CN112838671A - Electric energy management system based on broadband measuring device and inter-harmonic extraction method - Google Patents
Electric energy management system based on broadband measuring device and inter-harmonic extraction method Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00004—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by the power network being locally controlled
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
- G01R23/165—Spectrum analysis; Fourier analysis using filters
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
- G06F17/141—Discrete Fourier transforms
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The application relates to an electric energy management system, an extraction method, an extraction device and a substation. The electric energy management system comprises a dispatching master station and a plurality of substation stations, wherein each substation station comprises a broadband measuring device, and each broadband measuring device comprises a DSP module and a CPU module; the broadband measuring device is used for acquiring broadband electric signals in a power grid; the DSP module is used for acquiring the broadband electric signal and extracting inter-harmonic waves of the broadband electric signal; the CPU module is used for acquiring the inter-harmonic extraction result and sending the inter-harmonic extraction result to the scheduling master station; and the dispatching master station is used for receiving the inter-harmonic extraction result sent by each substation station and managing the power grid according to the result. The gap wave treatment system greatly reduces the data volume transmitted between the substation station and the dispatching master station, saves the hardware bandwidth cost and relieves the calculation pressure of the dispatching master station.
Description
Technical Field
The application relates to the technical field of power quality measurement, in particular to a power management system, an inter-harmonic extraction method, an extraction device and a substation.
Background
With the development of distributed power generation and smart grid technologies, a large number of novel power electronic devices, such as converters, inverters and the like, appear in each link of power generation, power transmission, power utilization and the like of a power system, the phenomenon of inter-harmonic interference is more and more severe when the novel power electronic devices are put into operation on a large scale, and the inter-harmonic interference affects the stable operation of the power devices, so that the monitoring and treatment of the inter-harmonic in the power grid are one of important tasks of the power department.
In the implementation process, the inventor finds that the traditional technology has at least the following problems: the traditional detection and treatment means has the problem of low efficiency.
Disclosure of Invention
Therefore, it is necessary to provide an electric energy management system, an inter-harmonic extraction method, an extraction device, and a substation in order to solve the above technical problems.
On one hand, the embodiment of the invention provides an electric energy management system which comprises a dispatching master station and a plurality of substation stations, wherein each substation station comprises a broadband measuring device, and each broadband measuring device comprises a broadband electric signal acquisition module and a data processing module; the broadband electric signal acquisition module is used for acquiring broadband electric signals in a power grid; the data processing module is used for acquiring the broadband electric signal, performing inter-harmonic extraction on the broadband electric signal, and sending the result of the inter-harmonic extraction to the scheduling master station; and the dispatching master station is used for receiving the inter-harmonic extraction result sent by each substation station and managing the power grid according to the inter-harmonic extraction result.
On the other hand, the embodiment of the invention also provides a substation station, which is applied to an electric energy management system, wherein the electric energy management system comprises a dispatching master station, the substation station comprises a broadband measuring device, and the broadband measuring device comprises a broadband electric signal acquisition module and a data processing module; the broadband electric signal acquisition module is used for acquiring broadband electric signals in a power grid; the data processing module is used for acquiring the broadband electric signal, performing inter-harmonic extraction on the broadband electric signal, and sending the result of the inter-harmonic extraction to the scheduling master station; and the inter-harmonic extraction result is used for indicating the dispatching master station to manage the power grid.
In one embodiment, the data processing module comprises a DSP module and a CPU module; the DSP module is used for acquiring the broadband electric signal and extracting inter-harmonic waves of the broadband electric signal; and the CPU module is used for acquiring the inter-harmonic extraction result and sending the inter-harmonic extraction result to the scheduling master station.
In one embodiment, the DSP modules include at least a first DSP module, a second DSP module, and a third DSP module; the first DSP module is used for acquiring the broadband electric signal and extracting inter-harmonic waves of the broadband electric signal; the second DSP module is used for acquiring the broadband electric signal and extracting harmonic waves of the broadband electric signal; the third DSP module is used for acquiring the broadband electric signal and extracting low-frequency components of the broadband electric signal; the CPU module is further used for obtaining a harmonic extraction result and a low-frequency component extraction result and sending the harmonic extraction result and the low-frequency component extraction result to the scheduling master station.
In one embodiment, the broadband measurement device further comprises a first filtering module; the first filtering module is used for carrying out band-pass filtering processing on the broadband electric signal to obtain a first filtering signal; the first DSP module is further used for obtaining the first filtering signal and performing inter-harmonic extraction on the first filtering signal.
In one embodiment, the broadband measurement device comprises a CAN bus therein, the CAN bus is used for connecting the DSP module and the CPU module, and the result of the inter-harmonic extraction is transmitted to the CPU module via the CAN bus.
In one embodiment, the data processing module includes a CAN bus for connecting the DSP module and the CPU module.
In one embodiment, the CPU module comprises a communication interface for transmitting the result of the inter-harmonic extraction to the scheduling master.
In another aspect, an embodiment of the present invention further provides an inter-harmonic extraction method, which is applied to the substation station described in any of the above embodiments, where the method includes: acquiring a broadband electric signal in a power grid; performing inter-harmonic extraction on the broadband electric signal; and sending the result of inter-harmonic extraction to the scheduling master station.
In one embodiment, the result of the inter-harmonic extraction comprises: the amplitude and phase of the inter-harmonics; the step of inter-harmonic extraction of the broadband electrical signal comprises: carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain an inter-harmonic filtering signal; carrying out complex modulation thinning processing on the inter-harmonic filtering signal; performing fast Fourier transform on the inter-harmonic filtering signal subjected to complex modulation and refinement; the magnitude and phase of the inter-harmonics are extracted from the result of the fast fourier transform.
In another aspect, an embodiment of the present invention further provides an inter-harmonic extraction apparatus, which is applied to the substation described in any of the above embodiments, where the apparatus includes: the data acquisition module is used for acquiring the broadband electric signal in the power grid; the data processing module is used for performing inter-harmonic extraction on the broadband electric signal; and the communication module is used for sending the inter-harmonic extraction result to a scheduling master station.
Based on the electric energy management system, the inter-harmonic extraction method, the extraction device and the substation, the broadband electric signal in the power grid is obtained through the broadband measurement device at the substation end of the substation, inter-harmonic extraction is carried out on the broadband electric signal through the data processing module at the substation end of the substation, finally, the result of the inter-harmonic extraction is sent to the dispatching master station, and the dispatching master station can make a strategy for inter-harmonic management according to the result of the inter-harmonic extraction so as to manage the inter-harmonic interference phenomenon in the power grid. The functions of signal acquisition, inter-harmonic extraction and the like are realized in the substation, the substation undertakes the task of inter-harmonic extraction calculation of the traditional dispatching master station, the real-time performance is good, the extraction speed is high, the inter-harmonic extraction result is sent to the dispatching master station, the data volume transmitted between the substation and the dispatching master station is greatly reduced, the hardware bandwidth cost is saved, the calculation pressure of the dispatching master station is relieved, and the monitoring and treatment effects on the inter-harmonic are improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of an embodiment of an electrical energy management system;
FIG. 2 is a block diagram of a data processing module according to an embodiment;
FIG. 3 is a schematic diagram of a data processing module according to an embodiment;
FIG. 4 is a schematic flow chart diagram of a method for inter-harmonic extraction in one embodiment;
FIG. 5 is a flow chart illustrating the steps of inter-harmonic extraction of a broadband electrical signal according to one embodiment;
fig. 6 is a block diagram showing the structure of an inter-harmonic extracting apparatus according to an embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.
It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be connected to the other element through intervening elements. Further, "connection" in the following embodiments is understood to mean "electrical connection", "communication connection", or the like, if there is a transfer of electrical signals or data between the connected objects.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, as used in this specification, the term "and/or" includes any and all combinations of the associated listed items.
As described in the background art, the scheduling master station in the prior art faces the problems of excessive calculation pressure and poor inter-harmonic monitoring and management effects, and the inventor researches and discovers that the problems occur because the power grid is a complex system, and in order to ensure safe and economic operation of the power grid, the scheduling master station needs to calculate and analyze the problems of harmonic interference, low-frequency oscillation, subsynchronous oscillation, super-synchronous oscillation, active and reactive power balance and the like besides paying attention to inter-harmonic management, and takes the analysis and calculation results as corresponding actions to deal with the phenomena of interference, oscillation and the like according to instructions sent to the substation station. The traditional substation station is generally responsible for acquiring real-time voltage or current data in a power grid required by a dispatching master station and receiving the dispatching of the dispatching master station to perform equipment action. In this mode, if the real-time current and voltage data collected by the substation are to be quickly transmitted to the scheduling master station, a large hardware bandwidth cost is required. In addition, the scheduling master station has numerous items needing to be operated, the processed data volume is huge, and the timely response to various problems in the power grid is difficult to ensure due to the computing capability of the current scheduling master station. It can be understood that the scheduling master station can complete the calculation and analysis through a hardware server and the like, and can also be realized through a cloud server.
Based on the reasons, the invention provides an electric energy management system, an inter-harmonic extraction method, an extraction device and a substation.
In one embodiment, as shown in FIG. 1, the present invention provides an electrical energy remediation system 10 comprising: the system comprises a dispatching master station and a plurality of substation stations, wherein each substation station comprises a broadband measuring device 310, and each broadband measuring device 310 comprises a broadband electric signal acquisition module 320 and a data processing module 330. The substation station collects the broadband electric signals in the power grid through the broadband electric signal collection module 320, transmits the broadband electric signals to the data processing module 330, and the data processing module 330 can extract and process the inter-harmonics of the broadband electric signals and transmit the extracted inter-harmonics to the dispatching master station. And the dispatching master station governs the inter-harmonics in the power grid according to the result of the inter-harmonic extraction.
In the electric energy management system 10, the functions of signal acquisition, inter-harmonic extraction and the like are realized at the substation station, the substation station undertakes the task of inter-harmonic extraction and calculation of the traditional dispatching master station, and the inter-harmonic is extracted by adopting a band-selecting Fourier algorithm, so that the real-time performance is good, the extraction speed is high, and then the inter-harmonic extraction result is sent to the dispatching master station, thereby greatly reducing the data volume transmitted between the substation station and the dispatching master station, saving the hardware bandwidth cost, relieving the calculation pressure of the dispatching master station, and improving the monitoring and management effects on the inter-harmonic.
Specifically, the broadband measuring device 310 is used for detecting various voltage and current signals within a specific frequency range, integrates functions of main measuring devices such as a measurement and control device, a synchronous phasor device and a fault recording device of a traditional substation station, uniformly measures current and voltage signals in a power grid, and reduces complexity of a data acquisition system of the substation station. Compared with the conventional measurement apparatus, the broadband measurement apparatus 310 is called a broadband measurement apparatus 310 because the frequency range of the signal acquired by the broadband measurement apparatus 310 is wider and the signal diversity is better.
The broadband electric signal refers to an ac voltage or current signal uniformly collected by the broadband measuring device 310 for subsequent analysis and calculation of power quality.
Inter-harmonics refer to waves whose frequency is not an integer multiple of the fundamental frequency, and may also be referred to as fractional harmonics, such as 0.5 th inter-harmonics, 1.5 th inter-harmonics, etc., and in the power grid, the fundamental frequency refers to 50Hz, which is equal to the power frequency. The inter-harmonics in the power grid are mainly generated by power electronic equipment including various frequency converters, converters and the like, three-phase windings of the generator are asymmetric, a transformer is saturated and the like. A large amount of inter-harmonics in a power grid easily cause voltage flicker and noise and vibration of a motor, and have great influence on audio equipment such as a radio and the like. The control of the dispatching master station on the intermediate harmonic of the power grid aims to reduce the influence of the intermediate harmonic on the stable operation of each device in the power grid, and the dispatching master station can achieve the control purpose by controlling the input and the use of equipment for controlling the harmonic and the intermediate harmonic. At present, the most widely used abatement equipment is a filter which is added in a power supply circuit of a power grid or each device, and the filter comprises an active filter and a passive filter.
In one embodiment, the data processing module is further configured to acquire the broadband electrical signal, perform harmonic extraction on the broadband electrical signal, and transmit a result of the harmonic extraction to the scheduling master station. And the dispatching master station receives the result of the harmonic extraction and governs the harmonic according to the result.
Specifically, harmonic refers to a signal having a frequency that is an integer multiple of the fundamental frequency, such as 3 rd harmonic, 5 th harmonic, and the like. The source, hazard, and treatment of harmonics are similar to those of inter-harmonics, and can be referred to in the description above for inter-harmonics.
In one embodiment, the data processing module is further configured to acquire the broadband electrical signal, perform low-frequency component extraction on the broadband electrical signal, and send a result of the low-frequency component extraction to the scheduling master station. And the scheduling master station receives the low-frequency component extraction result and governs the low-frequency component according to the low-frequency component extraction result.
In particular, the low frequency component refers to the oscillation of the relevant electrical quantity that can be observed when the grid is disturbed. Generally, the frequency of the oscillation is low, and the value range of the frequency comprises 0.1Hz-2.5Hz, so the oscillation is called as a low-frequency component. The main sources of low frequency components are: when the power grid is disturbed by the outside, the relative swing occurs between the rotors of the generator, and the damping winding of the generator is not enough to eliminate the disturbance, so that the continuous oscillation of the system is triggered, and the related electric quantity of the system oscillates accordingly. The occurrence of low-frequency components easily causes the malfunction of a protection device on a power transmission line or the disconnection of electric signals between different regional systems due to the loss of synchronization, which has great influence on the stable operation of a power grid. The power sector now governs low frequency components in the power grid, typically by PSS (power system stabilizer).
In one embodiment, the broadband electrical signal collection module 320 includes an ac sampling module for collecting broadband electrical signals. A voltage converter and a current converter are also arranged in the alternating current sampling module, and the collected large voltage or large current is converted into a small signal, so that subsequent analysis and calculation are facilitated.
The data processing module 330 integrates a multifunctional module for data processing and control into the broadband measurement device 310. In one embodiment, referring to fig. 2, the data processing module 330 includes a DSP module 334 and a CPU module 332. The DSP module 334 is configured to obtain a broadband electrical signal and perform inter-harmonic extraction on the broadband electrical signal. The CPU module 332 is configured to obtain a result of inter-harmonic extraction, and send the result of inter-harmonic extraction to the scheduling master station.
It is understood that the CPU module 332 is one of the core modules of the broadband measurement device 310. In one embodiment, the CPU module 332 is also used for data interaction with other modules of the broadband measurement device 310 and control of other functional modules, and can also communicate with other devices within the substation plant or devices outside the plant via various network protocols. The CPU module 332 executes a plurality of tasks for a long time, which may cause overheating of devices, affect the service life of the device, and affect the speed of data processing, and the task of analyzing and calculating the broadband electric signal is executed in the DSP module 334, which may accelerate the data processing efficiency and ensure stable operation of the system.
In one embodiment, the DSP block 334 comprises a high performance DSP chip.
It can be understood that the DSP chip has a stronger data processing capability than the CPU chip, the MCU chip, and the like, and particularly when processing a complex calculation task including fourier transform, the DSP chip can ensure a calculation speed and improve a real-time property of data processing.
In one embodiment, as shown in FIG. 3, the DSP modules 334 include at least a first DSP module 334A, a second DSP module 334B and a third DSP module 334C. The first DSP module 334A is configured to obtain a broadband electrical signal and perform harmonic extraction on the broadband electrical signal. The second DSP module 334B is configured to obtain the wideband electrical signal and perform inter-harmonic extraction on the wideband electrical signal. The third DSP module 334C is configured to obtain a wideband electrical signal and perform low frequency component extraction on the wideband electrical signal.
It can be understood that the first DSP module 334A, the second DSP module 334B, and the third DSP module 334C extract different interference factors affecting the power quality in the power grid, but the characteristics of the interference factors are different, and the interference factors are extracted by using a suitable algorithm, which can further improve the efficiency of data processing, but if all the algorithms are processed in the same DSP module, a certain delay is inevitably brought, and the real-time performance of data is reduced. In addition, the working period of the substation is relatively long, and if a plurality of calculation tasks are executed in the same DSP module for a long time, the calorific value of the device is too large, which affects the service life of the DSP module 334. Therefore, the DSP module 334 of this embodiment at least includes the first DSP module 334A, the second DSP module 334B, and the third DSP module 334C, and each DSP module individually extracts the main factors affecting the quality of the electric energy in the power grid, and can simultaneously extract various interference factors, thereby reducing the calculation pressure of each module, ensuring the real-time performance of the data, and simultaneously ensuring that each DSP module can stably operate for a long time.
In one embodiment, the result of inter-harmonic extraction includes: the magnitude and phase of the inter-harmonics. The step of inter-harmonic extraction of the broadband electric signal comprises the following steps: carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain an inter-harmonic filtering signal; carrying out complex modulation thinning processing on the inter-harmonic filtering signal; performing fast Fourier transform on the inter-harmonic filtering signal subjected to complex modulation and refinement; the magnitude and phase of the inter-harmonics are extracted from the result of the fast fourier transform.
The complex modulation thinning processing is a frequency resolution processing method for improving a Fourier analysis algorithm based on complex modulation frequency shift, the method can obtain higher frequency resolution and precision with smaller calculated amount, the traditional Fourier analysis algorithm can adopt the idea of reducing sampling frequency or increasing the number of sampling points to improve the resolution, but the two ideas greatly increase the storage amount and the calculated amount of data and have larger limitation. Meanwhile, in the traditional fourier analysis algorithm, the whole collected frequency band has the same frequency resolution, the starting point of the frequency band is zero frequency, but the frequency band which needs to be analyzed is often within a certain band-pass spectrum, if the whole collected frequency band is subjected to fourier analysis, a lot of useless information can be obtained, and the calculation power of data processing equipment is wasted.
Specifically, in one embodiment, the complex modulation refinement process may be implemented by:
step 1: and carrying out complex modulation frequency shift, and moving the center frequency of the band-pass spectrum to be analyzed to a frequency origin.
It is understood that the fourier analysis algorithm has a frequency shift characteristic, and the frequency spectrum can be shifted in the frequency domain by modulating the time domain signal according to the frequency shift characteristic. For example, if the frequency range of the spectrum to be analyzed is 25Hz to 75Hz, the time domain signal is modulated, the whole spectrum is shifted to the left by 50Hz, and the center frequency of the band-pass spectrum to be analyzed is shifted to the frequency origin.
Step 2: and anti-aliasing filtering, which is used for filtering the signals subjected to frequency shift so as to avoid the phenomenon of frequency spectrum aliasing.
It can be understood that according to the sampling theorem, some high-frequency signals overlap with low-frequency signals during sampling, and the distortion caused by the overlapping of frequency spectrums is called aliasing, so that the high-frequency signals in the signals need to be filtered out to avoid the occurrence of aliasing.
And step 3: resampling, namely acquiring the frequency-shifted and filtered time domain signals every D points to obtain refined signals; wherein the refined signal is used for performing a fast fourier transform.
It can be understood that this step reduces the band-pass spectrum interval, which is equivalent to reducing the sampling frequency to 1/D, and thus the frequency resolution is increased by a factor of D.
In one embodiment, the results of the harmonic extraction include: the amplitude and phase of the harmonics. The step of extracting the harmonic wave from the broadband electric signal comprises the following steps: carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain a harmonic filtering signal; carrying out full-phase processing on the harmonic filtering signal; carrying out fast Fourier transform on the harmonic wave filtering signal subjected to full-phase processing; the amplitude and phase of the harmonics are extracted from the result of the fast fourier transform.
It will be appreciated that full phase processing may take into account all truncation of the signal by multiple calculations, reducing the error. The traditional FFT algorithm is that firstly, signals are truncated based on a preset window function, then Fourier transform calculation analysis is carried out, if full-phase preprocessing is carried out before Fourier transform calculation analysis, the signals can be truncated continuously for multiple times, and then multiple groups of data obtained by multiple truncation are integrated. For example, a length 7 signal (m)0，m1...m6) Setting the length of the window function for truncation to 4, 4 successive truncations are required to obtain 4 sets of data ([ m ])0，m1，m2，m3]，[m1，m2，m3，m4]，[m2，m3，m4，m5]，[m3，m4，m5，m6])。
Specifically, in one embodiment, where the window function used for truncation is a hanning window, the full phase processing may be implemented by:
step 1: and presetting a Hanning window with N points, and after the signal passes through the Hanning window, solving convolution according to a Hanning window function to obtain a convolution window with 2N-1 points.
It will be appreciated that this step corresponds to multiple truncations of the signal. The adoption of the Hanning window for truncation and convolution can reduce the leakage of the frequency spectrum and increase the precision of subsequent analysis.
Step 2: and summing convolution windows of 2N-1 points, and normalizing the 2N-1 points according to the result of the summation.
And step 3: and multiplying the convolution windows of 1:2N-1 items by the normalized convolution windows respectively to obtain windowed 2N-1 points.
And 4, step 4: and adding the windowed 1 st item and the (N + 1) th item convolution window, and adding the 2 nd item and the (N + 2) th item convolution window.
It can be understood that the fast fourier transform may obtain a sum of a series of sinusoidal signals, each expression in the sinusoidal signal series represents harmonic and inter-harmonic signals of different times, but the result of extracting the harmonic and inter-harmonic refers to some physical quantity representing the characteristics of the harmonic and inter-harmonic, and the amplitude and phase parameters of each expression of the sinusoidal signals may represent the characteristics of the harmonic and inter-harmonic, and these parameters need to be extracted and sent to the scheduling master station as the result of extracting the harmonic and inter-harmonic to instruct the scheduling master station to perform harmonic and inter-harmonic suppression.
In one embodiment, the result of the low frequency component extraction includes the amplitude, frequency damping coefficient, and initial phase angle of the low frequency component. The step of extracting the low-frequency component of the broadband electric signal comprises the following steps: carrying out digital processing on the acquired broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting low-pass filtering to obtain a low-frequency component filtering signal; establishing a discrete linear prediction model based on a low-frequency component filtering signal of the power system; searching a characteristic root of a discrete linear prediction model; and determining the amplitude, the frequency, the damping coefficient and the initial phase angle of the low-frequency component corresponding to each model according to the characteristic root.
In one embodiment, the DSP module 334 further includes an analog-to-digital conversion unit for performing digital processing on the broadband electrical signal, and the first DSP module 334A is configured to obtain the digital processed broadband electrical signal and perform inter-harmonic extraction.
In one embodiment, the second DSP module 334B is further configured to obtain the digitized wideband electrical signal, and perform harmonic extraction on the digitized wideband electrical signal.
In one embodiment, the third DSP module 334C is further configured to obtain the digitized wideband electrical signal, and perform low frequency component extraction on the digitized wideband electrical signal.
In one embodiment, a first filtering module is further disposed in the broadband measuring device 310, and configured to perform band-pass filtering on the broadband electrical signal, where the broadband electrical signal is subjected to band-pass filtering to obtain a first filtered signal, and the first DSP module 334A is further configured to obtain the first filtered signal and perform inter-harmonic extraction on the first filtered signal according to a band-selection fourier algorithm.
It can be understood that the first filtered signal is a broadband electrical signal after being band-pass filtered by the first filtering module. Signals in the power grid may introduce some useless noise signals in links of power generation, power transmission, power transformation and the like, and the broadband measurement device 310 may also introduce some clutter in the process of collecting and performing analog-to-digital conversion on broadband electric signals, so that before inter-harmonic extraction is performed, a first filtering module is arranged in the DSP module 334 to filter out the useless signals, and the inter-harmonic extraction effect is improved. In addition, according to the research on the quality of electric energy by an electric power department and the like, the content of inter-harmonics of certain frequency bands in a power grid is large, so band-pass filtering is selected, only part of broadband electric signals can be reserved for key analysis, the calculated amount is reduced, and the calculating speed is improved.
In one embodiment, a FIR filter based on a kessel window design is included within the first filtering module.
It can be understood that the kessel window is a window function for designing the FIR filter, the FIR filter based on the kessel window has a steep transition band, and the ratio of the main lobe energy to the side lobe energy of the kessel window is nearly maximum, thereby improving the frequency selection performance. And by combining the actual requirements of engineering, the filter with ideal performance can be obtained by adjusting the shape parameters of the Kaiser window function.
Specifically, the Kaiser window function is composed of a zero-order Bessel function whose time-domain form is
In the formula: i is0(β) is a first type of deformed zeroth order bezier function; β is a shape parameter of the window function; n is the length of the window function; k is the current sample point. Determined by the following formula.
In the formula: α is the difference between the main lobe value and the side lobe value of the kaiser window function.
In one embodiment, a second filtering module is further disposed in the DSP module 334, the second filtering module is connected between the analog-to-digital conversion module and the second DSP module 334B, and is configured to perform band-pass filtering on the digital broadband signal, where the broadband electric signal is subjected to band-pass filtering to obtain a second filtered signal, and the second DSP module 334B is further configured to perform harmonic extraction on the second filtered signal.
It can be understood that the second filtered signal is a broadband electrical signal after being band-pass filtered by the second filtering module. The frequency band of the harmonic wave in the broadband electric signal is different from the inter-harmonic wave, and the frequency band with high harmonic wave content can be filtered out through the second filtering module for key analysis, so that the calculation amount is reduced, and the calculation speed is increased.
In one embodiment, a FIR filter based on a kessel window design is included within the second filtering module.
In one embodiment, a third filtering module is further disposed in the DSP module 334, the third filtering module is connected between the analog-to-digital conversion module and the third DSP module 334C, and is configured to perform low-pass filtering on the digital broadband signal, where the broadband electric signal is subjected to low-pass filtering to obtain a third filtered signal, and the third DSP module 334C is further configured to obtain the third filtered signal and perform low-frequency component extraction on the third filtered signal.
It can be understood that the third filtered signal is a broadband electrical signal after being low-pass filtered by the third filtering module.
In one embodiment, a FIR filter based on a kessel window design is included in the third filtering module.
In one embodiment, the data processing module 330 includes a CAN bus, and the DSP module 334 and the CPU module 332 are connected via the CAN bus. Specifically, in one embodiment, the first DSP module 334A, the second DSP module 334B, and the third DSP module 334C are connected to the CPU module 332 through a CAN bus, and after the first DSP module 334A, the second DSP module 334B, and the third DSP module 334C respectively calculate the inter-harmonic, and low-frequency component extraction results, the inter-harmonic, and low-frequency component extraction results are transmitted to the CPU module 332 through the CAN bus.
The CAN bus has the characteristics of strong real-time performance, strong anti-electromagnetic interference capability and the like, and has higher practical value when used in a complex electromagnetic environment of a substation.
In one embodiment, the CPU module 332 includes a communication interface therein, and the CPU module 332 obtains the inter-harmonic wave extraction result from the DSP module 334 and transmits the inter-harmonic wave extraction result to the scheduling master station through the communication interface.
It is understood that the communication interface includes, but is not limited to, an ethernet interface, a wireless interface, a GPIB interface, and the like. The CPU module 332 may select a corresponding communication interface according to a connection mode between the scheduling master station and the substation station. For example, the server of the scheduling master station is connected to the substation station through an optical fiber, and the CPU module 332 may send the data packet containing the inter-harmonic extraction result to the scheduling master station through an ethernet interface and through the optical fiber.
In an embodiment, the present invention further provides a substation, and the specific structure and function of the substation can be described in the above description of the substation in the electrical energy management system 10.
In an embodiment, as shown in fig. 4, the present invention further provides an inter-harmonic extraction method applied to the substation station in any of the above embodiments, where the method includes the steps of:
s100, acquiring a broadband electric signal in a power grid;
s300, performing inter-harmonic extraction on the broadband electric signal;
and S500, sending the inter-harmonic extraction result to a scheduling master station.
For the explanation of the technical features of the method provided in the present embodiment, reference may be made to the descriptions in the above embodiments.
In one embodiment, as shown in FIG. 5, the results of inter-harmonic extraction include: the amplitude and phase of the inter-harmonics; the step of inter-harmonic extraction of the broadband electrical signal comprises:
s310, carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal;
s330, filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain an inter-harmonic filtering signal;
s350, carrying out complex modulation thinning processing on the inter-harmonic filtering signal;
s370, performing fast Fourier transform on the inter-harmonic filtering signal subjected to complex modulation and refinement;
and S390, extracting the amplitude and the phase of the inter-harmonic from the result of the fast Fourier transform.
In an embodiment, the present invention further provides a harmonic extraction method applied to the substation station described in any one of the above embodiments, where the method includes: acquiring a broadband electric signal in a power grid; carrying out harmonic extraction on the broadband electric signal; the result of the harmonic extraction is transmitted to the scheduling master station 100.
In one embodiment, the results of the harmonic extraction include: the amplitude and phase of the harmonics; the step of extracting harmonics from the broadband electrical signal comprises: carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain a harmonic filtering signal; carrying out full-phase processing on the harmonic filtering signal; carrying out fast Fourier transform on the harmonic wave filtering signal subjected to the full-phase processing; extracting the amplitude and phase of the harmonic from the result of the fast fourier transform.
In an embodiment, the present invention further provides a low-frequency component extraction method, which is applied to the substation station 300 according to any of the above embodiments, and the method includes the steps of: acquiring a broadband electric signal in a power grid; extracting low-frequency components of the broadband electric signals; the result of the low frequency component extraction is transmitted to the scheduling master station 100.
In one embodiment, the result of the low frequency component extraction includes the amplitude, frequency damping coefficient, and initial phase angle of the low frequency component. The step of extracting the low-frequency component of the broadband electric signal comprises the following steps: carrying out digital processing on the acquired broadband electric signal to obtain a digital broadband electric signal; filtering interference noise in the digital broadband electric signal by adopting low-pass filtering to obtain a low-frequency component filtering signal; establishing a discrete linear prediction model based on a low-frequency component filtering signal of the power system; searching a characteristic root of a discrete linear prediction model; and determining the amplitude, the frequency, the damping coefficient and the initial phase angle of the low-frequency component corresponding to each model according to the characteristic root.
It should be understood that although the various steps in the flow charts of fig. 4-5 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 4-5 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least some of the other steps.
In an embodiment, as shown in fig. 6, the present invention further provides an inter-harmonic extraction apparatus applied to the substation station according to any of the above embodiments, where the apparatus includes: the device comprises a data acquisition module, a data processing module and a communication module.
The data acquisition module is used for acquiring the broadband electric signals in the power grid. The data processing module is used for performing inter-harmonic extraction on the broadband electric signal. And the communication module is used for sending the inter-harmonic extraction result to the scheduling master station.
In an embodiment, the present invention further provides a harmonic extraction device applied to the substation station described in any one of the above embodiments, where the harmonic extraction device includes: the device comprises a data acquisition module, a data processing module and a communication module.
The data acquisition module is used for acquiring the broadband electric signals in the power grid. And the data processing module is used for carrying out harmonic extraction on the broadband electric signal. And the communication module is used for sending the harmonic extraction result to a scheduling master station.
In an embodiment, the present invention further provides a low frequency component extraction device, which is applied to the substation station 300 according to any of the above embodiments, where the device includes: the device comprises a data acquisition module, a data processing module and a communication module.
The data acquisition module is used for acquiring the broadband electric signals in the power grid. And the data processing module is used for extracting low-frequency components of the broadband electric signals. The communication module is configured to send the result of the low frequency component extraction to the scheduling master station 100.
The respective modules in the inter-harmonic, and low-frequency component extraction means described above may be entirely or partially implemented by software, hardware, and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules. It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The electric energy management system is characterized by comprising a dispatching master station and a plurality of substation stations, wherein each substation station comprises a broadband measuring device, and each broadband measuring device comprises a broadband electric signal acquisition module and a data processing module;
the broadband electric signal acquisition module is used for acquiring broadband electric signals in a power grid;
the data processing module is used for acquiring the broadband electric signal, performing inter-harmonic extraction on the broadband electric signal, and sending the result of the inter-harmonic extraction to the scheduling master station;
and the dispatching master station is used for receiving the inter-harmonic extraction result sent by each substation station and managing the power grid according to the inter-harmonic extraction result.
2. A substation station is characterized by being applied to an electric energy management system, wherein the electric energy management system comprises a scheduling master station, the substation station comprises a broadband measuring device, and the broadband measuring device comprises a broadband electric signal acquisition module and a data processing module;
the broadband electric signal acquisition module is used for acquiring broadband electric signals in a power grid;
the data processing module is used for acquiring the broadband electric signal, performing inter-harmonic extraction on the broadband electric signal, and sending the result of the inter-harmonic extraction to the scheduling master station; and the inter-harmonic extraction result is used for indicating the dispatching master station to manage the power grid.
3. A substation station according to claim 2, wherein the data processing module comprises a DSP module and a CPU module;
the DSP module is used for acquiring the broadband electric signal and extracting inter-harmonic waves of the broadband electric signal;
and the CPU module is used for acquiring the inter-harmonic extraction result and sending the inter-harmonic extraction result to the scheduling master station.
4. A substation station according to claim 3, wherein the DSP modules comprise at least a first DSP module, a second DSP module and a third DSP module;
the first DSP module is used for acquiring the broadband electric signal and extracting inter-harmonic waves of the broadband electric signal;
the second DSP module is used for acquiring the broadband electric signal and extracting harmonic waves of the broadband electric signal;
the third DSP module is used for acquiring the broadband electric signal and extracting low-frequency components of the broadband electric signal;
the CPU module is further used for obtaining a harmonic extraction result and a low-frequency component extraction result and sending the harmonic extraction result and the low-frequency component extraction result to the scheduling master station.
5. A substation station according to claim 4, wherein the broadband measurement device further comprises a first filtering module;
the first filtering module is used for carrying out band-pass filtering processing on the broadband electric signal to obtain a first filtering signal;
the first DSP module is further used for obtaining the first filtering signal and performing inter-harmonic extraction on the first filtering signal.
6. A substation station according to claim 3, wherein the data processing module comprises a CAN bus for connecting the DSP module with the CPU module.
7. A substation station according to claim 3, characterized in that the CPU module comprises a communication interface for transmitting the result of the inter-harmonic extraction to the belonging scheduling master station.
8. An inter-harmonic extraction method, characterized in that it is applied to a substation station according to any one of claims 2 to 7, said method comprising the steps of:
acquiring a broadband electric signal in a power grid;
performing inter-harmonic extraction on the broadband electric signal;
and sending the result of inter-harmonic extraction to the scheduling master station.
9. The inter-harmonic extraction method according to claim 8, characterized in that the result of the inter-harmonic extraction includes: the amplitude and phase of the inter-harmonics;
the step of inter-harmonic extraction of the broadband electrical signal comprises:
carrying out digital processing on the broadband electric signal to obtain a digital broadband electric signal;
filtering interference noise in the digital broadband electric signal by adopting band-pass filtering to obtain an inter-harmonic filtering signal;
carrying out complex modulation thinning processing on the inter-harmonic filtering signal;
carrying out fast Fourier transform on the harmonic wave filtering signal subjected to complex modulation and refinement processing;
the magnitude and phase of the inter-harmonics are extracted from the result of the fast fourier transform.
10. An inter-harmonic extraction device, for use in a substation station according to any one of claims 2 to 7, the device comprising:
the data acquisition module is used for acquiring the broadband electric signal in the power grid;
the data processing module is used for performing inter-harmonic extraction on the broadband electric signal;
and the communication module is used for sending the inter-harmonic extraction result to a scheduling master station.
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