A harmonic intelligent detection method and system based on wavelet transform

Abstract

The present invention belongs to the field of electricity, and in particular, relates to a harmonic intelligent detection method and system based on wavelet transform. The method includes dividing a power-consuming load group into corresponding subgroups according to load type; setting detection equipment by load type to obtain power data corresponding to the subgroup; and processing power data based on wavelet transform to determine the source of harmonics. By dividing the power-consuming load group into corresponding subgroups according to load type, the interference in subsequent detection of harmonic sources can be reduced; setting detection equipment by load type to obtain power data of subgroups can improve the efficiency of detecting power data; and processing power data based on wavelet transform to determine the source of harmonics has high accuracy.

Description

Technical Field

[0001] The invention belongs to the field of electric power, and in particular relates to a harmonic intelligent detection method and system based on wavelet transform. Background Art

[0002] The current transmitted by the mainstream power system is alternating current, and its waveform should generally not change significantly. Power-consuming equipment will affect the waveform of the alternating current flowing into the power grid due to its circuit structure. The non-sinusoidal current generated by the power-consuming equipment is a harmonic source of the public power grid, and the harmonic source will inject harmonic current into the power grid, generating a harmonic voltage drop on the circuit impedance. When superimposed with the sinusoidal voltage, it will cause the grid voltage waveform to be distorted, thereby affecting the quality of the power supply. When the waveform of the alternating current is affected too much, it will affect the power of the power grid itself and have adverse effects, and the corresponding harmonic source needs to be found. Summary of the invention

[0003] In order to solve or improve the above problems, the present invention provides a harmonic intelligent detection method and system based on wavelet transform. The specific technical solution is as follows:

[0004] The present invention provides a harmonic intelligent detection method based on wavelet transform, comprising: dividing a power-consuming load group into corresponding subgroups according to the load type; setting a detection device according to the load type to obtain power data corresponding to the subgroup; and processing the power data based on wavelet transform to determine the source of harmonics.

[0005] Preferably, the processing of the power data based on wavelet transform to determine the source of harmonics includes: setting transformation parameters of the wavelet transform according to the load type, and processing the power data to determine the source of harmonics.

[0006] Preferably, setting the detection device through the load type to obtain the power data corresponding to the subgroup includes: obtaining the proportion of different types of loads within a variable area range; setting the subgroup according to the area range and the load type corresponding to the specified proportion.

[0007] Preferably, setting the subgroup according to the area range and the load type corresponding to the specified proportion includes: when the load proportion is not greater than the specified proportion threshold, expanding the area range until the load proportion within the expanded area range is greater than the specified proportion threshold; setting the subgroup according to the expanded area range and the corresponding load type.

[0008] Preferably, setting the transformation parameters of the wavelet transform according to the load type includes: setting the transformation parameters of the wavelet transform according to the load type and the corresponding proportion.

[0009] The present invention provides a harmonic intelligent detection system based on wavelet transform, comprising: a first unit, used to divide a power-consuming load group into corresponding subgroups according to the load type; a second unit, used to set a detection device according to the load type to obtain power data corresponding to the subgroup; and a third unit, used to process the power data based on wavelet transform to determine the source of harmonics.

[0010] Preferably, the processing of the power data based on wavelet transform to determine the source of harmonics includes: setting transformation parameters of the wavelet transform according to the load type, and processing the power data to determine the source of harmonics.

[0011] Preferably, setting the detection device through the load type to obtain the power data corresponding to the subgroup includes: obtaining the proportion of different types of loads within a variable area range; setting the subgroup according to the area range and the load type corresponding to the specified proportion.

[0012] Preferably, setting the subgroup according to the area range and the load type corresponding to the specified proportion includes: when the load proportion is not greater than the specified proportion threshold, expanding the area range until the load proportion within the expanded area range is greater than the specified proportion threshold; setting the subgroup according to the expanded area range and the corresponding load type.

[0013] Preferably, setting the transformation parameters of the wavelet transform according to the load type includes: setting the transformation parameters of the wavelet transform according to the load type and the corresponding proportion.

[0014] The beneficial effects of the present invention are as follows: by dividing the power-consuming load group into corresponding subgroups according to the load type, the interference in the subsequent detection of the harmonic source can be reduced; by setting the detection equipment according to the load type to obtain the power data of the subgroup, the efficiency of detecting the power data can be improved; and the power data is processed based on the wavelet transform to determine the harmonic source with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a harmonic intelligent detection method based on wavelet transform according to the present invention;

[0016] Figure 2 Schematic diagram of a harmonic intelligent detection system based on wavelet transform according to the present invention.

[0017] Description of main reference numerals:

[0018] 1-first unit, 2-second unit, 3-third unit. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0021] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0022] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0023] In order to solve or background the problem, Figure 1 The harmonic intelligent detection method based on wavelet transform shown includes: S1, dividing the power-consuming load group into corresponding subgroups according to the load type; S2, setting the detection equipment according to the load type to obtain the power data corresponding to the subgroup; S3, processing the power data based on wavelet transform to determine the source of the harmonics.

[0024] The power consumption load group is a collection of power consumption loads, which are referred to as loads for short. They include different types of power consumption equipment, whose circuit structures are different. When connected to AC power, the feedback generated is also different. Even if the circuit structures of the same type of power consumption equipment are not completely the same, the main or basic circuit structure is generally common. Therefore, when connected to AC power, the feedback generated is only different in value, but the essence of the feedback (feedback principle) is still the same. Therefore, dividing the same type of power consumption equipment into a subgroup is not easily affected by other power consumption equipment, and the power data obtained from the test is relatively stable without large fluctuations.

[0025] Different types of power-consuming devices have different patterns of changes in the output power data. For example, some devices have small changes in output voltage, but large changes in current intensity; on the contrary, some devices have small changes in output current intensity, but large changes in voltage; at the same time, the magnitude of power data changes is also different. Different detection equipment has different performance. According to the type of power-consuming equipment, the change pattern of its output power data can be estimated, and then the detection equipment that matches the change pattern can be selected to improve the efficiency of power data collection.

[0026] Wavelet transform (WT) inherits and develops the localization idea of ​​short-time Fourier transform, and overcomes the shortcomings of window size not changing with frequency. It can provide a "time-frequency" window that changes with frequency, and is an ideal tool for signal time-frequency analysis and processing. Power data is processed by wavelet transform, and the processing results are used to determine whether the power data output by the corresponding subgroup of power-consuming equipment has abnormal harmonics. If there are abnormal harmonics, it means that the power-consuming equipment in the subgroup has the source of harmonics. Repeat the detection process of steps S1 to S3, and finally determine which power-consuming equipment is the source of harmonics.

[0027] The processing of the power data based on wavelet transform to determine the source of harmonics includes: setting transformation parameters of the wavelet transform according to the load type, and processing the power data to determine the source of harmonics.

[0028] According to the type of load, the variation law of the output power data is estimated, and the values ​​of the sampling rate, approximation function, etc. in the transformation parameters of the wavelet transform are changed. By modifying the transformation parameters of the wavelet transform, the effect of the wavelet transform in processing power data can be improved.

[0029] The method of setting the detection device through the load type to obtain the power data corresponding to the subgroup includes: obtaining the proportion of different types of loads within a variable area range; and setting the subgroup according to the area range and the load type corresponding to the specified proportion.

[0030] A certain area range is set, and a certain coordinate / address is used as the starting point or center point to obtain a geographical area. Multiple power-consuming devices (i.e., loads) are set in the geographical area, and the ratio of the number of different types of power-consuming devices to the total number of power-consuming devices is used as the proportion of the corresponding type of power-consuming devices. Through the proportion of power-consuming devices, it can be known which type of power-consuming device will have a more significant impact on the operation of the power grid. By determining the influence of which type of power-consuming device, a reference can be provided for selecting which detection equipment and specific wavelet transform parameters.

[0031] The proportion of the same type of power-consuming equipment may be different in different geographical areas formed by different regional ranges. At the same time, in order to clarify which type of power-consuming equipment has the main impact on the power grid, it is necessary to study the power-consuming equipment that accounts for more than a certain proportion. To this end, the regional range can be changed to change the proportion of the load therein.

[0032] The setting of the subgroup according to the area range and the load type corresponding to the specified proportion includes: when the load proportion is not greater than the specified proportion threshold, expanding the area range until the load proportion within the expanded area range is greater than the specified proportion threshold; setting the subgroup according to the expanded area range and the corresponding load type.

[0033] The setting of the transformation parameters of the wavelet transform according to the load type includes: setting the transformation parameters of the wavelet transform according to the load type and the corresponding proportion.

[0034] The proportion of different types of loads, to a certain extent, indicates their impact on the power grid. By adjusting the sampling rate, approximation function and other parameters in the wavelet transform parameters according to the load type and the corresponding proportion, the effect of wavelet transform in processing power data can be improved by modifying the wavelet transform parameters.

[0035] The present invention provides a harmonic intelligent detection system based on wavelet transform, comprising: a first unit, used to divide a power-consuming load group into corresponding subgroups according to the load type; a second unit, used to set a detection device according to the load type to obtain power data corresponding to the subgroup; and a third unit, used to process the power data based on wavelet transform to determine the source of harmonics.

[0036] The load includes different types of power-consuming devices, and their circuit structures are different. When connected to AC power, the feedback generated is also different. For the same type of devices, even if the circuit structures are not completely the same, the main or basic circuit structure is generally the same. Therefore, when connected to AC power, the feedback generated is only different in value, and the essence of the feedback (feedback principle) is still the same. Therefore, the same type of devices are divided into a subgroup, and the power data obtained by the test is relatively stable, without large fluctuations, and with high accuracy.

[0037] Different types of power-consuming devices have different patterns of change in the output power data. For example, the output voltage of some devices changes very little, while the current intensity changes greatly. Conversely, the output current intensity of some devices changes little, while the voltage changes greatly. The amplitude of the change is also different, and different detection equipment has different performance. According to the type of power-consuming equipment, the change pattern of its output power data is estimated, and then the detection equipment that matches the change pattern is selected to improve the efficiency of power data collection.

[0038] Wavelet transform (WT) inherits and develops the localization idea of ​​short-time Fourier transform, while overcoming the shortcomings of window size not changing with frequency, and can provide a "time-frequency" window that changes with frequency, making it an ideal tool for signal time-frequency analysis and processing. Power data is processed by wavelet transform, and the processing results are used to determine whether the power data output by the power-consuming equipment of the corresponding subgroup contains abnormal harmonics. If so, it means that the power-consuming equipment of the subgroup has a source of harmonics.

[0039] The processing of the power data based on wavelet transform to determine the source of harmonics includes: setting transformation parameters of the wavelet transform according to the load type, and processing the power data to determine the source of harmonics.

[0040] According to the type of load, the change law of the output power data is estimated, and the sampling rate, approximation function and other parameters in the wavelet transform parameters are changed. By modifying the wavelet transform parameters, the effect of wavelet transform in processing power data can be improved.

[0041] The method of setting the detection device through the load type to obtain the power data corresponding to the subgroup includes: obtaining the proportion of different types of loads within a variable area range; and setting the subgroup according to the area range and the load type corresponding to the specified proportion.

[0042] The setting of the subgroup according to the area range and the load type corresponding to the specified proportion includes: when the load proportion is not greater than the specified proportion threshold, expanding the area range until the load proportion within the expanded area range is greater than the specified proportion threshold; setting the subgroup according to the expanded area range and the corresponding load type.

[0043] Taking a certain address as the starting point or center point, a certain area range is set to obtain a geographical area. Multiple power-consuming devices (i.e., loads) are set in this geographical area, and the ratio of the number of different types of power-consuming devices to the total number of power-consuming devices is used as the proportion of the corresponding type of power-consuming devices. Through the proportion, we can know which type of power-consuming device will have a more important impact on the operation of the power grid. The influence of which type of power-consuming device can be determined, which can provide a reference for selecting which detection equipment and specific wavelet transform parameters.

[0044] Different regional ranges form geographical areas, and even the proportion of the same type of power-consuming equipment may be different. At the same time, in order to study which type of power-consuming equipment has a major impact on the power grid, it is necessary to study power-consuming equipment that accounts for more than a certain proportion. For this purpose, the regional range can be changed to change the proportion of the load therein.

[0045] The setting of the transformation parameters of the wavelet transform according to the load type includes: setting the transformation parameters of the wavelet transform according to the load type and the corresponding proportion.

[0046] The proportion of different types of loads, to a certain extent, indicates their impact on the power grid. By adjusting the sampling rate, approximation function and other parameters in the wavelet transform parameters according to the load type and the corresponding proportion, the effect of wavelet transform in processing power data can be improved by modifying the wavelet transform parameters.

[0047] Those of ordinary skill in the art will appreciate that the units of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0048] In the embodiments provided in the present application, it should be understood that the division of units is merely a logical function division, and there may be other division methods in actual implementation, for example, multiple units may be combined into one unit, one unit may be split into multiple units, or some features may be ignored.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A harmonic intelligent detection method based on wavelet transform, characterized in that: include: According to the load type, the power consumption load group is divided into corresponding subgroups; Setting a detection device by the load type to obtain power data corresponding to the subgroup; comprising: Get the proportion of different types of loads within a variable area; Setting the subgroup according to the area range and the load type corresponding to the specified proportion; Processing the power data based on wavelet transform to determine the source of harmonics; comprising: Setting the transformation parameters of the wavelet transformation according to the load type, and processing the power data to determine the source of the harmonics; The setting of the subgroup according to the area range and the load type corresponding to the specified proportion includes: When the load ratio is not greater than the specified ratio threshold, the area is expanded until the expanded area The proportion of the load within the area is greater than a specified proportion threshold; The subgroup is set according to the enlarged area range and the corresponding load type; The step of setting the transformation parameters of the wavelet transform according to the load type comprises: According to the load type and the corresponding proportion, the transformation parameters of the wavelet transformation are set.

2. A harmonic intelligent detection system based on wavelet transform, characterized in that: include: A first unit is used to divide the power consumption load group into corresponding subgroups according to the load type; A second unit is used to set a detection device through the load type to obtain power data corresponding to the subgroup; A third unit is used for processing the power data based on wavelet transform to determine the source of harmonics; Processing the power data based on wavelet transform to determine the harmonic source comprises: setting the transformation parameters of the wavelet transform according to the load type, processing the power data to determine the source of the harmonics, The step of setting the detection device by the load type to obtain the power data corresponding to the subgroup includes: Get the proportion of different types of loads within a variable area; Setting the subgroup according to the area range and the load type corresponding to the specified proportion; The setting of the subgroup according to the area range and the load type corresponding to the specified proportion includes: When the load ratio is not greater than the specified ratio threshold, the area is expanded until the expanded area The proportion of the load within the area is greater than a specified proportion threshold; The subgroup is set according to the enlarged area range and the corresponding load type; The step of setting the transformation parameters of the wavelet transform according to the load type comprises: According to the load type and the corresponding proportion, the transformation parameters of the wavelet transformation are set.

Images