Phasor correction method and device, computer device and program product

Abstract

The application is suitable for the technical field of power system frequency measurement, and provides a phasor correction method and device, computer equipment and program product. The method comprises the following steps: for three continuous sampling points, combining the real part function and the imaginary part function of the three sampling points, a first expression about the system frequency and the real part value of the three sampling points is obtained, and a second expression about the system frequency and the imaginary part value of the three sampling points is obtained; according to the similar proportion principle, the first expression and the second expression are integrated to obtain a calculation formula of the system frequency; the current system frequency is calculated by using the real part value and the imaginary part value of the three sampling points and the calculation formula of the system frequency; the real part correction coefficient and the imaginary part correction coefficient are calculated based on the average frequency f avg in a period of time and the reference frequency f0; and the real part function and the imaginary part function of the sampling points are corrected according to the real part correction coefficient and the imaginary part correction coefficient. Thus, the system frequency can be accurately and efficiently calculated, and the system phasor can be corrected.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power system frequency measurement, and particularly relates to a phasor correction method and device, a computer device and a program product. BACKGROUND

[0002] In a power system, frequency is an important parameter and an important standard for measuring power quality of the power system. In recent years, with the rapid development of power technology, the installed capacity of new energy power plants (wind power plants and photovoltaic power plants) gradually increases, and the safe and stable operation of the grid in the region where the new energy power plants are connected is increasingly concerned. As an important standard for measuring power quality, frequency is more widely concerned. Due to the operation of many nonlinear electrical devices, the voltage and current waveforms of the grid are distorted into non-sinusoidal waves, and there are a large number of harmonic components. When the harmonic content of the system reaches a certain level, it will cause damage to the normal operation of the power system. Therefore, it is of great significance to accurately measure the real-time operating frequency of the power system and correct the phase based on the frequency. SUMMARY

[0003] The embodiments of the application provide a phasor correction method, device, computer device and program product, which can accurately and efficiently calculate the frequency of the system and adjust the system phasor.

[0004] In a first aspect, the embodiments of the application provide a phasor correction method, comprising:

[0005] For three sampling points of continuous alternating voltage, a first expression about the system frequency and the real part values U R(k-1) , U Rk , U R(k+1) of the three sampling points, and a second expression about the system frequency and the imaginary part values U I(k-1) , U Ik , U I(k+1) of the three sampling points are obtained by combining the real part function and the imaginary part function of the three sampling points, and the calculation formula of the system frequency is obtained by integrating the first expression and the second expression according to the similar proportion principle.

[0006] The current system frequency is calculated by using the real part values, the imaginary part values of the three sampling points and the calculation formula of the system frequency.

[0007] The real part correction coefficient and the imaginary part correction coefficient are calculated based on the average value f avg of the frequency in a period of time and the reference frequency f0, and the real part function and the imaginary part function of the sampling points are corrected according to the real part correction coefficient and the imaginary part correction coefficient.

[0008] In a possible implementation manner of the first aspect, the first expression includes the real part values U R(k-1) , U Rk , U R(k+1) of the three sampling points.R(k-1) , U Rk , U R(k+1) and The second expression includes imaginary part values U I(k-1) , U Ik , U I(k+1) and wherein T0 is a sampling period, and N is a total number of sampling points.

[0009] Specifically, the first expression is as follows:

[0010]

[0011] The second expression is as follows:

[0012]

[0013] Specifically, the calculation formula of the system frequency is as follows:

[0014]

[0015] In another implementation manner, the calculation formula of the system frequency is as follows:

[0016]

[0017] wherein n is a size of a calculation window, and an upper limit of n is N / 8.

[0018] Specifically, the real part correction coefficient is as follows:

[0019]

[0020] The imaginary part correction coefficient is as follows:

[0021]

[0022] wherein

[0023] Exemplarily, the real part function with the correction coefficient is as follows:

[0024]

[0025] The imaginary part function with the correction coefficient is as follows:

[0026]

[0027] wherein Δf is a frequency deviation.

[0028] In a second aspect, an embodiment of the present application provides a phasor correction device, comprising:

[0029] a frequency calculation module, configured to, for three sampling points in succession of the alternating voltage, combine a real part function and an imaginary part function of the three sampling points to obtain a first expression about the system frequency and the real part values U R(k-1) , U Rk , U R(k+1) of the three sampling points, and a second expression about the system frequency and the imaginary part values U I(k-1) , U Ik , U I(k+1) of the three sampling points, integrate the first expression and the second expression according to a similar proportion principle to obtain a calculation formula of the system frequency, and calculate the current system frequency by using the real part values, the imaginary part values and the calculation formula of the system frequency of the three sampling points

[0030] a phasor correction module, configured to calculate a real part correction coefficient and an imaginary part correction coefficient based on an average value f avg of the frequency in a period of time and a reference frequency f0, and correct the real part function and the imaginary part function of the sampling points according to the real part correction coefficient and the imaginary part correction coefficient.

[0031] In a third aspect, an embodiment of the present application provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method in any one of the first aspect when executing the computer program

[0032] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, including that the computer readable storage medium stores a computer program, and the computer program is executable on a processor to implement the steps in the method in any one of the first aspect.

[0033] In a fifth aspect, an embodiment of the present application provides a computer program product, when the computer program product is executed on a computer device, the computer device executes the method in any one of the first aspect.

[0034] It can be understood that the beneficial effects of the second aspect to the fifth aspect can be referred to the related description in the first aspect, and will not be repeated here.

[0035] Compared with the prior art, the embodiment of the present application has the following beneficial effects:

[0036] The present application uses the real and imaginary part sampling values of the three-point alternating voltage, and solves the frequency in the power system by using the similar proportion principle, which can accurately and efficiently calculate the system frequency, has the advantages of small overall algorithm calculation amount, fast reaction speed and high applicability, can shorten the measurement period, and balances the instantaneity and accuracy. Moreover, the phasor correction is performed by using the calculated system frequency, which can improve the stability of the system operation. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0038] Figure 1 is a flow chart of the phasor correction method provided by an embodiment of the present application;

[0039] Figure 2 is a structural schematic diagram of the phasor correction device provided by an embodiment of the present application;

[0040] Figure 3 is a structural schematic diagram of the computer device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0041] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted in order not to obscure the description of the present application with unnecessary details.

[0042] It should be understood that when used in the specification and the appended claims of the present application, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0043] It should also be understood that the term "and / or" as used in the specification and the appended claims of the present application means any combination of one or more of the associated listed items and all possible combinations thereof.

[0044] As used in the specification and the appended claims of the present application, the term "if" can be interpreted as "when" or "upon" or "in response to a determination" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [a described condition or event] is detected" can be interpreted as meaning "upon determining" or "in response to determining" or "upon detecting [a described condition or event]" or "in response to detecting [a described condition or event]" depending on the context.

[0045] In addition, in the description of the present application and the appended claims, the terms "first", "second", "third", etc. are used only to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0046] Reference in the description of the present application to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in additional embodiments", and so on, in various places in the specification are not necessarily all referring to the same embodiment, unless otherwise specifically stated. The terms "comprising", "including", "having" and their variants mean "including but not limited to", unless otherwise specifically indicated.

[0047] At present, the methods for frequency measurement in power systems are mainly divided into two categories, namely hardware-based measurement and algorithm-based measurement, considering simplicity and real-time performance.

[0048] (1) Hardware-based measurement method

[0049] There are mainly two kinds of commonly used hardware measurement methods, one is to use a measurement tool composed of a zero-crossing comparator, a square wave forming circuit and a counter. This method directly realizes frequency measurement by using the period and frequency of the system. The other is to use a phase-locked frequency multiplication circuit to track the system frequency online. This method combines the functions of phase-locked loop (PLL) and frequency multiplier, and is a circuit that can automatically adjust the frequency and phase of the output signal to keep it synchronized with the input signal. These two hardware-based methods use the function of peripheral circuits and do not need to occupy the processor time, but for the newly added external frequency measurement circuit, it needs to occupy the computer external interrupt port, and the external device is easily affected by external factors, which has certain challenges and complexity for hardware design.

[0050] (2) Algorithm-based measurement method

[0051] The algorithm frequency measurement method uses the peak value detection, accumulation summation and period calculation method to realize the measurement of the sampling frequency through the discrete values obtained, and then adjusts the sampling interval to realize that N sampling points per cycle are evenly distributed in each power frequency cycle in time. Compared with the hardware-based measurement method, the method does not need hardware circuit design, and the calculation is simple and convenient, and easy to realize. However, it needs to occupy a certain calculation time of the processor. The traditional measurement methods based on algorithm include the voltage zero-crossing method, the CROSS method based on interpolation, the least square method, the Kalman filter method and the method based on Fourier transform. Most of these methods have large calculation amount, cannot well suppress harmonic components, and cannot well unify the calculation accuracy and speed, which will affect the actual application.

[0052] The method frequently used in power system protection and measurement and control is the Fourier algorithm, which finds the component corresponding to the fundamental frequency by calculating the frequency spectrum of the signal to obtain the system frequency. The method has the characteristics of inherent insensitivity to harmonic component time lag and high precision and fast response, and is widely used. The following is the process of the traditional Fourier frequency measurement algorithm:

[0053] The analog quantity in the known system is shown in formula (1), wherein f0 is the power frequency 50 Hz, is the initial phase.

[0054]

[0055] In the process based on the Fourier calculation formula, since the frequency deviation Δf is unknown, the Fourier algorithm can only use the power frequency orthogonal function to calculate. The function formula of the real part and the imaginary part of the full-cycle Fourier calculation. First, set the orthogonal bases sin(2πf0t) and cos(2πf0t), and the real and imaginary part orthogonal functions are u r (t)=u(t)sin(2πf0t) and u i (t)=u(t)cos(2πf0t). The integral formulas of the real and imaginary part calculations are shown in formulas (2) and (3):

[0056]

[0057]

[0058] The real and imaginary part functions are shown in formulas (4) and (5):

[0059]

[0060] If the sampling point is N sampling intervals per cycle, N sampling points can be used. Then as shown in formula (6):

[0061]

[0062] After time series calculation, formula (7) is obtained:

[0063]

[0064] The system frequency is calculated by formula (8) (9) (10).

[0065]

[0066] (3) Analysis of traditional frequency measurement method

[0067] In the traditional frequency measurement method, the hardware-based method measures the frequency by means of the hardware devices of the peripheral circuit in the process of frequency measurement. Although it does not need to occupy the time of the processor, it has certain challenges to the overall hardware design, needs to occupy the external interrupt port of the computer, and is easily affected by the zero drift of the device and the harmonic, the real-time performance cannot be guaranteed, and it is not convenient. The algorithm-based frequency measurement method is more commonly used in recent years, but this method mostly has the problems of large calculation amount and unsatisfactory real-time performance, and the algorithm is relatively complex. The most commonly used frequency measurement method nowadays is still the Fourier transform method, which is widely used based on its simple calculation and inherent insensitive harmonic characteristics. However, when the traditional Fourier transform method adopts fixed frequency sampling or the sampling frequency cannot well track the system frequency, the calculation error will be large. And when the system frequency deviates from the rated frequency, the frequency calculation error will also be large.

[0068] In summary, the current traditional frequency measurement method mainly has the following problems:

[0069] 1) In the actual frequency measurement process, it is easily affected by the external harmonic frequency, and when the system frequency deviates from the rated frequency, the frequency calculation error is large;

[0070] 2) For the phase mutation and the frequency with large volatility, the mutation cannot be detected in time and accurately, resulting in large error in frequency calculation;

[0071] 3) For the algorithm with large calculation amount, the frequency measurement period is long, which affects the response speed and real-time performance of frequency measurement.

[0072] To solve the above problems, the application provides a phasor correction method. The method is based on a new fast and high-precision frequency measurement method, realizes fast measurement of the system frequency, and uses the measured system frequency to correct the real and imaginary part functions, taking into account the instantaneousness and accuracy, and has high applicability. The new fast and high-precision frequency measurement method uses three alternating voltage sampling points real and imaginary part information, calculates the system frequency according to the similar proportion principle, has the advantages of small calculation amount, fast reaction speed and strong applicability, and is more effective and accurate for frequency measurement of new energy stations, can shorten the measurement period, and takes into account the instantaneousness and accuracy.

[0073] The technical solutions in the embodiments of the application will be described in detail below.

[0074] Figure 1 is a flowchart of the phasor correction method provided by an embodiment of the application. As shown in Figure 1 , the method comprises the following steps:

[0075] Step 101, the current system frequency is calculated by using the real part value and the imaginary part value of the three sampling points of the alternating voltage and the calculation formula of the system frequency.

[0076] In an embodiment, the real part function and the imaginary part function of the sampling point can be obtained by using the Fourier transform algorithm to determine the orthogonal basis sin(2pif0t) and cos(2pif0t) of the alternating voltage, using the Fourier transform algorithm to determine the orthogonal functions u r (t)=u(t)sin(2pif0t) and u i (t)=u(t)cos(2pif0t) of the alternating voltage, and calculating the calculation formula of the real and imaginary part functions by the Fourier transform algorithm.

[0077] In an embodiment, the calculation formula of the system frequency can be obtained by the following way:

[0078] For the three sampling points of the alternating voltage, the first expression about the system frequency and the real part values U R(k-1) , U Rk , U R(k+1) of the three sampling points, and the second expression about the system frequency and the imaginary part values U I(k-1) , U Ik , U I(k+1) of the three sampling points are obtained by combining the real part function and the imaginary part function of the three sampling points, and the calculation formula of the system frequency is obtained by integrating the first expression and the second expression according to the similar proportion principle. The similar proportion principle means that the corresponding physical quantities of all the corresponding points representing the phenomenon maintain their fixed proportional relationship.

[0079] In one example, the first expression includes real part values of three sampling points U R(k-1) , Rk , R(k+1) and The second expression includes imaginary part values of three sampling points U I(k-1) , Ik , I(k+1) and wherein T0 is a sampling period, and N is a total number of sampling points.

[0080] The specific system frequency calculation formula will be described in detail later, and will not be described here.

[0081] In step 102, real part correction coefficients and imaginary part correction coefficients are calculated based on the average frequency in a period of time and the reference frequency, and the real part function and the imaginary part function of the sampling points are corrected according to the real part correction coefficients and the imaginary part correction coefficients.

[0082] Wherein the average frequency in a period of time can be represented by f avg , and the reference frequency is represented by f0.

[0083] Based on the system frequency obtained in step 101, considering the integrity of the phase information of the real part and imaginary part functions and the accuracy of the spectral characteristic analysis, to avoid signal distortion and adapt to actual application, the phasor correction operation of the real part and imaginary part functions can be performed through step 102, which not only ensures the integrity of the signal phase information, but also improves the accurate analysis of the spectral characteristics, avoids signal distortion, and meets the needs in actual application.

[0084] The three-point frequency measurement method of step 101 can be used to obtain the frequency values corresponding to all sampling points in a period of time, in order to reduce errors, the phasor correction is performed based on the obtained frequency. In one embodiment, the average frequency f avg in a period of time can be obtained by the following method: the average frequency in a period of time is obtained by the three-point frequency measurement method, and the specific calculation formula is Wherein If N is 48, the average value of the 24 continuous frequency values obtained is used as f avg .

[0085] At this point, the description of the flowchart shown in Figure 1 is completed.

[0086] Figure 1The flowchart shown calculates the system frequency size accurately and efficiently by using the "three-point" alternating voltage real and imaginary part sampling values, solving the frequency in the power system by using the similar proportion principle, and has the advantages of small overall algorithm calculation amount, fast reaction speed, high applicability, can shorten the measurement period, and takes into account the instantaneous and accuracy. And using the calculated system frequency to correct the phasor can improve the stability of the system operation.

[0087] The system frequency calculation of step 101 in the above is illustrated as follows:

[0088] Step 101 is based on the real and imaginary part numerical information of the selected three consecutive sampling points to solve. Specifically, the following calculation process is used to solve.

[0089] In one example, the analog quantity real and imaginary part functions obtained by Fourier transform are represented as shown in equations (11) and (12):

[0090]

[0091] Let Then the real and imaginary part functions can be written as equations (13) and (14):

[0092]

[0093] Substitute the information of the sampling points on both sides into the real part function and add them to obtain equation (15):

[0094]

[0095] Through calculation, equation (15) can be arranged as shown in equation (16):

[0096]

[0097] Simplifying equation (16) gives equation (17):

[0098]

[0099] Further transforming equation (17) gives equation (18), which is the first expression described in the above embodiment:

[0100]

[0101] Similarly, for the calculation of the imaginary part function, substitute the information of the sampling points on both sides into the imaginary part function expression, and after addition operation, arrange and simplify as shown in equation (19):

[0102]

[0103] Transforming formula (19) can obtain formula (20), which is the second expression described in the above embodiment:

[0104]

[0105] According to the principle of similar proportion, integrating formula (18) and (20) can obtain formula (21):

[0106]

[0107] After formula (21) is arranged, formula (22) can be obtained, which is the calculation formula of the system frequency f:

[0108]

[0109] Wherein, a refers to arc, which is the abbreviation of the inverse trigonometric function, and acos refers to the inverse cosine function, such as cos(a)=b, then arccos(b)=a. The meaning of a in formula (21), (22), (24) and (30) is the same.

[0110] On the basis of frequency measurement based on three continuous sampling points, the calculation window of the method can be extended, and the system frequency calculation after window extension can be expressed as formula (23):

[0111]

[0112] When n approaches N, the value of N / n will be smaller, the calculation error of the inverse cosine will be smaller, and the accuracy of the measured system frequency will be relatively higher. However, due to the limitation of the difference integration formula, the difference between two angles cannot be greater than 90 degrees, so n cannot approach N infinitely, and the upper limit of n is N / 8. Therefore, based on formula (23), if a 48-point sampling method is used, that is, N=48, the value of the calculation window n is 6. When n is 6, the system frequency calculation formula is shown in formula (24):

[0113]

[0114] Wherein, i is the current time, the result of the formula calculation is smooth, and the mean value filtering can be used to process it, the calculation is simple, the effect is good, and the calculation accuracy is high.

[0115] The following illustrates the phasor correction of step 102:

[0116] After obtaining the system frequency through step 101, in an embodiment, the real part correction coefficient and the imaginary part correction coefficient can be calculated in the following way:

[0117] f avgis the average value of the frequency in a period of time, and Then, formula (25) can be obtained:

[0118]

[0119] Further, the real part and imaginary part correction coefficients can be obtained as shown in formula (26) and (27):

[0120]

[0121] For The function can be fixed by a table since the curve is constant.

[0122] After the correction coefficient is obtained, for the real part and imaginary part functions with the correction coefficient, it can be expressed as shown in formula (28) and (29):

[0123]

[0124] Then, the corrected phase angle is shown in formula (30):

[0125]

[0126] Thus far, the description of the phasor correction method provided in the present application is completed.

[0127] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0128] Corresponding to the phasor correction method described in the above embodiment, Figure 2 The structural block diagram of the phasor correction device provided in the embodiments of the present application is shown, and only the parts related to the embodiments of the present application are shown for the convenience of description.

[0129] Referring to Figure 2 The device comprises a frequency calculation module 201 and a phasor correction module 202. Wherein:

[0130] The frequency calculation module 201 is used to obtain, for three sampling points of the alternating voltage in succession, the first expression about the system frequency and the real part values U R(k-1) , U Rk , U R(k+1) of the three sampling points, and the second expression about the system frequency and the imaginary part values U I(k-1) , U Ik , U I(k+1)a second expression, integrates the first expression and the second expression according to a similar proportion principle to obtain a calculation formula of the system frequency; and calculates the current system frequency by using the real part value and the imaginary part value of the three sampling points and the calculation formula of the system frequency.

[0131] a phasor correction module 202, configured to calculate real part correction coefficients and imaginary part correction coefficients based on the average value f avg and the reference frequency f0, and correct the real part function and the imaginary part function of the sampling point according to the real part correction coefficients and the imaginary part correction coefficients.

[0132] It should be noted that the information interaction and execution process between the above-mentioned apparatuses / units / modules are based on the same concept as the method embodiments of the present application, and the specific functions and technical effects brought by them can be referred to the method embodiments part, which will not be repeated here.

[0133] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be realized in the form of hardware or software function unit. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0134] The embodiments of the present application also provide a computer device, which comprises at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor implements the steps in any of the above method embodiments when executing the computer program.

[0135] The embodiments of the present application also provide a computer readable storage medium, which stores a computer program, wherein the computer program is executable by a processor to implement the steps in any of the above method embodiments.

[0136] The embodiments of the present application provide a computer program product, which, when running on a computer device, enables the computer device to implement the steps in any of the above method embodiments.

[0137] Figure 3 A structural schematic diagram of a computer device is provided for an embodiment of the present application. As shown in the figure, the computer device of this embodiment comprises at least one processor 30 (only one is shown in the figure), a memory 31, and a computer program 32 stored in the memory 31 and executable on the at least one processor 30, wherein the processor 30 implements the steps in any of the above-mentioned various visualization programming method embodiments when executing the computer program 32. Figure 3 Figure 3 The computer device can comprise, but is not limited to, the processor 30 and the memory 31. Those skilled in the art can understand that the computer device is merely an example and does not constitute a limitation on the computer device, and can comprise more or fewer components than shown in the figure, or combine certain components, or different components, for example, can also comprise an input / output device, a network access device, etc.

[0138] The computer device can comprise, but is not limited to, the processor 30 and the memory 31. Those skilled in the art can understand that the computer device is merely an example and does not constitute a limitation on the computer device, and can comprise more or fewer components than shown in the figure, or combine certain components, or different components, for example, can also comprise an input / output device, a network access device, etc. Figure 3 The processor 30 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic components, discrete hardware components, etc. The general-purpose processor can be a microprocessor or can also be any conventional processor.

[0139] The memory 31 can be an internal storage unit of the computer device in some embodiments, for example, a hard disk or a memory of the computer device. The memory 31 can also be an external storage device of the computer device in other embodiments, for example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 31 can comprise both an internal storage unit and an external storage device of the computer device. The memory 31 is used to store an operating system, an application program, a boot loader, data, and other programs, etc., for example, program codes of the computer program, etc. The memory 31 can also be used to temporarily store data that has been output or will be output.

[0140]

[0141] ​​The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the present application can implement all or part of the processes in the above-mentioned embodiment methods through a computer program to instruct relevant hardware to complete, and the computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium at least includes any entity or device capable of carrying the computer program code to the device / computer equipment, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc. In some jurisdictions, according to legislation and patent practice, the computer readable medium can not be an electrical carrier signal and a telecommunication signal.

[0142] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0143] Those skilled in the art can appreciate that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0144] In the embodiments provided in the present application, it should be understood that the disclosed apparatus / computer equipment and methods can be implemented in other ways. For example, the apparatus / computer equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division, and actual implementation can have another division manner. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0145] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may also be distributed to multiple network units. Part or all of the units can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0146] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A phasor correction method characterized by, The current system frequency is calculated by using a calculation formula of real part values, imaginary part values of the three sampling points and the system frequency. For three sampling points continuous in alternating voltage, combining real part function and imaginary part function of three sampling points, a first expression about system frequency and real part value of three sampling points , , , and a second expression about system frequency and imaginary part value of three sampling points , , are obtained, and according to similar proportion principle, the first expression and the second expression are integrated to obtain a calculation formula of system frequency. The calculation formula of the system frequency is as follows: based on an average value of the frequency over a period of time and a reference frequency calculating a real part correction coefficient and an imaginary part correction coefficient, and correcting a real part function and an imaginary part function of the sampling point according to the real part correction coefficient and the imaginary part correction coefficient The first expression includes real part values of three sampling points , , and ; the second expression includes imaginary part values of the three sampling points , , and ; wherein, is a sampling period, and N is a total number of sampling points. The first expression is: ; The second expression is: ; The system frequency is calculated as follows: .

2. The method of claim 1, wherein, Wherein, n is the size of the calculation window, and the upper limit of n is N / 8. ； The real part correction coefficient is:

3. The method of claim 1, wherein, The imaginary part correction coefficient is: ； The real part function with the correction coefficient is: ； wherein .

4. The method of claim 3, wherein, The imaginary part function with the correction coefficient is: ； The current system frequency is calculated by using a calculation formula of real part values, imaginary part values of the three sampling points and the system frequency. ； wherein is the frequency deviation.

5. A phasor correction device characterized by comprising: The processor realizes the method of any one of claims 1 to 4 when executing the computer program. The frequency calculation module is used to obtain the real part value of the system frequency relative to the three sampling points by combining the real and imaginary parts of the functions at the three sampling points, for three consecutive sampling points of the AC voltage. , , The first expression, and the imaginary part of the system frequency with respect to the three sampling points. , , The second expression is used to integrate the first and second expressions according to the principle of similarity ratio, so as to obtain the formula for calculating the system frequency; When the computer program product runs on the computer device, the computer device executes the method of any one of claims 1 to 4. a phasor correction module configured to correct a real part function and an imaginary part function of the sampling point based on an average value of the frequency in a period of time and the reference frequency calculate a real part correction coefficient and an imaginary part correction coefficient, and correct the real part function and the imaginary part function of the sampling point according to the real part correction coefficient and the imaginary part correction coefficient The first expression includes real part values of three sampling points , , and ; the second expression includes imaginary part values of the three sampling points , , and ; wherein, is a sampling period, and N is a total number of sampling points. The first expression is: ; The second expression is: ; The system frequency is calculated as follows: .

6. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, ​ 7. A computer program product, characterised in that, ​

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