Grounding electrode line fault detection method, system, equipment and medium

Abstract

The invention relates to the technical field of grounding electrode line fault detection, and discloses a grounding electrode line fault detection method, system and device and a medium, and the method comprises the steps: obtaining the electrical data of a grounding electrode line, carrying out the feature extraction, and constructing a modulus network. Real-time impedance, real-time phase, standard impedance and standard phase are obtained through a network. A determination is made based on the data to determine whether to start a further determination process. And outputting a fault detection result according to a judgment result. Under various fault working conditions, the protection method provided by the invention can reliably identify the fault of the grounding electrode line, has strong anti-transition resistance capability, and effectively solves the problem that a dead zone exists in a traditional protection scheme. According to the invention, only 12-time harmonic voltage and current at the head end of the grounding electrode line need to be used for calculation, and extra high-frequency signal injection equipment does not need to be installed.

Description

Technical Field

[0001] This application relates to the technical field of grounding electrode line fault detection, and particularly to a grounding electrode line fault detection method, system, device, and medium. Background Art

[0002] As an important part of modern power systems, UHV DC transmission technology is widely used in scenarios of long-distance and large-capacity electric energy transmission, as well as in realizing the asynchronous interconnection between asynchronous power grids. Among them, the grounding electrode line operating in the parallel mode of double-circuit lines on the same tower plays a crucial role in the UHV DC transmission system, and its main function is to conduct the unbalanced current in the DC system. In order to mitigate the adverse effects of DC bias on converter station equipment and prevent potential safety threats caused by large currents entering the ground, the designed lengths of some current grounding electrode lines have increased significantly, generally exceeding 100 km, and even reaching more than 200 km. However, as the length of the grounding electrode line increases, the operating difficulty of the line in harsh meteorological conditions and complex geographical environments also increases, and the probability of the grounding electrode line failing also increases accordingly, which poses more stringent requirements and challenges to the safety and reliability of the UHV DC transmission system.

[0003] The grounding electrode lines of currently built and put into operation UHV DC transmission systems are usually configured with overcurrent protection, current imbalance protection, and an impedance monitoring system based on high-frequency injection signals. However, when the UHV DC transmission system is in the bipolar balanced operation mode, the unbalanced current flowing through the grounding electrode line is approximately equal to 0, and at this time, the overcurrent protection and imbalance protection will fail. The impedance monitoring system for grounding electrode lines based on high-frequency signal injection has the principle of injecting a high-frequency current signal of 13.95 kHz at the head end of the grounding electrode line, and then calculating the same-frequency measured impedance at the injection point and monitoring the change in the measured impedance to identify the operating state of the grounding electrode line. This method has, to a certain extent, solved the defects of the aforementioned protection strategies. However, since the wavelength of the injected signal is much smaller than the actual length of the grounding electrode line, there are multiple protection dead zones in the long-distance range of the grounding electrode line for the impedance monitoring principle, and the impedance monitoring system may not be able to accurately monitor the faults of the grounding electrode line.

[0004] It can be seen that the existing grounding electrode line protection faces problems of low reliability and protection refusal in practical applications, and cannot meet the performance requirements for grounding electrode line fault detection in actual projects. Therefore, it is of great theoretical and practical significance to study a stable and reliable grounding electrode line fault detection method. Summary of the Invention

[0005] In view of the above existing problems, this application is proposed.

[0006] Therefore, the present application provides a method, system, device and medium for detecting faults in the grounding electrode line, which can solve the problems of difficult operation and high fault probability of the grounding electrode line in the UHV DC transmission system.

[0007] To solve the above technical problems, the present application provides the following technical solutions:

[0008] In a first aspect, the present application provides a method for detecting faults in a grounding electrode line, including:

[0009] Obtain the port electrical quantity data of the target grounding electrode line, and perform first feature extraction on the electrical quantity data;

[0010] Construct a grounding electrode line modulus network according to the first feature extraction result;

[0011] Obtain a first real-time impedance, a first real-time phase, a second standard impedance, and a second standard phase according to the grounding electrode line modulus network;

[0012] Perform a first judgment on the first real-time impedance and the second standard impedance, and determine whether to initiate a second judgment based on the result of the first judgment;

[0013] The second judgment is made according to the first real-time phase and the second standard phase;

[0014] Use the result of the first judgment or the result of the second judgment as the fault detection result of the target grounding electrode line.

[0015] As a preferred solution of the method for detecting faults in the grounding electrode line according to the present application, wherein: the first judgment includes:

[0016] Preset a first fault judgment threshold;

[0017] Obtain a first target difference between the first real-time impedance and the second standard impedance;

[0018] Compare the first target difference with the first fault judgment threshold to obtain the result of the first judgment.

[0019] As a preferred solution of the method for detecting faults in the grounding electrode line according to the present application, wherein: the second judgment includes:

[0020] Determine whether to initiate a second judgment according to the result of the first judgment;

[0021] If the result of the first judgment is that the fault has been confirmed, no second judgment is made;

[0022] If the result of the first judgment is that the fault has not been confirmed, then according to the preset second fault judgment threshold;

[0023] Obtain a second target difference between the first real-time phase and the second standard phase;

[0024] And compare the second target difference with the second fault judgment threshold to obtain the result of the second judgment.

[0025] As a preferred solution of the grounding electrode line fault detection method described in the present application, wherein: the grounding electrode line modulus network includes:

[0026] The grounding electrode line modulus network includes a zero-mode network and a line-mode network;

[0027] The head-end voltages of the zero-mode network and the line-mode network are determined by the head-end voltage of the grounding electrode line through a first transformation matrix;

[0028] The tail-end voltages of the zero-mode network and the line-mode network are determined by the tail-end voltage of the grounding electrode line through a second transformation matrix;

[0029] The head-end currents of the zero-mode network and the line-mode network are determined by the head-end current of the grounding electrode line through a third transformation matrix;

[0030] The tail-end currents of the zero-mode network and the line-mode network are determined by the tail-end current of the grounding electrode line through a fourth transformation matrix.

[0031] As a preferred solution of the grounding electrode line fault detection method described in the present application, wherein: the obtaining of the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network includes:

[0032] The first real-time impedance is obtained from the harmonic voltages corresponding to the head-end voltage in the zero-mode network of the grounding electrode line and the harmonic currents corresponding to the head-end current in the zero-mode network of the grounding electrode line;

[0033] The first real-time phase is obtained from the harmonic measurement impedances during the normal operation of the grounding electrode line.

[0034] As a preferred solution of the grounding electrode line fault detection method described in the present application, wherein: the obtaining of the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network further includes:

[0035] The second standard impedance is obtained from the harmonic voltages of the head-end measured in real time of the grounding electrode line and the harmonic currents of the head-end measured in real time of the grounding electrode line;

[0036] The second standard phase is obtained from the real-time harmonic measurement impedance of the grounding electrode line.

[0037] This preferred solution can more effectively identify faults in the line by accurately calculating the impedance and phase of the grounding electrode line at different harmonic frequencies.

[0038] As a preferred solution of the grounding electrode line fault detection method described in this application, wherein: using the result of the first judgment or the result of the second judgment as the target grounding electrode line fault detection result includes:

[0039] The fault detection result includes a ground fault state, a disconnection fault state, and a normal operation state;

[0040] If both the first judgment result and the second judgment result after sequential judgment are that the fault is not confirmed, the grounding electrode line is in a normal operation state.

[0041] In a second aspect, this application provides a grounding electrode line fault detection system, including:

[0042] A feature extraction module, configured to obtain port electrical quantity data of the target grounding electrode line and perform first feature extraction on the electrical quantity data;

[0043] A network establishment module, configured to construct a grounding electrode line modulus network according to the first feature extraction result;

[0044] A data acquisition module, configured to obtain a first real-time impedance, a first real-time phase, a second standard impedance, and a second standard phase according to the grounding electrode line modulus network;

[0045] A judgment module, configured to perform a first judgment on the first real-time impedance and the second standard impedance, and determine whether to initiate a second judgment based on the result of the first judgment;

[0046] The second judgment is performed according to the first real-time phase and the second standard phase;

[0047] A detection module, configured to use the result of the first judgment or the result of the second judgment as the target grounding electrode line fault detection result.

[0048] In a third aspect, this application provides an electronic device, including a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the method described above when executing the computer program. [[ID=E34]]

[0049] In a fourth aspect, this application provides a computer-readable storage medium, on which a computer program is stored, and the computer program implements the steps of the method described above when executed by a processor.

[0050] Compared with the prior art, the beneficial effects of this application are as follows: This application proposes a method for detecting faults in the grounding electrode line, obtaining the port electrical quantity data of the target grounding electrode line, and performing first feature extraction on the electrical quantity data; constructing a grounding electrode line modulus network according to the first feature extraction result; obtaining the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network; performing a first judgment on the first real-time impedance and the second standard impedance, and determining whether to start a second judgment based on the result of the first judgment; the second judgment is based on the first real-time phase and the second standard phase; using the result of the first judgment or the result of the second judgment as the fault detection result of the target grounding electrode line. Aiming at the problem of protection dead zones existing in the grounding electrode line of the current UHV DC transmission system, under various fault conditions, the protection method proposed in this application can reliably identify the faults occurring in the grounding electrode line, has strong resistance to transition resistance, and effectively solves the problem of dead zones existing in the traditional protection scheme. This application only needs to calculate using the 12th harmonic voltage and current at the head end of the grounding electrode line, and there is no need to additionally install high-frequency signal injection equipment. Therefore, the current measurement points installed at the near-station end of the traditional unbalanced protection of the grounding electrode line and the neutral bus voltage measurement points can meet the data acquisition requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0052] Figure 1 It is a flowchart of a method for detecting faults in a grounding electrode line provided by an embodiment of this application.

[0053] Figure 2 It is a detailed flowchart of a method for detecting faults in a grounding electrode line provided by an embodiment of this application.

[0054] Figure 3 It is a simplified schematic diagram of a UHV DC transmission system including a grounding electrode line for a method for detecting faults in a grounding electrode line provided by an embodiment of this application.

[0055] Figure 4 It is an equivalent circuit schematic diagram of a grounding electrode line when it is operating normally for a method for detecting faults in a grounding electrode line provided by an embodiment of this application.

[0056] Figure 5 It is a schematic diagram of a modulus network of a grounding electrode line when it is operating normally for a method for detecting faults in a grounding electrode line provided by an embodiment of this application.

[0057] Figure 6 Schematic diagram of the amplitude and phase characteristics of the harmonic measurement impedance when a single-line ground fault occurs in the ground electrode line of a ground electrode line fault detection method provided by an embodiment of the present application.

[0058] Figure 7 Internal structure diagram of an electronic device of a ground electrode line fault detection method provided by an embodiment of the present application. Detailed implementation manners

[0059] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0060] Embodiment 1, referring to Figures 1-7 , which is the first embodiment of the present application. This embodiment provides a ground electrode line fault detection method, including:

[0061] In the existing related technologies, there are some problems, such as the problem of protection dead zones, resulting in the inability to accurately detect ground electrode line faults.

[0062] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to elaborate in detail how to implement this ground electrode line fault detection method;

[0063] Figure 1 The flowchart of a ground electrode line fault detection method is shown, including:

[0064] S101, obtain the port electrical quantity data of the target ground electrode line, and perform first feature extraction on the electrical quantity data;

[0065] As Figure 3 shown, the present application needs to utilize the voltage and current signals at the head end of the ground electrode line. Therefore, two current measurement points are installed at the head end of the ground electrode line to respectively obtain the current waveform recording data of the two lines A voltage measurement point is installed on the neutral bus of the ground electrode to obtain the measured voltage at the head end of the line To improve the calculation accuracy of the harmonic measurement impedance, a matching resistor Rp is installed at the end of the ground electrode line, and its resistance value is equal to the wave impedance of the ground electrode line To reduce the influence of the matching resistor on the actual operation, an LC parallel resonance filter with a resonance frequency of 600 Hz is installed at both ends of the matching resistor, and its function is to provide a path for the DC component.

[0066] In the embodiments of the present application, the electrical quantity data of the first section of the grounding electrode line includes the voltage at the head end of the grounding electrode line and the head-end currents of two circuits of grounding electrode lines

[0067] In an optional embodiment, the first feature extraction can be implemented by algorithms such as wavelet transform, Fourier transform, or Hilbert-Huang transform to extract the characteristic harmonic components in the electrical quantity data. These characteristic harmonic components can reflect the operating state of the grounding electrode line and provide key information for subsequent construction of the grounding electrode line modulus network and fault judgment.

[0068] In the embodiments of the present application, the characteristic harmonic components (i.e., the first feature) in the electrical quantity data are extracted by S-transform. In view of the good time-frequency characteristics of S-transform, the 12th harmonic voltage in the electrical quantity data collected by the grounding electrode line is extracted by the present application The 12th harmonic current of the first circuit and the 12th harmonic current of the second circuit

[0069] It should be noted that obtaining the port electrical quantity data of the target grounding electrode line and performing the first feature extraction on the electrical quantity data can accurately obtain the key information during the operation of the grounding electrode line and provide data support for subsequent construction of the grounding electrode line modulus network and fault judgment. Through feature extraction, the characteristic harmonic components in the electrical quantity data can be effectively extracted, and these components are crucial for reflecting the operating state of the grounding electrode line. By using algorithms such as S-transform, key data such as the 12th harmonic voltage and current can be accurately extracted, providing a strong guarantee for the accurate calculation of subsequent steps. At the same time, this step is also the basis for implementing the protection method proposed in the present application, laying a solid foundation for the reliability and accuracy of subsequent fault detection.

[0070] S102. According to the first feature extraction result, construct a grounding electrode line modulus network;

[0071] In an optional embodiment, different methods and technologies can be used to construct the grounding electrode line modulus network. The grounding electrode line modulus network is a key component in the fault detection system and is constructed based on the characteristic harmonic components extracted from the electrical quantity data.

[0072] In an optional embodiment, the modulus network includes a zero-mode network and a line-mode network, and these two networks respectively reflect different electrical characteristics of the grounding electrode line. The zero-mode network mainly focuses on characteristics such as the capacitance current to the ground of the grounding electrode line, while the line-mode network more reflects characteristics such as the mutual inductance between lines. By constructing such a modulus network, the electrical behavior of the grounding electrode line can be more comprehensively understood and analyzed, thereby providing a more accurate information basis for fault detection.

[0073] Specifically, in the process of constructing the modulus network, transformation matrices are needed to determine the voltages and currents at the head and end of the network. These transformation matrices are calculated based on the electrical parameters and topological structure of the grounding electrode line, and they can convert the actual electrical quantity data into equivalent electrical quantities in the modulus network, thus facilitating subsequent analysis and processing.

[0074] In an alternative embodiment, the modulus network of the grounding electrode line can also be established by other existing technologies. For example, an electromagnetic transient simulation software such as PSCAD / EMTDC can be used to build a UHV DC transmission system model including the grounding electrode line to simulate the actual operating conditions. Through simulation analysis, the accuracy and reliability of the constructed modulus network of the grounding electrode line and the fault detection method can be verified. During the simulation, different fault types and fault locations can be set, the response of the fault detection method can be observed, and the method can be optimized and improved according to the simulation results. In addition, various interference factors in actual operation, such as noise and measurement errors, can be considered to evaluate the robustness of the method to interference. Through simulation analysis, the practicality and reliability of the fault detection method can be further improved, providing strong support for actual applications.

[0075] In the embodiment of the present application, the modulus network of the grounding electrode line is constructed by separately establishing a zero-mode network and a line-mode network. As Figure 4 shown, it is an equivalent circuit of the grounding electrode line in normal operation provided by the embodiment of the present application. In the figure: is the head-end 12th harmonic voltage; and are the incoming currents of the grounding electrode line respectively; the head-end 12th harmonic current is the sum of the currents flowing through the two lines of the grounding electrode, that is is the pole-site current; Rp is the matching resistance.

[0076] In the embodiment of the present application, the modulus network of the grounding electrode line includes:

[0077] The modulus network of the grounding electrode line includes a zero-mode network and a line-mode network;

[0078] The head-end voltages of the zero-mode network and the line-mode network are determined by the head-end voltage of the grounding electrode line through a first transformation matrix;

[0079] The end voltages of the zero-mode network and the line-mode network are determined by the end voltage of the grounding electrode line through a second transformation matrix;

[0080] The head-end currents of the zero-mode network and the line-mode network are determined by the head-end current of the grounding electrode line through a third transformation matrix;

[0081] The end currents of the zero-mode network and the line-mode network are determined by the end current of the grounding electrode line through the fourth transformation matrix.

[0082] Using the Karenbauer transformation matrix Decouple the voltages and currents at the beginning and end of the grounding electrode line to obtain the zero-mode network and the line-mode network during the normal operation of the grounding electrode line as follows:

[0083]

[0084] It should be noted that the middle part in the above formula (1) is, in sequence, the first transformation matrix, the second transformation matrix, the third transformation matrix, and the fourth transformation matrix.

[0085] Among them, represents the voltage at the beginning of the grounding electrode line, represents the voltage at the beginning of the first grounding electrode line, represents the voltage at the beginning of the second grounding electrode line, represents the voltage at the beginning of the zero-mode network of the grounding electrode line, represents the voltage at the beginning of the line-mode network of the grounding electrode line, represents the voltage at the end of the grounding electrode line, represents the voltage at the end of the first grounding electrode line, represents the voltage at the end of the second grounding electrode line, represents the voltage at the end of the zero-mode network of the grounding electrode line, represents the voltage at the end of the line-mode network of the grounding electrode line, represents the current at the beginning of the grounding electrode line, represents the current at the beginning of the first grounding electrode line, represents the current at the beginning of the second grounding electrode line, represents the current at the beginning of the zero-mode network of the grounding electrode line, represents the current at the beginning of the line-mode network of the grounding electrode line, represents the current at the end of the grounding electrode line, represents the current at the end of the first grounding electrode line, represents the current at the end of the second grounding electrode line, represents the current at the end of the zero-mode network of the grounding electrode line, represents the current at the end of the line-mode network of the grounding electrode line.

[0086] It should be noted that, based on the first feature extraction results, constructing a grounding electrode line modulus network can clearly reflect the electrical characteristics of the grounding electrode line, providing an accurate model foundation for subsequent fault diagnosis. After constructing the modulus network, fault characteristics can be extracted and analyzed based on this network, enabling accurate detection of grounding electrode line faults. Furthermore, the constructed modulus network exhibits good adaptability and robustness, capable of handling different fault types and locations, improving the accuracy and reliability of fault detection.

[0087] S103, obtaining a first real-time impedance, a first real-time phase, a second standard impedance, and a second standard phase according to the grounding electrode line modulus network;

[0088] In an embodiment of the present application, obtaining the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network includes:

[0089] The first real-time impedance is obtained by a plurality of harmonic voltages corresponding to the first-end voltage in the grounding electrode line zero-mode network and a plurality of harmonic currents corresponding to the first-end current in the grounding electrode line zero-mode network;

[0090] The first real-time phase is obtained by measuring impedance of several harmonics during normal operation of the grounding electrode line.

[0091] In the embodiment of the present application, obtaining the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network further includes:

[0092] The second standard impedance is obtained based on several harmonic voltages and several harmonic currents of the first end measured in real time at the grounding electrode line;

[0093] The second standard phase is obtained based on the real-time harmonic measurement impedance of the grounding electrode line.

[0094] Specifically, according to the zero mode network and line mode network, when the grounding electrode line is operating normally, the line mode component is 0 and only the zero mode component exists. The corresponding modulus network is as follows: Figure 5 shown.

[0095] Furthermore, for the distributed parameter model of the grounding electrode line modulus network, the voltage and current relationship between any two points on the line can be obtained as follows:

[0096]

[0097] Where, subscripts h and k represent any two nodes on the line; γ is the propagation coefficient of the grounding electrode line; Z C is the wave impedance of the grounding electrode line; Z and Y are the impedance and admittance matrices per unit length of the grounding electrode line respectively.

[0098] Further, in the modulus network after the decoupling of the grounding electrode line, the harmonic measurement impedance during the normal operation of the grounding electrode line can be obtained by using the voltage-current relationship formula.

[0099] In an alternative embodiment, the harmonic measurement impedance at the head end in the zero-mode network of the grounding electrode line is:

[0100]

[0101] In the formula, is the zero-mode 12th harmonic impedance of the grounding electrode line, is the equivalent resistance of the matching resistor in the zero-mode network, and its resistance value is equal to

[0102] In an alternative embodiment, during the normal operation of the grounding electrode line, the harmonic measurement impedance (i.e., the first real-time impedance) during the normal operation of the grounding electrode line can be obtained according to the modulus network of the grounding electrode line. and the phase (i.e., the first real-time phase) are:

[0103]

[0104] In the formula, represents the harmonic measurement impedance during the normal operation of the grounding electrode line, represents the phase of the harmonic measurement impedance during the normal operation of the grounding electrode line, represents the head-end 12th harmonic voltage during the normal operation of the grounding electrode line, represents the head-end 12th harmonic current during the normal operation of the grounding electrode line, represents the 12th harmonic voltage corresponding to the head-end voltage in the zero-mode network of the grounding electrode line, represents the 12th harmonic current corresponding to the head-end current in the zero-mode network of the grounding electrode line, represents the zero-mode 12th harmonic impedance of the grounding electrode line, and Arg represents the phase-taking operation.

[0105] In an alternative embodiment, the real-time harmonic measurement impedance of the grounding electrode line is obtained by using the characteristic harmonic components. and the phase

[0106]

[0107] In the formula, represents the real-time harmonic measurement impedance of the grounding electrode line (i.e., the second standard impedance), represents the phase of the real-time harmonic measurement impedance of the grounding electrode line (i.e., the second standard phase), is the 12th harmonic voltage at the head end for real-time measurement of the grounding electrode line; is the 12th harmonic current at the head end for real-time measurement of the grounding electrode line.

[0108] In an optional embodiment, the 12th harmonic current at the head end of the grounding electrode line is:

[0109]

[0110] wherein, represents the 12th harmonic current corresponding to the current at the head end of the first grounding electrode line and represents the 12th harmonic current corresponding to the current at the head end of the second grounding electrode line .

[0111] It should be noted that obtaining the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network can provide more accurate data support for subsequent fault judgment. By comparing the differences between the first real-time impedance, the first real-time phase and the second standard impedance, the second standard phase, it is possible to more accurately determine whether there is a fault in the grounding electrode line. In addition, using these real-time data, the operating state of the grounding electrode line can also be monitored and evaluated in real time to ensure the stable operation of the power system. Therefore, this step plays an important role in the fault detection of the grounding electrode line.

[0112] S104, make a first judgment on the first real-time impedance and the second standard impedance, and judge whether to start a second judgment based on the result of the first judgment;

[0113] In the embodiment of the present application, the second judgment is made according to the first real-time phase and the second standard phase;

[0114] In the embodiment of the present application, the first judgment includes:

[0115] Preset a first fault judgment threshold;

[0116] Obtain the first target difference between the first real-time impedance and the second standard impedance;

[0117] Compare the first target difference with the first fault judgment threshold to obtain the result of the first judgment.

[0118] In the embodiment of the present application, the second judgment includes:

[0119] Judge whether to start the second judgment according to the result of the first judgment;

[0120] If the result of the first judgment is that the fault has been confirmed, the second judgment is not performed;

[0121] ​If the result of the first determination is that the fault is not confirmed, then according to a preset second fault determination threshold;

[0122] Obtain a second target difference between the first real-time phase and the second standard phase;

[0123] And compare the second target difference with the second fault determination threshold to obtain the result of the second determination.

[0124] In an alternative embodiment, the first determination and the second determination are for more accurately determining the fault condition of the grounding electrode line. The first determination and the second determination can be implemented using different algorithms or models to improve the accuracy and reliability of fault detection. For example, the first determination can adopt a threshold-based comparison method, and by setting a reasonable threshold, it is determined whether the difference between the real-time impedance and the standard impedance exceeds the normal range. If the difference exceeds the threshold, it is preliminarily determined that a fault may exist. The second determination, on the other hand, can adopt a more complex algorithm, such as a machine learning algorithm or a deep learning algorithm, to perform a more in-depth analysis and comparison of the real-time phase and the standard phase to further confirm the existence of the fault.

[0125] In an alternative embodiment, the first determination and the second determination can also adopt methods based on fuzzy logic or expert systems, and combine the professional knowledge and experience of the power system to comprehensively evaluate the fault condition of the grounding electrode line. These methods can consider more fault characteristics and factors, thereby providing a more comprehensive and accurate fault determination result. For example, the fuzzy logic method can perform a fuzzy evaluation of the fault degree of the grounding electrode line by setting fuzzy sets and fuzzy rules, and obtain the probability distribution of the fault possibility. The expert system, on the other hand, can utilize expert knowledge and experience to establish a knowledge base and an inference engine for fault determination, and perform fault reasoning and determination based on real-time data and information.

[0126] Specifically, the present application is designed in the following manner. Calculate whether the amplitude difference of the harmonic measurement impedance of the grounding electrode line satisfies the fault detection criterion of Equation (9) (i.e., the first determination):

[0127]

[0128] Z in the formula dif is the first target difference. If Equation (9) is satisfied, it can be determined that a fault has occurred in the grounding electrode line, and an alarm signal indicating that a fault has occurred in the grounding electrode line is issued.

[0129] If Equation (9) is not satisfied, calculate whether the phase difference of the harmonic measurement impedance of the grounding electrode line satisfies the fault detection criterion shown in Equation (10) (i.e., the second determination):

[0130]

[0131] In the formula This is the second target difference. If Equation (10) is satisfied, it is determined that a fault has occurred on the grounding electrode line, and an alarm signal indicating a fault on the grounding electrode line is issued. Otherwise, the grounding electrode line is in normal operation.

[0132] It should be noted that considering the influence of actual transformer measurement errors and other factors on the protection criterion, the impedance setting value (i.e., the first fault judgment threshold) Z of the fault detection criterion set is taken as The phase setting value (i.e., the second fault judgment threshold) is taken as 5°.

[0133] It should also be noted that the 12th harmonic component at the head end of the grounding electrode line is extracted through the S transform to calculate the real-time harmonic measurement impedance Then calculate the amplitude difference Z of the characteristic harmonic measurement impedance dif and the setting value Z of the fault detection criterion set for comparison. When the grounding electrode line is in normal operation, the 12th harmonic measurement impedance measured at the head end is theoretically equal to At this time, both the impedance amplitude difference and the phase difference are equal to 0, which is much smaller than the protection setting value. At this time, the fault detection device will not issue an alarm signal. When a fault occurs on the grounding electrode line, the 12th harmonic measurement impedance measured at the head end will change due to the change of the equivalent circuit and the modulus network. If the amplitude difference of the harmonic measurement impedance satisfies Z dif ≥Z set it can be judged that a fault has occurred on the grounding electrode line; if the amplitude difference of the harmonic measurement impedance does not meet the detection criterion, the phase difference of the harmonic measurement impedance is further used for fault discrimination. If the phase difference of the harmonic measurement impedance satisfies it is considered that a fault has occurred on the grounding electrode line, and an alarm signal indicating a fault on the grounding electrode line is issued. Otherwise, the grounding electrode line is in normal operation.

[0134] It should also be noted that making the first judgment on the first real-time impedance and the second standard impedance and judging whether to start the second judgment based on the result of the first judgment can improve the efficiency of fault detection while ensuring the accuracy of fault detection. Specifically, by making the first judgment first, the grounding electrode lines that may have faults can be quickly screened out. For the cases where the result of the first judgment is that the fault has been confirmed, the fault can be directly processed without the need to make the second judgment, thus saving the detection time. For the cases where the result of the first judgment is that the fault has not been confirmed, the second judgment is started, and a more complex algorithm or model is used to deeply analyze and compare the real-time phase and the standard phase to further confirm the existence of the fault, improving the accuracy of fault detection. Such a design not only avoids unnecessary repeated detections but also ensures that faults can be detected in a timely and accurate manner, which is beneficial to the stable operation of the power system.

[0135] S105, use the result of the first judgment or the result of the second judgment as the target ground electrode line fault detection result.

[0136] In the embodiment of the present application, using the result of the first judgment or the result of the second judgment as the target ground electrode line fault detection result includes:

[0137] The fault detection result includes a ground fault state, a disconnection fault state, and a normal operation state;

[0138] If both the first judgment result and the second judgment result after sequential judgment are that the fault is not confirmed, the ground electrode line is in a normal operation state.

[0139] In summary, the present application proposes a method for detecting ground electrode line faults, which obtains the port electrical quantity data of the target ground electrode line and performs first feature extraction on the electrical quantity data; according to the first feature extraction result, constructs a ground electrode line modulus network; obtains the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the ground electrode line modulus network; performs a first judgment on the first real-time impedance and the second standard impedance, and determines whether to start a second judgment based on the result of the first judgment; the second judgment is based on the first real-time phase and the second standard phase; uses the result of the first judgment or the result of the second judgment as the target ground electrode line fault detection result. Aiming at the problem of protection dead zones existing in the ground electrode line of the current UHV DC transmission system, in various fault conditions, the protection method proposed in the present application can reliably identify the faults occurring in the ground electrode line, has strong resistance to transition resistance, and effectively solves the problem of dead zones existing in the traditional protection scheme. The present application only needs to calculate using the 12th harmonic voltage and current at the head end of the ground electrode line, and does not require additional high-frequency signal injection equipment. Therefore, using the current measurement points installed at the near-station end of the traditional ground electrode line unbalanced protection and the neutral bus voltage measurement points can meet the data acquisition requirements.

[0140] Example 2, refer to Figure 2 , Figure 6 , Table 1 and Table 2, which is the first embodiment of the present application. As Figure 2 shown, provides a detailed method flow chart. Step 1: Obtain the electrical quantity data at the head end of the ground electrode line:

[0141] Step 2: Use the S transform to extract the characteristic harmonic components in the electrical quantity data;

[0142] Step 3: Construct a ground electrode line modulus network and calculate the harmonic measurement impedance and phase

[0143] Step 4: Using the characteristic harmonic components, obtain the real-time harmonic measurement impedance of the grounding electrode line and phase

[0144] Step 5: Calculate whether the amplitude difference of the harmonic measurement impedance of the grounding electrode line satisfies the fault detection criterion of Equation (9):

[0145]

[0146] If Equation (9) is satisfied, it can be determined that a fault has occurred on the grounding electrode line, and an alarm signal indicating that a fault has occurred on the grounding electrode line is issued.

[0147] If Equation (9) is not satisfied, calculate whether the phase difference of the harmonic measurement impedance of the grounding electrode line satisfies the fault detection criterion shown in Equation (10):

[0148]

[0149] If Equation (10) is satisfied, it is determined that a fault has occurred on the grounding electrode line, and an alarm signal indicating that a fault has occurred on the grounding electrode line is issued; otherwise, the grounding electrode line is in normal operation.

[0150] To verify the effectiveness and reliability of the protection method proposed in this application, a simulation model of a UHV DC transmission system including a grounding electrode system is established using PSCAD / EMTDC software. Among them, the rated transmission capacity of the DC system in bipolar operation mode is 8000 MW, the unbalanced current flowing through the grounding electrode line is about 45 A, the grounding electrode line adopts a phase-domain frequency-dependent model, and the line length is 101 km. The impedance and admittance matrices per unit length of the grounding electrode line at 600 Hz are as follows:

[0151]

[0152] Figure 6 For the amplitude and phase characteristics of the harmonic measurement impedance when a single-line grounding fault occurs on the grounding electrode line, the transition resistances considered are 0 Ω (a) and 300 Ω (b). The algorithm is verified for different types of faults occurring at different fault points on the grounding electrode line. The specific simulation result data are shown in Tables 1 and 2. In the tables, “+” indicates that the grounding electrode line fault is identified and an alarm signal indicating that a fault has occurred on the grounding electrode line is issued.

[0153] Table 1 Test results of grounding faults on the grounding electrode line

[0154]

[0155]

[0156] Table 2 Test results of open-circuit faults on the grounding electrode line

[0157]

[0158] As can be seen from Table 1 and Table 2, the fault detection algorithm proposed in the application examples can quickly and accurately detect high-resistance grounding faults and open-circuit faults occurring in the grounding electrode line.

[0159] The present application provides a method for detecting faults in a grounding electrode line based on the amplitude and phase characteristics of harmonic measurement impedance, effectively solving the problem of protection dead zones existing in the grounding electrode line of the current UHV DC transmission system, being able to reliably identify grounding faults and open-circuit faults occurring in the grounding electrode line, and having strong resistance to transition resistance.

[0160] The present application only needs to calculate using the 12th harmonic voltage and current at the head end of the grounding electrode line, without the need to additionally install high-frequency signal injection equipment. Therefore, using the current measurement point installed at the near-station end of the traditional unbalanced protection of the grounding electrode line and the neutral bus voltage measurement point can meet the data acquisition requirements.

[0161] Embodiment 3, the present embodiment also provides a grounding electrode line fault detection system, including:

[0162] A feature extraction module, configured to obtain port electrical quantity data of a target grounding electrode line and perform first feature extraction on the electrical quantity data;

[0163] A network establishment module, configured to construct a grounding electrode line modulus network according to the first feature extraction result;

[0164] A data acquisition module, configured to obtain a first real-time impedance, a first real-time phase, a second standard impedance, and a second standard phase according to the grounding electrode line modulus network;

[0165] A judgment module, configured to perform a first judgment on the first real-time impedance and the second standard impedance, and judge whether to start a second judgment based on the result of the first judgment;

[0166] The second judgment is made according to the first real-time phase and the second standard phase;

[0167] A detection module, configured to use the result of the first judgment or the result of the second judgment as the grounding electrode line fault detection result.

[0168] The above-mentioned various unit modules can be embedded in the processor of the electronic device in a hardware form or be independent of it, or can be stored in the memory of the electronic device in a software form, so that the processor can call and execute the operations corresponding to the above various modules.

[0169] The present embodiment also provides an electronic device, which can be a terminal, and its internal structure diagram can be as Figure 7As shown in the figure. The electronic device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the electronic device is used to communicate with an external terminal in a wired or wireless manner. The wireless manner can be implemented through WIFI, a carrier network, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a method for detecting a ground electrode line fault. The display screen of the electronic device can be a liquid crystal display screen or an electronic ink display screen. The input device of the electronic device can be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the electronic device, or an external keyboard, a touchpad, or a mouse, etc.

[0170] This embodiment also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0171] Obtain the port electrical quantity data of the target ground electrode line, and perform first feature extraction on the electrical quantity data;

[0172] According to the first feature extraction result, construct a ground electrode line modulus network;

[0173] Obtain the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the ground electrode line modulus network;

[0174] Perform a first judgment on the first real-time impedance and the second standard impedance, and based on the result of the first judgment, judge whether to start a second judgment;

[0175] The second judgment is made according to the first real-time phase and the second standard phase;

[0176] Use the result of the first judgment or the result of the second judgment as the detection result of the ground electrode line fault of the target. It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application, and they should all be covered within the scope of the claims of the present application.

[0177] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code. The solutions in the embodiments of the present application can be implemented in various computer languages.

[0178] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0179] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0180] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0181] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present application.

[0182] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to cover these changes and modifications.

Claims

1. A method for detecting a ground electrode line fault, characterized in that, Including: Obtain the port electrical quantity data of the target grounding electrode line, and perform first feature extraction on the electrical quantity data; Construct a grounding electrode line modulus network according to the result of the first feature extraction; Obtain the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network; Perform a first judgment on the first real-time impedance and the second standard impedance, and judge whether to start a second judgment based on the result of the first judgment; The second judgment is performed according to the first real-time phase and the second standard phase; Use the result of the first judgment or the result of the second judgment as the fault detection result of the target grounding electrode line.

2. The method for detecting a ground electrode line fault according to claim 1, characterized in that, The first judgment includes: Preset a first fault judgment threshold; Obtain a first target difference between the first real-time impedance and the second standard impedance; Compare the first target difference with the first fault judgment threshold to obtain the result of the first judgment.

3. The method for detecting a ground electrode line fault according to claim 2, wherein, The second judgment includes: Judge whether to start the second judgment according to the result of the first judgment; If the result of the first judgment is that the fault has been confirmed, do not perform the second judgment; If the result of the first judgment is that the fault has not been confirmed, then according to the preset second fault judgment threshold; Obtain a second target difference between the first real-time phase and the second standard phase; And compare the second target difference with the second fault judgment threshold to obtain the result of the second judgment.

4. The method for detecting a ground electrode line fault according to claim 3, characterized in that, The grounding electrode line modulus network includes: The grounding electrode line modulus network includes a zero-mode network and a line-mode network; The head-end voltage of the zero-mode network and the line-mode network is determined by the head-end voltage of the grounding electrode line through a first transformation matrix; The end voltage of the zero-mode network and the line-mode network is determined by the end voltage of the grounding electrode line through a second transformation matrix; The head-end current of the zero-mode network and the line-mode network is determined by the head-end current of the grounding electrode line through a third transformation matrix; The end current of the zero-mode network and the line-mode network is determined by the end current of the grounding electrode line through a fourth transformation matrix.

5. The method for detecting a ground electrode line fault according to claim 4, wherein The obtaining of the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network includes: The first real-time impedance is obtained from the harmonic voltages corresponding to the head-end voltage in the zero-mode network of the grounding electrode line and the harmonic currents corresponding to the head-end current in the zero-mode network of the grounding electrode line; The first real-time phase is obtained from the harmonic measurement impedances at several times during the normal operation of the grounding electrode line.

6. The method for detecting a ground electrode line fault according to claim 5, characterized in that, The obtaining of the first real-time impedance, the first real-time phase, the second standard impedance, and the second standard phase according to the grounding electrode line modulus network further includes: The second standard impedance is obtained according to the harmonic voltages at the head-end measured in real time of the grounding electrode line and the harmonic currents at the head-end measured in real time of the grounding electrode line; The second standard phase is obtained according to the real-time harmonic measurement impedance of the grounding electrode line.

7. The method for detecting a ground electrode line fault according to claim 6, characterized in that The using of the result of the first judgment or the result of the second judgment as the fault detection result of the target grounding electrode line includes: The fault detection result includes a ground fault state, a disconnection fault state, and a normal operation state; If both the first judgment result and the second judgment result after sequential judgment are that the fault is not confirmed, the ground electrode line is in a normal operating state.

8. A ground electrode line fault detection system applying the method according to any one of claims 1 to 7, characterized in that, Including: A feature extraction module, configured to obtain port electrical quantity data of a target ground electrode line and perform first feature extraction on the electrical quantity data; A network establishment module, configured to construct a ground electrode line modulus network according to the first feature extraction result; A data acquisition module, configured to obtain a first real-time impedance, a first real-time phase, a second standard impedance, and a second standard phase according to the ground electrode line modulus network; A judgment module, configured to perform a first judgment on the first real-time impedance and the second standard impedance, and judge whether to start a second judgment based on the result of the first judgment; The second judgment is performed according to the first real-time phase and the second standard phase; A detection module, configured to use the result of the first judgment or the result of the second judgment as the fault detection result of the target ground electrode line.

9. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of a method for detecting a ground electrode line fault according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of a method for detecting a ground electrode line fault according to any one of claims 1 to 7.

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