A method and system for detecting a single-phase broken conductor fault of a power transmission line

Abstract

The application relates to the technical field of power transmission line fault detection, in particular to a power transmission line single-phase broken line fault detection method and system. The method comprises the following steps: acquiring three-phase voltages, phase differences, three-phase currents and negative sequence currents at each detection point of a power transmission line; analyzing voltage distribution fluctuation degrees of each phase at each detection point of the power transmission line and discrete conditions of the phase differences at each detection point, and combining a correlation between any two-phase voltages to obtain voltage broken line indexes of each detection point of the power transmission line; according to balance characteristics of three-phase currents of the power transmission line, detecting fluctuation amplitudes of each phase current through a sudden change of the negative sequence current to obtain three-phase abnormal indexes of each detection point of the power transmission line; and then obtaining single-phase broken line confidence degrees of each detection point of the power transmission line to detect a single-phase broken line fault of the power transmission line. The application can improve the precision of single-phase broken line fault detection of the power transmission line.

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 power grids 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:

[0005] This application provides a method for detecting single-phase open-circuit faults in transmission lines, including the following steps:

[0006] 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;

[0007] 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.

[0008] 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.

[0009] 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.

[0010] Preferably, the three-phase voltage, BA phase difference, CB phase difference and AC phase difference of each detection point are respectively 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, and the phase voltage sequence includes A-phase, B-phase and C-phase voltage sequence.

[0011] The peak value and the valley value in each phase voltage sequence are extracted, and the average of the dispersion degree of the peak value and the dispersion degree of the valley value in each phase voltage sequence is calculated, which is recorded as a first average value. The cumulative sum of the first average value calculated by each phase voltage sequence is recorded as a first sum value of each detection point.

[0012] Preferably, the average of the elements of the three phase difference sequences is respectively calculated and recorded as The dispersion degree between the first average value and the second average value of each detection point is recorded as a first dispersion value of each detection point.

[0013] The cross-correlation values of the A-phase and B-phase voltage sequences with a lag value of 1, the cross-correlation values of the B-phase and C-phase voltage sequences with a lag value of 1, and the cross-correlation values of the C-phase and A-phase voltage sequences with a lag value of 1 are respectively obtained, and the average of the three cross-correlation values is recorded as a second average value of each detection point.

[0014] Preferably, the acquisition of the voltage broken line index of each detection point of the power transmission line is further:

[0015] ; in the formula, is the voltage broken line index of the i th detection point, is the first sum value of the detection point i; is the first dispersion value of the detection point i; is the second average value of the detection point i; is a constant to avoid a denominator of 0.

[0016] Preferably, the acquisition of the three-phase abnormality index of each detection point of the power transmission line is further:

[0017] ; in the formula, is the three-phase abnormality index of the i th detection point, is the second sum value of the detection point i, wherein the sum value of the A-phase, B-phase and C-phase currents of the detection point i at the same time is calculated, and the cumulative sum of the sum value of the three-phase currents at all times is recorded as the second sum value of the detection point i; N is the number of mutation points in the negative sequence current sequence; is the first product of the detection point i.

[0018] ​​​​Preferably, the phase currents and the negative sequence currents of each detection point are respectively arranged in time sequence to form phase current sequences and negative sequence current sequences of each detection point, and each mutation point in the negative sequence current sequences is extracted, the mutation point with the smallest bit sequence is taken as a starting mutation point, and the phase current sequences are divided into two subsequences according to the bit sequence of the starting mutation point in the negative sequence current sequences, wherein the phase current sequences include A-phase current sequences, B-phase current sequences and C-phase current sequences.

[0019] Preferably, the absolute difference values of the two subsequences of each phase current sequence are respectively taken as first difference values of the phase current sequences, the number of first difference values of all phase current sequences that are not zero is counted, and the product of the sum of the first difference values of all phase current sequences and the number is taken as a first product of each detection point.

[0020] Preferably, the obtaining of the single-phase line break confidence of each detection point of the power transmission line is further:

[0021] ; in the formula, is the single-phase line break confidence of the i th detection point, is the ratio of the three-phase abnormality index of the adjacent previous detection point of the i th detection point to the three-phase abnormality index of the i th detection point.

[0022] Preferably, the single-phase line break confidence of each detection point is obtained, and 3 In principle, when the single-phase line break confidence of the detection point does not belong to the range of 3 , a single-phase line break fault occurs at the corresponding detection point, otherwise, no single-phase line break fault occurs at the corresponding detection point.

[0023] The embodiment of the application also provides a power transmission line single-phase line break fault detection system, which comprises a memory, a processor and a computer program stored in the memory and running on the processor, and the processor implements the steps of the power transmission line single-phase line break fault detection method of any one of the above.

[0024] As can be seen from the above, the power transmission line single-phase line break fault detection method and system provided by the application at least have the following beneficial effects:

[0025] The application can reflect whether the three-phase voltage at the detection point has an abnormal phenomenon by constructing the voltage line break index, further obtain the three-phase abnormality index to reflect whether the changes of the three-phase current and the three-phase voltage conform to the characteristics of the single-phase line break fault, and then distinguish the power fluctuation and the real fault, and according to the single-phase line break confidence, the application can further analyze whether the power data change of the detection point conforms to the line break fault characteristics in combination with the line data of the adjacent detection point.

[0026] In summary, the present application is directed to the prior art does not take into account that single-phase line break ungrounded fault after the negative sequence current amplitude is relatively weak, thus prone to false detection problem; the present application by constructing single-phase line break confidence, can accurately analyze whether the data characteristics collected at the detection point conform to the single-phase line break fault characteristics, and then improve the accuracy of the single-phase line break fault detection of the power transmission line, and protect the power supply stability of the power transmission line. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0028] Figure 1 A step flow chart of a single-phase line break fault detection method of a power transmission line provided by the present application;

[0029] Figure 2 A block diagram of a single-phase line break fault detection system of a power transmission line provided by the present application. DETAILED DESCRIPTION

[0030] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific implementation, structure, features and effects of a single-phase line break fault detection method and system according to the present application are described in detail as follows by combining with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0031] Unless otherwise defined and limited, such as the terms "comprise", "include" or any other variants thereof, are intended to cover non-exclusive inclusion, so that the circuit structure, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or includes elements inherent to such article or device. Without more limitation, the element limited by the statement "including one" does not exclude the presence of another identical element in the article or device including the element. In addition, the term "and / or" used herein includes any and all combinations of one or more related listed items. All technical and scientific terms used herein have the same meaning as understood by those skilled in the art of the technology to which the present application belongs.

[0032] The application provides a single-phase line breakage fault detection method and system for a power transmission line.

[0033] Please refer to Figure 1 which shows a step flow chart of a single-phase line breakage fault detection method provided by an embodiment of the application, and includes the following steps.

[0034] Step 1: Obtain the three-phase voltage, phase difference between any two-phase voltage, three-phase current and negative sequence current at each detection point of the power transmission line.

[0035] In the embodiment, a plurality of detection points are arranged on the power transmission line to collect power data of the power transmission line, and the distance between each detection point is 5 km in the embodiment. The voltage of A, B and C three-phase, the phase difference between three-phase voltage, three-phase current and negative sequence current of the power transmission line are collected at each detection point through a three-phase voltage sensor, a phase table, a three-phase current sensor and a negative sequence current transformer, respectively. All data are synchronously collected, the collection frequency is 1 KHz, and the time length of each collection period is 10 seconds. It should be noted that, in view of the problem of large amount of data in the analysis process, and in order to accurately detect the single-phase line breakage fault of the power transmission line, preferably, the time interval between adjacent two collection periods is 24 hours in the embodiment.

[0036] In the embodiment, the i-th detection point of the current collection period is taken as an example to analyze whether a single-phase line breakage ungrounded fault occurs at the position of the power transmission line. For the data collected at the i-th detection point, the A-phase voltage sequence, the B-phase voltage sequence, the C-phase voltage sequence, the BA phase difference sequence, the CB phase difference sequence, the AC phase difference sequence, the A-phase current sequence, the B-phase current sequence, the C-phase current sequence and the negative sequence current sequence of the i-th detection point are respectively constructed in time sequence order.

[0037] Preferably, in the embodiment, in order to eliminate the dimensional influence between data, all data are normalized. The normalization methods include Z-score, maximum value normalization and maximum minimum value normalization. The implementer can select a normalization method in an actual application scenario, and the embodiment does not specially limit the normalization method. Preferably, the maximum minimum value normalization is adopted in the embodiment, and the specific normalization process is a prior art, which will not be described herein again.

[0038] Step 2: Analyze the amplitude distribution fluctuation degree of each-phase voltage at each detection point of the power transmission line, and the dispersion of the phase difference between any two-phase voltage at each detection point, and combine the correlation between any two-phase voltage to obtain the voltage line breakage index of each detection point of the power transmission line.

[0039] When a phase of the power transmission line is broken but not grounded, the power transmission system will suddenly change from a balanced state to an unbalanced state. At the moment of the breakage, the electromagnetic transient process will be caused by the generation of arc or the separation of the conductor, which will further cause the transient mutation of the voltage of the broken phase. Subsequently, after the transient process decays and enters the steady state, the voltage of the broken phase will change significantly because the conductor of the broken phase is disconnected from the power supply, although the voltage can be maintained due to the electric field coupling effect between the power supply and the load side. Therefore, the mutation degree and difference of the three-phase voltage at each detection point can be analyzed to preliminarily analyze whether the breakage fault occurs.

[0040] Because the three-phase voltage of the transmission current will change significantly when the breakage fault occurs, and the voltage of the broken phase will decrease after the fault, the amplitude of the voltage of the broken phase will change greatly. Because the waveform of the three-phase voltage is a sine wave, the waveform itself has a large initial fluctuation. Therefore, in this embodiment, the amplitude of the three-phase voltage is analyzed to reflect whether the three-phase voltage has a fault.

[0041] In this embodiment, the A-phase voltage sequence of the ith detection point is taken as an example for analysis and description. The peak values and valley values in the A-phase voltage sequence are obtained by the extreme point detection algorithm, and then the dispersion degrees between all the peak values and the dispersion degrees between all the valley values are calculated. The average of the two dispersion degrees is denoted as the first average value of the A-phase voltage sequence of the ith detection point. The first average value can reflect the fluctuation degree of the amplitude of the A-phase voltage at the ith detection point. The greater the value is, the greater the possibility of the breakage fault is. It should be noted that the calculation of the dispersion degree is not limited to the variance, the coefficient of variation, and the standard deviation. In this embodiment, the coefficient of variation is used for calculation.

[0042] Correspondingly, the first average values of the B-phase and C-phase voltage sequences are calculated by using the above process of this embodiment, and the sum of all the first average values is denoted as the first sum value of the ith detection point. The first sum value can reflect whether the three-phase voltage at the ith detection point has an abnormal fluctuation. The greater the value is, the more inconsistent the voltage amplitude is, and the more likely the breakage fault is.

[0043] In addition, if the breakage fault does not occur, the waveforms and phase differences between the three-phase voltages will be consistent.

[0044] In this embodiment, the BA phase difference sequence is taken as an example. Each element of the BA phase difference sequence can reflect the time lag of the B-phase voltage compared with the A-phase voltage at each time. If the A-phase or the B-phase of the three-phase voltage is broken, the phase difference between the A-phase and the B-phase after the breakage will change, which will no longer be consistent with the phase differences between the other phases. Moreover, with the passage of time, the phase difference between the three phase difference sequences will be greater.

[0045] Therefore, in the embodiment, the mean values of the BA phase difference sequence, the CB phase difference sequence, and the AC phase difference sequence are respectively calculated , and the dispersion degree between is recorded as the first dispersion value of the detection point i. The first dispersion value can reflect the consistency degree of the phase difference between the three phases, and the greater the first dispersion value, the greater the possibility that the three-phase voltage does not conform to the standard voltage.

[0046] Since there is a phase difference between the three-phase voltages, there will be errors in directly calculating the voltage waveform similarity. Therefore, in the embodiment, the cross-correlation values of any two-phase voltage sequences at different lag values are analyzed. Specifically, in the embodiment, the cross-correlation values of the A-phase and B-phase voltage sequences at a lag value of , the cross-correlation values of the B-phase and C-phase voltage sequences at a lag value of , and the cross-correlation values of the C-phase and A-phase voltage sequences at a lag value of are obtained, and the mean value of the three cross-correlation values is recorded as the second mean value of the detection point i. The second mean value can reflect the waveform difference between the three-phase voltages at the detection point i, and the smaller the value, the greater the waveform difference between the voltages. It should be noted that the calculation process of the cross-correlation values of different-phase voltage sequences at different lag values is a prior art, which is not specially limited in the embodiment and will not be described here.

[0047] Therefore, in the embodiment, the voltage line-break index of the i-th detection point is constructed according to the first dispersion degree and the second mean value of each detection point , and preferably, the relationship is specifically calculated as follows in the embodiment:

[0048] ; in the formula, is the first sum value of the detection point i; is the first dispersion value of the detection point i; is the second mean value of the detection point i; In order to avoid the denominator being a constant of 0, the value range is (0.005, 0.01), the value has little effect on the calculation and can be ignored, and 0.008 is taken in the embodiment.

[0049] It can be understood through the above process that the voltage line-break index can reflect whether abnormal fluctuation occurs in the three-phase voltage at the i-th detection point; the greater the value, the greater the possibility that an abnormality occurs in a phase of the three-phase voltage, and thus the greater the possibility that the single-phase line-break ungrounded fault occurs in the power transmission line at the i-th detection point.

[0050] Step 3: According to the balance characteristics of the three-phase current of the power transmission line, the fluctuation amplitude of each phase current is detected through the mutation of the negative sequence current, and then the three-phase abnormality index of each detection point of the power transmission line is obtained in combination with the voltage broken line index.

[0051] Further, considering that if the power transmission power of the power supply side changes, it may also cause the voltage in the power transmission line to fluctuate, thereby causing the voltage broken line index to be larger. Therefore, it may be erroneous to evaluate whether the power transmission line has a broken line fault only by the three-phase voltage, and further analysis is required.

[0052] Since when the broken line fault occurs, not only the three-phase voltage will abnormally fluctuate, but also the three-phase current will change accordingly: the current of the broken phase will drop to 0 or close to 0, and the currents of the remaining two phases will also change, and after the fault occurs, the three-phase current is no longer balanced, and negative sequence current will be generated.

[0053] Since the voltage fluctuation caused by the change of the power transmission power does not affect the three-phase balance of the current, the three-phase current sum at the same time of the A-phase, B-phase and C-phase currents of the detection point i is calculated, and the cumulative sum of the three-phase current sums obtained at all times is obtained, which is recorded as the second sum value of the detection point i in this embodiment for the convenience of understanding and description. The three-phase current sum at each time can reflect whether the current at each time still has the characteristic of three-phase current balance; the second sum value can reflect the overall imbalance of the three-phase current in the power transmission line at the i-th detection point, and the greater the value, the greater the imbalance of the three-phase current, thereby reflecting the greater the possibility that the fluctuation of the three-phase voltage is caused by the broken line fault rather than the power transmission power.

[0054] Further, since the broken line fault will cause the change of the three-phase current sequence and the generation of the negative sequence current, the fault occurrence time can be located by analyzing the negative sequence current, and the difference between the three-phase currents before and after the fault occurs can be analyzed, thereby further analyzing the possibility of the fault occurrence.

[0055] All mutation points in the negative sequence current sequence are obtained by the mutation point detection algorithm, and the mutation point with the smallest bit sequence is recorded as the starting mutation point.

[0056] In this embodiment, taking the B-phase current sequence as an example, the B-phase current sequence is divided into two subsequences according to the bit sequence of the starting mutation point in the negative sequence current, and the range of the two subsequences is calculated respectively, and the absolute difference between the two ranges is recorded as the first difference value of the B-phase current sequence. The first difference value can reflect whether the maximum fluctuation amplitude of the B-phase current before and after the starting mutation point is consistent, and the greater the value, the greater the fluctuation change of the B-phase current, which is more consistent with the characteristics generated by the broken line fault.

[0057] Accordingly, the first difference of the A-phase and C-phase current sequences can be obtained respectively according to the above process of the embodiment, the number z of the first differences that are not 0 is counted, and then the product of the number z and the sum of the three first differences is recorded as the first product of the detection point i. The first product can reflect the overall abnormality degree of the three-phase current at the i th detection point; the greater the value, the more the number of phases in which abnormal fluctuations occur in the three-phase current and the greater the abnormality degree, which is more in line with the characteristics of the broken line fault.

[0058] Further, in the embodiment, the second sum of each detection point and the first product are combined with the voltage broken line index of each detection point to construct a three-phase abnormality index of the i th detection point , and preferably, the specific calculation relationship in the embodiment is:

[0059] ; in the formula, is the second sum of the detection point i; N is the number of mutation points in the negative sequence current sequence, where N is 0, indicating that no negative sequence current is generated; is the first product of the detection point i.

[0060] It can be understood through the above process that the three-phase abnormality index can not only reflect whether the changes of the three-phase current and three-phase voltage at the i th detection point are in line with the characteristics of the broken line fault; the greater the value, the more the changes of the three-phase current and three-phase voltage at the i th detection point are in line with the characteristics of the single-phase broken line ungrounded fault, and the greater the possibility of the broken line fault of the power transmission line at the i th detection point.

[0061] Step 4: The single-phase broken line confidence of each detection point of the power transmission line is obtained by the difference degree of the three-phase abnormality index between adjacent detection points on the power transmission line, combined with the three-phase abnormality index of each detection point, to detect the single-phase broken line fault of the power transmission line.

[0062] Further, when the single-phase broken line ungrounded fault occurs, the detection points close to the power supply side before the broken point position are less affected, so the collected data of the detection points will not change greatly; the detection points far from the power supply side after the broken point position are greatly affected by the broken line fault, so the detection points will be greatly affected. Therefore, the adjacent detection points of the i th detection point can be combined to further detect.

[0063] Further, in the embodiment, for the convenience of understanding and description, the ratio of the three-phase abnormality index of the adjacent previous detection point of the i th detection point to the three-phase abnormality index of the i th detection point is recorded as the first ratio of the i th detection point. Preferably, in the embodiment, all the detection points are sorted from near to far according to the distance of each detection point from the power supply side of the power transmission line, and the three-phase abnormality index of the adjacent previous detection point of the i th detection point is obtained , the ratio of and is recorded as the first ratio of the ith detection point, wherein, The role of is to avoid the situation that the numerator and denominator are zero in the ratio calculation process, and the value is 0.008 in this embodiment.

[0064] It can be understood that the first ratio can reflect the difference between the detection point i and its adjacent detection point in the state of the power transmission line; the smaller the value is, the greater the difference in the state of the line is, and the greater the possibility of single-phase broken line fault of the power transmission line at the ith detection point is. It should be noted that both the numerator and the denominator are related to The summation is to avoid the calculation risk that both the numerator and the denominator may be zero under the normal line state, and if the ith detection point is the first detection point, the first ratio is set to 1, indicating that no fault detection is performed through the upstream detection point.

[0065] Therefore, in this embodiment, according to the difference between the three-phase abnormal indices of adjacent detection points and the three-phase abnormal index of each detection point, the single-phase broken line confidence of the ith detection point is constructed as , preferably, in this embodiment, the specific calculation relationship is:

[0066] ; in the formula, is the ratio of the three-phase abnormal index of the adjacent previous detection point of the ith detection point to the three-phase abnormal index of the ith detection point, that is, the first ratio of the ith detection point. The single-phase broken line confidence can further reflect the possibility of the occurrence of the broken line fault at the ith detection point by combining the feature that the single-phase broken line fault has inconsistent effects on the upstream and downstream, and the greater the value is, the greater the possibility of the occurrence of the broken line fault is.

[0067] It should be noted that the greater the three-phase abnormal index of the ith detection point is, the higher the single-phase broken line confidence of the ith detection point is, and at the same time, the smaller the first ratio of the ith detection point is, the greater the possibility of the occurrence of the single-phase broken line fault of the power transmission line at the ith detection point is, so the higher the single-phase broken line confidence of the ith detection point is. In the calculation process of the single-phase broken line confidence of the ith detection point in this embodiment, the purpose of dividing the three-phase abnormal index of the ith detection point by the first ratio is to further highlight the possibility of the occurrence of the single-phase broken line fault at the ith detection point, so as to highlight the confidence degree of the occurrence of the single-phase broken line fault at the ith detection point.

[0068] Further, according to the above process of this embodiment, the single-phase broken line confidence of each detection point is obtained by using the calculation method of the single-phase broken line confidence of the ith detection point in the current period, and the three-phase abnormal indices of the upstream and downstream detection points are compared. The principle of statistics and the specific statistical process are known to those skilled in the art and are not described in detail in the present embodiment.

[0069] Specifically, when the single-phase broken line confidence of the ith detection point does not belong to the range of 3 , it is determined that the ith detection point of the power transmission line has a single-phase broken line ungrounded fault, and timely maintenance of the power transmission line is required to ensure the stability of power transmission; when the single-phase broken line confidence of the ith detection point belongs to the range of 3 , it is determined that no single-phase broken line fault occurs at the ith detection point, and the power supply stability of the power transmission line is good. Correspondingly, all detection points of the power transmission line are detected in the same way, thereby realizing detection of the entire power transmission line. It should be noted that, in order to improve the single-phase broken line fault detection accuracy of the power transmission line, relevant operators need to re-detect the detection points determined to have a single-phase broken line fault, so as to ensure the accuracy of single-phase broken line fault detection of the power transmission line.

[0070] Based on the same inventive concept as the above method, the present embodiment also provides a single-phase broken line fault detection system for a power transmission line, which comprises a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the steps of the single-phase broken line fault detection method for the power transmission line according to any one of the above methods when executing the computer program.

[0071] Preferably, in the present embodiment, the single-phase broken line fault detection system for the power transmission line comprises a power transmission line data acquisition module, a power transmission line voltage broken line detection module, a power transmission line three-phase anomaly detection module, and a power transmission line single-phase broken line evaluation module, wherein:

[0072] The power transmission line data acquisition module acquires the three-phase voltage, the phase difference between any two-phase voltage, the three-phase current, and the negative sequence current at each detection point of the power transmission line; the power transmission line voltage broken line detection module analyzes the amplitude distribution fluctuation degree of each phase voltage at each detection point of the power transmission line and the dispersion of the phase difference between any two-phase voltage at each detection point, and combines the correlation between any two-phase voltage to obtain the voltage broken line index of each detection point of the power transmission line; the power transmission line three-phase anomaly detection module detects the fluctuation amplitude of each phase current according to the balance characteristics of the three-phase current of the power transmission line and through the sudden change of the negative sequence current, and further obtains the three-phase anomaly index of each detection point of the power transmission line in combination with the voltage broken line index; and the power transmission line single-phase broken line evaluation module acquires the single-phase broken line confidence of each detection point of the power transmission line through the difference degree of the three-phase anomaly index between adjacent detection points on the power transmission line in combination with the three-phase anomaly index of each detection point, so as to detect the single-phase broken line fault of the power transmission line.

[0073] Specifically, a block diagram of the single-phase broken conductor fault detection system of the power transmission line in the embodiment is shown in Figure 2

[0074] It can be understood that the above-mentioned sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. Moreover, the above-mentioned description is made for specific embodiments of the present application. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

[0075] Each of the embodiments in the present specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments.

[0076] The above is only the implementation of the present application, and is not used to limit the scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the present application specification and drawings, or directly or indirectly applied in other related technical fields, is also included in the protection scope of the present 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. The first product of detection point i; 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.

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 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.

8. 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 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.

9. 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 1-8.

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