Over-current control method, device and equipment for power distribution terminal

Abstract

The invention provides an overcurrent control method, device and equipment for a power distribution terminal, and relates to the technical field of power grids. The sampling values of the sampling points of the mutual inductor are analyzed to obtain the phase of each sampling point, and the phase and the slope of each sampling point are combined to calculate the current effective value of the power distribution terminal, so that the overcurrent control of the power distribution terminal is carried out. Compared with an FFT algorithm or an integral method for calculating the current effective value of the power distribution terminal for over-current control, the current effective value of the power distribution terminal is calculated by adopting the phase and the slope of each sampling point, so that the influence of current waveform distortion is avoided, the accuracy of the current effective value is improved, and the accuracy of over-current control of the power distribution terminal is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power grid, and in particular to an overcurrent control method, device and equipment for a power distribution terminal. Background Art

[0002] In the power system, circuit breakers and distribution terminals are key protection and control devices that are responsible for quickly cutting off the circuit when the current rises abnormally, preventing equipment damage and fire and other safety accidents. Overcurrent control is one of the main functions of the distribution terminal, and its implementation depends on the accurate monitoring and analysis of analog quantities such as current in the power grid. In order to achieve this function, current transformers are usually installed at appropriate locations in the power grid. These transformers can convert high currents into low current signals in proportion, which is convenient for subsequent signal processing and measurement.

[0003] The analog signal output by the current transformer is then captured by the data acquisition system, and the effective value of the current is calculated through the algorithm. This effective value is an important basis for evaluating whether the current exceeds the preset threshold and triggering the action of the distribution terminal. The calculation of the effective value usually adopts the FFT algorithm or the integration method, and is based on the complete waveform of the signal, ensuring accurate reflection of the actual current state.

[0004] However, in actual applications, when the sampling process is disturbed or the performance of the transformer is limited, the collected current waveform may be distorted, especially the clipping distortion phenomenon, that is, the peak value of the signal is improperly reduced, resulting in the calculated effective value not being able to truly reflect the actual current. If this distortion is not discovered and corrected in time, once a power grid line fails, the distribution terminal that relies on this erroneous data for overcurrent judgment may refuse to operate and fail to cut off the faulty line in time, thereby increasing the risk of serious consequences such as equipment damage, power outages and even fires. Summary of the invention

[0005] The present invention provides an overcurrent control method, device and equipment for a power distribution terminal, which can improve the accuracy of overcurrent control of the power distribution terminal.

[0006] In a first aspect, the present invention provides an overcurrent control method for a distribution terminal, the method comprising: obtaining sampling values ​​of multiple sampling points at the output end of a transformer corresponding to the distribution terminal; determining the phase of each sampling point based on the sampling values ​​of the multiple sampling points; calculating the phase and slope of each sampling point based on the phase and sampling value of each sampling point; determining the effective value of the current of the distribution terminal based on the phase and slope of each sampling point; and performing overcurrent control based on the effective value of the current of the distribution terminal.

[0007] In a possible implementation, the method further includes: comparing the size relationship between the sampling values ​​of multiple sampling points and the overcurrent amplitude to obtain a comparison result; if the comparison result is that the sampling values ​​of multiple consecutive sampling points are greater than the overcurrent amplitude, determining that the distribution terminal is in an overcurrent state; and controlling the circuit breaker corresponding to the distribution terminal to disconnect.

[0008] In a possible implementation, determining the phase of each sampling point based on the sampling values ​​of the multiple sampling points includes: determining multiple zero-crossing sampling points based on the sampling values ​​of the multiple sampling points; determining the phase of the zero-crossing sampling points based on the sampling values ​​of the multiple zero-crossing sampling points; and determining the phase of the multiple sampling points based on the phase of the zero-crossing sampling points and the phase difference between the sampling points.

[0009] In one possible implementation, the effective value of the current at the distribution terminal is determined based on the phase and slope of each sampling point, including: calculating the sampling difference between two sampling points of the multi-zero point based on the sampling value of the zero-crossing sampling point; determining the current peak value of the distribution terminal based on the sampling difference between the two sampling points of the multi-zero point and the phase difference between the two sampling points of the multi-zero point; determining the effective value of the current at the distribution terminal based on the current peak value of the distribution terminal.

[0010] In one possible implementation, overcurrent control is performed based on the effective value of the current of the distribution terminal, including: if the effective value of the current of the distribution terminal is greater than the overcurrent effective value, determining that the distribution terminal is in an overcurrent state; and controlling the circuit breaker corresponding to the distribution terminal to disconnect.

[0011] In one possible implementation, overcurrent control is performed based on the effective value of the current at the distribution terminal, including: if the effective value of the current at the distribution terminal is greater than the effective value of the overcurrent, then counting the number of overcurrent times in which the effective value of the current calculated at the zero-crossing sampling point within a cycle is greater than the effective value of the overcurrent; if the number of overcurrent times is greater than or equal to the set number of times, then determining that the distribution terminal is in an overcurrent state; and controlling the circuit breaker corresponding to the distribution terminal to disconnect.

[0012] In a second aspect, an embodiment of the present invention provides an overcurrent control device for a distribution terminal, the device comprising: an analog quantity acquisition module and a processing module, the analog quantity acquisition module being used to obtain sampling values ​​of multiple sampling points at the output end of a transformer corresponding to the distribution terminal; a processing module being used to determine the phase of each sampling point based on the sampling values ​​of the multiple sampling points; calculating the phase and slope of each sampling point based on the phase and sampling value of each sampling point; determining the effective current value of the distribution terminal based on the phase and slope at each sampling point; and performing overcurrent control based on the effective current value of the distribution terminal.

[0013] In a possible implementation, the processing module is also used to compare the size relationship between the sampling values ​​of multiple sampling points and the overcurrent amplitude to obtain a comparison result; if the comparison result is that the sampling values ​​of multiple consecutive sampling points are greater than the overcurrent amplitude, it is determined that the distribution terminal is in an overcurrent state; and the circuit breaker corresponding to the distribution terminal is controlled to disconnect.

[0014] In one possible implementation, the processing module is specifically used to determine multiple zero-crossing sampling points based on the sampling values ​​of the multiple sampling points; determine the phases of the zero-crossing sampling points based on the sampling values ​​of the multiple zero-crossing sampling points; and determine the phases of the multiple sampling points based on the phases of the zero-crossing sampling points and the phase differences between the sampling points.

[0015] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, the memory storing a computer program, the processor being used to call and run the computer program stored in the memory to perform the steps of the method described in the first aspect and any possible implementation method of the first aspect.

[0016] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and wherein when the computer program is executed by a processor, the steps of the method described in the first aspect and any possible implementation method of the first aspect are implemented.

[0017] The present invention provides an overcurrent control method, device and equipment for a distribution terminal. The present invention analyzes the sampling values ​​of the mutual inductor sampling points to obtain the phase of each sampling point, and combines the phase and slope of each sampling point to calculate the effective value of the current of the distribution terminal, thereby performing overcurrent control of the distribution terminal. Compared with using the FFT algorithm or the integration method to calculate the effective value of the current of the distribution terminal for overcurrent control, the present invention uses the phase and slope of each sampling point to calculate the effective value of the current of the distribution terminal, thereby avoiding the influence of current waveform distortion, improving the accuracy of the effective value of the current, and improving the accuracy of overcurrent control of the distribution terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 It is a flow chart of an overcurrent control method of a power distribution terminal provided by an embodiment of the present invention;

[0020] Figure 2This is a data schematic diagram of a sampling point of a power distribution terminal provided by an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of sampling data of a distribution terminal transformer with clipping distortion provided by an embodiment of the present invention;

[0022] Figure 4 This is a data schematic diagram of 32-point sampling provided by an embodiment of the present invention;

[0023] Figure 5 It is a structural schematic diagram of an overcurrent control device of a power distribution terminal provided by an embodiment of the present invention;

[0024] Figure 6 It is a structural schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0026] In the description of the present invention, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, "at least one" and "plurality" refer to two or more. The words "first", "second", etc. do not limit the quantity and execution order, and the words "first", "second", etc. do not limit them to be different.

[0027] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0028] In addition, the terms "including" and "having" and any variations thereof mentioned in the description of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or modules is not limited to the listed steps or modules, but may optionally include other steps or modules that are not listed, or may optionally include other steps or modules that are inherent to these processes, methods, products or devices.

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following will be described through specific embodiments in conjunction with the accompanying drawings of the present invention.

[0030] As described in the background technology, the overcurrent trip setting of the field equipment is set to 8A. When the line has an overcurrent fault and the grid current is 9A, due to the distortion of the sampling circuit of the circuit breaker transformer or the terminal transformer, the effective value using the FFT or integration algorithm may be less than 8A, which cannot reach the set value, and the switch refuses to move, and the line fault cannot be removed. In this case, it is necessary to use the sampling point of the effective area without the top elimination to determine whether the current current value is greater than the set value.

[0031] Based on the above problems, Figure 1 As shown, an embodiment of the present invention provides an overcurrent control method for a power distribution terminal. The method includes steps S101-S105.

[0032] S101. Acquire sampling values ​​of a plurality of sampling points at an output end of a transformer corresponding to a power distribution terminal.

[0033] S102: Determine the phase of each sampling point based on the sampling values ​​of the multiple sampling points.

[0034] As a possible implementation manner, step S102 may be specifically implemented as steps S1021 - S1023 .

[0035] S1021. Determine a plurality of zero-crossing sampling points based on the sampling values ​​of the plurality of sampling points.

[0036] S1022: Determine the phase of the zero-crossing sampling point based on the sampling values ​​of the plurality of zero-crossing sampling points.

[0037] S1023: Determine the phases of multiple sampling points based on the phases of the sampling points at the zero-crossing point and the phase differences between the sampling points.

[0038] S103: Calculate the phase and slope of each sampling point based on the phase and sampling value of each sampling point.

[0039] S104: Determine the effective value of the current at the power distribution terminal based on the phase and slope at each sampling point.

[0040] As a possible implementation manner, step S104 may be specifically implemented as steps S1041 - S1043 .

[0041] S1041. Calculate the sampling difference between two multi-zero sampling points based on the sampling value of the zero-crossing sampling point.

[0042] S1042: Determine the current peak value of the power distribution terminal based on the sampling difference between the two sampling points of the multi-zero point and the phase difference between the two sampling points of the multi-zero point.

[0043] S1043. Determine the effective value of the current at the distribution terminal based on the current peak value of the distribution terminal.

[0044] S105. Perform overcurrent control based on the effective value of the current at the power distribution terminal.

[0045] As a possible implementation, if the effective value of the current of the distribution terminal is greater than the overcurrent effective value, the embodiment of the present invention can determine that the distribution terminal is in an overcurrent state; and control the circuit breaker corresponding to the distribution terminal to disconnect.

[0046] As another possible implementation method, if the effective value of the current at the distribution terminal is greater than the effective value of the overcurrent, the embodiment of the present invention can also count the number of overcurrent times when the effective value of the current calculated at the zero-crossing sampling point within a cycle is greater than the effective value of the overcurrent; if the number of overcurrent times is greater than or equal to the set number of times, it is determined that the distribution terminal is in an overcurrent state; and the circuit breaker corresponding to the distribution terminal is controlled to disconnect.

[0047] It should be noted that in order to avoid false operation caused by interference signals, the phase and slope of multiple consecutive sampling points can be used to calculate the effective values ​​of multiple distribution terminal currents. When multiple current effective values ​​are all greater than the overcurrent threshold, it is determined to be an overcurrent state and overcurrent control is performed.

[0048] In addition, the present invention also greatly speeds up the response time for judging the overcurrent state. If FFT calculation is used, at least one cycle is required to judge whether it is an overcurrent state. For example, if the frequency is 50Hz, one cycle is 20ms. However, the time for four consecutive sampling points of the present invention is 2.5ms. If 32 points are sampled, it is 4 / 32*20=2.5ms. That is, the present invention only needs 2.5ms to judge whether there is an overcurrent, which shortens the overcurrent removal time and improves the line safety.

[0049] The present invention provides an overcurrent control method for a distribution terminal, which analyzes the sampling values ​​of the mutual inductor sampling points to obtain the phase of each sampling point, and combines the phase and slope of each sampling point to calculate the effective value of the current of the distribution terminal, thereby performing overcurrent control of the distribution terminal. Compared with using the FFT algorithm or the integration method to calculate the effective value of the current of the distribution terminal for overcurrent control, the present invention uses the phase and slope of each sampling point to calculate the effective value of the current of the distribution terminal, thereby avoiding the influence of current waveform distortion, improving the accuracy of the effective value of the current, and improving the accuracy of overcurrent control of the distribution terminal.

[0050] The above-mentioned overcurrent control method of the present invention is based on the current being a sine wave. The larger the effective value, the larger the slope of the two adjacent sampling points. For fixed equipment, when the current effective value and frequency are known, the slope of every two adjacent sampling points in the same phase is fixed. When the slope of the sampling point is greater than the slope corresponding to the fixed value, it can be considered that an overcurrent fault has occurred. The slope is △Y / △X. Since △X is a fixed interval, there is no need to calculate the slope. The absolute value of △Y of the adjacent sampling points is calculated. The effective value is then inferred by the absolute value of △Y of the effective sampling point. That is, the absolute value of △Y of the adjacent sampling points is calculated. The effective value is then inferred by the absolute value of △Y of the effective sampling point. The algorithm is relatively simple and has high reliability.

[0051] like Figure 2 As shown, an embodiment of the present invention provides a data schematic diagram of a distribution terminal sampling point. Figure 2 The sampling interval is 360 / 32=11.25 degrees. From the trigonometric function, we know that the values ​​of each sampling point are AD(n)=Imax*Sin(11.25n+θ), where n is the sampling point and θ is the initial phase angle.

[0052] So we know: Imax = AD(n) / Sin(11.25n+θ). I effective value = Imax / 1.414. The calculation of Imax requires the sampling point order n and the value of the initial phase angle θ. If 128 points are sampled, the interval is 360 / 32 = 2.8125 degrees

[0053] like Figure 3 As shown, an embodiment of the present invention provides a schematic diagram of sampling data of a distribution terminal transformer with clipping distortion. Since the initial phase angle of the analog quantity collected by the device is random from 0 to 360 degrees. If a zero-crossing point is found in the cache, the sampling points near the zero-crossing point are used for calculation, and the n corresponding to the AD value near the zero point can be considered to be (±) 1, and θ can be considered to be 0.

[0054] If you find the 12th or 28th point, you know:

[0055] 11-point AD sampling value = Imax*Sin(11.25*(1)+180)

[0056] 12-point AD sampling value = Imax*Sin(11.25*0+180)

[0057] 11-point AD sampling value = Imax*Sin(11.25*(-1)+180)

[0058] or:

[0059] 27-point AD sampling value = Imax*Sin(11.25*(-1))

[0060] 28-point AD sampling value = Imax*Sin(11.25*0)

[0061] 29-point AD sampling value = Imax*Sin(11.25*(1))

[0062] As above, according to the sampling value of the sampling point, after finding the zero-crossing point, Imax = AD (n) / Sin (11.25n + θ). It can be simplified to Imax = AD (zero-crossing point) / Sin (11.25).

[0063] After finding the sampling value near the zero point, due to the randomness of the initial sampling phase angle, the sampling point near the zero point is uncertain between -11.25° and 11.25° (same as 0 and 11.25°). Directly using the simplified formula Imax = AD (zero point) / Sin (11.25) for calculation, the error is large.

[0064] Therefore, the zero-crossing difference is used to infer the effective value. The calculation formula is optimized to: Imax = AD (zero-crossing difference) / (Sin (11.25) - Sin (0)), because Sin (0) = 0, that is: Imax = AD (zero-crossing difference) / Sin (11.25).

[0065] The error data of the overcurrent control method for the power distribution terminal provided by the embodiment of the present invention is shown in Table 1.

[0066] Table 1

[0067]

[0068] As shown in Table 1, the difference between the two sampling points near the zero point. The maximum sampling difference is 2.4947 at 5.625° and -5.625°. The minimum sampling difference is 2.4827 at 0° and 11.25°.

[0069] If the formula Imax=AD (zero-crossing point difference) / Sin(11.25) is used for calculation, Sin11.25 is 0.1951.

[0070] 2.4947 / Sin11.25 / 1.414=9.04298A, error is 0.477%

[0071] 2.4827 / Sin11.25 / 1.414=8.99948A, error is -0.005%

[0072] The standard requires a 5% error. This requirement can be met.

[0073] Assuming the applied current is 30A, the telemetry value is: maximum 30.47, minimum 29.67. The maximum error is 1.566%. The AD zero crossing difference value is: maximum 1797, minimum 1739. The fluctuation error is 3.335% relative to the minimum value. It is 1.667% relative to the middle value. It is consistent with the actual telemetry value.

[0074] It should be noted that the purpose of using the zero-point difference to infer the effective value is to determine whether the analog value is greater than the overcurrent protection setting value to avoid refusal to operate. If the sampling point value near the zero point is distorted due to electromagnetic interference, the calculated difference may be too large, and the inferred effective value may be greater than the actual value, causing false operation. Therefore, it is necessary to add an anti-interference mechanism.

[0075] If the difference of four consecutive sampling points (interference can be filtered out) within one cycle is greater than the difference of the corresponding points of the sine wave corresponding to the protection setting (32-point sampling), it is considered that overcurrent has occurred. Only then can the zero-crossing point difference be used to calculate the effective value.

[0076] That is, if the overcurrent setting is set to 9A, the actual analog value is 9.1A.

[0077] The actual analog sampling difference between -22.5° and -11.25° is greater than the 9A constant corresponding to the difference between -22.5° and -11.25°.

[0078] The actual analog quantity sampling difference between -11.25° and 0° is greater than the 9A constant corresponding to the difference between -11.25° and 0°.

[0079] The actual sampling difference between the analog quantity 0° and -11.25° is greater than the 9A constant corresponding to the difference between 0° and -11.25°.

[0080] The actual sampling difference between the analog quantity 11.25° and 22.5° is greater than the 9A constant corresponding to the difference between 11.25° and 22.5°.

[0081] Can be simplified to:

[0082] The difference between 11.25° and 22.5° corresponding to 4 consecutive sampling differences (to prevent false operation) is greater than the set value.

[0083] Anti-malfunction analysis:

[0084] A distortion of one point in the 32-point buffer will not cause false movement: the difference between at most two consecutive sampling points is greater than the fixed value.

[0085] The distortion of two points in the 32-point buffer will not cause false movement: the difference of at most three consecutive sampling points is greater than the fixed value.

[0086] If three points in the 32-point buffer are distorted, it will cause misoperation. If the difference of up to 4 consecutive sampling points is greater than the set value, it will cause misoperation.

[0087] Considering the mutation amount, the three distortion points in the 32-point cache will not move accidentally: due to the coordination of the mutation amount, the adjustment points can prevent accidental movement.

[0088] It should be noted that for the equipment with 6.8A top elimination on site. Use 32-point cache (32 cycles): If you consider using 4 consecutive points of anti-interference measures, it is effective within a maximum of 17.7A. No effective 4 consecutive points can be found for more than 17.7A. Increase the number of consecutive vertices to be greater than or equal to 11 (when 11 points are eliminated, the maximum number of consecutive vertices that are not eliminated is 5, and the difference satisfies the 4 consecutive points of anti-interference), and no longer consider using 4 consecutive points of anti-interference measures. It can be judged that the current is greater than 17.7A, and the zero-crossing point is directly used to infer the effective value. The maximum effective value can be calculated to be 34.8A. Advantages of using 32-point cache: The calculation amount is 1 / 4 of the 128-point cache. Disadvantages of using 32-point cache: Because the standard requires the protection accuracy to meet 10 times the rated value. If it is a 1A rated device, 32-point cache is available. If it is a 5A rated device, 32-point cache is not available.

[0089] Use 128-point cache (128 cycles): If you consider using 4-point continuous anti-interference measures, it is effective within a maximum of 69A. No effective 4-point continuous points can be found for more than 69A. Increase the number of continuous eliminated vertices to be greater than or equal to 59 (when 59 points are eliminated, the maximum number of consecutive uneliminated vertices is 5, and the difference satisfies the 4-point continuous anti-interference), and no longer consider using 4-point continuous anti-interference measures. It can be judged that the current is greater than 69A, and the zero-crossing point is directly used to infer the effective value. The maximum effective value that can be calculated is 138A. The disadvantage of using 128-point cache is: the amount of calculation is 4 times that of 32-point cache. The advantage of using 128-point cache: 5A rated equipment, 128-point cache is available. For equipment without 128 cache, the recording cache can be used for calculation.

[0090] Optionally, the overcurrent control method for the power distribution terminal provided in the embodiment of the present invention further includes steps S201-S203.

[0091] S201 , comparing the magnitude relationships between the sampling values ​​of multiple sampling points and the overcurrent amplitude to obtain a comparison result.

[0092] S202: If the comparison result is that the sampling values ​​of multiple consecutive sampling points are greater than the overcurrent amplitude, it is determined that the power distribution terminal is in an overcurrent state.

[0093] S203. Control the circuit breaker corresponding to the power distribution terminal to disconnect.

[0094] The above-mentioned overcurrent control method of the present invention is based on the fact that the current is a sine wave. The larger the effective value, the larger the discrete sampling point value of the same phase. For example, the fixed value is set to 9A, and the maximum amplitude is 9*1.414. If the sampling point value is greater than 9*1.414, it means that the collected current value is greater than the set value. In order to improve the accuracy, it can be judged that multiple consecutive points are greater than the maximum amplitude of the fixed value, and it is considered that an overcurrent fault has occurred.

[0095] Exemplarily, after entering the telemetry calculation function, if there is a peak elimination in the cache, 4 consecutive sampling differences (greater than the difference between 2.8125° and 5.625° corresponding to the overcurrent protection current setting or 59 consecutive points are peak eliminated. The zero-crossing point difference calculation effective value algorithm is started.

[0096] Exemplarily, the embodiment of the present invention can find the minimum constant value among the three overcurrent constants and post-acceleration, and calculate the absolute value of the difference between the two points 2.8125° and 5.625° corresponding to the minimum constant value. The Sin values ​​corresponding to 2.8125° and 5.625° are 0.049067 and 0.098017. The two-point theoretical sampling values ​​are "constant value * 1.414 * 0.049067, constant value * 1.414 * 0.098017". The constant value needs to be converted into a sampling point value (refer to the conversion process of the mutation amount).

[0097] The embodiment of the present invention can add a zero-crossing point difference value estimation effective value sub-function, the return value is the telemetry value, and the parameter is the current channel number. It is called after the protection current telemetry is calculated.

[0098] Determine whether the top is eliminated: According to the current Head, find the starting position of the AD cache used to calculate the telemetry value (128-point cache), make a for loop, and loop 68 times (pay attention to the U-turn problem). If the current sampling point cache has a point value greater than 32000 (32767) or less than -28000, the top elimination counter is accumulated.

[0099] Anti-interference measures (4 consecutive differences are greater than the fixed difference): When the top-off counter is greater than or equal to 3 and less than the fixed value of 59, make a for loop according to the current Head, loop 68 times (pay attention to the U-turn problem), and loop to calculate the absolute value of the difference between the AD cache [head+n] and the AD cache [head+n+1]. When the absolute value of the difference is greater than the absolute value of the difference between the two points 2.8125° and 5.625° corresponding to the minimum fixed value, the difference is greater than the fixed value counter accumulation, and when 4 consecutive differences meet the conditions, exit the loop. When it is less than the absolute value of the difference between the two points 2.8125° and 5.625° corresponding to the minimum fixed value, the counter is cleared to 0.

[0100] Find the zero-crossing point and calculate the zero-crossing point difference: when (the top-off counter is greater than or equal to 3 and the difference is greater than the fixed value counter is greater than or equal to 4) or the top-off counter is greater than or equal to 59. According to the current Head, make a for loop and loop 68 times. When the positive and negative signs of AD buffer [head+n] and AD buffer [head+n+1] are different, and the positive sign of AD buffer [head+n] and AD buffer [head+n+1] is less than the top-off value (32000) (avoid the problem of finding the wrong zero-crossing point due to DC bias, where the positive top-off value minus a negative DC bias directly becomes a negative top-off value.

[0101] Calculate the absolute value of the difference between AD cache [head+n] and AD cache [head+n+1].

[0102] Zero-crossing point difference calculation effective value: Imax = zero-crossing point difference / (SIN2.8125-SIN0)

[0103] That is, I effective value = Imax*range / coefficient.

[0104] Inferred telemetry is only assigned to the protection telemetry value and is used to upload overcurrent event reports and fault events. No measurement telemetry is updated.

[0105] like Figure 4 As shown, for an overcurrent setting of 9A, 8.55A must be set to prevent false operation and 9.45A must be set to prevent refusal to operate. The maximum difference between adjacent sampling points obtained for an overcurrent setting of 9A is 2.4947. The maximum difference between adjacent sampling points of 8.55A is 2.37 and will not cause false operation. The maximum difference between adjacent sampling points of 9.45A has 4 differences greater than the difference corresponding to 9A. It can operate. In order to avoid false operation due to interference, a 3-cycle filter is performed.

[0106] When the secondary sampling transformer hardware is topped out, a software algorithm is used to avoid the problem of failure to operate due to sampling distortion in the power grid. It can be used as a supplement to the FFT and integration algorithms, greatly improving the reliability of the power distribution terminal equipment.

[0107] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0108] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0109] Figure 5 The schematic diagram of the structure of an overcurrent control device for a power distribution terminal provided by an embodiment of the present invention is shown. The overcurrent control device 300 includes an analog quantity acquisition module 301 and a processing module 302 .

[0110] The analog quantity acquisition module 301 is used to obtain the sampling values ​​of multiple sampling points of the transformer of the power distribution terminal.

[0111] The processing module 302 is used to determine the phase of each sampling point based on the sampling values ​​of multiple sampling points; calculate the phase and slope of each sampling point based on the phase and sampling value of each sampling point; determine the effective value of the current of the distribution terminal based on the phase and slope of each sampling point; and perform overcurrent control based on the effective value of the current of the distribution terminal.

[0112] Figure 6 Schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Figure 6 As shown, the electronic device 400 includes: a processor 401, a memory 402, and a computer program 403 stored in the memory 402 and executable on the processor 401. When the processor 401 executes the computer program 403, the steps in the above-mentioned method embodiments are implemented, for example Figure 1 Alternatively, when the processor 401 executes the computer program 403, the functions of each module / unit in the above-mentioned device embodiments are realized, for example, Figure 5 The functions of the analog quantity acquisition module 301 and the processing module 302 are shown.

[0113] Exemplarily, the computer program 403 may be divided into one or more modules / units, which are stored in the memory 402 and executed by the processor 401 to implement the present invention. The one or more modules / units may be capable of implementing a particular Figure 3 A series of computer program instruction segments with certain functions, which are used to describe the execution process of the computer program 403 in the electronic device 400. For example, the computer program 403 can be divided into Figure 5 The analog quantity acquisition module 301 and the processing module 302 are shown.

[0114] The processor 401 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0115] The memory 402 may be an internal storage unit of the electronic device 400, such as a hard disk or memory of the electronic device 400. The memory 402 may also be an external storage device of the electronic device 400, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device 400. Further, the memory 402 may also include both an internal storage unit of the electronic device 400 and an external storage device. The memory 402 is used to store the computer program and other programs and data required by the terminal. The memory 402 may also be used to temporarily store data that has been output or is to be output.

[0116] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for overcurrent control of a power distribution terminal, characterized in that: include: Obtaining sampling values ​​of multiple sampling points at the output end of the transformer corresponding to the power distribution terminal; Determine the phase of each sampling point based on the sampling values ​​of the multiple sampling points; Based on the phase and sampling value of each sampling point, the phase and slope of each sampling point are calculated; Determine the effective value of the current at the power distribution terminal based on the phase and slope in each sampling point; Overcurrent control is performed based on the effective value of the current at the power distribution terminal.

2. The overcurrent control method of the power distribution terminal according to claim 1, characterized in that: The method further comprises: Comparing the magnitude relationship between the sampling values ​​of the plurality of sampling points and the overcurrent amplitude to obtain a comparison result; If the comparison result is that the sampling values ​​of multiple consecutive sampling points are greater than the overcurrent amplitude, it is determined that the power distribution terminal is in an overcurrent state; Control the circuit breaker corresponding to the power distribution terminal to disconnect.

3. The overcurrent control method of the power distribution terminal according to claim 1, characterized in that: The determining the phase of each sampling point based on the sampling values ​​of the multiple sampling points includes: Determine a plurality of zero-crossing sampling points based on the sampling values ​​of the plurality of sampling points; Determine the phase of the zero-crossing sampling point based on the sampling values ​​of the plurality of zero-crossing sampling points; The phases of the plurality of sampling points are determined based on the phases of the sampling points of the zero-crossing point and the phase differences between the sampling points.

4. The overcurrent control method of the power distribution terminal according to claim 1, characterized in that: The method of determining the effective value of the current of the power distribution terminal based on the phase and slope of each sampling point includes: Based on the sampling value of the zero-crossing sampling point, the sampling difference between two sampling points of the multi-zero point is calculated; Determine the current peak value of the power distribution terminal based on the sampling difference between the two sampling points of the multi-zero point and the phase difference between the two sampling points of the multi-zero point; Based on the current peak value of the power distribution terminal, the effective value of the current of the power distribution terminal is determined.

5. The overcurrent control method of the power distribution terminal according to claim 1, characterized in that: The overcurrent control based on the effective value of the current of the power distribution terminal includes: If the effective value of the current of the power distribution terminal is greater than the overcurrent effective value, it is determined that the power distribution terminal is in an overcurrent state; and the circuit breaker corresponding to the power distribution terminal is controlled to disconnect.

6. The overcurrent control method of the power distribution terminal according to claim 1, characterized in that: The overcurrent control based on the effective value of the current of the power distribution terminal includes: If the effective value of the current of the power distribution terminal is greater than the effective value of the overcurrent, then the number of overcurrent times during which the effective value of the current calculated at the zero-crossing sampling point within a cycle is greater than the effective value of the overcurrent is counted; If the number of overcurrent occurrences is greater than or equal to a set number of times, it is determined that the power distribution terminal is in an overcurrent state; and the circuit breaker corresponding to the power distribution terminal is controlled to disconnect.

7. An overcurrent control device for a power distribution terminal, characterized in that: include: The analog quantity acquisition module is used to obtain the sampling values ​​of multiple sampling points at the output end of the transformer corresponding to the power distribution terminal; A processing module, configured to determine the phase of each sampling point based on the sampling values ​​of the plurality of sampling points; calculate the phase and slope of each sampling point based on the phase and sampling value of each sampling point; and determine the effective value of the current of the power distribution terminal based on the phase and slope of each sampling point; Overcurrent control is performed based on the effective value of the current at the power distribution terminal.

8. The overcurrent control device for a power distribution terminal according to claim 1, characterized in that: The processing module is further used to compare the magnitude relationship between the sampling values ​​of the multiple sampling points and the overcurrent amplitude to obtain a comparison result; If the comparison result is that the sampling values ​​of multiple consecutive sampling points are greater than the overcurrent amplitude, it is determined that the power distribution terminal is in an overcurrent state; and the circuit breaker corresponding to the power distribution terminal is controlled to be disconnected.

9. The overcurrent control device for a power distribution terminal according to claim 1, characterized in that: The processing module is specifically used to determine multiple zero-crossing sampling points based on the sampling values ​​of multiple sampling points; determine the phases of the zero-crossing sampling points based on the sampling values ​​of the multiple zero-crossing sampling points; and determine the phases of the multiple sampling points based on the phases of the zero-crossing sampling points and the phase differences between the sampling points.

10. An electronic device, characterized in that: The electronic device comprises a memory and a processor, the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute the steps of the method according to any one of claims 1 to 5.

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