Method, device, equipment and computer storage medium for identifying faults within and outside the area

Abstract

This application discloses a method, apparatus, equipment, and computer storage medium for identifying faults within and outside the protection zone, relating to the field of power system technology. The method includes: after protection is activated, acquiring the line-mode voltage and line-mode current at each end of a UHVDC line within a sampling time window; calculating the forward and reverse traveling waves of voltage at each end based on the line-mode voltage and line-mode current; calculating the forward and reverse differential traveling waves of voltage within the sampling time window based on the forward and reverse traveling waves of voltage at each end; and determining the fault type based on the forward and reverse differential traveling waves of voltage within the sampling time window, whereby the fault type includes either an internal or external fault. According to the embodiments of this application, the speed and sensitivity of UHVDC transmission line protection can be effectively improved.

Description

Technical Field

[0001] This application belongs to the field of power system technology, and in particular relates to a method, device, equipment and computer storage medium for identifying faults inside and outside the region. Background Technology

[0002] Currently, with the development of Ultra-High-Voltage Direct-Current (UHVDC) technology, the requirements for relay protection in its transmission lines are becoming increasingly stringent. When a DC transmission line experiences a fault due to external environmental factors or the quality of on-site facilities, it is necessary to quickly and accurately identify and analyze the fault type, and promptly implement corresponding relay protection or line intervention to avoid large-scale power accidents.

[0003] The traditional current differential protection principle is based on Kirchhoff's laws, assuming that the protected element is a lumped parameter element, thus concluding that the current on both sides is equal.

[0004] However, the operating speed of the current differential protection in current UHVDC projects is currently on the order of seconds, which is far from meeting the requirements for rapid fault identification. Furthermore, the protection is not sensitive enough when an intra-zone fault with transition resistance occurs. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, and computer storage medium for identifying faults inside and outside the protection zone, which can effectively improve the speed and sensitivity of UHVDC transmission line protection.

[0006] In a first aspect, embodiments of this application provide a method for identifying faults inside and outside a region, the method comprising:

[0007] After the protection is activated, the line-mode voltage and line-mode current of each end of the UHVDC line are acquired within the sampling time window.

[0008] Based on the line-mode voltage and line-mode current, the forward and reverse traveling waves of the voltage at each end of the two-terminal circuit are calculated.

[0009] Based on the forward and reverse traveling waves of the voltage at each end of the double-ended circuit, the forward differential voltage traveling wave and the reverse differential voltage traveling wave within the sampling time window are calculated.

[0010] The fault type is determined based on the forward and reverse voltage differential traveling waves within the sampling time window. The fault type includes faults within the zone or faults outside the zone.

[0011] In some possible implementations, the voltage reverse traveling wave at each end of the two terminals is calculated based on the line-mode voltage and line-mode current, including:

[0012] High-pass filtering is applied to line-mode voltage and line-mode current;

[0013] Based on the line-mode voltage and line-mode current obtained through high-pass filtering, the reverse voltage traveling wave at each end of the two terminals is calculated.

[0014] In some possible implementations, the cutoff frequency of the high-pass filter is between 10 Hz and 100 Hz.

[0015] In some possible implementations, the fault type is determined based on the forward and reverse voltage differential traveling waves within the sampling time window, including:

[0016] Based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window, the forward voltage differential traveling wave difference and the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are obtained.

[0017] The absolute values ​​of the forward voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are added together to obtain the first sum of differences under the sampling time window; and the absolute values ​​of the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are added together to obtain the second sum of differences under the sampling time window.

[0018] The fault type is determined based on the sum of the first and second differences within the sampling time window.

[0019] In some possible implementations, the fault type is determined based on the sum of a first difference and the sum of a second difference within the sampling time window, including:

[0020] If the sum of the first difference is greater than the first protection setting and / or the sum of the second difference is greater than the second protection setting, the fault type is determined to be an intra-zone fault.

[0021] If the sum of the first difference is not greater than the first protection setting and the sum of the second difference is not greater than the second protection setting, the fault type is determined to be an external fault.

[0022] In some possible implementations, the first protection setting and the second protection setting are determined based on the maximum voltage differential traveling wave of an external fault in an engineering simulation or field experiment corresponding to the UHVDC line.

[0023] Secondly, embodiments of this application provide a fault identification device for areas inside and outside the zone, the fault identification device for areas inside and outside the zone includes:

[0024] The acquisition module is used to acquire the line-mode voltage and line-mode current of each end of the UHVDC line within the sampling time window after the protection is activated.

[0025] The first calculation module is used to calculate the forward and reverse traveling waves of the voltage at each end of the two terminals based on the line-mode voltage and line-mode current.

[0026] The second calculation module is used to calculate the positive voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window based on the positive voltage traveling wave and the reverse voltage traveling wave of each end in the double-ended circuit.

[0027] The determination module is used to determine the fault type based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window. The fault type includes in-zone faults or out-of-zone faults.

[0028] Thirdly, embodiments of this application provide a fault identification device for areas inside and outside the zone, the fault identification device for areas inside and outside the zone includes:

[0029] Processor and memory storing computer program instructions;

[0030] When the processor executes the computer program instructions, it implements the fault identification method inside and outside the area provided in any of the above embodiments of this application.

[0031] Fourthly, embodiments of this application provide a computer storage medium storing computer program instructions, which, when executed by a processor, implement the fault identification method for areas inside and outside the region provided in any of the embodiments of this application described above.

[0032] Fifthly, embodiments of this application provide a computer program product in which instructions are executed by the processor of an electronic device, causing the electronic device to perform the fault identification method for areas inside and outside the region provided in any of the embodiments of this application described above.

[0033] The fault identification method, apparatus, device, and computer storage medium of this application embodiment can, after protection is activated, acquire the line-mode voltage and line-mode current at both ends of the UHVDC line within a sampling time window, calculate the forward and reverse traveling waves of voltage at each end, and further calculate the forward and reverse differential traveling waves of voltage within the sampling time window, thereby determining whether the fault type is an external or internal fault. Compared to traditional current differential protection based on Kirchhoff's laws, the fault identification method, apparatus, device, and computer storage medium provided in this application embodiment, by employing traveling wave differential protection based on the invariance of traveling wave transmission on the distributed parameter line model, effectively improves the speed and sensitivity of UHVDC transmission line protection. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating an embodiment of the fault identification method inside and outside the area provided in this application;

[0036] Figure 2 This is a schematic diagram of a simulation model of an ultra-high voltage direct current transmission system provided in an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of the fault location provided in an embodiment of this application;

[0038] Figure 4a This application provides an embodiment of the voltage and current waveforms on the M side of the F1 fault.

[0039] Figure 4b This is a waveform of the N-side voltage and current of F1 fault provided in an embodiment of this application;

[0040] Figure 4c This is the differential traveling wave result of the F1 fault M-side protection provided in one embodiment of this application;

[0041] Figure 5a This application provides an embodiment of the voltage and current waveforms on the M side of the F2 fault.

[0042] Figure 5b This application provides an embodiment of the voltage and current waveforms on the N-side of fault F2.

[0043] Figure 5c This is the differential traveling wave result of the F2 fault M-side protection provided in one embodiment of this application;

[0044] Figure 6a This is a waveform of the voltage and current on the M side of the F3 fault provided in an embodiment of this application;

[0045] Figure 6b This is a waveform of the N-side voltage and current of fault F3 provided in an embodiment of this application;

[0046] Figure 6c This is the differential traveling wave result of the F3 fault M-side protection provided in one embodiment of this application;

[0047] Figure 7 This is a schematic diagram of the structure of an internal and external fault identification device provided in an embodiment of this application;

[0048] Figure 8 This is a schematic diagram of the structure of an internal and external fault identification device provided in an embodiment of this application. Detailed Implementation

[0049] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0051] As described in the background section, the operating speed of current differential protection in current UHVDC projects is currently on the order of seconds, which is far from meeting the requirements for rapid fault identification. Furthermore, the sensitivity of current differential protection is insufficient when an intra-zone fault with transition resistance occurs.

[0052] To solve the above problems, the inventors discovered through research that when the line is fault-free, due to the invariance of traveling wave transmission on the distributed parameter line model, the differential traveling wave at both ends of the line is equal to 0; however, when a fault occurs in the line's fault zone, the condition for the invariance of traveling wave transmission is broken, and at this time, the differential traveling wave will not be equal to 0.

[0053] Based on this, embodiments of this application provide a method, apparatus, device, storage medium, and computer program product for identifying faults inside and outside the region. It should be noted that the embodiments provided in this application are not intended to limit the scope of this application.

[0054] The following section first introduces the fault identification method for areas inside and outside the region provided in the embodiments of this application.

[0055] Figure 1A flowchart illustrating an embodiment of the fault identification method for areas inside and outside the specified area is shown. This fault identification method is applied to an electronic device, which may include a server or a user terminal, etc. Figure 1 As shown, the fault identification method inside and outside the area includes the following steps:

[0056] S110, after the protection is activated, acquires the line-mode voltage and line-mode current of each end of the UHVDC line within the sampling time window;

[0057] S120, based on the line-mode voltage and line-mode current, calculates the forward and reverse traveling waves of the voltage at each end of the two terminals;

[0058] S130, based on the forward and reverse traveling waves of the voltage at each end of the double-ended circuit, calculate the forward differential traveling wave and the reverse differential traveling wave within the sampling time window;

[0059] S140 determines the fault type based on the forward and reverse voltage differential traveling waves within the sampling time window. The fault type includes faults within the zone or faults outside the zone.

[0060] The fault identification method for both inside and outside the protection zone of this application can, after protection is activated, obtain the line-mode voltage and line-mode current at both ends of the UHVDC line within a sampling time window, calculate the forward and reverse traveling waves of voltage at each end, and further calculate the forward and reverse differential traveling waves of voltage within the sampling time window, thereby determining whether the fault type is an outside or inside the protection zone. Compared to traditional current differential protection based on Kirchhoff's laws, the fault identification method for both inside and outside the protection zone provided in this application adopts traveling wave differential protection based on the invariance of traveling wave transmission on the distributed parameter line model, effectively improving the speed and sensitivity of UHVDC transmission line protection.

[0061] The specific implementation methods of steps 110 to 140 above will be described in detail below.

[0062] In S110, the specific value of the sampling time window can be determined according to the actual engineering needs. For example, the sampling time window is 5 milliseconds.

[0063] It should be noted that the two ends of an UHVDC transmission line can include a first end and a second end on the UHVDC line. A communication channel can be established between the first end and the second end to realize the exchange of relevant data such as line-mode voltage and line-mode current between the two ends. Specifically, the aforementioned first end can be the rectifier end or the inverter end of the UHVDC transmission line. When the first end is the rectifier end, the second end is the inverter end; if the first end is the inverter end of the transmission line, then the second end is the rectifier end of the transmission line.

[0064] In the specific implementation of step 110 above, since the fault conditions in ultra-high voltage DC transmission lines are often detected by starting elements installed in the transmission lines.

[0065] Therefore, it is possible to obtain the line-mode voltage and line-mode current at each end of the UHVDC line within the sampling time window when any starting element applicable to UHVDC line protection is activated.

[0066] To facilitate understanding, the actual processing procedure for line parameters at both ends of the line is described below.

[0067] In ultra-high voltage direct current (UHVDC) transmission lines, taking the local end (first end) as an example, the local end samples the voltage and current of its positive and negative lines at a certain sampling frequency. Based on the sampled voltage and current of the positive and negative lines, it obtains the line-mode voltage and current corresponding to the sampling time through pole-mode transformation, and stores the line-mode voltage and current obtained through pole-mode transformation in the local end's equipment or database. Simultaneously, the local end (first end) communicates with the opposite end (second end), continuously receiving the line-mode voltage and current corresponding to each sampling time from the opposite end, and similarly stores the received data from the opposite end in the local end's equipment or database.

[0068] It should be noted that the first and second ends in the above-mentioned double-ended configuration can be considered each other's "local" and "reciprocal" ends. If the first end is considered the local end, then the second end is the reciprocal end of the first end; conversely, if the second end is considered the local end, then the first end is the reciprocal end of the second end. Therefore, the data processing operations described above, using the first end of the line as an example, actually also occur at the second end of the transmission line.

[0069] In S120, based on the acquired two-terminal line-mode voltage and line-mode current, the forward and reverse traveling waves of the voltage at each end of the two terminals are calculated.

[0070] For example, taking the first end of the line as the local end and the second end of the line as the opposite end, let the distance from the local end to the starting point of the transmission line be x = 0, and the distance from the opposite end to the starting point of the transmission line be x = 1.

[0071] After the protection is activated at this end, when this end receives the t0 data u(l,t0) and i(l,t0) sent from the other end, the positive and negative voltage traveling waves of the other end within the sampling time window can be calculated. The specific calculation formula is as follows:

[0072]

[0073] Among them, T W u is the length of the time window. f (l,t) represents the positive traveling voltage wave at time t at the opposite end of the line, u r(l,t) represents the reverse traveling wave of the voltage at time t at the opposite end of the line, u(l,t) represents the line-mode voltage at time t at the opposite end of the line, i(l,t) represents the line-mode current at time t at the opposite end of the line, and Z c This is the line wave impedance.

[0074] Then, based on the line-mode voltage, line-mode current, and propagation delay of the second terminal in the dual-terminal configuration, the forward and reverse traveling waves of the voltage at this terminal are calculated using the following formulas:

[0075]

[0076] Where τ is the propagation delay, T W u is the length of the time window. f (0, t-τ) represents the positive traveling voltage wave at the line terminal at time t-τ, u r (0,t+τ) represents the reverse traveling wave of the voltage at this end of the line at time t+τ, u(0,t-τ) represents the line-mode voltage at this end of the line at time t-τ, i(0,t-τ) represents the line-mode current at this end of the line at time t-τ, u(0,t+τ) represents the line-mode voltage at this end of the line at time t+τ, i(0,t+τ) represents the line-mode current at this end of the line at time t+τ, Z c This is the line wave impedance.

[0077] In some implementations, considering the strong correlation between high-frequency components and line faults when signal abrupt changes due to line faults, and the relatively stable line impedance at high frequencies, the calculation of the voltage reverse traveling wave at each end based on the line-mode voltage and line-mode current can include, to ensure the accuracy of subsequent fault identification results:

[0078] High-pass filtering is applied to line-mode voltage and line-mode current;

[0079] Based on the line-mode voltage and line-mode current obtained through high-pass filtering, the reverse voltage traveling wave at each end of the two terminals is calculated.

[0080] In this way, the line-mode voltage and line-mode current at both ends are high-pass filtered, further eliminating interference data and improving the accuracy of subsequent judgments.

[0081] In this embodiment, the cutoff frequency of the high-pass filter is not strictly limited, and can be determined according to the actual engineering requirements and on-site engineering conditions.

[0082] In some implementations, to further ensure the rationality and effectiveness of the high-pass filtering, the cutoff frequency of the high-pass filter can be between 10 Hz and 100 Hz. For example, in this embodiment, the cutoff frequency of the high-pass filter can be specifically set to 50 Hz.

[0083] In S130, after calculating the forward and reverse traveling waves of the voltage of the above-mentioned double-ended line, the forward and reverse differential traveling waves of the voltage within the sampling time window can be calculated from the forward and reverse traveling waves of the voltage at each end of the double-ended line.

[0084] In S140, in specific implementation, the fault type can be determined based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window. The fault type includes faults within the zone or faults outside the zone.

[0085] For example, the fault type can be determined to be an intra-zone fault if the absolute value of the forward voltage differential traveling wave or the reverse voltage differential traveling wave corresponding to at least one sampling moment within the sampling time window is greater than a preset threshold; otherwise, the line fault type is an extra-zone fault.

[0086] In some implementations, considering high-frequency noise interference and the transient nature of high-frequency noise occurrence, to further ensure the accuracy of fault type identification, the above-mentioned determination of the fault type based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window may include:

[0087] Based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window, the forward voltage differential traveling wave difference and the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are obtained.

[0088] The absolute values ​​of the forward voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are added together to obtain the first sum of differences under the sampling time window; and the absolute values ​​of the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are added together to obtain the second sum of differences under the sampling time window.

[0089] The fault type is determined based on the sum of the first and second differences within the sampling time window.

[0090] Specifically, fault identification based on differential traveling waves at a single sampling moment is transformed into judgment by combining differential traveling waves at multiple sampling moments within the sampling time window, thereby enabling more accurate and reasonable identification of faults inside and outside the area.

[0091] In this way, differential traveling wave interference caused by transient high-frequency noise can be effectively removed. At the same time, high-frequency differential traveling waves caused by signal mutations caused by faults can be accurately identified, and the actual fault judgment results will not be affected by the above operations.

[0092] In this embodiment, the formulas for calculating the sum of the first and second differences within the sampling time window are as follows:

[0093]

[0094] Among them, D f For the sampling time window T W The sum of the first differences within, D r For the sampling time window T W The second sum of differences within, u f (0, t-τ) represents the positive traveling voltage wave at the line terminal at time t-τ, u r (0, t+τ) represents the reverse traveling wave of the voltage at this end of the line at time t+τ, u f (l,t) represents the positive traveling voltage wave at the opposite end of the line at time t, u r (l,t) represents the reverse traveling wave of the voltage at the opposite end of the line at time t.

[0095] In some implementations, the fault type is determined by combining the traveling wave frequency characteristics of faults inside and outside the area, based on the sum of the first and second differences under the sampling time window. Specifically, this may include:

[0096] If the sum of the first difference is greater than the first protection setting and / or the sum of the second difference is greater than the second protection setting, the fault type is determined to be an intra-zone fault.

[0097] If the sum of the first difference is not greater than the first protection setting and the sum of the second difference is not greater than the second protection setting, the fault type is determined to be an external fault.

[0098] Specifically, the formula for determining faults within the aforementioned area is as follows:

[0099] D f >D set1 ||D r >D set2

[0100] Among them, D f For the sampling time window T W The sum of the first differences within, D r For the sampling time window T W The second sum of differences within, D set1 As the first protection setting, D set2 This is the second protection setting.

[0101] It should be noted that this application does not impose strict restrictions on the specific values ​​of the first protection setting and the second protection setting mentioned above. The values ​​can be flexibly set according to actual protection needs and on-site engineering environment.

[0102] In some implementations, in order to more reasonably identify faults within the line area, the first protection setting and the second protection setting can be determined based on the maximum voltage differential traveling wave of faults outside the area in the engineering simulation or field experiment corresponding to the UHVDC line.

[0103] In this way, the first and second protection settings mentioned above can be used to reasonably distinguish between faults inside and outside the protection zone.

[0104] In summary, the above embodiments provide a method for identifying faults inside and outside the protection zone. When the protection of an UHVDC transmission line is activated, it acquires the line-mode voltage and line-mode current at both ends of the UHVDC line within a sampling time window, calculates the forward and reverse traveling waves of voltage at each end, and further calculates the forward and reverse differential traveling waves of voltage within the sampling time window. This allows it to determine whether the fault type is an external or internal fault. Compared to traditional current differential protection based on Kirchhoff's laws, this method employs traveling wave differential protection based on the invariance of traveling wave transmission on the distributed parameter line model, enhancing speed and ensuring the sensitivity of the line protection.

[0105] Please see below. Figure 2 To verify the above-mentioned fault detection method, this application uses the PSCAD / EMTDC electromagnetic transient simulation program to build a system as follows: Figure 2 The simulation model of the ultra-high voltage direct current transmission system shown is shown.

[0106] Figure 2 This is a schematic diagram of a simulation model of an ultra-high voltage direct current transmission system provided in an embodiment of this application. Figure 2 The parameters of the model shown are set as follows: rated voltage is set to ±1100kV, rated current is set to 5kA, transmission line length is 3284km, and smoothing reactor value is 75mH.

[0107] The parameter settings involved in the above fault detection method are as follows: sampling time window T W The value is set to 3ms, the first protection setting is set to 9000kV, and the second protection setting is set to 9000kV.

[0108] Specifically, after decoupling the positive and negative poles of the UHV transmission line, the various fault points set in the simulation can be as follows: Figure 3 As shown.

[0109] Figure 3 This is a schematic diagram of the fault location provided in an embodiment of this application. Figure 3 The faults set in the system include fault F1, fault F2 and fault F3, which are set at different locations on the transmission line.

[0110] The following sections respectively address... Figure 3The faults F1, F2 and F3 shown are simulated, analyzed and judged.

[0111] (1) Regarding fault F1:

[0112] Specifically, such as Figure 3 As shown, a fault F1 is set in the middle zone of the line, the fault type is positive fault, the fault distance is 1682km from the midpoint of the line to side M, and the fault transition resistance is 1000Ω.

[0113] Taking the M-side protection as an example, by sampling the positive and negative voltages on the M-side of the transmission line, the fault F1 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 4a As shown, Figure 4a This is a waveform of the voltage and current on the M side of the F1 fault provided in an embodiment of this application.

[0114] Taking N-side protection as an example, by sampling the positive and negative voltages on the N-side of the transmission line, the fault F1 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 4b As shown, Figure 4b This is a waveform of the N-side voltage and current of F1 fault provided in an embodiment of this application.

[0115] By performing pole-mode transformation based on the aforementioned positive and negative voltages and currents in the simulation program, and then calculating the forward and reverse traveling waves of the voltage across both terminals based on the line-mode voltage and current components obtained from the pole-mode transformation, it is possible to further obtain, as shown below. Figure 4c The results of the differential traveling wave protection on the M side of the F1 fault are shown.

[0116] Thus, based on Figure 4c The differential traveling wave results of the protection on the M side of the F1 fault shown can be used to determine the first sum of differences and the second sum of differences described in the aforementioned embodiments, thereby enabling the determination of the fault type of the F1 fault.

[0117] The simulation results show that within a certain period after the fault occurs, the sum of the first difference is greater than the first protection setting, and the sum of the second difference is also greater than the second protection setting. Therefore, fault F1 can be correctly identified as an intra-zone fault.

[0118] (2) Regarding fault F2:

[0119] Specifically, such as Figure 3 As shown, an external fault F2 is set between the smoothing reactor and the protection measurement point. The fault type is a positive fault, and the fault transition resistance is 1e-4Ω.

[0120] Taking the M-side protection as an example, by sampling the positive and negative voltages on the M-side of the transmission line, the fault F2 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 5a As shown, Figure 5a This is a waveform of the voltage and current on the M side of the F2 fault provided in an embodiment of this application.

[0121] Taking N-side protection as an example, by sampling the positive and negative voltages on the N-side of the transmission line, the fault F2 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 5b As shown, Figure 5b This is a waveform of the N-side voltage and current of the F2 fault provided in an embodiment of this application.

[0122] By performing pole-mode transformation based on the aforementioned positive and negative voltages and currents in the simulation program, and then calculating the forward and reverse traveling waves of the voltage across both terminals based on the line-mode voltage and current components obtained from the pole-mode transformation, it is possible to further obtain, as shown below. Figure 5c The results of the differential traveling wave protection on the M side of the F2 fault are shown.

[0123] Thus, based on Figure 5c The differential traveling wave results of the protection on the M side of the F2 fault shown can be used to determine the first sum of differences and the second sum of differences described in the aforementioned embodiments, thereby enabling the determination of the fault type of the F2 fault.

[0124] The simulation results show that the sum of the first difference is always less than the first protection setting, and the sum of the second difference is also always less than the second protection setting. Therefore, fault F2 can be correctly identified as an external fault.

[0125] (3) Regarding fault F3:

[0126] Specifically, such as Figure 3 As shown, an external fault F3 is set outside the smoothing reactor, the fault type is positive fault, and the fault transition resistance is 1e-4Ω.

[0127] Taking the M-side protection as an example, by sampling the positive and negative voltages on the M side of the transmission line, the fault F3 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 6a As shown, Figure 6a This is a waveform of the voltage and current on the M side of the F3 fault provided in an embodiment of this application.

[0128] Taking N-side protection as an example, by sampling the positive and negative voltages on the N-side of the transmission line, the fault F3 voltage and current waveforms obtained within the sampling time window can be as follows: Figure 6b As shown, Figure 6b This is a waveform of the N-side voltage and current of the F3 fault provided in an embodiment of this application.

[0129] By performing pole-mode transformation based on the aforementioned positive and negative voltages and currents in the simulation program, and then calculating the forward and reverse traveling waves of the voltage across both terminals based on the line-mode voltage and current components obtained from the pole-mode transformation, it is possible to further obtain, as shown below. Figure 6c The differential traveling wave results for the M-side protection during the F3 fault are shown.

[0130] Thus, based on Figure 6c The differential traveling wave results of the protection on the M side of the F3 fault shown can be used to determine the first sum of differences and the second sum of differences described in the aforementioned embodiments, thereby enabling the determination of the fault type of the F3 fault.

[0131] The simulation results show that the sum of the first difference is always less than the first protection setting, and the sum of the second difference is also always less than the second protection setting. Therefore, fault F3 can be correctly identified as an external fault.

[0132] The simulation results above show that the fault identification method provided in this application, which adopts traveling wave differential protection based on the traveling wave transmission invariance on the distributed parameter line model, can effectively and quickly identify the fault type in UHVDC transmission lines, while also effectively ensuring the sensitivity of traveling wave protection.

[0133] Based on the fault identification method for areas inside and outside the zone provided in the above embodiments, this application also provides a fault identification device for areas inside and outside the zone corresponding to the above fault identification method. The following describes... Figure 7 A detailed introduction to the fault identification devices inside and outside the area is provided.

[0134] Figure 7 A schematic diagram of the structure of an internal / external fault identification device provided in an embodiment of this application is shown. Figure 7 The fault identification device 700 shown includes:

[0135] The acquisition module 710 is used to acquire the line-mode voltage and line-mode current of each end of the UHVDC line within the sampling time window after the protection is activated.

[0136] The first calculation module 720 is used to calculate the forward and reverse traveling waves of voltage at each end of the double-ended circuit based on the line-mode voltage and line-mode current.

[0137] The second calculation module 730 is used to calculate the positive voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window based on the positive voltage traveling wave and the reverse voltage traveling wave of each end in the double-ended circuit.

[0138] The determination module 740 is used to determine the fault type based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window. The fault type includes in-zone faults or out-of-zone faults.

[0139] The fault identification device for both inside and outside the protection zone of this application embodiment can, after the protection is activated, acquire the line-mode voltage and line-mode current at both ends of the UHVDC line within the sampling time window through corresponding functional modules, calculate the forward and reverse traveling waves of voltage at each end, and further calculate the forward and reverse differential traveling waves of voltage within the sampling time window, thereby determining whether the fault type is an external or internal fault. Compared with traditional current differential protection based on Kirchhoff's laws, the fault identification device for both inside and outside the protection zone provided in this application embodiment adopts traveling wave differential protection based on the invariance of traveling wave transmission on the distributed parameter line model, effectively improving the speed and sensitivity of UHVDC transmission line protection.

[0140] In some possible implementations, the first computing module 720 may specifically include:

[0141] The high-pass filter submodule can be used to perform high-pass filtering on line-mode voltage and line-mode current;

[0142] The calculation submodule can be used to calculate the voltage reverse traveling wave at each end of the two terminals based on the line-mode voltage and line-mode current obtained through high-pass filtering.

[0143] In some possible implementations, the cutoff frequency of the high-pass filter can be between 10 Hz and 100 Hz.

[0144] In some possible implementations, the determining module 740 may specifically include:

[0145] The first submodule can be used to obtain the difference between the forward and reverse voltage differential traveling waves at each sampling time point within the sampling time window, based on the forward and reverse voltage differential traveling waves within the sampling time window.

[0146] The second submodule can be used to add the absolute values ​​of the forward voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window to obtain the first difference sum under the sampling time window; and to add the absolute values ​​of the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window to obtain the second difference sum under the sampling time window.

[0147] The determination submodule can be used to determine the fault type based on the first sum of differences and the second sum of differences under the sampling time window.

[0148] In some possible implementations, the submodule is determined, which may specifically include:

[0149] The first determining unit can be used to determine the fault type as an intra-zone fault when the sum of the first differences is greater than the first protection setting and / or the sum of the second differences is greater than the second protection setting.

[0150] The second determining unit can be used to determine the fault type as an external fault when the sum of the first differences is not greater than the first protection setting and the sum of the second differences is not greater than the second protection setting.

[0151] In some possible implementations, the first protection setting and the second protection setting can be determined based on the maximum voltage differential traveling wave of an external fault in an engineering simulation or field experiment corresponding to the UHVDC line.

[0152] Figure 8 This is a schematic diagram of the structure of an internal and external fault identification device provided in an embodiment of this application.

[0153] The fault identification device inside and outside the zone may include a processor 801 and a memory 802 storing computer program instructions.

[0154] Specifically, the processor 801 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0155] Memory 802 may include mass storage for data or instructions. For example, and not limitingly, memory 802 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 802 may include removable or non-removable (or fixed) media. Where appropriate, memory 802 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 802 is non-volatile solid-state memory.

[0156] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0157] The processor 801 reads and executes computer program instructions stored in the memory 802 to implement any of the fault identification methods inside and outside the area in the above embodiments.

[0158] In one example, the fault identification device inside and outside the data area may further include a communication interface 803 and a bus 810. For example, Figure 8 As shown, the processor 801, memory 802, and communication interface 803 are connected through bus 810 and complete communication with each other.

[0159] The communication interface 803 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0160] Bus 810 includes hardware, software, or both, that couples components of fault identification devices within and outside the zone together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 810 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0161] The fault identification device inside and outside the zone executes the fault identification method inside and outside the zone in the embodiments of this application, thereby achieving Figure 1 The method for identifying faults inside and outside the zone is described.

[0162] Furthermore, in conjunction with the fault identification methods for areas inside and outside the zones described in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any one of the fault identification methods for areas inside and outside the zones described in the above embodiments.

[0163] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0164] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0165] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0166] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0167] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for identifying faults inside and outside a zone, characterized in that, The method includes: After the protection is activated, the line-mode voltage and line-mode current of each end of the UHVDC line are acquired within the sampling time window. Based on the line mode voltage and the line mode current, the forward voltage traveling wave and the reverse voltage traveling wave of each of the two terminals are calculated. Based on the forward and reverse traveling waves of the voltage at each of the two ends, the forward differential traveling wave and the reverse differential traveling wave within the sampling time window are calculated. The fault type is determined based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window. The fault type includes in-zone faults or out-of-zone faults. The step of determining the fault type based on the forward and reverse voltage differential traveling waves within the sampling time window includes: Based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window, the forward voltage differential traveling wave difference and the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are obtained. The absolute values ​​of the forward voltage differential traveling wave differences corresponding to each sampling time point within the sampling time window are added together to obtain the first sum of differences under the sampling time window; and the absolute values ​​of the reverse voltage differential traveling wave differences corresponding to each sampling time point within the sampling time window are added together to obtain the second sum of differences under the sampling time window. The fault type is determined based on the sum of the first and second differences within the sampling time window. The method of determining the fault type based on the sum of the first and second differences within the sampling time window includes: If the sum of the first differences is greater than the first protection setting and / or the sum of the second differences is greater than the second protection setting, the fault type is determined to be an intra-zone fault. If the sum of the first difference is not greater than the first protection setting and the sum of the second difference is not greater than the second protection setting, the fault type is determined to be an external fault.

2. The method according to claim 1, characterized in that, The step of calculating the voltage reverse traveling wave at each of the two terminals based on the line-mode voltage and the line-mode current includes: High-pass filtering is applied to the line-mode voltage and the line-mode current; Based on the line-mode voltage and line-mode current obtained through high-pass filtering, the voltage reverse traveling wave of each end of the two terminals is calculated.

3. The method according to claim 2, characterized in that, The cutoff frequency of the high-pass filter is between 10 Hz and 100 Hz.

4. The method according to claim 1, characterized in that, The first protection setting and the second protection setting are determined based on the maximum voltage differential traveling wave of the external fault in the engineering simulation or field experiment corresponding to the UHVDC line.

5. A fault identification device for areas inside and outside the zone, characterized in that, The device includes: The acquisition module is used to acquire the line-mode voltage and line-mode current of each end of the UHVDC line within the sampling time window after the protection is activated. The first calculation module is used to calculate the forward voltage traveling wave and the reverse voltage traveling wave of each of the two terminals based on the line mode voltage and the line mode current. The second calculation module is used to calculate the positive voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window based on the positive voltage traveling wave and the reverse voltage traveling wave of each of the two ends. The determination module is used to determine the fault type based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window. The fault type includes in-zone fault or out-of-zone fault. The step of determining the fault type based on the forward and reverse voltage differential traveling waves within the sampling time window includes: Based on the forward voltage differential traveling wave and the reverse voltage differential traveling wave within the sampling time window, the forward voltage differential traveling wave difference and the reverse voltage differential traveling wave difference corresponding to each sampling time point within the sampling time window are obtained. The absolute values ​​of the forward voltage differential traveling wave differences corresponding to each sampling time point within the sampling time window are added together to obtain the first sum of differences under the sampling time window; and the absolute values ​​of the reverse voltage differential traveling wave differences corresponding to each sampling time point within the sampling time window are added together to obtain the second sum of differences under the sampling time window. The fault type is determined based on the sum of the first and second differences within the sampling time window. The method of determining the fault type based on the sum of the first and second differences within the sampling time window includes: If the sum of the first differences is greater than the first protection setting and / or the sum of the second differences is greater than the second protection setting, the fault type is determined to be an intra-zone fault. If the sum of the first difference is not greater than the first protection setting and the sum of the second difference is not greater than the second protection setting, the fault type is determined to be an external fault.

6. A fault identification device for areas inside and outside the zone, characterized in that, The device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the fault identification method inside and outside the area as described in any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, which, when executed by a processor, implement the fault identification method for areas inside and outside the region as described in any one of claims 1-4.

8. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs the fault identification method inside and outside the area as described in any one of claims 1-4.

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