CN109307795B - Waveform point detection method and device - Google Patents
Waveform point detection method and device Download PDFInfo
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- CN109307795B CN109307795B CN201811458030.1A CN201811458030A CN109307795B CN 109307795 B CN109307795 B CN 109307795B CN 201811458030 A CN201811458030 A CN 201811458030A CN 109307795 B CN109307795 B CN 109307795B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/02—Measuring effective values, i.e. root-mean-square values
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
- G01R19/0053—Noise discrimination; Analog sampling; Measuring transients
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/12—Measuring rate of change
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
Abstract
The embodiment of the application provides a waveform point detection method and a waveform point detection device. The method comprises the following steps: sampling to obtain the instantaneous value waveform of the three-phase voltage; calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and determining a target analysis phase based on the effective values of the sampling points of each phase; obtaining sampling point serial numbers corresponding to a starting point and an end point of voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase; and obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase. The method is based on the characteristic that the change rate of the effective value of the voltage after the voltage sag occurs and ends changes violently, finds the starting point and the ending point of the voltage sag by using the change rate of the effective value of each sampling point, and calculates to obtain a corresponding angle. Therefore, the accuracy of finding the voltage dip waveform point can be improved.
Description
Technical Field
The application relates to the technical field of power systems, in particular to a waveform point detection method and device.
Background
Power electronics are used in modern industrial production and are particularly sensitive to disturbances in the quality of the electrical energy. Once these devices cannot work normally or stop working due to voltage sag, the whole production line is affected, which may cause damages such as device shutdown, product rejection, tool damage, and production period extension. Therefore, the voltage sag has an influence on various devices and industries, and it is necessary to study the start and stop points of the voltage sag.
The start and stop of the voltage sag are generally determined by an effective threshold method at present, namely, waveform points of the voltage sag are searched by the effective threshold method. The effective threshold method is to set a threshold value, and then waveform point detection is performed according to the threshold value. In the existing standard, the threshold is specified to be 90% of the steady-state voltage effective value, which is actually 90% of the steady-state voltage effective value of the phase since only the phase with the most severe voltage sag is considered. For the most severe phase of sag, when a sampling point of which the effective value is lower than the threshold value is detected, the algorithm is triggered, and the first point of which the effective value is lower than the threshold value is output as the sampling point of the starting point; after the waveform starting point is detected, when the sampling point of which the effective value is greater than the threshold value is detected, the algorithm is triggered again, the effective value is recovered to the first point above the threshold value and is output as the sampling point of the end point.
The effective threshold method takes 90% of the effective value of the steady-state voltage as a threshold value, and the threshold value is used as a basis for detecting the waveform point, but the position of the real waveform point should be the position where the voltage instantaneous value temporarily drops and ends the temporary drop, which is obviously different from the point with the threshold value of 90%, so that the accuracy of the waveform point obtained by the effective threshold method is not high.
Disclosure of Invention
In order to overcome the above-mentioned deficiencies in the prior art, an embodiment of the present application provides a waveform point detection method and apparatus, which can find a starting point and an ending point where a voltage sag occurs by using an effective value change rate of each sampling point based on a characteristic that an effective value change rate of a voltage after the voltage sag occurs and ends changes drastically, and calculate a corresponding angle, thereby improving an accuracy of finding a waveform point where the voltage sag occurs.
In a first aspect, an embodiment of the present application provides a waveform point detection method, including:
sampling to obtain the instantaneous value waveform of three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point serial number;
calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and determining a target analysis phase based on the effective values of the sampling points of each phase;
obtaining sampling point serial numbers corresponding to a starting point and an end point of voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase;
and obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase.
In a second aspect, embodiments of the present application provide an apparatus for detecting a point on a wave, the apparatus comprising:
the sampling module is used for sampling and acquiring the instantaneous value waveform of the three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point serial number;
the determining module is used for calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase and determining a target analysis phase based on the effective value of each sampling point of each phase;
the acquisition module is used for acquiring sampling point serial numbers corresponding to a starting point and an end point of voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase;
and the angle calculation module is used for obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase.
Compared with the prior art, the method has the following beneficial effects:
the embodiment of the application provides a waveform point detection method and a waveform point detection device. Firstly, sampling to obtain the instantaneous value waveform of three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point number. And then calculating an effective value of each sampling point of each phase voltage according to the instantaneous voltage value of each sampling point of each phase, and determining which phase of the three phases is used as a target analysis phase based on the effective value. After the target analysis phase is determined, according to the change rate of the effective value corresponding to each sampling point of the target analysis phase, the sampling points corresponding to the voltage sag starting point and the voltage sag ending point are found from the plurality of sampling points of the phase, and the sampling point numbers corresponding to the starting point and the voltage sag ending point are obtained. And finally, obtaining the angle of the starting point and the angle of the ending point of the voltage sag according to the sampling point numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase. Therefore, based on the characteristic that the change rate of the effective value of the voltage after the voltage sag occurs and ends changes violently, the change rate of the effective value of each sampling point is used for finding the starting point and the ending point of the voltage sag, and corresponding angles are obtained through calculation, so that the accuracy of finding voltage sag waveform points is improved.
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic structural diagram of a detection apparatus provided in an embodiment of the present application.
Fig. 2 is a schematic flow chart of a waveform point detection method according to an embodiment of the present application.
Fig. 3 is a flowchart illustrating sub-steps included in step S130 in fig. 2.
Fig. 4 is a schematic diagram of obtaining a first target sampling point and a second target sampling point according to an embodiment of the present application.
Fig. 5 is a flowchart illustrating sub-steps included in step S140 in fig. 2.
FIG. 6 is a voltage dip waveform point diagram according to an embodiment of the present application.
FIG. 7 is a block diagram of an apparatus for detecting a point on a wave according to an embodiment of the present disclosure.
Icon: 100-a detection device; 110-a memory; 120-a memory controller; 130-a processor; 200-wave spot detection means; 210-a sampling module; 220-a determination module; 230-an obtaining module; 240-angle calculation module.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a detection apparatus 100 according to an embodiment of the present disclosure. The detection device 100 in the embodiment of the present application may be, but is not limited to, a desktop computer, a server, and the like. As shown in fig. 1, the detection apparatus 100 includes: memory 110, memory controller 120, and processor 130.
The elements of the memory 110, the memory controller 120 and the processor 130 are electrically connected directly or indirectly to realize data transmission or interaction. For example, the components may be electrically connected to each other via one or more communication buses or signal lines. Stored in the memory 110 is a point on wave detection device 200, said point on wave detection device 200 comprising at least one software functional module which can be stored in the form of software or firmware (firmware) in said memory 110. The processor 130 executes various functional applications and data processing, i.e., implements the point on wave detection method in the embodiments of the present application, by executing software programs and modules stored in the memory 110, such as the point on wave detection device 200 in the embodiments of the present application.
The Memory 110 may be, but is not limited to, a Random Access Memory (RAM), a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Read-Only Memory (EPROM), an electrically Erasable Read-Only Memory (EEPROM), and the like. The memory 110 is used for storing a program, and the processor 130 executes the program after receiving the execution instruction. Access to the memory 110 by the processor 130 and possibly other components may be under the control of the memory controller 120.
The processor 130 may be an integrated circuit chip having signal processing capabilities. The Processor 130 may be a general-purpose Processor including a Central Processing Unit (CPU), a Network Processor (NP), and the like. But may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
It will be appreciated that the configuration shown in FIG. 1 is merely illustrative and that the detection apparatus 100 may also include more or fewer components than shown in FIG. 1, or have a different configuration than shown in FIG. 1. The components shown in fig. 1 may be implemented in hardware, software, or a combination thereof.
Referring to fig. 2, fig. 2 is a schematic flow chart of a waveform point detection method according to an embodiment of the present application. The method is applied to the detection device 100. The specific flow of the waveform point detection method is described in detail below.
And step S110, sampling and acquiring the instantaneous value waveform of the three-phase voltage.
In the present embodiment, first, instantaneous value waveforms of three-phase voltages, that is, an instantaneous value waveform of an a-phase voltage, an instantaneous value waveform of a B-phase voltage, and an instantaneous value waveform of a C-phase voltage are obtained through sampling. The instantaneous waveform of each phase voltage includes a plurality of sampling points. The waveform period of the instantaneous value corresponds to a sampling period, and the number of sampling points in each sampling period is multiple. After a sampling point is obtained, information of the sampling point is obtained, and the information of the sampling point can include an instantaneous voltage value, a sampling moment, a sampling point serial number and the like of the sampling point. Optionally, the sampling point sequence numbers are named according to the sequence of the sampling times, that is, according to the sampling sequence, for example, there are sampling points a, b, and c according to the sampling times, then the sampling point sequence number of the sampling point a may be 1, the sampling point sequence number of the sampling point b may be 2, and the sampling point sequence number of the sampling point c may be 3.
And step S120, calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and determining a target analysis phase based on the effective values of the sampling points of each phase.
In this embodiment, only the phase with the most severe voltage sag is considered. After the instantaneous value waveform of each phase is obtained, an effective value (i.e., an effective voltage value) is calculated according to the instantaneous voltage value of each sampling point in the instantaneous value waveform. And then, selecting the sampling point with the minimum effective value in all the sampling points (including the sampling point of the phase A, the sampling point of the phase B and the sampling point of the phase C) through comparison, and taking a phase corresponding to the sampling point as a target analysis phase. For example, if the effective value of one sampling point of the a phase is the sampling point with the minimum effective value among all the sampling points, the a phase is the target analysis phase, and the a phase is the phase with the most severe voltage sag among the three phases.
In the present embodiment, the effective value of each sampling point can be calculated in the following manner.
For the sampling points after the first sampling period, a sliding window of one period is taken from each sampling point in the past, and then a root mean square value is calculated according to the instantaneous voltage value of each sampling point in the period to serve as the effective value of the sampling point. As an implementation manner, each sampling point after the first sampling period is sequentially used as a stopping point of a calculation period, and a root mean square value is calculated according to an instantaneous voltage value of each sampling point in the calculation period and a first preset formula, wherein the root mean square value is an effective value of the stopping point of the calculation period. By the method, the effective value of each sampling point after the first sampling period can be obtained. Wherein the number of sampling points in the calculation period is the same as the number of sampling points in the sampling period.
Optionally, in this embodiment, the first preset formula is:
wherein, Vrms(n) samples with a sample number nAnd the effective value of the point, V (i) represents the instantaneous voltage value of the sampling point with the sampling point serial number i, and wd represents the number of the sampling points in one sampling period. The number of sampling points in one sampling period is the same as the number of sampling points in one calculation period, namely wd.
Only the effective value of each sampling point after the first sampling period can be calculated by the method. In actual analysis, the effective value of each sampling point in the first sampling period needs to be reserved. Optionally, in an implementation manner of this embodiment, the valid values of all sampling points in the first sampling period are set to the same normal valid value, so that the valid values of all sampling points can be obtained. Namely, the effective value of each sampling point in each phase of the first sampling period is obtained based on a second preset formula, wherein the second preset formula is as follows:
Vrms(n)＝Vrms(wd+1) n＝1,2,...,wd (2)
the following illustrates how to calculate the valid value of each sampling point after the first sampling period.
Assume that there are 10 sample points in a sample period, and there are sample points 1, 2, 3, 4, … in sample order. In calculating the effective value of sample point 11, sample point 11 is taken as the stop point of a calculation period, which includes sample points 2, 3, …, 11. Based on formula (1), firstly calculating the square of the instantaneous voltage value of a sampling point 2, the square of the instantaneous voltage value of a sampling point 3 and the square of the instantaneous voltage value of a sampling point 11 of …, and calculating the sum of the 10 squares; dividing the sum by the number of sampling points 10 in a sampling period to obtain a quotient; and finally, the quotient is set aside, and the effective value of the sampling point 11 is obtained. The calculation of the effective values for the other samples after the first sample is the same as described above.
Step S130, obtaining sampling point serial numbers corresponding to a starting point and an end point of the voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase.
Referring to fig. 3, fig. 3 is a flowchart illustrating sub-steps included in step S130 in fig. 2. Step S130 may include substep S131, substep S132, and substep S133.
And a substep S131 of calculating the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase.
In this embodiment, the time difference between two adjacent sampling points is fixed and is Δ t according to the sampling order. After the target analysis phase is determined, each sampling point of the target analysis phase may be grouped into a sequence of significant values according to a sampling order (or sampling time). And then calculating the difference between the effective values of two adjacent sampling points in the effective value sequence, dividing the difference by the sampling time difference of the two sampling points, and taking the absolute value of the obtained quotient as the effective value change rate of the sampling point.
Optionally, the step of calculating an effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase includes: and calculating to obtain the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase, the time interval between adjacent sampling points and a third preset formula. Wherein the third preset formula is as follows:
wherein M isrms(n) represents the rate of change of the effective value of a sampling point having a sampling point number n, Δ t represents the time interval between adjacent sampling points, Vrms(n) represents the effective value of the sampling point with the sampling point number n.
And a substep S132 of comparing the effective value change rate of each sampling point with a preset threshold value in sequence according to the sampling sequence, taking the sampling point with the first effective value change rate larger than the preset threshold value as a first target sampling point, and taking the sampling point with the last effective value change rate larger than the preset threshold value as a second target sampling point.
And a substep S133, taking the sampling point number of the first target sampling point as the sampling point number corresponding to the starting point, and taking the difference between the sampling point number of the first target sampling point and the number of sampling points in one sampling period as the sampling point number corresponding to the ending point.
In this embodiment, a threshold value may be preset as the preset threshold value. Optionally, the preset threshold is x × Vrms(1). In one embodiment of this embodiment, x is 5. According to the sampling sequence, selecting a first sampling point with an effective value change rate larger than the preset threshold value as a first target sampling point, and selecting a last sampling point with an effective value change rate larger than the preset threshold value as a second target sampling point. The first target sampling point is the position of the starting point of the voltage sag, and the sampling point corresponding to the number of the sampling points in one period subtracted from the number of the sampling points of the second target sampling point is the position of the ending point of the voltage sag.
The first sampling point and the last sampling point of which the effective value change rate is greater than the preset threshold value respectively correspond to points at which the effective value just begins to change and ends to change. The point where the effective value starts to change is indeed the starting point, but the point where the effective value ends to change is not the ending point. The effective value in this embodiment is to take a sliding window forward for each sampling point n of the original voltage waveform, and take the root mean square value of the instantaneous voltage values of all sampling points in the sliding window. The sampling point of the previous cycle on the instantaneous value waveform corresponding to the point at which the effective value found by this method is completely restored is actually already the normal voltage. Therefore, the point where the effective value changes at the end is located one period after the real end point, and the sampling point number obtained by subtracting the number of the sampling points in one period from the sampling point number of the found second target sampling point is the sampling number of the real end point.
Referring to fig. 4, fig. 4 is a schematic diagram of obtaining a first target sampling point and a second target sampling point according to an embodiment of the present application. According to the preset threshold, the sampling point serial numbers of the sampling points of the target analysis phase and the effective value change rate, the sampling point (first target sampling point) with the first effective value change rate larger than the preset change rate can be obtained, and the sampling point (second target sampling point) with the first effective value change rate larger than the preset change rate can be obtained.
Step S140, obtaining an angle of the starting point and an angle of the ending point where the voltage sag occurs based on the sampling point numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase.
In this embodiment, the voltage sag waveform points can be divided into a starting point and an ending point, which are the corresponding phase angle values of the voltage at the point where the sag occurs and the sag ends, respectively. The starting point corresponds to the phase angle of the voltage before the voltage sag occurs, measured with reference to the last positive zero crossing of the voltage before the sag, this point being the beginning of the transition phase from the voltage before the sag to the sag voltage. Similarly, the end point is the phase angle of the voltage measured with reference to the first positive zero crossing of the voltage after the voltage sag occurs, which is the end of the transient phase from the voltage sag to the voltage after the sag.
Referring to fig. 5 and fig. 6, fig. 5 is a flowchart illustrating sub-steps included in step S140 in fig. 2, and fig. 6 is a schematic diagram illustrating voltage dip waveform points according to an embodiment of the present disclosure. Step S140 may include sub-step S141, sub-step S142, sub-step S143, and sub-step S144.
And a substep S141, taking a sampling point closest to the starting point among the sampling points of the target analysis phase as an upward zero-crossing point as a first reference sampling point according to the starting point and the instantaneous value waveform of the target analysis phase.
Wherein the first reference sample point is located before the start point in a sampling order.
And a substep S142, calculating an angle of the starting point based on the serial numbers of the sampling points of the first reference sampling point and the serial numbers of the sampling points of the starting point.
And a substep S143, taking a closest one of the sampling points of the target analysis phase to the end point as an upward zero-crossing point as a second reference sampling point according to the end point and the instantaneous value waveform of the target analysis phase.
Wherein the second reference sampling point is located after the end point in a sampling order.
And a substep S144, calculating the angle of the end point based on the serial numbers of the sampling points of the second reference sampling point and the serial numbers of the sampling points of the end point.
In this embodiment, according to the instantaneous value waveforms of the starting point and the target analysis phase, one upward zero-crossing point, which is closest to the starting point and the ending point respectively, in the sampling points of the target analysis phase is obtained as a reference sampling point, and the angle of the sampling points is 0 °. Wherein the reference sample point is also a sample point. And then calculating the angles of the starting point and the ending point on the basis of the reference sampling point to be used as the starting point and the ending point of the voltage sag.
As shown in fig. 6, assuming that there are 100 sampling points in a sampling period, the sampling point number of the starting point is 524, and the sampling point number of the upward zero crossing point (i.e., the first reference sampling point) corresponding to the starting point is 455, the angle of the starting point is:
therefore, by calculating the effective value change rate of each sampling point, the position of the voltage sag waveform point can be accurately found by utilizing the mode according to the characteristics that the effective value change rate is increased violently after the sag occurs and is reduced to be close to zero after the sag is finished. And the validity of the method is verified after a large amount of simulation and actual measurement data detection. Therefore, the accuracy of obtaining the voltage sag duration can be guaranteed by the method.
The voltage sag is a phenomenon that the effective value of the power supply voltage suddenly drops and rises again in a short time and returns to normal. The duration of this phenomenon in power systems is mostly between 0.1s and 1.5 s. Residual voltage is often used in describing voltage sag, and the residual voltage refers to the minimum value of the effective value of the voltage in the process of voltage sag.
Referring to fig. 7, fig. 7 is a block diagram illustrating an exemplary embodiment of a waveform point detection apparatus 200 according to the present disclosure. The waveform point detection device 200 may include a sampling module 210, a determination module 220, an obtaining module 230, and an angle calculation module 240.
And the sampling module 210 is used for sampling and acquiring the instantaneous value waveform of the three-phase voltage.
The information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point serial number.
In this embodiment, the sampling module 210 is configured to execute step S110 in fig. 2, and the detailed description about the sampling module 210 may refer to the description of step S110 in fig. 2.
And the determining module 220 is configured to calculate an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and determine the target analysis phase based on the effective value of each sampling point of each phase.
In this embodiment, the determining module 220 calculates an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and the manner of determining the target analysis phase based on the effective values of the sampling points of each phase includes:
sequentially taking each sampling point after the first sampling period as a stop point of a calculation period, and calculating to obtain an effective value of each sampling point after the first sampling period according to an instantaneous voltage value of each sampling point in the calculation period and a first preset formula, wherein the first preset formula is as follows:
wherein, Vrms(n) represents the effective value of the sampling point with the sampling point serial number n, V (i) represents the instantaneous voltage value of the sampling point with the sampling point serial number i, wd represents the number of the sampling points in one sampling period, and the number of the sampling points in one sampling period is the same as the number of the sampling points in one calculation period;
obtaining an effective value of each sampling point in each phase of the first sampling period based on a second preset formula, wherein the second preset formula is as follows:
Vrms(n)＝Vrms(wd+1) n＝1,2,...,wd
and comparing the effective values of all sampling points of the three-phase voltage, and taking one phase corresponding to the minimum effective value as the target analysis phase.
In this embodiment, the determining module 220 is configured to execute step S120 in fig. 2, and the specific description about the determining module 220 may refer to the description about step S120 in fig. 2.
The obtaining module 230 is configured to obtain, according to the effective value change rate corresponding to each sampling point of the target analysis phase, sampling point sequence numbers corresponding to a starting point and an ending point of the voltage sag.
In this embodiment, the manner for the obtaining module 230 to obtain the serial numbers of the sampling points corresponding to the starting point and the ending point of the voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase includes:
calculating the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase;
according to the sampling sequence, sequentially comparing the effective value change rate of each sampling point with a preset threshold value, taking the sampling point with the first effective value change rate larger than the preset threshold value as a first target sampling point, and taking the sampling point with the last effective value change rate larger than the preset threshold value as a second target sampling point;
and taking the sampling point serial number of the first target sampling point as the sampling point serial number corresponding to the starting point, and taking the difference between the sampling point serial number of the first target sampling point and the number of the sampling points in one sampling period as the sampling point serial number corresponding to the end point.
Optionally, the manner of calculating, by the obtaining module 230, the effective value variation rate of each sampling point according to the effective value of each sampling point of the target analysis phase includes:
calculating to obtain the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase, the time interval between adjacent sampling points and a third preset formula, wherein the third preset formula is as follows:
wherein M isrms(n) represents the rate of change of the effective value of a sampling point with a sampling point number n, and Δ t represents the time interval between adjacent sampling pointsPartition, Vrms(n) represents the effective value of the sampling point with the sampling point number n.
In this embodiment, the obtaining module 230 is configured to execute step S130 in fig. 2, and the detailed description about the obtaining module 230 may refer to the description of step S130 in fig. 2.
And the angle calculation module 240 is configured to obtain an angle of the starting point and an angle of the ending point where the voltage sag occurs based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase.
In this embodiment, the manner of obtaining the angle of the starting point and the angle of the ending point where the voltage sag occurs by the angle calculation module 240 based on the sampling point numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase includes:
according to the starting point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the starting point and is an upward zero crossing point in the sampling points of the target analysis phase as a first reference sampling point, wherein the first reference sampling point is positioned in front of the starting point according to the sampling sequence;
calculating to obtain the angle of the starting point based on the serial numbers of the sampling points of the first reference sampling point and the serial numbers of the sampling points of the starting point;
according to the end point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the end point and is an upward zero crossing point in the sampling points of the target analysis phase as a second reference sampling point, wherein the second reference sampling point is positioned behind the end point according to the sampling sequence;
and calculating to obtain the angle of the end point based on the sampling point serial number of the second reference sampling point and the sampling point serial number of the end point.
In the present embodiment, the angle calculating module 240 is configured to execute step S140 in fig. 2, and the detailed description about the angle calculating module 240 may refer to the description of step S140 in fig. 2.
Embodiments of the present application also provide a readable storage medium having stored thereon executable computer instructions that, when executed by a processor, implement the method of waveform point detection.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In summary, the present application provides a method and an apparatus for detecting waveform points. Firstly, sampling to obtain the instantaneous value waveform of three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point number. And then calculating an effective value of each sampling point of each phase voltage according to the instantaneous voltage value of each sampling point of each phase, and determining which phase of the three phases is used as a target analysis phase based on the effective value. After the target analysis phase is determined, according to the change rate of the effective value corresponding to each sampling point of the target analysis phase, the sampling points corresponding to the voltage sag starting point and the voltage sag ending point are found from the plurality of sampling points of the phase, and the sampling point numbers corresponding to the starting point and the voltage sag ending point are obtained. And finally, obtaining the angle of the starting point and the angle of the ending point of the voltage sag according to the sampling point numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase. Therefore, based on the characteristic that the change rate of the effective value of the voltage after the voltage sag occurs and ends changes violently, the change rate of the effective value of each sampling point is used for finding the starting point and the ending point of the voltage sag, and corresponding angles are obtained through calculation, so that the accuracy of finding voltage sag waveform points is improved.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (8)
1. A method of waveform point detection, the method comprising:
sampling to obtain the instantaneous value waveform of three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point serial number;
calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase, and determining a target analysis phase based on the effective values of the sampling points of each phase;
obtaining sampling point serial numbers corresponding to a starting point and an end point of voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase;
obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase;
the step of obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase comprises the following steps:
according to the starting point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the starting point and is an upward zero crossing point in the sampling points of the target analysis phase as a first reference sampling point, wherein the first reference sampling point is positioned in front of the starting point according to the sampling sequence;
calculating to obtain the angle of the starting point based on the serial numbers of the sampling points of the first reference sampling point and the serial numbers of the sampling points of the starting point;
according to the end point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the end point and is an upward zero crossing point in the sampling points of the target analysis phase as a second reference sampling point, wherein the second reference sampling point is positioned behind the end point according to the sampling sequence;
and calculating to obtain the angle of the end point based on the sampling point serial number of the second reference sampling point and the sampling point serial number of the end point.
2. The method of claim 1, wherein the step of calculating an effective value for each sampling point from the instantaneous voltage values of each sampling point for each phase and determining the target analysis phase based on the effective values of the sampling points for each phase comprises:
sequentially taking each sampling point after the first sampling period as a stop point of a calculation period, and calculating to obtain an effective value of each sampling point after the first sampling period according to an instantaneous voltage value of each sampling point in the calculation period and a first preset formula, wherein the first preset formula is as follows:
wherein, Vrms(n) represents the effective value of the sampling point with the sampling point serial number n, V (i) represents the instantaneous voltage value of the sampling point with the sampling point serial number i, wd represents the number of the sampling points in one sampling period, and the number of the sampling points in one sampling period is the same as the number of the sampling points in one calculation period;
obtaining an effective value of each sampling point in each phase of the first sampling period based on a second preset formula, wherein the second preset formula is as follows:
Vrms(n)＝Vrms(wd+1)n＝1,2,...,wd
and comparing the effective values of all sampling points of the three-phase voltage, and taking one phase corresponding to the minimum effective value as the target analysis phase.
3. The method according to claim 1, wherein the step of obtaining the serial numbers of the sampling points corresponding to the starting point and the ending point of the voltage sag according to the change rate of the effective value corresponding to each sampling point of the target analysis phase comprises:
calculating the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase;
according to the sampling sequence, sequentially comparing the effective value change rate of each sampling point with a preset threshold value, taking the sampling point with the first effective value change rate larger than the preset threshold value as a first target sampling point, and taking the sampling point with the last effective value change rate larger than the preset threshold value as a second target sampling point;
and taking the sampling point serial number of the first target sampling point as the sampling point serial number corresponding to the starting point, and taking the difference between the sampling point serial number of the first target sampling point and the number of the sampling points in one sampling period as the sampling point serial number corresponding to the end point.
4. The method according to claim 3, wherein the step of calculating the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase comprises:
calculating to obtain the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase, the time interval between adjacent sampling points and a third preset formula, wherein the third preset formula is as follows:
wherein M isrms(n) represents the rate of change of the effective value of a sampling point having a sampling point number n, Δ t represents the time interval between adjacent sampling points, Vrms(n) represents the effective value of the sampling point with the sampling point number n.
5. An apparatus for waveform point detection, the apparatus comprising:
the sampling module is used for sampling and acquiring the instantaneous value waveform of the three-phase voltage, wherein the information of each sampling point in the instantaneous value waveform of each phase voltage comprises an instantaneous voltage value and a sampling point serial number;
the determining module is used for calculating an effective value of each sampling point according to the instantaneous voltage value of each sampling point of each phase and determining a target analysis phase based on the effective value of each sampling point of each phase;
the acquisition module is used for acquiring sampling point serial numbers corresponding to a starting point and an end point of voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase;
the angle calculation module is used for obtaining the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase;
the mode that the angle calculation module obtains the angle of the starting point and the angle of the ending point of the voltage sag based on the sampling point serial numbers corresponding to the starting point and the ending point and the instantaneous value waveform of the target analysis phase comprises the following steps:
according to the starting point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the starting point and is an upward zero crossing point in the sampling points of the target analysis phase as a first reference sampling point, wherein the first reference sampling point is positioned in front of the starting point according to the sampling sequence;
calculating to obtain the angle of the starting point based on the serial numbers of the sampling points of the first reference sampling point and the serial numbers of the sampling points of the starting point;
according to the end point and the instantaneous value waveform of the target analysis phase, taking a sampling point which is closest to the end point and is an upward zero crossing point in the sampling points of the target analysis phase as a second reference sampling point, wherein the second reference sampling point is positioned behind the end point according to the sampling sequence;
and calculating to obtain the angle of the end point based on the sampling point serial number of the second reference sampling point and the sampling point serial number of the end point.
6. The apparatus of claim 5, wherein the determining module calculates an effective value of each sampling point from the instantaneous voltage values of each sampling point of each phase, and the determining the target analysis phase based on the effective values of the sampling points of each phase comprises:
sequentially taking each sampling point after the first sampling period as a stop point of a calculation period, and calculating to obtain an effective value of each sampling point after the first sampling period according to an instantaneous voltage value of each sampling point in the calculation period and a first preset formula, wherein the first preset formula is as follows:
wherein, Vrms(n) represents the effective value of the sampling point with the sampling point serial number n, V (i) represents the instantaneous voltage value of the sampling point with the sampling point serial number i, wd represents the number of the sampling points in one sampling period, and the number of the sampling points in one sampling period is the same as the number of the sampling points in one calculation period;
obtaining an effective value of each sampling point in each phase of the first sampling period based on a second preset formula, wherein the second preset formula is as follows:
Vrms(n)＝Vrms(wd+1)n＝1,2,...,wd
and comparing the effective values of all sampling points of the three-phase voltage, and taking one phase corresponding to the minimum effective value as the target analysis phase.
7. The apparatus of claim 5, wherein the manner for the obtaining module to obtain the serial numbers of the sampling points corresponding to the starting point and the ending point of the voltage sag according to the effective value change rate corresponding to each sampling point of the target analysis phase comprises:
calculating the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase;
according to the sampling sequence, sequentially comparing the effective value change rate of each sampling point with a preset threshold value, taking the sampling point with the first effective value change rate larger than the preset threshold value as a first target sampling point, and taking the sampling point with the last effective value change rate larger than the preset threshold value as a second target sampling point;
and taking the sampling point serial number of the first target sampling point as the sampling point serial number corresponding to the starting point, and taking the difference between the sampling point serial number of the first target sampling point and the number of the sampling points in one sampling period as the sampling point serial number corresponding to the end point.
8. The apparatus of claim 7, wherein the obtaining module calculates the effective value variation rate of each sampling point according to the effective value of each sampling point of the target analysis phase by:
calculating to obtain the effective value change rate of each sampling point according to the effective value of each sampling point of the target analysis phase, the time interval between adjacent sampling points and a third preset formula, wherein the third preset formula is as follows:
wherein M isrms(n) represents the rate of change of the effective value of a sampling point having a sampling point number n, Δ t represents the time interval between adjacent sampling points, Vrms(n) represents the effective value of the sampling point with the sampling point number n.
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| CN112116013B (en) * | 2020-09-24 | 2021-07-20 | 四川大学 | Voltage sag event normalization method based on waveform characteristics |
| CN113176437B (en) * | 2021-03-26 | 2022-10-25 | 东南大学溧阳研究院 | Method and device for rapidly detecting voltage abnormity |
| CN113917252A (en) * | 2021-09-10 | 2022-01-11 | 联芯集成电路制造(厦门)有限公司 | Arc defect detection method for semiconductor machine |
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