CN112415329A - Voltage sag identification method and device, computer equipment and storage medium - Google Patents
Voltage sag identification method and device, computer equipment and storage medium Download PDFInfo
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Abstract
The application relates to a voltage sag identification method and device, computer equipment and a storage medium. The method comprises the following steps: when voltage sag of a power supply network is detected, current and voltage sampling is carried out on the power supply network within a preset time length to obtain multiple groups of sampling data, multiple voltage sag related parameters such as voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation are calculated according to the multiple groups of sampling data, the obtained multiple voltage sag related parameters are compared with corresponding preset threshold values respectively to obtain a comparison result, and a voltage sag identification result is determined according to the comparison result. By adopting the method, the global process of the voltage sag can be better characterized by carrying out collaborative analysis and judgment on various parameters, and the problem of high misjudgment rate of the voltage sag identification method is solved.
Description
Technical Field
The present disclosure relates to the field of voltage sag technologies, and in particular, to a method and an apparatus for identifying a voltage sag, a computer device, and a storage medium.
Background
With the development of scientific technology and the large-scale application of sensitive power utilization equipment in industrial production, the voltage quality requirement of a power supply system is higher and higher. Voltage sag is a common problem of power quality, and is generally caused by faults of a power grid and a power transformation facility or sudden large changes of loads, and identification of the voltage sag refers to identification of a generation cause of the voltage sag according to detected voltage sag data characteristics, and is one of important evaluation indexes of the voltage sag. Accurate identification of voltage sag not only facilitates evaluation of regional power distribution systems and selection of reasonable governing measures, but also can serve as an important basis for coordination disputes among power supply departments, users and equipment suppliers in the power market environment. Therefore, research on a series of problems such as monitoring, analysis and solution of voltage sag disturbance is more important.
In the conventional technology, voltage sag is identified through a voltage effective value, and the voltage sag is simply identified according to the magnitude of the sag amplitude caused by different voltage sag and whether voltage jump is generated at the end of the sag.
However, in the conventional method, the amplitude characteristic of the voltage effective value and the voltage jump are used as characteristic quantities to identify the voltage sag, and the reference parameter for analysis and judgment is too single, so that the problem of high misjudgment rate of the voltage sag may exist.
Disclosure of Invention
In view of the above, there is a need to provide a voltage sag identification method, apparatus, computer device and storage medium capable of identifying the cause of voltage sag generation when a voltage sag occurs in a power supply network.
A method of voltage sag identification, the method comprising:
if voltage sag of a power supply network is detected, sampling current and voltage of the power supply network within a preset time length to obtain multiple groups of sampling data, wherein each group of sampling data comprises a voltage value and a current value at a corresponding sampling moment;
calculating a voltage slope difference, a duration, a voltage effective value amplitude deviation and a current effective value amplitude deviation according to the multiple groups of sampling data, wherein the voltage slope difference is used for representing the slope change characteristics of voltage at the beginning of voltage sag and at the end of voltage sag, the duration is used for representing the duration from the beginning of voltage sag to the end of voltage sag, the voltage effective value amplitude deviation is used for representing the amplitude change of the voltage in the voltage sag process, and the current effective value amplitude deviation is used for representing the amplitude change of the current in the voltage sag process;
comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and determining a voltage sag identification result according to the comparison result.
According to the voltage sag identification method, when a power supply network has voltage sag, a plurality of relevant influence parameters representing the voltage sag process are calculated by collecting the voltage value and the current value of the power supply network at the sampling moment, and the specific reason of the voltage sag is obtained according to the influence parameters and the corresponding preset threshold. According to the method, multi-parameter analysis and judgment are carried out through a multi-voltage sag process under the actual condition, the overall process of voltage sag can be better represented, the error rate of analysis and judgment is effectively reduced, and therefore the judgment error caused by only analyzing the amplitude of the voltage effective value in the prior art can be reduced.
In one embodiment, the comparison result includes a first value and a second value, the first value is used for indicating that the comparison result is greater than the corresponding preset threshold value, and the second value is used for indicating that the comparison result is less than the corresponding preset threshold value; the determining a voltage sag identification result according to the comparison result includes:
adding the voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with a first numerical value or a second numerical value obtained by comparing the corresponding preset threshold values respectively, and determining a voltage sag identification result by using the added sum value;
when the sum is larger than a preset identification threshold value, starting the induction motor or switching on and off the transformer as a voltage sag identification result;
and when the sum is less than or equal to the preset identification threshold, taking the short circuit as a voltage sag identification result.
In one embodiment, the voltage slope difference is calculated according to a first formula:
the first formula is:
wherein the content of the first and second substances,
k1、k2respectively representing the voltage slopes at the beginning of the voltage sag and at the end of the sag, U0Indicating the voltage value at the beginning of a voltage sag, UsIndicating the voltage value at the end of the voltage sag, UnRepresents the minimum value of voltage during the voltage sag, t0Indicating the time at which the voltage sag begins, tsIndicating the time at the end of the voltage sag, tnRepresenting the time at which the voltage is at its minimum during the voltage sag.
In one embodiment, the duration is calculated according to a second formula:
the second formula is:
Δt＝ts-t0
wherein, t0Indicating the time at which the voltage sag begins, tsIndicating the time at which the voltage sag ended.
In one embodiment, the voltage virtual value amplitude deviation is calculated according to a third formula:
the third formula is:
wherein, U0Indicating the voltage value at the beginning of a voltage sag, UsIndicating the voltage value at the end of the voltage sag.
In one embodiment, the current effective value amplitude deviation is calculated according to a fourth formula:
the fourth formula is:
wherein, I0Indicates the value of the current at the beginning of the voltage sag, ImRepresenting the maximum current value during a voltage sag.
In one embodiment, before sampling the current and the voltage of the power supply network for a preset time period if a voltage sag of the power supply network is detected, the method further includes:
acquiring the voltage amplitude of the power supply network;
if the voltage amplitude is larger than or equal to a preset voltage sag threshold value, determining that no voltage sag occurs in the power supply network;
if the voltage amplitude is smaller than the voltage sag threshold value, determining that voltage sag occurs in the power supply network;
wherein the obtaining of the voltage amplitude of the power supply network comprises:
collecting a voltage signal of the power supply network;
performing signal conditioning on the acquired voltage signal;
converting the conditioned voltage signal into a voltage digital signal;
and obtaining the voltage amplitude value by performing generalized hyperbolic S conversion on the obtained voltage digital signal.
In this embodiment, a method for collecting the voltage of the power supply network and preliminarily judging whether the voltage sag occurs in the power supply network is provided, so that the accuracy of judging whether the voltage sag occurs in the power supply network by the voltage sag identification method is improved.
A voltage sag identification device, the device comprising:
the acquisition module is used for acquiring the current value and the voltage value of the power supply network;
the detection module is used for detecting whether voltage sag occurs in the power supply network;
the processing module is used for calculating voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation according to the multiple groups of sampling data;
the comparison module is used for comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and the display module is used for displaying the voltage sag identification result.
A computer device comprising a memory and a processor, the memory storing a computer program, the processor implementing the following steps when executing the computer program:
collecting the current value and the voltage value of a power supply network;
detecting whether a voltage sag occurs in a power supply network;
calculating voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation according to multiple groups of sampling data;
comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and displaying the voltage sag identification result.
A computer-readable storage medium, on which a computer program is stored which, when executed by a processor, carries out the steps of:
collecting the current value and the voltage value of a power supply network;
detecting whether a voltage sag occurs in a power supply network;
calculating voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation according to multiple groups of sampling data;
comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and displaying the voltage sag identification result.
Drawings
FIG. 1 is a flow diagram illustrating a voltage sag identification method according to an embodiment;
FIG. 2 is a flow chart illustrating a voltage sag identification method according to an embodiment;
FIG. 3 is a block diagram of a voltage sag identification device in accordance with one embodiment;
FIG. 4 is a block diagram of a voltage sag identification device according to another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The voltage sag identification method provided by the application can be implemented in a corresponding terminal by a computer program written in a programming language, wherein the terminal can be but is not limited to various personal computers, notebook computers, smart phones, tablet computers and portable wearable devices.
The method comprises the steps of presetting the duration of current and voltage sampling of a power supply network when the terminal detects that voltage sag occurs in the power supply network, and presetting multi-parameter thresholds in the method, wherein the multi-parameter thresholds specifically comprise a voltage slope difference delta k, a duration delta t, a voltage effective value amplitude deviation delta U and a current effective value amplitude deviation delta I.
When the detection module of the terminal detects that the voltage dip occurs in the power supply network, the specific basis for detecting that the voltage dip occurs in the power supply network by the terminal detection module comprises the following steps: the terminal acquires the voltage amplitude of the power supply network, and when the voltage amplitude is lower than a preset voltage sag threshold value, the voltage sag is determined; also comprises setting voltage sag at a certain time for the terminal artificially.
In one embodiment, as shown in fig. 1, a method for identifying a voltage sag is provided, comprising the following steps:
s101, when the detection module of the terminal detects that the voltage dip occurs in the power supply network, the specific basis for detecting that the voltage dip occurs in the power supply network by the terminal detection module comprises the following steps: the terminal acquires the voltage amplitude of the power supply network, and when the voltage amplitude is lower than a preset voltage sag threshold value, the voltage sag is determined; also comprises setting voltage sag at a certain time for the terminal artificially.
The terminal comprises a processing module, an acquisition module and a processing module, wherein the acquisition module in the terminal samples current and voltage of a power supply network within a preset time period to obtain a plurality of groups of sampling data, and the terminal acquires a current voltage value and a current value from the power supply network through the acquisition module and inputs the current voltage value and the current value into the processing module within the preset time period.
The signal acquisition of terminal includes 3 voltage transformers and 3 current transformers at least, gathers power supply network three-phase voltage and current respectively, and voltage transformer and current transformer output are the clamp circuit that the diode constitutes, avoid causing the destruction that voltage transformer and current transformer output signal surpass the input range of AD converter and cause because of electric wire netting voltage fluctuation or accident.
S102, converting the obtained voltage value and current value into digital quantity at intervals through a data converter in the processing module to obtain the voltage value, the current value and the time formationSample data set (U) ofi,Ii,ti) In the present embodiment, the data converter is preferably an a/D converter.
And a data processing device in the processing module performs data processing on the obtained sampling data group, and specifically comprises the steps of obtaining a voltage slope difference delta k, a duration delta t, a voltage effective value amplitude deviation delta U and a current effective value amplitude deviation delta I according to voltage slope processing, duration processing, voltage effective value amplitude deviation processing and current effective value amplitude deviation processing.
The voltage slope processing specifically comprises: according to the voltage value U at the beginning of the voltage sag0Voltage value U at the end of voltage sagsMinimum value of voltage U in voltage sagnTime t at the beginning of the voltage sag0Time t at the end of the voltage sagsTime t at minimum voltage during voltage sagn。
The voltage slope k at the beginning of the voltage sag is obtained1And the voltage slope k at the end of the voltage sag2Wherein
And calculating the voltage slope difference delta k according to a first formula:
the duration processing specifically includes: according to the time t when the voltage sag begins0And time t at the end of the voltage sags，
And calculating the duration time delta t according to a second formula:
Δt＝ts-t0 (2)
the voltage effective value amplitude deviation processing specifically comprises the following steps: according to the voltage value U at the beginning of the voltage sag0And voltage value U at the end of voltage sags。
And calculating to obtain the voltage effective value amplitude deviation delta U according to a third formula:
the current effective value amplitude deviation processing specifically comprises the following steps: according to the current value I at the beginning of the voltage sag0Maximum current value during voltage sag Im。
And calculating to obtain the current effective value amplitude deviation delta I according to a fourth formula:
after the voltage slope difference delta k, the duration delta t, the voltage effective value amplitude deviation delta U and the current effective value amplitude deviation delta I are obtained by processing a plurality of groups of sampling data, the obtained values are input into a comparison module for processing.
S103, comparing the obtained voltage slope difference delta k, the duration delta t, the voltage effective value amplitude deviation delta U and the current effective value amplitude deviation delta I with corresponding preset threshold values in a comparison module respectively,
the comparison module comprises a voltage slope difference threshold memory, a duration threshold memory, a voltage effective value amplitude deviation threshold memory and a current effective value amplitude deviation threshold memory, and the preset voltage slope difference threshold, the duration threshold, the voltage effective value amplitude deviation threshold and the current effective value amplitude deviation threshold are stored in the memories.
The comparison module also comprises a voltage slope difference comparator, a duration time delta t comparator, a voltage effective value amplitude deviation comparator and a current effective value amplitude deviation comparator;
specifically, the voltage slope difference comparator compares the input voltage slope difference Δ k with a voltage slope difference threshold preset in the voltage slope difference threshold memory to obtain a comparison result.
The duration comparator compares the input duration delta t with a duration threshold preset in the duration threshold memory to obtain a comparison result.
And the voltage effective value amplitude deviation threshold comparator compares the input voltage effective value amplitude deviation delta U with a voltage effective value amplitude deviation threshold preset in the voltage effective value amplitude deviation threshold storage to obtain a comparison result.
And the current effective value amplitude deviation threshold comparator compares the input current effective value amplitude deviation delta I with a current effective value amplitude deviation threshold preset in a current effective value amplitude deviation threshold storage to obtain a comparison result.
And S104, determining the identification result of the voltage sag according to the comparison result. The method comprises the following steps:
the obtained comparison result comprises a first numerical value and a second numerical value, the first numerical value is used for indicating that the first numerical value is larger than the corresponding preset threshold value, and the second numerical value is used for indicating that the second numerical value is smaller than the corresponding preset threshold value.
In the voltage slope difference comparator, when the input voltage slope difference delta k is larger than a preset voltage slope difference threshold value, a first numerical value is output; otherwise, outputting a second value. In the present embodiment, the voltage slope difference threshold may be set to 0.05.
In the duration comparator, when the input duration delta t is greater than a preset duration threshold, a first numerical value is output; otherwise, outputting a second value. In the present embodiment, the duration threshold may be set to 0.1.
In the voltage effective value amplitude deviation threshold comparator, when the input voltage effective value amplitude deviation delta U is greater than a preset voltage effective value amplitude deviation threshold, the fact that the power supply network does not belong to voltage sag and does not output results is shown; otherwise, outputting a second value. In this embodiment, the voltage effective value amplitude deviation threshold may be set to 0.8.
In the current effective value amplitude deviation threshold comparator, when the input current effective value amplitude deviation delta I is larger than a preset current effective value amplitude deviation threshold, a second numerical value is output; otherwise, outputting the first numerical value. In this embodiment, the current effective value magnitude deviation threshold may be set to 4.
And accumulating all the obtained first numerical values and second numerical values to obtain an accumulation result, and judging the specific reason of the voltage sag according to the accumulation result.
In one embodiment, the first value may be set to 1, the second value may be set to 0, and the accumulated result is obtained, if the accumulated result is greater than 2, the cause of the voltage sag is the induction motor start or the transformer trip; if the accumulated result is less than or equal to 2, the cause of the voltage sag is short circuit.
And finally, displaying the specific reason of the voltage sag through a display module, wherein the means of displaying comprises but not limited to displaying images through a screen or displaying sounds through voice.
In one embodiment, when a voltage sag in the power supply network is detected, before sampling the current and voltage of the power supply network for a preset time period, as shown in fig. 2, the method further includes:
obtaining a voltage amplitude of a power supply network, wherein obtaining the amplitude of the power supply network comprises:
s201, collecting voltage signals of a power supply network, and conditioning the collected voltage signals, wherein the conditioning specifically comprises filtering higher harmonics and noise of the input voltage signals by using a low-pass filter, outputting analog square wave signals through a voltage zero-crossing comparator, and finally stabilizing the voltage by a voltage stabilizing circuit to output standard voltage square wave signals;
s202, converting the obtained standard voltage square wave signal into a voltage digital signal through an A/D converter, wherein the A/D converter specifically adopts an AD7606 chip, 16-bit 8-channel simultaneous sampling can be realized, and the sampling frequency can reach 200KHz at most;
s203, performing generalized hyperbolic S transformation on the obtained voltage digital signal, wherein the discretization form of the generalized hyperbolic S transformation is as follows:
in the formula, the values of j, m and N are respectively 0,1,2 and 3 … … N-1, N is the number of sampling points, and T is the sampling time;
the generalized hyperbolic S transformation is carried out by adopting a generalized hyperbolic window function expression as follows:
wherein, alpha and beta are respectively forward taper and backward taper; λ is the curvature of the window function, which is in the same dimension as time; mu is a window width adjusting factor and represents a selection mode of the generalized hyperbolic S transformation window width; gamma is a window width change rate adjustment factor and represents the change rate of the window width; t represents time, f represents frequency; the time-frequency resolution and the change mode of the generalized hyperbolic S transform can be flexibly adjusted by changing the parameters mu and gamma.
In the method, firstly, the voltage signal is subjected to generalized hyperbolic S transformation to obtain an S transformation complex matrix; performing modulus calculation on each element in the S-transform complex matrix to obtain an S-mode matrix; and solving the voltage amplitude according to the S-mode matrix. The generalized hyperbolic S transform in the discrete form can be realized by means of a fast fourier algorithm and a convolution theorem, which is very fast, and the specific S transform process in this embodiment is as follows:
1) fast Fourier transform of a computed voltage digital signal
2) Fast Fourier transform G for calculating generalized hyperbolic window function under each frequencyHS(m,n)；
3) For frequency n, shift spectrum
To
4) By frequency, sample point calculation
5) Calculating the inverse fast Fourier transform of B (m, n) to obtain S transform spectrum
S204, finally comparing the obtained voltage amplitude with a preset voltage sag threshold, in this embodiment, comparing the obtained voltage amplitude with a sag threshold of 0.9UN, and if the voltage amplitude is greater than or equal to 0.9UN, no voltage sag occurs; if the voltage magnitude is less than 0.9UN, a voltage sag occurs.
In one embodiment, as shown in fig. 3, there is provided a voltage sag identification device, including: collection module, detection module, processing module, comparison module and show module, wherein:
the acquisition module is used for acquiring the current value and the voltage value of the power supply network;
the detection module is used for detecting whether voltage sag occurs in the power supply network;
the processing module is used for calculating voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation according to the multiple groups of sampling data;
the comparison module is used for comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and the display module is used for displaying the voltage sag identification result.
In another embodiment, as shown in fig. 4, the voltage sag identification apparatus further includes:
the preprocessing module is used for conditioning the acquired voltage signals, converting the conditioned voltage signals into voltage digital signals, and obtaining voltage amplitude values through generalized hyperbolic S conversion of the obtained voltage digital signals;
and the pre-judgment module is used for comparing the voltage amplitude obtained by the pre-processing module with a voltage sag threshold value and judging whether a voltage sag occurs in the power supply network.
The specific preprocessing module comprises a signal conditioning device,
the signal conditioning device comprises a low-pass filter, a voltage zero-crossing comparator and a voltage stabilizing circuit, wherein the low-pass filter is used for filtering higher harmonics and noise of an input voltage signal, the voltage zero-crossing comparator is used for outputting an analog square wave signal, and the voltage stabilizing circuit is used for stabilizing voltage and outputting the voltage;
and the A/D conversion device is used for converting the obtained standard voltage square wave signal into an AD7606 chip of a voltage digital signal through an A/D converter.
And the S conversion device is used for carrying out generalized hyperbolic S conversion on the obtained voltage digital signal to obtain a voltage amplitude.
The pre-judging module comprises a device for comparing the voltage amplitude obtained by the pre-processing module with a voltage sag threshold value and judging whether a voltage sag occurs in the power supply network, when the pre-judging module judges that the voltage sag occurs in the current power supply network, the acquisition module and the detection module are directly conducted, and data acquired by the acquisition module are directly input into the detection module.
For the specific limitations of the voltage sag identification device, reference may be made to the limitations of the voltage sag identification method in the above, and details thereof are not repeated herein. The modules in the voltage sag identification device can be wholly or partially implemented by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for identifying a voltage sag, the method comprising:
if voltage sag of a power supply network is detected, sampling current and voltage of the power supply network within a preset time length to obtain multiple groups of sampling data, wherein each group of sampling data comprises a voltage value and a current value at a corresponding sampling moment;
calculating a voltage slope difference, a duration, a voltage effective value amplitude deviation and a current effective value amplitude deviation according to the multiple groups of sampling data, wherein the voltage slope difference is used for representing the slope change characteristics of voltage at the beginning of voltage sag and at the end of voltage sag, the duration is used for representing the duration from the beginning of voltage sag to the end of voltage sag, the voltage effective value amplitude deviation is used for representing the amplitude change of the voltage in the voltage sag process, and the current effective value amplitude deviation is used for representing the amplitude change of the current in the voltage sag process;
comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and determining a voltage sag identification result according to the comparison result.
2. The method of claim 1, wherein the comparison result comprises a first value and a second value, the first value is used for indicating that the comparison result is greater than a corresponding preset threshold value, and the second value is used for indicating that the comparison result is less than the corresponding preset threshold value; the determining a voltage sag identification result according to the comparison result includes:
adding the voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with a first numerical value or a second numerical value obtained by comparing the corresponding preset threshold values respectively, and determining a voltage sag identification result by using the added sum value;
wherein the determining the voltage sag identification result using the added sum comprises:
when the sum is larger than a preset identification threshold value, starting the induction motor or switching on or off the transformer as a voltage sag identification result;
and when the sum is less than or equal to the preset identification threshold, taking the short circuit as a voltage sag identification result.
3. The method of claim 1, wherein the voltage slope difference is calculated according to a first formula:
the first formula is:
wherein the content of the first and second substances,
k1、k2respectively representing the voltage slopes at the beginning of the voltage sag and at the end of the sag, U0Indicating the voltage value at the beginning of a voltage sag, UsIndicating the voltage value at the end of the voltage sag, UnRepresents the minimum value of voltage during the voltage sag, t0Indicating the time at which the voltage sag begins, tsIndicating the time at the end of the voltage sag, tnRepresenting the time at which the voltage is at its minimum during the voltage sag.
4. The method of claim 1, wherein the duration is calculated according to a second formula:
the second formula is:
Δt＝ts-t0
wherein, t0Indicating the time at which the voltage sag begins, tsIndicating the time at which the voltage sag ended.
5. The method of claim 1, wherein the voltage virtual value magnitude deviation is calculated according to a third formula:
the third formula is:
wherein, U0Indicating the voltage value at the beginning of a voltage sag, UsIndicating the voltage value at the end of the voltage sag.
6. The method according to claim 1, wherein the current virtual value magnitude deviation is calculated according to a fourth formula:
the fourth formula is:
wherein, I0Indicates the value of the current at the beginning of the voltage sag, ImRepresenting the maximum current value during a voltage sag.
7. The method of claim 1, wherein if a voltage sag in a power supply network is detected, prior to sampling current and voltage in the power supply network for a predetermined period of time, the method further comprises:
acquiring the voltage amplitude of the power supply network;
if the voltage amplitude is larger than or equal to a preset voltage sag threshold value, determining that no voltage sag occurs in the power supply network;
if the voltage amplitude is smaller than the voltage sag threshold value, determining that voltage sag occurs in the power supply network;
wherein the obtaining of the voltage amplitude of the power supply network comprises:
collecting a voltage signal of the power supply network;
performing signal conditioning on the acquired voltage signal;
converting the conditioned voltage signal into a voltage digital signal;
and obtaining the voltage amplitude value by performing generalized hyperbolic S conversion on the obtained voltage digital signal.
8. An apparatus for identifying voltage sags, the apparatus comprising:
the acquisition module is used for acquiring the current value and the voltage value of the power supply network;
the detection module is used for detecting whether voltage sag occurs in the power supply network;
the processing module is used for calculating voltage slope difference, duration, voltage effective value amplitude deviation and current effective value amplitude deviation according to the multiple groups of sampling data;
the comparison module is used for comparing the obtained voltage slope difference, the duration, the voltage effective value amplitude deviation and the current effective value amplitude deviation with corresponding preset thresholds respectively to obtain comparison results;
and the display module is used for displaying the voltage sag identification result.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the method of any of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 7.
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