Harmonic current determination method and device, computer equipment, storage medium and program product

Abstract

The invention relates to a harmonic current determination method and device, computer equipment, a storage medium and a program product. The method comprises the steps of firstly obtaining sine and cosine signals with the same single-phase voltage in a power grid system and power grid three-phase current in the power grid system, then carrying out data processing on the power grid three-phase current based on the sine and cosine signals to obtain fundamental frequency three-phase current of the power grid system, and finally, according to the power grid three-phase current and the fundamental frequency three-phase current, carrying out data processing on the fundamental frequency three-phase current. And determining the harmonic current of the power grid system. According to the harmonic current determination method provided by the invention, data processing is performed on the three-phase current of the power grid through the sine and cosine signals, so that the problem of inaccurate harmonic current detection caused by inaccurate phase locking of a phase-locked loop under the condition that the three-phase current of the power grid side is unbalanced or a direct current component exists is solved, and thus the determination accuracy of the harmonic current is improved.

Description

Technical Field

[0001] The present application relates to the field of power grid electric energy technology, and in particular to a method, device, computer equipment, storage medium and program product for determining harmonic current. Background Art

[0002] In the power system, with the access of large-scale nonlinear loads, there is a large harmonic content in the grid current, which seriously affects the normal operation of the power system.

[0003] In order to better control the harmonic current on the grid side, it is necessary to determine the harmonic current more accurately. At present, the common methods for determining harmonic current include adaptive detection method, Fourier transform detection method, wavelet transform and neural network detection method. In addition, the commonly used harmonic current detection method in practice is the IP-IQ detection method based on instantaneous reactive power theory, because it has a small amount of calculation and high accuracy. However, the current IP-IQ detection method based on instantaneous reactive power theory will have calculation errors due to the imbalance of the grid or the presence of DC components in the phase-locked loop.

[0004] Therefore, the harmonic current determined by the above method has the problem of low accuracy. Summary of the invention

[0005] Based on this, it is necessary to provide a method, device, computer equipment, storage medium and program product for determining harmonic currents of a power grid system, which can accurately determine the harmonic currents of the power grid system, in response to the above technical problems.

[0006] In a first aspect, the present application provides a method for determining harmonic current, comprising:

[0007] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0008] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0009] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0010] In one embodiment, the three-phase current of the power grid is processed based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system, including:

[0011] Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0012] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are processed by coordinate dimension upgrading to obtain the fundamental frequency three-phase current.

[0013] In one embodiment, the method further comprises:

[0014] The instantaneous active current and the instantaneous reactive current are filtered respectively to obtain the base frequency instantaneous active current and the base frequency instantaneous reactive current;

[0015] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are transformed into coordinates by dimension-upgrading to obtain the base frequency three-phase current, including:

[0016] Based on the sine and cosine signals, the base-frequency instantaneous active current and the base-frequency instantaneous reactive current are subjected to coordinate dimension-upgrading transformation to obtain the base-frequency three-phase current.

[0017] In one embodiment, the filtering process includes notch filter filtering process.

[0018] In one embodiment, the obtaining of the sine and cosine signals with the same single-phase voltage in the power grid system includes:

[0019] Obtaining the three-phase voltage of the power grid in the power grid system;

[0020] The three-phase voltage of the power grid is subjected to coordinate transformation to obtain sine and cosine signals.

[0021] In one embodiment, the coordinate conversion process includes dimension reduction coordinate conversion process, orthogonal process, positive and negative sequence process and dimension increase coordinate conversion process. The coordinate conversion process of the three-phase voltage of the power grid is performed to obtain the sine and cosine signals, including:

[0022] Performing dimension reduction coordinate transformation on the three-phase voltage of the power grid to obtain a first voltage and a second voltage;

[0023] Performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals;

[0024] Performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component;

[0025] The first positive sequence component and the second positive sequence component are processed by dimension-raising coordinate transformation to obtain sine and cosine signals.

[0026] In a second aspect, the present application also provides a device for determining harmonic current, comprising:

[0027] An acquisition module, used for acquiring the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0028] A processing module, used for performing data processing on the three-phase current of the power grid based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system;

[0029] The determination module is used to determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current.

[0030] In a third aspect, the present application further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0031] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0032] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0033] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0034] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0035] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0036] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0037] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0038] In a fifth aspect, the present application further provides a computer program product, including a computer program, which implements the following steps when executed by a processor:

[0039] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0040] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0041] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0042] The above-mentioned method, device, computer equipment, storage medium and program product for determining harmonic current first obtain the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system, then process the three-phase current of the power grid based on the sine and cosine signals to obtain the fundamental frequency three-phase current of the power grid system, and finally determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current. The above-mentioned method for determining harmonic current processes the three-phase current of the power grid through sine and cosine signals to solve the problem of inaccurate harmonic current detection caused by inaccurate phase-locked loop when the three-phase current on the power grid side is unbalanced or there is a DC component, thereby improving the accuracy of determining harmonic current. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0044] FIG1 is a diagram showing an application environment of a method for determining harmonic current in one embodiment;

[0045] Figure 2 is a flow chart of a method for determining harmonic current in one embodiment;

[0046] Figure 3 is a flow chart of a method for determining harmonic current in another embodiment;

[0047] Figure 4 is a flow chart of a method for determining harmonic current in another embodiment;

[0048] Figure 5 is a flow chart of a method for determining harmonic current in another embodiment;

[0049] Figure 6 is a flow chart of a method for determining harmonic current in another embodiment;

[0050] Figure 7 is a flow chart of a method for determining harmonic current in another embodiment;

[0051] Figure 8 A schematic diagram of a harmonic current detection process in one embodiment;

[0052] Fig. 9 A schematic diagram of an orthogonal processing circuit in one embodiment;

[0053] FIG10 is a structural block diagram of a device for determining harmonic current in one embodiment;

[0054] FIG. 11 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0056] In the power system, with the access of large-scale nonlinear loads, there is a large harmonic content in the grid current, which seriously affects the normal operation of the power system.

[0057] In order to better control the harmonic current on the grid side, it is necessary to determine the harmonic current more accurately. At present, the common methods for determining harmonic current include adaptive detection method, Fourier transform detection method, wavelet transform and neural network detection method. However, the sensitivity of the adaptive detection method is too low to be suitable for the detection of rapid control of harmonic current. The computational complexity of the Fourier transform detection method is high and it is not suitable for real-time detection. The detection methods based on wavelet transform and neural network are not yet mature in practical applications.

[0058] In addition, the commonly used harmonic current detection method in practice is the IP-IQ detection method based on the instantaneous reactive power theory, because it has a small amount of calculation and high accuracy. However, the current IP-IQ detection method based on the instantaneous reactive power theory will have calculation errors due to the unbalanced power grid or the presence of a DC component in the phase-locked loop. Therefore, the harmonic current determined by the above method has the problem of low accuracy. This application aims to solve this problem.

[0059] After the above introduction to the background technology of the method for determining harmonic current provided by the embodiment of the present application, the implementation environment involved in the method for determining harmonic current provided by the embodiment of the present application will be briefly described below. The method for determining harmonic current provided by the embodiment of the present application can be applied in the implementation environment as shown in Figure 1. The implementation environment includes a server 104, and the server 104 can be implemented with an independent server 104 or a server cluster composed of multiple servers 104, and the data storage system 102 can store the data that the server 104 needs to process. The data storage system 102 can be integrated on the server 104, or it can be placed on the cloud or other network servers. Among them, the data storage system 102 can obtain the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system, and the server 104 can obtain the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system from the data storage system 102, and determine the harmonic current of the power grid system based on the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system.

[0060] In other possible implementations, the method for determining harmonic current provided in the embodiment of the present application can also be applied to a terminal, which can be, but is not limited to, various personal computers, laptops, smart phones, tablet computers, IoT devices, and portable wearable devices. IoT devices can be smart speakers, smart TVs, smart air conditioners, smart car-mounted devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc.

[0061] After introducing the application scenarios of the method for determining harmonic current provided by the embodiments of the present application, the following focuses on introducing the method for determining harmonic current described in the present application.

[0062] In one embodiment, Figure 2 As shown, a method for determining harmonic current is provided, and the method is applied to the server in FIG1 as an example for description, and includes the following steps:

[0063] S201, obtaining sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current in the power grid system.

[0064] In an embodiment of the present application, a second-order generalized integral phase-locked loop with a DC eliminator can be used to obtain sine and cosine signals with the same single-phase voltage in the power grid system, and the three-phase current of the power grid system can be measured based on a zero flux circuit.

[0065] S202: Based on the sine and cosine signals, data processing is performed on the three-phase current of the power grid to obtain the base frequency three-phase current of the power grid system.

[0066] Among them, data processing includes coordinate dimensionality reduction processing, filtering processing and coordinate dimensionality increase processing.

[0067] In an embodiment of the present application, after obtaining the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system, data processing can be performed on the three-phase current of the power grid based on the sine and cosine signals to obtain the baseband three-phase current of the power grid system.

[0068] S203. Determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current.

[0069] In the embodiment of the present application, after the three-phase current of the power grid and the fundamental frequency three-phase current are obtained as described above, the difference between the three-phase current of the power grid and the fundamental frequency three-phase current can be used as the harmonic current of the power grid system.

[0070] The method for determining harmonic current provided in the embodiment of the present application first obtains the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system, then processes the three-phase current of the power grid based on the sine and cosine signals to obtain the fundamental frequency three-phase current of the power grid system, and finally determines the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current. The above-mentioned method for determining harmonic current processes the three-phase current of the power grid through sine and cosine signals to solve the problem of inaccurate harmonic current detection caused by inaccurate phase-locked loop when the three-phase current on the power grid side is unbalanced or there is a DC component, thereby improving the accuracy of determining harmonic current.

[0071] In one embodiment, Figure 2 Based on the embodiment shown, the process of obtaining the base frequency three-phase current of the power grid system can be described as follows: Figure 3 As shown, the above S202 "processing the three-phase current of the power grid based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system" includes:

[0072] S301. Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system.

[0073] In the embodiment of the present application, after the sine and cosine signals and the three-phase current of the power grid are obtained as described above, the three-phase current of the power grid can be subjected to coordinate dimension reduction processing based on the sine and cosine signals to obtain the instantaneous active current and instantaneous reactive current of the power grid system.

[0074] Optionally, the sine and cosine signals calculated by the phase-locked loop can be used to perform coordinate reduction transformation on the three-phase current signal of the power grid to obtain the instantaneous active current and instantaneous reactive current , refer to the following formula (1), the instantaneous active current and instantaneous reactive current It can be expressed as:

[0075]

[0076] in, are two different coordinate conversion coefficients, , and That is the three-phase current signal of the power grid, and That is, the sine and cosine signals with the same single-phase voltage in the power grid system.

[0077] S302: Based on the sine and cosine signals, the instantaneous active current and the instantaneous reactive current are subjected to coordinate dimension-upgrading processing to obtain a fundamental frequency three-phase current.

[0078] In an embodiment of the present application, after the sine and cosine signals, instantaneous active current and instantaneous reactive current are obtained as mentioned above, the instantaneous active current and instantaneous reactive current can be processed by coordinate dimension upscaling based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system.

[0079] Optionally, the sine and cosine signals calculated by the phase-locked loop can be used to perform coordinate dimension-upgrading processing on the instantaneous active current and instantaneous reactive current obtained above, so as to obtain the base-frequency three-phase current of the power grid system. Referring to the following formula (2), the base-frequency three-phase current of the power grid system can be expressed as:

[0080]

[0081] in, are two different coordinate conversion coefficients, , and That is the fundamental frequency three-phase current signal, and That is, the sine and cosine signals with the same single-phase voltage in the power grid system, and They are the instantaneous active current of the fundamental frequency and the instantaneous reactive current of the fundamental frequency. It should be noted that the instantaneous active current of the fundamental frequency and base frequency instantaneous reactive current The method for obtaining may refer to the following step S303.

[0082] The method for acquiring the fundamental frequency three-phase current provided in the embodiment of the present application performs coordinate dimension reduction processing and coordinate dimension increase processing on the three-phase current of the power grid in sequence based on sine and cosine signals to obtain the fundamental frequency three-phase current, thereby greatly improving the accuracy of acquiring the fundamental frequency three-phase current.

[0083] In one embodiment, Figure 3 Based on the embodiment shown, Figure 4 As shown, the above method also includes:

[0084] S303 , filtering the instantaneous active current and the instantaneous reactive current respectively to obtain a base-frequency instantaneous active current and a base-frequency instantaneous reactive current.

[0085] In an embodiment of the present application, after the instantaneous active current and the instantaneous reactive current are obtained as described above, the instantaneous active current and the instantaneous reactive current can be filtered respectively to obtain the filtered baseband instantaneous active current and the filtered baseband instantaneous reactive current.

[0086] Optionally, the instantaneous active current and the instantaneous reactive current can be filtered by using the NF-LPF filtering algorithm to obtain the filtered baseband instantaneous active current and the filtered baseband instantaneous reactive current. The NF-LPF filtering algorithm is composed of a notch filter and a low-pass filter in cascade. The transfer function of the notch filter with harmonic selectivity when filtering the instantaneous active current and the instantaneous reactive current is shown in the following formula (3):

[0087]

[0088] Where s is the input signal frequency, is the depth of the notch filter, The larger the value, the stronger the anti-interference ability of the notch filter is, but the response time is longer. The smaller the value, the weaker the anti-interference ability of the notch filter, but the shorter the response time. In the embodiment of the present application, The selected value of is 0.707, The value of , is the notch frequency, which can be selected according to the grid side requirements.

[0089] It should be noted that the NF-LPF filtering algorithm NF-LPF can filter the instantaneous active current and the instantaneous reactive current separately by cascading multiple notch-filters and low-pass filters of the required frequency to obtain the baseband instantaneous active current and the baseband instantaneous reactive current.

[0090] The above S302 “based on the sine and cosine signals, performing coordinate dimension-upgrading conversion on the active current and the instantaneous reactive current to obtain the base-frequency three-phase current” includes:

[0091] S302 . Based on the sine and cosine signals, perform coordinate up-dimensional transformation on the base-frequency active current and the base-frequency instantaneous reactive current to obtain the base-frequency three-phase current.

[0092] In an embodiment of the present application, after the sine and cosine signals, instantaneous active current and instantaneous reactive current are obtained as mentioned above, the instantaneous active current and instantaneous reactive current can be processed by coordinate dimension upscaling based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system.

[0093] The filtering processing method provided in the embodiment of the present application cascades a multi-band notch filter before the low-pass filter to filter out harmonic currents in a specific frequency band, thereby improving the accuracy of the harmonic current determined by the harmonic detection algorithm.

[0094] In one embodiment, Figure 2 Based on the embodiment shown, the process of obtaining the sine and cosine signals with the same single-phase voltage in the power grid system can be described as follows: Figure 5 As shown, the above S201 "obtaining sine and cosine signals with the same single-phase voltage in the power grid system" includes:

[0095] S401. Obtain the three-phase voltage of the power grid in the power grid system.

[0096] In the embodiment of the present application, before obtaining the sine and cosine signals with the same single-phase voltage in the power grid system, the three-phase voltage of the power grid in the power grid system can be obtained. Optionally, a voltmeter can be used to obtain the three-phase voltage of the power grid in the power grid system, or a voltage sensor can be used to obtain the three-phase voltage of the power grid in the power grid system.

[0097] S402, performing coordinate conversion processing on the three-phase voltage of the power grid to obtain sine and cosine signals.

[0098] The coordinate transformation processing includes dimensionality reduction coordinate transformation processing, orthogonal processing, positive and negative sequence processing and dimensionality increase coordinate transformation processing.

[0099] In the embodiment of the present application, after the three-phase voltage of the power grid is obtained as described above, the three-phase voltage of the power grid can be subjected to coordinate transformation processing to obtain sine and cosine signals with the same single-phase voltage in the power grid system.

[0100] Optionally, the following provides a process for performing coordinate transformation on the three-phase voltage of the power grid to obtain sine and cosine signals, see Figure 6 The above S402 "performs coordinate conversion processing on the three-phase voltage of the power grid to obtain sine and cosine signals" includes:

[0101] S501 , performing dimension reduction coordinate transformation processing on the three-phase voltage of the power grid to obtain a first voltage and a second voltage.

[0102] Among them, the dimension reduction coordinate transformation process refers to the transformation from the three-phase coordinate system to processing.

[0103] In the embodiment of the present application, after the three-phase voltage of the power grid is obtained as described above, the three-phase voltage of the power grid can be converted from the three-phase coordinate system to , get the first voltage and the second voltage .

[0104] S502 , performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage.

[0105] The first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals.

[0106] In the embodiment of the present application, the first voltage is obtained and the second voltage Afterwards, the first voltage and the second voltage Orthogonal processing is performed to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage.

[0107] Optionally, for the first voltage , the first signal can be obtained by using the second-order generalized integral orthogonal generator (INFC-SOGI-QSG) with a DC canceller for orthogonal processing. and the second signal ; For the first voltage , the third signal can be obtained by using the second-order generalized integral quadrature generator (INFC-SOGI-QSG) with DC canceller for orthogonal processing. and the fourth signal .

[0108] It should be noted that the INFC-SOGI-QSG provided in the embodiment of the present application adds a DC eliminator link on the basis of the traditional SOGI-QSG, which is equivalent to adding an integrator. The output of the integrator is proportional to the output voltage. After addition, the signal is fed back to the input grid, thereby eliminating the influence of the DC component on the phase-locked loop and obtaining an orthogonal signal. and .

[0109] S503 , performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component.

[0110] In an embodiment of the present application, after the first signal, the second signal, the third signal and the fourth signal are acquired as described above, positive and negative sequence processing can be performed on the first signal and the fourth signal to obtain a first positive sequence component, and positive and negative sequence processing can be performed on the second signal and the third signal to obtain a second positive sequence component.

[0111] Optionally, referring to the following formula (4), a method for determining the first positive sequence component is provided:

[0112]

[0113] in, is the first positive sequence component, It refers to the first signal. Refers to the fourth signal.

[0114] Optionally, referring to the following formula (5), a method for determining the second positive sequence component is provided:

[0115]

[0116] in, is the second positive sequence component, is the second signal, Refers to the third signal.

[0117] S504 , performing dimension-raising coordinate transformation processing on the first positive sequence component and the second positive sequence component to obtain sine and cosine signals.

[0118] In the embodiment of the present application, after the first positive sequence component and the second positive sequence component are obtained, the first positive sequence component and the second positive sequence component may be subjected to dimensional coordinate conversion processing to obtain sine and cosine signals. and the second positive sequence component Afterwards, the first positive sequence component can be obtained and the second positive sequence component The inverse transformation is performed to the dq coordinate system, and phase locking is achieved through SRF-PLL, and the sine and cosine signals are calculated.

[0119] The method for obtaining sine and cosine signals provided in the embodiment of the present application provides a theoretical basis for subsequently determining the fundamental frequency three-phase current based on the sine and cosine signals.

[0120] In one embodiment, Figure 7 As shown, a method for determining harmonic current is also provided, including:

[0121] S10, obtaining a three-phase current of a power grid and a three-phase voltage of a power grid in the power grid system;

[0122] S11, performing dimension reduction coordinate transformation processing on the three-phase voltage of the power grid to obtain a first voltage and a second voltage;

[0123] S12, performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage;

[0124] S13, performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component;

[0125] S14, performing dimension-upgrading coordinate conversion processing on the first positive sequence component and the second positive sequence component to obtain sine and cosine signals;

[0126] S15. Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0127] S16, filtering the instantaneous active current and the instantaneous reactive current respectively to obtain a base frequency instantaneous active current and a base frequency instantaneous reactive current;

[0128] S17, based on the sine and cosine signals, performing coordinate dimension-upgrading conversion on the base-frequency instantaneous active current and the base-frequency instantaneous reactive current to obtain the base-frequency three-phase current;

[0129] S18. Determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current.

[0130] See also Figure 8 , and also provides a specific implementation step of a method for determining harmonic current. First, the three-phase voltage of the power grid in the power grid system is obtained. , and , and the three-phase voltage of the power grid , and Perform dimensionality reduction conversion to obtain the first voltage and the second voltage , then, the first voltage and the second voltage Perform orthogonal processing respectively (see orthogonal processing circuit for details) Fig. 9 As shown, the input of the orthogonal processing circuit is voltage , the output is two orthogonal signals and ), and obtain the first voltage The corresponding first signal and the second signal , and the second voltage The corresponding third signal and the fourth signal , and then for the first signal and the fourth signal Perform positive and negative sequence processing to obtain the first positive sequence component , and for the second signal and the third signal Perform positive and negative sequence processing to obtain the second positive sequence component , then, the first positive sequence component and the second positive sequence component Perform dimensional coordinate transformation to obtain sine and cosine signals , again, obtain the three-phase current of the power grid system , and , based on sine and cosine signals , for the three-phase current of the power grid , and Perform coordinate dimension reduction processing to obtain the instantaneous active current of the power grid system and instantaneous reactive current , and then the instantaneous active current and instantaneous reactive current Perform filtering respectively to obtain the base frequency instantaneous active current and base frequency instantaneous reactive current , and based on the sine and cosine signals , the instantaneous active current of the fundamental frequency and base frequency instantaneous reactive current Perform coordinate dimension conversion to obtain the base frequency three-phase current , and , and then based on the three-phase current of the power grid system , and , respectively, and the fundamental frequency three-phase current , and The difference between the two determines the harmonic current of the power grid system. , and .

[0131] The method for determining harmonic current provided in the embodiment of the present application first obtains the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system, then processes the three-phase current of the power grid based on the sine and cosine signals to obtain the fundamental frequency three-phase current of the power grid system, and finally determines the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current. The above-mentioned method for determining harmonic current processes the three-phase current of the power grid through sine and cosine signals to solve the problem of inaccurate harmonic current detection caused by inaccurate phase-locked loop when the three-phase current on the power grid side is unbalanced or there is a DC component, thereby improving the accuracy of determining harmonic current.

[0132] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0133] Based on the same inventive concept, the embodiment of the present application also provides a harmonic current determination device for implementing the harmonic current determination method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in the embodiments of one or more harmonic current determination devices provided below can refer to the limitations of the harmonic current determination method above, and will not be repeated here.

[0134] In an exemplary embodiment, as shown in FIG10 , a device for determining harmonic current is provided, comprising: an acquisition module 10, a processing module 11 and a determination module 12, wherein:

[0135] The acquisition module 10 is used to acquire the sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system.

[0136] The processing module 11 is used to perform data processing on the three-phase current of the power grid based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system.

[0137] The determination module 12 is used to determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current.

[0138] In an exemplary embodiment, the processing module 11 includes a dimensionality reduction processing unit and a dimensionality increase processing unit, wherein:

[0139] The dimension reduction processing unit is specifically used to perform coordinate dimension reduction processing on the three-phase current of the power grid based on the sine and cosine signals to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0140] The dimension-upgrading processing unit is specifically used to perform coordinate dimension-upgrading processing on the instantaneous active current and the instantaneous reactive current based on the sine and cosine signals to obtain the fundamental frequency three-phase current.

[0141] In an exemplary embodiment, the processing module 11 further includes: a filtering unit, specifically configured to filter the instantaneous active current and the instantaneous reactive current respectively to obtain a base frequency instantaneous active current and a base frequency instantaneous reactive current;

[0142] The above-mentioned dimension-increasing processing unit is specifically used to perform coordinate dimension-increasing conversion on the base-frequency instantaneous active current and the base-frequency instantaneous reactive current based on the sine and cosine signals to obtain the base-frequency three-phase current.

[0143] In an exemplary embodiment, the filtering process includes a notch filter filtering process.

[0144] In an exemplary embodiment, the acquisition module 10 includes: an acquisition unit and a conversion processing unit, wherein:

[0145] An acquisition unit, specifically used to acquire the three-phase voltage of the power grid in the power grid system;

[0146] The conversion processing unit is specifically used to perform coordinate conversion processing on the three-phase voltage of the power grid to obtain sine and cosine signals.

[0147] In an exemplary embodiment, the above-mentioned coordinate transformation processing includes dimensionality reduction coordinate transformation processing, orthogonal processing, positive and negative sequence processing and dimensionality increase coordinate transformation processing. The above-mentioned conversion processing unit is specifically used to perform dimensionality reduction coordinate transformation processing on the three-phase voltage of the power grid to obtain a first voltage and a second voltage; perform orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals; perform positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and perform positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component; perform dimensionality increase coordinate transformation processing on the first positive sequence component and the second positive sequence component to obtain sine and cosine signals.

[0148] Each module in the above harmonic current determination device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0149] In an exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be shown in FIG11. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store three-phase current data of the power grid. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for determining harmonic current is implemented.

[0150] Those skilled in the art will understand that the structure shown in FIG. 11 is merely a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0151] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0152] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0153] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0154] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0155] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0156] Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0157] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are processed by coordinate dimension upgrading to obtain the fundamental frequency three-phase current.

[0158] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0159] The instantaneous active current and the instantaneous reactive current are filtered respectively to obtain the base frequency instantaneous active current and the base frequency instantaneous reactive current;

[0160] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are transformed into coordinates by dimension-upgrading to obtain the base frequency three-phase current, including:

[0161] Based on the sine and cosine signals, the base-frequency instantaneous active current and the base-frequency instantaneous reactive current are subjected to coordinate dimension-upgrading transformation to obtain the base-frequency three-phase current.

[0162] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0163] The above-mentioned filtering process includes notch filter filtering process.

[0164] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0165] Obtaining the three-phase voltage of the power grid in the power grid system;

[0166] The three-phase voltage of the power grid is subjected to coordinate transformation to obtain sine and cosine signals.

[0167] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0168] Performing dimension reduction coordinate transformation on the three-phase voltage of the power grid to obtain a first voltage and a second voltage;

[0169] Performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals;

[0170] Performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component;

[0171] The first positive sequence component and the second positive sequence component are processed by dimension-raising coordinate transformation to obtain sine and cosine signals.

[0172] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0173] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0174] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0175] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0176] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0177] Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0178] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are processed by coordinate dimension upgrading to obtain the fundamental frequency three-phase current.

[0179] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0180] The instantaneous active current and the instantaneous reactive current are filtered respectively to obtain the base frequency instantaneous active current and the base frequency instantaneous reactive current;

[0181] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are transformed into coordinates by dimension-upgrading to obtain the base frequency three-phase current, including:

[0182] Based on the sine and cosine signals, the base-frequency instantaneous active current and the base-frequency instantaneous reactive current are subjected to coordinate dimension-upgrading transformation to obtain the base-frequency three-phase current.

[0183] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0184] The above-mentioned filtering process includes notch filter filtering process.

[0185] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0186] Obtaining the three-phase voltage of the power grid in the power grid system;

[0187] The three-phase voltage of the power grid is subjected to coordinate transformation to obtain sine and cosine signals.

[0188] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0189] Performing dimension reduction coordinate transformation on the three-phase voltage of the power grid to obtain a first voltage and a second voltage;

[0190] Performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals;

[0191] Performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component;

[0192] The first positive sequence component and the second positive sequence component are subjected to dimensionality-raising coordinate transformation to obtain sine and cosine signals.

[0193] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0194] Acquire the same sine and cosine signals of the single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system;

[0195] Based on the sine and cosine signals, the three-phase current of the power grid is processed to obtain the base frequency three-phase current of the power grid system;

[0196] The harmonic current of the power grid system is determined based on the three-phase current of the power grid and the fundamental frequency three-phase current.

[0197] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0198] Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system;

[0199] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are processed by coordinate dimension upgrading to obtain the fundamental frequency three-phase current.

[0200] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0201] The instantaneous active current and the instantaneous reactive current are filtered respectively to obtain the base frequency instantaneous active current and the base frequency instantaneous reactive current;

[0202] Based on the sine and cosine signals, the instantaneous active current and instantaneous reactive current are transformed into coordinates by dimension-upgrading to obtain the base frequency three-phase current, including:

[0203] Based on the sine and cosine signals, the base-frequency instantaneous active current and the base-frequency instantaneous reactive current are subjected to coordinate dimension-upgrading transformation to obtain the base-frequency three-phase current.

[0204] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0205] The above-mentioned filtering process includes notch filter filtering process.

[0206] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0207] Obtaining the three-phase voltage of the power grid in the power grid system;

[0208] The three-phase voltage of the power grid is subjected to coordinate transformation to obtain sine and cosine signals.

[0209] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0210] Performing dimension reduction coordinate transformation on the three-phase voltage of the power grid to obtain a first voltage and a second voltage;

[0211] Performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals;

[0212] Performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component;

[0213] The first positive sequence component and the second positive sequence component are processed by dimension-raising coordinate transformation to obtain sine and cosine signals.

[0214] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0215] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0216] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for determining harmonic current, characterized in that: The method comprises: Acquire sine and cosine signals with the same single-phase voltage in the power grid system and the three-phase current of the power grid in the power grid system; Based on the sine and cosine signals, data processing is performed on the three-phase current of the power grid to obtain the base frequency three-phase current of the power grid system; The harmonic current of the power grid system is determined according to the power grid three-phase current and the fundamental frequency three-phase current.

2. The method according to claim 1, characterized in that The method of performing data processing on the three-phase current of the power grid based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system includes: Based on the sine and cosine signals, coordinate dimension reduction processing is performed on the three-phase current of the power grid to obtain the instantaneous active current and instantaneous reactive current of the power grid system; Based on the sine and cosine signals, the instantaneous active current and the instantaneous reactive current are subjected to coordinate dimension-upgrading processing to obtain the fundamental frequency three-phase current.

3. The method according to claim 2, characterized in that The method further comprises: Performing filtering processing on the instantaneous active current and the instantaneous reactive current respectively to obtain a base-frequency instantaneous active current and a base-frequency instantaneous reactive current; The step of performing coordinate dimension-upgrading transformation on the instantaneous active current and the instantaneous reactive current based on the sine and cosine signals to obtain the fundamental frequency three-phase current comprises: Based on the sine and cosine signals, the base-frequency instantaneous active current and the base-frequency instantaneous reactive current are subjected to coordinate dimension-upgrading transformation to obtain the base-frequency three-phase current.

4. The method according to claim 3, characterized in that The filtering process includes a notch filter filtering process.

5. The method according to claim 1, characterized in that The method of obtaining the sine and cosine signals with the same single-phase voltage in the power grid system includes: Obtaining a three-phase voltage of a power grid in the power grid system; The three-phase voltage of the power grid is subjected to coordinate transformation processing to obtain the sine and cosine signals.

6. The method according to claim 5, characterized in that The coordinate conversion process includes dimension reduction coordinate conversion process, orthogonal process, positive and negative sequence process and dimension increase coordinate conversion process. The coordinate conversion process of the three-phase voltage of the power grid is performed to obtain the sine and cosine signals, including: Performing a dimension reduction coordinate transformation process on the three-phase voltage of the power grid to obtain a first voltage and a second voltage; Performing orthogonal processing on the first voltage and the second voltage respectively to obtain a first signal and a second signal corresponding to the first voltage, and a third signal and a fourth signal corresponding to the second voltage; the first signal and the second signal are a group of orthogonal signals; the third signal and the fourth signal are a group of orthogonal signals; Performing positive and negative sequence processing on the first signal and the fourth signal to obtain a first positive sequence component, and performing positive and negative sequence processing on the second signal and the third signal to obtain a second positive sequence component; The first positive sequence component and the second positive sequence component are subjected to dimensionality-raising coordinate transformation to obtain the sine and cosine signals.

7. A device for determining harmonic current, characterized in that: The device comprises: An acquisition module, used for acquiring a sine and cosine signal having the same single-phase voltage as the power grid system and a three-phase current of the power grid in the power grid system; A processing module, configured to perform data processing on the three-phase current of the power grid based on the sine and cosine signals to obtain the base frequency three-phase current of the power grid system; The determination module is used to determine the harmonic current of the power grid system according to the three-phase current of the power grid and the fundamental frequency three-phase current.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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