Power grid communication data processing system based on remote communication unit

Abstract

The invention relates to the technical field of remote opening control, and discloses a power grid communication data processing system based on a remote communication unit, and the system comprises the steps: collecting the three-phase voltage traveling wave and temperature of a power grid according to a fixed time interval based on the remote communication unit in a safe operation time period of the power grid; determining a three-phase voltage traveling wave corresponding to the temperature T to extract a head wave zero-crossing density and a shoulder zero-crossing density at the temperature T, and determining a temperature wave baseline value corresponding to the temperature T; acquiring a voltage amplitude of the power grid, and triggering to acquire a fault three-phase voltage traveling wave of the power grid in response to voltage amplitude overrun; calculating a temperature wave monitoring value based on the fault three-phase voltage traveling wave; according to the temperature wave baseline value and the temperature wave monitoring value, carrying out correction processing on a preset reference speed to obtain an equivalent propagation speed; and calculating a correction fault distance according to the equivalent propagation speed and a timestamp corresponding to the head wave zero cross density of the fault three-phase voltage traveling wave, determining a fault section according to the fault distance, and carrying out opening control processing.

Description

Technical Field

[0001] This invention relates to the field of remote tripping control technology, and more specifically, to a power grid communication data processing system based on a remote communication unit. Background Technology

[0002] Traveling wave ranging in power systems is a method for determining the distance to a fault point by analyzing the propagation behavior of high-frequency voltage or current waves generated at the initial moment of a short-circuit fault in the conductor. Especially in high-voltage transmission lines, relying on the arrival time and propagation speed of the first traveling wave, rapid fault location can be achieved at the local end, thereby triggering regional tripping control and preventing the accident from escalating.

[0003] In typical engineering practice, to improve the speed of protection action, the single-ended traveling wave positioning algorithm is often used, and its basic operation is as follows:

[0004] After the fault occurs, the traveling wave propagates along the line at a known constant propagation speed v0;

[0005] After receiving the first wave, the protection device or remote communication unit calculates the distance based on the trigger time t0:

[0006] d = v0·t0

[0007] However, in practical applications, the above methods have serious applicability limitations in high dielectric loss and long-distance cable lines. For example, XLPE insulated submarine cables, commonly used for offshore wind farm grid connection, can reach lengths of 30 to 60 km. XLPE insulated submarine cables have the following problems:

[0008] As the propagation distance increases, high-frequency components (above 100kHz) are rapidly absorbed by the cable dielectric and the additional impedance of the conductor; the initial fault wave gradually loses its clear steep wavefront during propagation, instead exhibiting a gently rising shoulder-shaped waveform, resulting in blurred waveform boundaries; the propagation speed varies at different frequency components, especially when high-frequency components are almost lost due to strong attenuation, the equivalent propagation speed of the initial wave is significantly lower than the theoretical value; as the cable temperature changes, the dielectric constant changes accordingly, further affecting the wave propagation speed and waveform broadening;

[0009] Based on the above factors, the boundary of the first traveling wave received by the local sampling device is no longer clear, and the frequency components corresponding to the arrival time drift, resulting in a systematic error in the fault distance calculated using a constant propagation velocity v0. Especially when the remote communication unit is deployed at a shore station, and the offshore booster station cannot be synchronized, relying solely on local ranging data can easily lead to the following problems when errors exist:

[0010] 1. Determine that the fault point deviates from the actual sectionalizing switch, causing false tripping or failure to trip;

[0011] 2. Increased ranging error affects the efficiency of scheduling and maintenance positioning;

[0012] 3. If the protection device misjudges a section, it may trigger a system linkage error trip, resulting in a chain of faults.

[0013] Therefore, the existing single-ended traveling wave fault location method has a systematic location error in long-distance high dielectric loss lines, which leads to misjudgment of the tripping section and affects the accuracy of tripping and the reliability of power supply. Summary of the Invention

[0014] This invention provides a power grid communication data processing system based on a remote communication unit, which solves the technical problem that the existing single-ended traveling wave fault location method has systematic location errors in long-distance high dielectric loss lines, leading to misjudgment of tripping sections and affecting the accuracy of tripping and the reliability of power supply.

[0015] This invention provides a power grid communication data processing system based on a remote communication unit, comprising:

[0016] The data acquisition module is used to collect the three-phase voltage traveling wave and temperature of the power grid at fixed time intervals based on the remote communication unit during the safe operation period of the power grid.

[0017] The data extraction module is used to determine the three-phase voltage traveling wave corresponding to temperature T, so as to extract the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, and determine the temperature wave baseline value corresponding to temperature T.

[0018] The fault identification module is used to acquire the voltage amplitude of the power grid during the monitoring period, and in response to the voltage amplitude exceeding the limit, it triggers the acquisition of the fault three-phase voltage traveling wave of the power grid.

[0019] The temperature monitoring module is used to calculate the temperature monitoring value based on the traveling wave of the three-phase voltage under fault.

[0020] The monitoring and correction module is used to correct the preset reference velocity based on the temperature wave baseline value and the temperature wave monitoring value to obtain the equivalent propagation velocity;

[0021] The fault location module is used to calculate the corrected fault distance based on the timestamp corresponding to the first wave zero crossover density of the equivalent propagation velocity and the three-phase voltage traveling wave of the fault, and to determine the fault section based on the fault distance.

[0022] The tripping control module is used to perform tripping control processing on faulty sections.

[0023] Furthermore, the three-phase voltage traveling wave corresponding to temperature T is determined to extract the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, including:

[0024] S21, extract the first wave zero-crossing density of the three-phase voltage traveling wave, including:

[0025]

[0026] Where p∈[A,B,C], A, B, and C represent phases A, B, and C respectively, ZCD0(p) represents the first wave zero-crossing density of phase p, Δt represents the fixed time interval, and u p (t) represents the sampled value of the voltage traveling wave of the p-th phase at time t, u p (t+Δt) represents the sampled value of the voltage traveling wave of the p-th phase at time t+Δt, and 1[·] represents the indicator function, if u p (t)u p If (t+Δt)<0, then the value is 1; otherwise, the value is 0.

[0027] S22, extract the shoulder zero-crossing density of the three-phase voltage traveling wave, including:

[0028]

[0029] Where ZCD2(p) represents the shoulder zero cross density of the p-th phase.

[0030] Furthermore, determining the baseline value of the temperature wave corresponding to temperature T includes:

[0031] S23, the baseline value of the temperature wave corresponding to temperature T is calculated based on the first wave zero-crossing density and the shoulder zero-crossing density of the three-phase voltage traveling wave, as follows:

[0032]

[0033] Where K(T) represents the baseline value of the temperature wave corresponding to temperature T, and |[A,B,C]| represents the number of elements in [A,B,C].

[0034] Furthermore, during the monitoring period, the voltage amplitude of the power grid is acquired, and in response to the voltage amplitude exceeding the limit, the fault three-phase voltage traveling wave of the power grid is triggered, including:

[0035] The voltage traveling waves of phases A, B, and C are sampled at time s at fixed time intervals, and the average of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s.

[0036] The voltage traveling waves of phases A, B, and C are sampled at time s-1 at fixed time intervals, and the average value of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s-1.

[0037] The difference between the total voltage at time s and the total voltage at time s-1 is taken as the voltage amplitude;

[0038] If the voltage amplitude is greater than or equal to the preset amplitude threshold, then mark the voltage amplitude as exceeding the limit once;

[0039] When the voltage amplitude exceeds the limit for a preset number of times, the fault three-phase voltage traveling wave of the power grid is triggered.

[0040] Furthermore, the temperature wave monitoring values ​​are calculated based on the traveling wave of the three-phase voltage during a fault, including:

[0041] For the faulty three-phase voltage traveling wave, repeat steps 21 to 23 to obtain the temperature wave monitoring value.

[0042] Furthermore, based on the baseline temperature wave value and the temperature wave monitoring value, the preset reference velocity is corrected to obtain the equivalent propagation velocity, including:

[0043] Determine the temperature S corresponding to the traveling wave of the three-phase voltage under fault;

[0044] The temperature wave deviation ΔK is obtained by subtracting the baseline value of temperature S from the temperature wave monitoring value.

[0045] The correction factor CF is generated based on the temperature wave deviation, where CF = exp(-m·ΔK); and m is the preset correction coefficient.

[0046] Multiply the preset reference velocity v0 by the correction factor CF to obtain the equivalent propagation velocity.

[0047] Furthermore, based on the equivalent propagation velocity and the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave, the corrected fault distance is calculated, including:

[0048] Extract the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave;

[0049] The propagation time is determined based on the timestamp corresponding to the first wave of zero crossover density;

[0050] The product of the propagation time and the equivalent propagation speed is used as the corrected fault distance.

[0051] Furthermore, the faulty section is determined based on the fault distance, including:

[0052] The power grid is divided into M management sections based on the switch;

[0053] Determine the actual distance range for each management section;

[0054] The fault segment is obtained by querying the actual distance range based on the corrected fault distance.

[0055] Furthermore, the faulty section is controlled by tripping the circuit breaker, including: determining the circuit breaker corresponding to the faulty section and issuing a tripping command.

[0056] The beneficial effects of this invention are as follows: By introducing a zero-crossing density comparison mechanism between the temperature wave baseline value and the temperature wave monitoring value, a breakthrough is achieved in maintaining a constant propagation speed in traditional single-ended traveling wave ranging. This enables real-time correction of the equivalent propagation speed in long-distance, high-dielectric-loss lines, accurately calculating the relationship between the arrival time of the fault point and the propagation distance. This invention not only significantly reduces the systematic ranging error caused by traveling wave distortion, but also accurately identifies fault sections and reliably trips circuit breakers under single-ended communication unit conditions, fundamentally improving the tripping accuracy and grid stability in remote distributed power supply scenarios. Attached Figure Description

[0057] Figure 1 This is a block diagram of the present invention. Detailed Implementation

[0058] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0059] like Figure 1 As shown, a power grid communication data processing system based on a remote communication unit includes:

[0060] The data acquisition module is used to collect the three-phase voltage traveling wave and temperature of the power grid at fixed time intervals based on the remote communication unit during the safe operation period of the power grid.

[0061] The data extraction module is used to determine the three-phase voltage traveling wave corresponding to temperature T, so as to extract the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, and determine the temperature wave baseline value corresponding to temperature T.

[0062] The fault identification module is used to acquire the voltage amplitude of the power grid during the monitoring period, and in response to the voltage amplitude exceeding the limit, it triggers the acquisition of the fault three-phase voltage traveling wave of the power grid.

[0063] The temperature monitoring module is used to calculate the temperature monitoring value based on the traveling wave of the three-phase voltage under fault.

[0064] The monitoring and correction module is used to correct the preset reference velocity based on the temperature wave baseline value and the temperature wave monitoring value to obtain the equivalent propagation velocity;

[0065] The fault location module is used to calculate the corrected fault distance based on the timestamp corresponding to the first wave zero crossover density of the equivalent propagation velocity and the three-phase voltage traveling wave of the fault, and to determine the fault section based on the fault distance.

[0066] The tripping control module is used to perform tripping control processing on faulty sections.

[0067] It should be noted that the safe operation period of the power grid refers to the state in which the power grid is free from faults such as short circuits and overloads, and the voltage and current waveforms are stable and within the normal operating parameter range. The core purpose of collecting data during this period is to obtain the baseline characteristics without fault interference. That is, since subsequent fault location requires correction of the propagation speed by comparing the waveform differences between the fault state and the normal state, the waveform and temperature data during safe operation can truly reflect the inherent characteristics of the line under normal attenuation and normal temperature influence, avoiding distortion of the baseline characteristics caused by fault signal interference.

[0068] The remote communication unit is a hardware device deployed at transmission line monitoring points (near shore stations or offshore substations), possessing data acquisition, temporary storage, and preliminary processing capabilities. Using the remote communication unit as the primary data acquisition component adapts to the deployment requirements of remote scenarios such as submarine cables.

[0069] Three-phase voltage traveling waves refer to high-frequency voltage fluctuation signals generated by changes in line conditions in phases A, B, and C of a power grid, which propagate along the line in the form of waves. Physically, traveling waves contain components of different frequencies. The initial wave (the waveform at the beginning of propagation) is dominated by high-frequency components above 100kHz, while the subsequent shoulder waveform is dominated by low-frequency components below 50kHz. The zero-crossing density (number of zero crossings) of the waveform directly reflects the attenuation degree of the high-frequency components; that is, the higher the proportion of high-frequency components, the greater the zero-crossing density. Collecting three-phase voltage traveling waves is to extract waveform characteristics reflecting high-frequency attenuation. When the power grid is operating safely, the traveling wave is free from fault interference. The ratio of the zero-crossing density of the initial wave to that of the shoulder (i.e., the temperature baseline value) can accurately reflect the inherent high-frequency attenuation law of the line. The coupling relationship between this ratio and distance and temperature is a direct manifestation of the high-attenuation, high-dielectric-loss physical characteristics of submarine cables. By collecting data at fixed time intervals, waveform data at different times can be accumulated, ensuring that the zero-crossing density ratio at a specific temperature can be extracted subsequently, thus obtaining the temperature baseline value.

[0070] Temperature specifically refers to the temperature of the cable itself, which significantly affects the dielectric properties of XLPE insulated submarine cables: the dielectric constant of XLPE changes with temperature, altering the propagation speed of traveling waves; simultaneously, increased temperature exacerbates dielectric loss, further amplifying the attenuation of high-frequency components, ultimately leading to waveform stretching and more pronounced differences in characteristics between the first wave and the shoulder. Synchronous temperature acquisition is crucial for establishing a baseline correlation for temperature waveform characteristics. As mentioned earlier, temperature affects the propagation speed and high-frequency attenuation of traveling waves through dielectric constant and dielectric loss; therefore, the zero-crossing density ratio inherently differs at different temperatures. Only by synchronously recording temperature can the temperature state corresponding to a given zero-crossing density ratio be clearly identified in subsequent processing, thus forming a complete reference relationship between temperature T and the temperature waveform baseline value K(T).

[0071] In one embodiment of the present invention, determining the three-phase voltage traveling wave corresponding to temperature T, and extracting the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, includes:

[0072] S21, extract the first wave zero-crossing density of the three-phase voltage traveling wave, including:

[0073]

[0074] Where p∈[A,B,C], A, B, and C represent phases A, B, and C respectively, ZCD0(p) represents the first wave zero-crossing density of phase p, Δt represents the fixed time interval, and u p (t) represents the sampled value of the voltage traveling wave of the p-th phase at time t, u p (t+Δt) represents the sampled value of the voltage traveling wave of the p-th phase at time t+Δt, and 1[·] represents the indicator function, if u p (t)u p If (t+Δt)<0, then the value is 1; otherwise, the value is 0.

[0075] S22, extract the shoulder zero-crossing density of the three-phase voltage traveling wave, including:

[0076]

[0077] Where ZCD2(p) represents the shoulder zero cross density of the p-th phase.

[0078] It should be noted that XLPE submarine cables attenuate high-frequency components (>100kHz) much more than low-frequency components (<50kHz). During the propagation of the traveling wave generated by the fault, high-frequency components are rapidly attenuated due to their large attenuation constant (up to 0.04dB / m at 1MHz), while low-frequency components are preserved due to their small attenuation constant (only about 1 / 10 of that of high-frequency components). This difference in attenuation is directly reflected in the waveform timing.

[0079] In the initial propagation phase of the traveling wave (0 to 20 μs), the high-frequency components have not yet been completely attenuated and still dominate the waveform changes. At this time, the initial waveform changes drastically due to the high frequency components, and the zero-crossing points (zero crossings) are dense. The zero-crossing density during this period can directly reflect the initial energy state of the high-frequency components. After 20 μs of propagation, the high-frequency components have significantly attenuated, and the low-frequency components become dominant, that is, the waveform enters the shoulder stage (20-60 μs). At this time, the waveform changes gently, the zero crossing points are sparse, and the zero-crossing density can reflect the retention state of the low-frequency components.

[0080] It should be noted that extracting the zero-crossing density of the first wave of a three-phase voltage traveling wave essentially involves counting the number of zero-crossing points within the first wave's time period. The time range corresponding to the first wave is 0 to 20 μs, because the first wave in the initial stage of traveling wave propagation mainly contains high-frequency components (above 100 kHz), and the waveform characteristics within this time period can directly reflect the attenuation state of the high-frequency components. (Formula) In this context, p represents phase A, phase B, or phase C, ensuring that each of the three phases is processed separately to cover the entire line waveform. ZCD0(p) is the zero-crossing density of the first wave of phase p, and its value is determined by the accumulation result of the indicator function. The function determines whether the voltage values ​​at two adjacent sampling times have opposite signs: when the voltage traveling wave of phase p reaches a sampling value u at time t... p (t) and the sampled value u at time t+Δt p When the product of (t+Δt) is less than 0, it indicates that the voltage waveform crosses zero between two moments (from positive to negative or negative to positive). In this case, the indicator function takes a value of 1 and is included in the statistics. If the product is greater than or equal to 0, it does not cross zero, and the indicator function takes a value of 0. By accumulating the judgment results of all adjacent sampling moments in the range of 0 to 20μs-Δt, the obtained ZCD0(p) is the total number of zero-crossing points in the first wave of that phase. Its value is positively correlated with the proportion of high-frequency components in the first wave. That is, the more high-frequency components there are, the more drastic the waveform change, and the more zero-crossing points there are.

[0081] It should be noted that this refers to the shoulder waveform following the first wave, corresponding to a time range of 20 to 60 μs. The shoulder waveform mainly contains low-frequency components (below 50 kHz) because high-frequency components attenuate rapidly during propagation, leaving the remaining low-frequency components to form a smooth shoulder waveform. ZCD2(p) is the shoulder zero-crossing density of the p-th phase, which is also calculated by counting the number of zero-crossings within this time period using an indicator function: the voltage values ​​at adjacent sampling times within the range of 20 μs to 60 μs-Δt are judged to have opposite signs, and the results of the indicator function are accumulated to obtain the total number of shoulder zero-crossings. Because the shoulder has a high proportion of low-frequency components and the waveform changes smoothly, the value of ZCD2(p) is usually smaller than that of ZCD0(p) of the first wave.

[0082] It should be noted that by dividing the time windows into the first wave and the shoulder, and separately counting the number of zero-crossing points in the two periods, the waveform difference between the first wave, dominated by high-frequency components, and the shoulder, dominated by low-frequency components, is essentially converted into a quantifiable value (zero-crossing density). This extraction method is based on the physical characteristics of traveling waves in high-attenuation, high-dielectric-loss submarine cables, where high frequencies attenuate rapidly and low frequencies are retained more, ensuring that the extracted ZCD0(p) and ZCD2(p) can truly reflect the high-frequency component differences between the first wave and the shoulder.

[0083] In one embodiment of the present invention, determining the temperature wave baseline value corresponding to temperature T includes:

[0084] S23, the baseline value of the temperature wave corresponding to temperature T is calculated based on the first wave zero-crossing density and the shoulder zero-crossing density of the three-phase voltage traveling wave, as follows:

[0085]

[0086] Where K(T) represents the baseline value of the temperature wave corresponding to temperature T, and |[A,B,C]| represents the number of elements in [A,B,C].

[0087] It should be noted that the formula for calculating the baseline value of the temperature wave is... Essentially, this is an averaging process of the ratio of the first-wave density to the shoulder zero-crossing density in the three-phase system. The first-wave zero-crossing density ZCD0(p) reflects the density of high-frequency components in the first wave (0 to 20 μs), while the shoulder zero-crossing density ZCD2(p) reflects the density of low-frequency components in the shoulder (20 to 60 μs). The ratio directly quantifies the proportion of high-frequency components; a larger proportion indicates less high-frequency attenuation in the first wave, which is closely related to the propagation distance and temperature characteristics of the traveling wave. This ratio is calculated for phases A, B, and C, and then averaged (divided by the number of three-phase elements, 3) to obtain the temperature wave baseline value K(T) corresponding to temperature T. Averaging is then used to adapt to the characteristics of a three-phase power grid: in practice, the three-phase traveling wave may fluctuate due to load imbalance and slight differences in line parameters. Averaging the three phases can offset the interference of occasional fluctuations in a single phase, making K(T) more stably reflect the overall waveform characteristics at temperature T and avoiding reference distortion caused by single-phase data deviation.

[0088] Temperature within the cable affects the dielectric constant and dielectric loss of the XLPE medium, thus altering the attenuation rate of high-frequency components. As temperature increases, the decrease in dielectric constant slightly increases the high-frequency propagation speed, while changes in dielectric loss further influence high-frequency attenuation, ultimately leading to a regular change in the ratio of the zero-crossing density between the initial wave and the shoulder. Calculating K(T) at this temperature essentially records the relationship between "temperature T → high-frequency attenuation →" The inherent correspondence is the benchmark for subsequent fault location: when a fault occurs, by comparing the temperature wave monitoring value at the fault (the ratio calculated by the same principle) with the temperature wave baseline value K(T) at that temperature T, the deviation between the high frequency attenuation at the fault and the normal state can be directly reflected, thereby correcting the propagation speed.

[0089] In one embodiment of the present invention, during the monitoring period, the voltage amplitude of the power grid is acquired, and in response to the voltage amplitude exceeding the limit, the fault three-phase voltage traveling wave of the power grid is acquired, including:

[0090] The voltage traveling waves of phases A, B, and C are sampled at time s at fixed time intervals, and the average of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s.

[0091] The voltage traveling waves of phases A, B, and C are sampled at time s-1 at fixed time intervals, and the average value of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s-1.

[0092] The difference between the total voltage at time s and the total voltage at time s-1 is taken as the voltage amplitude;

[0093] If the voltage amplitude is greater than or equal to the preset amplitude threshold, then mark the voltage amplitude as exceeding the limit once;

[0094] When the voltage amplitude exceeds the limit for a preset number of times, the fault three-phase voltage traveling wave of the power grid is triggered.

[0095] It should be noted that voltage traveling wave samples of phases A, B, and C at time s are acquired at fixed time intervals, and the average of the three-phase samples is calculated as the total voltage at time s. Similarly, the average of the three-phase samples at time s-1 is obtained as the total voltage at time s-1. The three-phase average is used instead of single-phase values ​​because the power grid is a three-phase system. During normal operation, single-phase load fluctuations (such as momentary imbalances) may occur, but the overall three-phase state is more stable. The total voltage reflects the overall voltage level of the power grid, avoiding misjudgments of faults due to occasional single-phase fluctuations. The difference between the total voltage at time s and time s-1 is used as the voltage amplitude, which directly reflects the magnitude of voltage change. During normal operation, the power grid voltage fluctuations are gradual, and the voltage amplitude is small; however, when a short-circuit fault occurs, the voltage will suddenly change (such as a sharp drop or rise), and the voltage amplitude will increase significantly. Therefore, the voltage amplitude is the core characteristic quantity for fault identification. If the voltage amplitude reaches a preset amplitude threshold, it is marked as an over-limit occurrence. Only when the cumulative number of over-limit occurrences reaches a preset number is the acquisition of the faulty three-phase voltage traveling wave triggered. Therefore, considering the interference characteristics of the power grid in actual operation, namely the possibility of transient noise (such as short-term pulses generated by equipment switching), which may cause a single voltage amplitude to exceed the limit, but is not a real fault, transient interference can be filtered out by multiple limit exceedance judgments, ensuring that data acquisition is only triggered when there is a continuous voltage anomaly (i.e., a real fault).

[0096] In one embodiment of the present invention, the calculation of temperature wave monitoring values ​​based on the traveling wave of the three-phase voltage under fault includes:

[0097] For the faulty three-phase voltage traveling wave, repeat steps 21 to 23 to obtain the temperature wave monitoring value.

[0098] It should be noted that for the traveling voltage waves of phases A, B, and C collected during a fault, the initial wave zero-crossing density of each phase is first calculated within a time window of 0 to 20 μs using method S21; then, the shoulder zero-crossing density of each phase is calculated within a time window of 20 to 60 μs using method S22; finally, the ratio of the initial wave density to the shoulder zero-crossing density of each phase is calculated using method S23, and the average of the three ratios is taken as the temperature wave monitoring value.

[0099] In one embodiment of the present invention, a preset reference velocity is corrected based on the temperature wave baseline value and the temperature wave monitoring value to obtain an equivalent propagation velocity, including:

[0100] Determine the temperature S corresponding to the traveling wave of the three-phase voltage under fault;

[0101] The temperature wave deviation ΔK is obtained by subtracting the baseline value of temperature S from the temperature wave monitoring value.

[0102] The correction factor CF is generated based on the temperature wave deviation, where CF = exp(-m·ΔK); and m is the preset correction coefficient.

[0103] Multiply the preset reference velocity v0 by the correction factor CF to obtain the equivalent propagation velocity.

[0104] It is important to clarify that determining the temperature S corresponding to the three-phase voltage traveling wave during a fault is crucial. The temperature baseline value is a reference established at different temperatures during safe grid operation (i.e., K(T) corresponding to temperature T). However, the propagation of the traveling wave during a fault is affected by the current temperature. Temperature changes the dielectric constant and dielectric loss of the XLPE dielectric, directly affecting the attenuation and propagation speed of high-frequency components. Therefore, the actual temperature S at the time of the fault must be clearly defined to use the temperature baseline value at that temperature (i.e., K(S) corresponding to temperature S) as a comparison benchmark, avoiding the loss of physical meaning due to temperature mismatch causing the deviation between the baseline and the monitored value. For example, comparing a 25-degree baseline with a 40-degree monitored value will include the inherent temperature difference, rather than the fault-related attenuation difference. The temperature deviation is the difference between the temperature baseline value K(S) corresponding to temperature S and the temperature monitoring value at the time of the fault. The temperature baseline value K(S) reflects the ratio of high-frequency and low-frequency components during normal operation at temperature S, while the temperature monitoring value K1 reflects this ratio at the same temperature during the fault. The deviation between the two directly quantifies the difference in high-frequency attenuation between the faulty traveling wave and the normal traveling wave: the farther the fault point, the longer the traveling wave propagation distance, the more severe the attenuation of high-frequency components, the smaller the temperature wave monitoring value, and the larger the temperature wave deviation; conversely, the closer the fault point, the smaller the temperature wave deviation. Therefore, temperature wave deviation is a core quantitative indicator reflecting the fault distance and the degree of high-frequency attenuation.

[0105] The equivalent propagation speed is obtained by multiplying the preset reference speed by a correction factor. The preset reference speed is the theoretical propagation speed during line design (e.g., 200 m / μs). However, in high-attenuation, high-dielectric-loss submarine cables, the actual propagation speed will deviate due to high-frequency attenuation. The essence of the equivalent propagation speed is to dynamically adjust the theoretical speed using a correction factor. The correction factor adapts the preset reference speed according to the actual attenuation situation reflected by temperature deviation. The final equivalent propagation speed eliminates the speed deviation caused by high-frequency attenuation and temperature effects, and is closer to the actual propagation speed of traveling waves.

[0106] In one embodiment of the present invention, the corrected fault distance is calculated based on the timestamp corresponding to the first wave zero-crossing density of the equivalent propagation velocity and the fault three-phase voltage traveling wave, including:

[0107] Extract the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave;

[0108] The propagation time is determined based on the timestamp corresponding to the first wave of zero crossover density;

[0109] The product of the propagation time and the equivalent propagation speed is used as the corrected fault distance.

[0110] It should be noted that the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave is extracted. The first wave zero-crossing density is the number of zero-crossing points counted within a time window of 0 to 20 μs. The corresponding timestamp refers to the moment when the first zero-crossing occurs in the first wave. This moment is the core characteristic point of the traveling wave arriving at the monitoring point: zero crossing is a topological property of the waveform. Even if the amplitude of the fault traveling wave is distorted due to attenuation (such as the reduction of the first wave amplitude in a high dielectric loss submarine cable), the zero-crossing moment can still be stably identified, avoiding the time identification error caused by amplitude ambiguity in the traditional wavehead arrival method.

[0111] The propagation time is determined based on the timestamp corresponding to the first wave's zero-crossing density. The propagation time is the time it takes for the faulty traveling wave to travel from the fault point to the monitoring point of the remote communication unit, determined by the difference between the first wave's zero-crossing timestamp and the time of the fault occurrence. Because the first wave's zero-crossing timestamp accurately reflects the arrival time of the traveling wave, the calculation error of the propagation time is significantly lower than that of traditional methods. Traditional methods rely on wavefront amplitude inflection point identification, which can easily lead to time errors in high-attenuation submarine cables due to wavefront ambiguity. This invention, however, controls the propagation time error to within microseconds by using the zero-crossing timestamp.

[0112] The product of propagation time and equivalent propagation speed is used as the fault correction distance. The equivalent propagation speed is a dynamic value obtained by correcting the deviation between the baseline value and the monitored value of the thermal wave, thus eliminating the influence of high attenuation and high dielectric loss on the propagation speed deviating from the theoretical value. The propagation time is determined based on the zero-crossing timestamp, eliminating the error of wavefront identification ambiguity. The product of the two is essentially a combination of dynamic correction speed and precise propagation time, directly reflecting the actual distance between the fault point and the monitoring point. That is, compared with the traditional fixed speed and ambiguous time calculation method, this invention fundamentally avoids the two core error sources in high dielectric loss submarine cables, making the ranging results more consistent with reality.

[0113] In one embodiment of the present invention, determining the fault section based on the fault distance includes:

[0114] The power grid is divided into M management sections based on the switch;

[0115] Determine the actual distance range for each management section;

[0116] The fault segment is obtained by querying the actual distance range based on the corrected fault distance.

[0117] It should be noted that the power grid is divided into M management sections based on power switches. Power switches are actual segmented control devices in power grid operation (such as sectionalizing switches along submarine cables). Each power switch corresponds to a specific power supply range. Dividing the power grid into sections by power switches essentially associates the distance between power grid sections with physical control units. That is, the section division is not subjectively set, but perfectly matches the actual control range of the power switches in operation and maintenance. For example, if a power switch is installed every 10km along a submarine cable, it corresponds to section 1 (0-10km), section 2 (10-20km), etc., ensuring that subsequent fault sections can directly correspond to specific power switch control units, providing a clear target for switching operations. The distance range of each section is determined by the physical location of the corresponding power switch. For example, section 1's range is the distance between power switches 1 and 2 (e.g., 0-10km), section 2's range is the distance between power switches 2 and 3 (e.g., 10-20km), and so on. This range is a fixed value determined in advance through line design parameters and actual measurements, forming a correspondence table of section number and distance range, providing a standardized basis for subsequent queries. By comparing the corrected fault distance with the preset correspondence table of section number and distance range, it can be determined which section the distance falls within. For example, if the corrected fault distance is 15km, and the range of section 2 is 10 to 20km, then the fault is determined to be in section 2.

[0118] In one embodiment of the present invention, the tripping control process for the faulty section includes: determining the circuit breaker corresponding to the faulty section and issuing a tripping command.

[0119] It is important to clarify the identification of the switch corresponding to the faulty section. In power grid design and operation, each managed section is controlled by a specific switch; for example, section 1 corresponds to switch 1, and section 2 corresponds to switch 2. This correspondence is a pre-defined, fixed association based on the switch division of sections. Since the faulty section has been accurately identified by correcting the fault distance, the switch requiring operation can be directly located using the section number-distance range correspondence table. The switch-opening command is the signal that controls the switch to disconnect, its function being to cut off the connection between the faulty section and other parts of the power grid, preventing the fault current from continuing to spread or affecting the power supply to non-faulty areas. The command issuance relies on the communication function of the remote communication unit to ensure that it reaches the switch within a short time after the fault occurs, achieving rapid isolation.

[0120] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A power grid communication data processing system based on a remote communication unit, characterized in that, include: The data acquisition module is used to collect the three-phase voltage traveling wave and temperature of the power grid at fixed time intervals based on the remote communication unit during the safe operation period of the power grid. The data extraction module is used to determine the three-phase voltage traveling wave corresponding to temperature T, so as to extract the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, and determine the temperature wave baseline value corresponding to temperature T. The fault identification module is used to acquire the voltage amplitude of the power grid during the monitoring period, and in response to the voltage amplitude exceeding the limit, it triggers the acquisition of the fault three-phase voltage traveling wave of the power grid. The temperature monitoring module is used to calculate the temperature monitoring value based on the traveling wave of the three-phase voltage under fault. The monitoring and correction module is used to correct the preset reference velocity based on the temperature wave baseline value and the temperature wave monitoring value to obtain the equivalent propagation velocity; The fault location module is used to calculate the corrected fault distance based on the timestamp corresponding to the first wave zero crossover density of the equivalent propagation velocity and the three-phase voltage traveling wave of the fault, and to determine the fault section based on the fault distance. The tripping control module is used to perform tripping control processing on faulty sections.

2. The power grid communication data processing system based on a remote communication unit according to claim 1, characterized in that, Determine the three-phase voltage traveling wave corresponding to temperature T, and extract the first wave zero-crossing density and the shoulder zero-crossing density at temperature T, including: S21, extract the first wave zero-crossing density of the three-phase voltage traveling wave, including: Where p∈[A,B,C], A, B, and C represent phases A, B, and C respectively, ZCD0(p) represents the first wave zero-crossing density of phase p, Δt represents the fixed time interval, and u p (t) represents the sampled value of the voltage traveling wave of the p-th phase at time t, u p (t+Δt) represents the sampled value of the voltage traveling wave of the p-th phase at time t+Δt, and 1[·] represents the indicator function, if u p (t)u p If (t+Δt)<0, then the value is 1; otherwise, the value is 0. S22, extract the shoulder zero-crossing density of the three-phase voltage traveling wave, including: Where ZCD2(p) represents the shoulder zero cross density of the p-th phase.

3. The power grid communication data processing system based on a remote communication unit according to claim 2, characterized in that, Determine the baseline temperature wave value corresponding to temperature T, including: S23, the baseline value of the temperature wave corresponding to temperature T is calculated based on the first wave zero-crossing density and the shoulder zero-crossing density of the three-phase voltage traveling wave, as follows: Where K(T) represents the baseline value of the temperature wave corresponding to temperature T, and |[A,B,C]| represents the number of elements in [A,B,C].

4. The power grid communication data processing system based on a remote communication unit according to claim 3, characterized in that, During the monitoring period, the voltage amplitude of the power grid is acquired, and in response to the voltage amplitude exceeding the limit, the fault three-phase voltage traveling wave of the power grid is acquired, including: The voltage traveling waves of phases A, B, and C are sampled at time s at fixed time intervals, and the average of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s. The voltage traveling waves of phases A, B, and C are sampled at time s-1 at fixed time intervals, and the average value of the sampled values ​​of phases A, B, and C is calculated as the total voltage at time s-1. The difference between the total voltage at time s and the total voltage at time s-1 is taken as the voltage amplitude; If the voltage amplitude is greater than or equal to the preset amplitude threshold, then mark the voltage amplitude as exceeding the limit once; When the voltage amplitude exceeds the limit for a preset number of times, the fault three-phase voltage traveling wave of the power grid is triggered.

5. A power grid communication data processing system based on a remote communication unit according to claim 4, characterized in that, Temperature monitoring values ​​are calculated based on the traveling wave of the three-phase voltage during a fault, including: For the faulty three-phase voltage traveling wave, repeat steps 21 to 23 to obtain the temperature wave monitoring value.

6. A power grid communication data processing system based on a remote communication unit according to claim 5, characterized in that, Based on the baseline temperature wave value and the temperature wave monitoring value, the preset reference velocity is corrected to obtain the equivalent propagation velocity, including: Determine the temperature S corresponding to the traveling wave of the three-phase voltage under fault; The temperature wave deviation ΔK is obtained by subtracting the baseline value of temperature S from the temperature wave monitoring value. The correction factor CF is generated based on the temperature wave deviation, where CF = exp(-m·ΔK); and m is the preset correction coefficient. Multiply the preset reference velocity v0 by the correction factor CF to obtain the equivalent propagation velocity.

7. A power grid communication data processing system based on a remote communication unit according to claim 6, characterized in that, The corrected fault distance is calculated based on the equivalent propagation velocity and the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave, including: Extract the timestamp corresponding to the first wave zero-crossing density of the fault three-phase voltage traveling wave; The propagation time is determined based on the timestamp corresponding to the first wave of zero crossover density; The product of the propagation time and the equivalent propagation speed is used as the corrected fault distance.

8. A power grid communication data processing system based on a remote communication unit according to claim 7, characterized in that, The fault section is determined based on the distance to the fault, including: The power grid is divided into M management sections based on the switch; Determine the actual distance range for each management section; The fault segment is obtained by querying the actual distance range based on the corrected fault distance.

9. A power grid communication data processing system based on a remote communication unit according to claim 8, characterized in that, The process of tripping the circuit breaker in the faulty section includes: determining the circuit breaker corresponding to the faulty section and issuing a tripping command.

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