaly index between adjacent detection points on the transmission line and combining the three-phase anomaly index of each detection point, the confidence level of single-phase open circuit at each detection point of the transmission line can be obtained to detect single-phase open circuit faults in the transmission line.

2. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 1, characterized in that, The three-phase voltages, BA phase difference, CB phase difference, and AC phase difference at each detection point are arranged in time sequence to form the phase voltage sequence, BA phase difference sequence, CB phase difference sequence, and AC phase difference sequence at each detection point. The phase voltage sequence includes the A phase, B phase, and C phase voltage sequences. The peak and valley values ​​in each phase voltage sequence are extracted, and the average value of the dispersion of the peak and valley values ​​in each phase voltage sequence is calculated and denoted as the first mean. The sum of the first mean values ​​calculated for each phase voltage sequence is denoted as the first sum value for each detection point.

3. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 2, characterized in that, Calculate the mean of the elements of the three phase difference sequences respectively, and denot it as . ,Will The degree of dispersion between them is denoted as the first discrete value of each detection point; Obtain the voltage sequences of phase A and phase B with lag values ​​respectively. The cross-correlation value of phase B and phase C voltage sequences with lag value The cross-correlation value of phase C voltage and phase A voltage sequence with lag value The cross-correlation values ​​of the three points are used to calculate the mean of the three cross-correlation values, which is then recorded as the second mean of each detection point.

4. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 3, characterized in that, The voltage disconnection index at each detection point of the transmission line is further obtained as follows: In the formula, Let be the voltage disconnection index at the i-th detection point. Let i be the first sum value of the detection point; Let i be the first discrete value of the detection point i; The second mean of detection point i; To avoid constants with a denominator of 0.

5. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 1, characterized in that, The acquisition of the three-phase anomaly index at each detection point of the transmission line is further as follows: In the formula, Let i be the three-phase anomaly index at the i-th detection point. Let N be the second sum value of detection point i, where the sum of the three-phase currents A, B, and C at detection point i at the same moment is calculated, and the cumulative sum of the three-phase currents at all moments is recorded as the second sum value of detection point i; N is the number of abrupt change points in the negative sequence current sequence. It is the first product of the detection point i.

6. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 5, characterized in that, The phase currents and negative sequence currents at each detection point are arranged according to time sequence to form the phase current sequence and negative sequence current sequence at each detection point. The abrupt change points in the negative sequence current sequence are extracted, and the abrupt change point with the smallest position is taken as the starting abrupt change point. According to the position of the starting abrupt change point in the negative sequence current sequence, each phase current sequence is divided into two sub-sequences. Each phase current sequence includes the A phase current sequence, the B phase current sequence, and the C phase current sequence.

7. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 6, characterized in that, The absolute difference between the ranges of the two subsequences of each phase current sequence is taken as the first difference of each phase current sequence. The number of non-zero first differences among all phase current sequences is counted. The sum of the first differences of all phase current sequences and the product of the count are taken as the first product of each detection point.

8. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 1, characterized in that, The acquisition of the single-phase open circuit confidence level at each detection point of the transmission line is further as follows: In the formula, Let i be the confidence level of a single-phase open circuit at the i-th detection point. It is the ratio of the three-phase anomaly index of the adjacent preceding detection point to the three-phase anomaly index of the i-th detection point.

9. The method for detecting single-phase open-circuit faults in transmission lines as described in claim 1, characterized in that, Obtain the single-phase open circuit confidence level at each detection point, and perform 3... According to statistical principles, when the confidence level of a single-phase open circuit at a test point does not belong to 3... If the range is met, a single-phase open circuit fault occurs at the corresponding detection point; otherwise, no single-phase open circuit fault occurs at the corresponding detection point.

10. A single-phase open-circuit fault detection system for transmission lines, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for detecting single-phase open circuit faults in transmission lines as described in any one of claims 1-9.

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