CN111814708B - Low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation - Google Patents
Low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation Download PDFInfo
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Abstract
The invention discloses a low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation, which is used for extracting a required signal. Will input signal v i Sampling and inverse Park-changed output signals are used as input signals, and grid voltage vector angles are utilizedObtaining a direct current signal v of an input signal in a rotating orthogonal coordinate system d ,v q By applying a DC signal v d ,v q The ideal direct current signal v 'is obtained after the filtering by a low-pass filter' d ,v′ q The required output signal is obtained through the vector angle of the power grid voltage and the inverse Park change. The invention can solve the problem that the sampling signal is easy to be interfered by noise in a complex electromagnetic environment, and improves the accuracy and stability of the extraction of the amplitude phase angle characteristics of the input signal.
Description
Technical Field
The invention relates to a feature extraction method of an input signal, in particular to a low-pass filtering feedback decoupling feature signal extraction method of the input signal based on coordinate transformation.
Background
The non-contact pressure measurement plays an important role in the field of power equipment fault judgment, and the core is a feature extraction method for sampling signals. In the past, researchers have done much work in terms of feature extraction. The feature extraction method is mainly composed of two types at present: statistical analysis and time-frequency domain analysis. The statistical analysis method refers to an extraction method for extracting main features which can represent the characteristics of the sampled signals by utilizing the characteristics and parameters of the statistical distribution of the sampled signals, and the extraction method mainly comprises a statistical operator, weibull parameters, image features and the like. The time cost for extracting the statistical features is high and the success rate is low.
The time-frequency domain analysis method is also called a waveform analysis method and mainly comprises time domain and frequency domain characteristics, wavelet domain characteristics and chaotic characteristics, but in actual field application, a sampling signal is usually influenced by a field complex electromagnetic environment, the signal-to-noise ratio is low, attenuation distortion is serious, so that the characteristic quantity is difficult to accurately extract by the method, the method is easy to be interfered by noise, and the identification effect is unstable.
Disclosure of Invention
The purpose of the invention is that: aiming at the defects of the prior art, the low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation is provided, the problem that a sampling signal is easy to be interfered by noise in a complex electromagnetic environment is solved, and the accuracy and the stability of the input signal amplitude phase angle characteristic extraction are improved.
The purpose of the invention is realized in the following way: the low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation comprises the following specific steps:
1) Will sample the signal v i And feedback signal v' β As input signal v α ＝v i ,v β ＝v' β ；
2) Virtual out of 50Hz frequency grid voltage vector angleReference angle pair v as Park transform α ,v β Performing Park conversion to obtain a direct current signal v d ,v q ；
3) Converting Park-converted direct current signal v d ,v q Filtering the attenuated high frequency component by a low pass filter to obtain a direct current component v' d ,v' q The v' d Mainly representing the voltage amplitude of the input, v' q A phase difference representing mainly the input voltage;
4) Filtered DC component v' d ,v' q By giving the voltage vector angle of the power gridPerforming inverse Park change to obtain power frequency signal and feedback signal v 'expected to be obtained' α ,v' β The v' α Is the expected power frequency signal, v' β Is a feedback signal;
5) For characteristic signal v' α Extracting the feedback signal v' β Feedback is carried out, the relation between the first path of output and the first path of input is represented by a bandpass characteristic, and the relation between the second path of output and the first path of input is represented by a low-pass characteristic;
the v is i Sampling signals for a secondary circuit of a power grid by using inverse Park transformationThe converted second path output v' β As a second input.
Setting a grid voltage vector angleThe method for performing Park conversion on the input signal comprises the following specific steps:
given the grid voltage vector angleUsing voltage vector angle->For voltage v in two-phase stationary coordinate system α ,v β Performing Park conversion to obtain d and q components of the voltage under the synchronous rotation coordinate system, wherein the d-axis component represents the input voltage v in a steady state i The q-axis component represents v i Is a phase angle characteristic of (a).
The method for extracting the characteristic signal based on the low-pass filtering feedback decoupling of the coordinate transformation according to claim 1, wherein the method comprises the following steps of: the low-pass filter in the step 3 isWherein omega p Is the cut-off frequency of the low pass filter.
The output signal v' α And v i The relation of (2) is expressed in terms of frequencyFor the central bandpass characteristic, output signal v' α Embodiment v i Fundamental frequency amplitude and phase angle characteristics of (a); output signal v' β And v i The relation of (2) shows a low-pass characteristic, and the output signal v' β Embodiment v i Amplitude characteristic, phase angle and input signal v i By 90 °, i.e
Wherein, the convolution operation is represented, the laplace transformation is simultaneously carried out on the two sides of the above formula, and the following formula can be obtained by arrangement:
bringing the low-pass filter function in the step 3 into the above way to obtain
In the step 5, the first path of output is the power frequency signal expected to be obtained, the characteristic signal near the fundamental frequency of the input signal is extracted, and the amplitude and phase angle of the characteristic signal are the sampling signal v i Filtering outThe second output is used as feedback in addition to the standard sinusoidal signal of the out-of-band signal.
The beneficial effects of the invention are as follows: the method can solve the problem that the sampled signal is easy to be interfered by noise in a complex electromagnetic environment, and improves the accuracy and stability of the extraction of the amplitude phase angle characteristics of the input signal.
Drawings
FIG. 1 is a schematic diagram of the control structure of the method of the present invention;
FIG. 2 is a schematic diagram of a first bandpass filter characteristic of the present invention;
FIG. 3 is a diagram illustrating a second low pass filter characteristic of the present invention;
FIG. 4 is a schematic of an input signal with third and fifth harmonics;
FIG. 5 is a schematic diagram of a first output signal after passing through an algorithm module;
FIG. 6 is a schematic diagram of two output signals after passing through an algorithm module;
FIG. 7 is a diagram showing the result of FFT analysis of an input signal;
fig. 8 is a schematic diagram of FFT analysis results of the first output signal.
Detailed Description
The invention is further described in detail below with reference to the attached drawing figures of the specification:
the invention relates to a low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation, which comprises the following five steps: 1. the sampling signal and the feedback signal after the inverse Park transformation form a static orthogonal coordinate system; 2. the vector angle of the power grid voltage is used as a reference angle to carry out Park conversion on an input signal; 3. low-pass filtering of the direct current signal; 4. inverse Park conversion of the filtered DC signal; 5. extracting the band-pass filtered output signal and feeding back the low-pass filtered output signal;
step one, utilizing a first path of sampling signal v i Feedback signal v' β As input signal v α ＝v i ,v β ＝v' β 。
Step two, virtualizing a grid voltage vector angle with the frequency of 50HzReference angle pair v as Park transform α ,v β Performing Park conversion to obtain a direct current signal v d ,v q 。
Step three, converting the Park converted direct current signal v d ,v q Filtering the attenuated high frequency component by a low pass filter to obtain a direct current component v' d ,v' q ，v' d Mainly representing the voltage amplitude of the input, v' q Mainly representing the phase difference of the input voltages.
Step four, performing inverse Park change on the filtered direct current component to obtain a power frequency signal and a feedback signal v 'which are expected to be obtained' α ,v' β ，v' α Is the expected power frequency signal, v' β Orthogonal signals required to construct a stationary coordinate system.
Step five, for the characteristic signal v' α Extracting the feedback signal v' β And feedback is carried out, the relation between the first path of output and input is represented by a bandpass characteristic, and the relation between the second path of output and input is represented by a low-pass characteristic.
The process of forming a static orthogonal coordinate system by the sampling signal and the feedback signal after the inverse Park transformation comprises the following steps:
step 1.1 sampling to obtain a power grid secondary circuit sampling signal as a first path input v i ；
Step 1.2
Will sample the signal v i Feedback signal v' β As an input signal.
The process of Park conversion of the input signal by taking the vector angle of the power grid voltage as a reference angle comprises the following steps:
step 2.1 virtualizing a grid voltage vector angle of 50Hz frequencyUsing voltage vector angle->For voltage v in two-phase stationary coordinate system α ,v β Performing Park conversion to obtain d and q components v of the voltage under the synchronous rotation coordinate system d ,v q In steady state, the d-axis component represents the input voltage v i The q-axis component represents the input voltage v i Is a phase angle characteristic of (a).
The low-pass filtering process of the direct current signal comprises the following steps:
step 3.1 inputting the signal v d ,v q Through a low pass filterFiltering out high frequency noise, omega p Obtaining the direct current component v 'for the cut-off frequency of the low-pass filter' d ,v' q In steady state, the d-axis component represents the input voltage v i The q-axis component represents the input voltage v i The decoupling of the state quantity is achieved.
The inverse Park conversion process of the filtered direct current signal comprises the following steps:
step 4.1 v' d ,v' q Obtaining a power frequency signal v 'expected to be output through inverse Park conversion' α ,v' β ；
Step 4.2 output Signal v' α And input signal v i Is of (2)Expressed in terms of frequencyFor the central bandpass characteristic, output signal v' α Can embody the input signal v i Is a fundamental frequency characteristic of (a).
Step 4.3 output Signal v' β And input signal v i The relation of (2) shows a low-pass characteristic, and the output signal v' β Can embody the input signal v i Amplitude characteristic, phase angle and input signal v i By 90 deg..
Wherein, the convolution operation is represented, the laplace transformation is simultaneously carried out on the two sides of the above formula, and the following formula can be obtained by arrangement:
the low pass filter function in step 3.1 is brought into the above equation:
the extraction of the band-pass filtering output signal and the feedback process of the low-pass filtering output signal:
step 5.1, wherein the first path of output is the power frequency signal expected to be obtained, the characteristic signal near the fundamental frequency of the input signal is extracted, and the amplitude and phase angle of the characteristic signal are the input sampling signal v i Filtering outStandard sinusoidal signals other than the out-of-band signals.
Step 5.2 wherein the second output is used as the feedback and input signal v i A stationary orthogonal coordinate system is constructed.
The specific experimental parameters are as follows:
Claims (2)
1. a low-pass filtering feedback decoupling characteristic signal extraction method based on coordinate transformation is characterized by comprising the following steps of: the method comprises the following steps:
1) Will sample the signal v i And feedback signal v' β As input signal v α ＝v i ,v β ＝v' β ；
2) Virtual out of 50Hz frequency grid voltage vector angleV as reference angle of Park transformation to two-phase stationary coordinate system α ,v β Performing Park conversion to obtain d-component and q-component direct current signals v of voltage under synchronous rotation coordinate system d ,v q The method comprises the steps of carrying out a first treatment on the surface of the In steady state, the d-axis component represents v i The q-axis component represents v i Phase angle characteristics of (2);
3) Converting Park-converted direct current signal v d ,v q Filtering the attenuated high frequency component by a low pass filter to obtain a direct current component v' d ,v' q The v' d Mainly representing the voltage amplitude of the input, v' q A phase difference representing mainly the input voltage;
the low-pass filter in the step 3) isWherein omega p Is the cut-off frequency of the low pass filter;
4) Filtered DC component v' d ,v' q By giving the voltage vector angle of the power gridPerforming inverse Park change to obtain power frequency signal v 'expected to be obtained' α And feedback signal v' β ；
5) For power frequency signal v' α Extracting the feedback signal v' β Feedback is carried out, the relation between the first path of output and the first path of input is represented by a bandpass characteristic, and the relation between the second path of output and the first path of input is represented by a low-pass characteristic;
the first path input v i Sampling signal for secondary circuit of power grid, and outputting v 'by using second circuit after inverse Park conversion' β As a second input;
v' α and v i The relation of (2) is expressed in terms of frequencyBand-pass characteristic as center, v' α Embodiment v i Fundamental frequency amplitude and phase angle characteristics of (a); v' β And v i The relationship of (2) is expressed as low-pass characteristic, v' β Embodiment v i Amplitude characteristic, phase angle and v i By 90 °, i.e
Wherein, the convolution operation is represented, the laplace transformation is simultaneously carried out on the two sides of the above formula, and the following formula can be obtained by arrangement:
bringing the low-pass filter function in the step 3 into the above way to obtain
2. The method for extracting the low-pass filtering feedback decoupling characteristic signal based on the coordinate transformation according to claim 1, wherein the method comprises the following steps of: the first path of output in the step 5) is the power frequency signal expected to be obtained, and the fundamental wave frequency of the input signal is extractedA near characteristic signal whose amplitude and phase angle are the input sampling signal v i Filtering outThe second output is used as feedback in addition to the standard sinusoidal signal of the out-of-band signal.
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| GB868196A (en) * | 1956-03-27 | 1961-05-17 | Emi Ltd | Improvements relating to electrical analogue co-ordinate conversion apparatus |
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| JP2009038885A (en) * | 2007-08-01 | 2009-02-19 | Daihen Corp | Signal extracting device and reactive power compensator containing the same |
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| CN105375809A (en) * | 2015-12-10 | 2016-03-02 | 中国矿业大学 | Output feedback decoupling-based low switching frequency control method for PWM converter |
| CN106921304A (en) * | 2017-02-21 | 2017-07-04 | 广州致远电子股份有限公司 | Single-phase inversion control method and system |
| CN108123634A (en) * | 2016-11-25 | 2018-06-05 | 南京航空航天大学 | A kind of polarity inversion output type inverter and its control method with power decoupled |
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- 2020-07-14 CN CN202010673820.2A patent/CN111814708B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB859942A (en) * | 1956-03-03 | 1961-01-25 | Emi Ltd | Improvements relating to electrical phase shift networks |
| GB868196A (en) * | 1956-03-27 | 1961-05-17 | Emi Ltd | Improvements relating to electrical analogue co-ordinate conversion apparatus |
| JP2005295521A (en) * | 2004-03-10 | 2005-10-20 | Matsushita Electric Ind Co Ltd | Data converter device and data conversion method, and transmitter circuit, communications device and electronic device using the same |
| JP2009038885A (en) * | 2007-08-01 | 2009-02-19 | Daihen Corp | Signal extracting device and reactive power compensator containing the same |
| JP2013102670A (en) * | 2011-10-21 | 2013-05-23 | Daihen Corp | Control apparatus for single-phase power conversion apparatus |
| CN105375809A (en) * | 2015-12-10 | 2016-03-02 | 中国矿业大学 | Output feedback decoupling-based low switching frequency control method for PWM converter |
| CN108123634A (en) * | 2016-11-25 | 2018-06-05 | 南京航空航天大学 | A kind of polarity inversion output type inverter and its control method with power decoupled |
| CN106921304A (en) * | 2017-02-21 | 2017-07-04 | 广州致远电子股份有限公司 | Single-phase inversion control method and system |
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