CN109765420A - Rapid detection method temporarily drops in a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq - Google Patents
Rapid detection method temporarily drops in a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq Download PDFInfo
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Abstract
The invention discloses a kind of single-phase voltages converted based on Morphologic filters and method of derivation α β-dq temporarily to drop rapid detection method, includes the following steps: that S1, the structural element combined by a certain percentage using cosine-shaped and triangle filter the single-phase voltage signal detected for the first time;S2, using by combination form filter filtered signal derivation for the first time, construct α β phase voltage;S3, it is filtered out using cosine morphological filter because the noise signal of calculus of differences amplification is interfered;S4, pass through dq transformation on this basis, and non-straight flow is filtered out using straight line mode filter to dq transformation results;S5, voltage dip amplitude and phase angle are calculated.The present invention can quickly and accurately detect amplitude, duration and the phase change of voltage dip.
Description
Technical field
The present invention relates to voltage dip detection fields, and in particular to one kind is based on Morphologic filters and method of derivation α β-dq
Rapid detection method temporarily drops in the single-phase voltage of transformation.
Background technique
Power quality problem is always the Hot Contents of electric system research, as what smart grid was built is constantly progressive,
The technology in electric automatization field constantly improve, and requirement of the people to power supply quality is gradually increased.Voltage dip, also known as voltage fall
It falls, as one kind most common in transient power quality problem and most serious, all can therefore cause huge economic damage every year
It loses, it is related studies have shown that because economic loss caused by Problem of Voltage Temporary-Drop accounts for whole power quality problems 70% ~ 90%.For electricity
The temporary drop problem of pressure, dynamic electric voltage recovery device (DVR) are common voltage transient occurs to fall and jump etc. to disturb in electric system
When timely compensation system power quality device, and how in real time, accurately detect the amplitude of voltage dip, phase hit and
The parameters such as beginning and ending time are to determine the important indicator of its compensation performance quality.In addition to this, with the development of technology, some intelligence
The power quality compensator of type also starts the detection speed and precision to voltage dip and makes requirement.Therefore, power train is analyzed
Signal characteristic when voltage dip occurs for system, proposes that method quick and that accurately monitoring voltage temporarily drops is very necessary.
Research about electric voltage temporary drop detecting method is always extensively by the concern of domestic and foreign scholars, by recent years domestic
The analysis of outer document, the more method of application is RMS to DC method, dq converter technique, Wavelet Transform, Fourier transformation at present
Method, HHT converter technique etc..RMS to DC method can accurately detect the depth of voltage dip, but can not provide generation voltage
Temporarily phase hit when drop, and there are longer detection delays.The complexity such as Wavelet Transform, fourier transform method, HHT converter technique
The algorithm majority based on frequency-domain analysis due to calculation amount is larger and engineering on the factors such as be difficult to realize, there are the limitations of itself
Property.Dq converter technique is a kind of coordinate transformation method based on Instantaneous Power Theory, compared to other algorithms based on transform domain are played, is had
The advantages that principle is simple, calculation amount is small, strong real-time, but traditional dq converter technique, which only can be suitably used for three-phase symmetric voltage, temporarily to drop
Detection, and voltage dip in practice is mostly single-phase fault.Common mostly exists for the improved dq converter technique of single-phase fault
Postpone certain angle on the basis of original signal as converted and postponing 60 ° of virtual three-phase electricities of construction after 90 ° of delay using α β-dq
The method of pressure, but delay-angle is equivalent to and artificially increases detection delay, inevitably affects real-time.
There is distortion and the interference of noise in the voltage in actual electric network system, most cases can use analog or digital filtering
Device, such as traditional Butterworth LPF, but the delay character of this kind of filter equally influences whether the real-time of voltage dip
The features such as monitoring, the filter based on mathematical morphology has calculation amount small in contrast, and precision is high, and no time domain deviates.
Summary of the invention
To solve the above problems, the present invention provides a kind of lists converted based on Morphologic filters and method of derivation α β-dq
Phase voltage sag rapid detection method can quickly and accurately detect that amplitude, duration and the phase of voltage dip become
Change.
To achieve the above object, the technical scheme adopted by the invention is as follows:
Rapid detection method temporarily drops in a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq, including as follows
Step:
S1, the structural element combined by a certain percentage using cosine-shaped and triangle filter the single-phase voltage signal detected for the first time
Wave;
S2, using by combination form filter filtered signal derivation for the first time, construct α β phase voltage;
S3, it is filtered out using cosine morphological filter because the noise signal of calculus of differences amplification is interfered;
S4, pass through dq transformation on this basis, and non-straight flow is filtered out using straight line mode filter to dq transformation results;
S5, voltage dip amplitude and phase angle are calculate by the following formula:
In formula:WithFor DC component,For the instantaneous voltage virtual value of single-phase voltage U,For the angle of initial phase
Angle value, i.e. phase angle.
In the step S2, constructed according to the single-phase voltage of actual measurementWith, then it is transformed to directly by following formula
Flow componentWith;
In formula: ω is the angular speed that dq coordinate system is rotated relative to α β coordinate system, and t is the time of rotation.
α β-dq of the present invention with mathematical morphology and based on method of derivation is transformed to theoretical basis, and it is single to propose a kind of detection
The new method of phase voltage sag substitutes traditional Butterworth filter with the morphological filter of different structure element, effectively overcomes
Method of derivation can amplification system noise influence, reduce detection delay, can fast and effeciently detect the width of voltage dip
Value, beginning and ending time and phase hit.
Detailed description of the invention
Fig. 1 is that a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq of the embodiment of the present invention is temporarily dropped
The flow chart of rapid detection method;
Fig. 2 is longitudinal cosine type and combined structure element;
Transformation of the Fig. 3 between α β-dq coordinate system;
Fig. 4 is the comparison of different performance of filter;
Fig. 5 is algorithm flow testing result;
In figure: (a) amplitude detection result;(b) phase hit testing result;
Fig. 6 is the influence schematic diagram for reducing filter module to result;
(a) testing result signal not filtered for the first time;(b) not to the testing result of method of derivation result filtering;(c) only dq is become
The testing result of DC quantity filtering after changing;
Fig. 7 is that test experience result temporarily drops in analog voltage;
(a) fall 75% the first data of amplitude;(b) fall 75% the second data of amplitude;(c) fall 50% data of amplitude;
(d) fall 25% data of amplitude.
Specific embodiment
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention
Protection scope.
As shown in Figure 1, the embodiment of the invention provides a kind of lists converted based on Morphologic filters and method of derivation α β-dq
Phase voltage sag rapid detection method, includes the following steps:
S1, the structural element combined by a certain percentage using cosine-shaped and triangle filter the single-phase voltage signal detected for the first time
Wave;
S2, using by combination form filter filtered signal derivation for the first time, construct α β phase voltage;
S3, it is filtered out using cosine morphological filter because the noise signal of calculus of differences amplification is interfered, reduces noise jamming to algorithm
Influence.The left side Fig. 2 is cosine-shaped structural element, and the right side is the composite structure element that joined triangular structure feature.
S4, pass through dq transformation on this basis, and non-straight flow is filtered out using straight line mode filter to dq transformation results;
S5, voltage dip amplitude and phase angle are calculate by the following formula:
In formula:WithFor DC component,For the instantaneous voltage virtual value of single-phase voltage U,For the angle of initial phase
Value, i.e. phase angle.
In the step S2, the premise using method of derivation is construction α β-dq coordinate transform system, and Fig. 3 is α β-dq coordinate transform
Schematic diagram,UFor the voltage vector static relative to dq coordinate system, dq coordinate system is rotated relative to α β coordinate system with angular velocity omega,
The then voltage vector of any time tUIt is projected as in α β reference axis and dq reference axis
The voltage vector in α β reference axis is transformed under dq coordinate system by coordinate transform, there is following relationship:
It is constructed according to the single-phase voltage of actual measurementWith, then DC component is transformed to by formula (2)With, use
Formula (3) and formula (4) can find out the instantaneous voltage virtual value of single-phase voltage UWith initial phaseAngle value.
It is constructed using method of derivationWithPrinciple it is very simple, it is assumed that the single-phase city's electric signal detected isFor the amplitude of voltage, by rightThe available formula of derivationFurther according toBetween relationship following transform can be obtained:
The algorithm differentiated is only applicable to continuous analog signal, and the data as used in practical calculate are discrete number
Signal needs to carry out signal difference processing, therefore the α β-dq for actually using method of derivation is transformed to that it is poor to seek original signal item by item
Point as a result, then to voltage signalDerivation then become
If system communication cycle is, then can will be in formulaIt replaces with
Theoretically whenWhen sufficiently small, the result of difference derivation can be very close to the knot differentiated to desired voltage waveform
Fruit, thus in engineering can by increase sample frequency by control errors in allowed limits.
Analysis of simulation experiment
Single-phase voltage, which is built, using Matlab/Simulink software herein temporarily drops model, sample frequency 12.8K, network voltage
Amplitude is 300V, and frequency is power frequency 50HZ, when emulation a length of 0.2s(2560 sampled point), network voltage is in t=0.07s(the
896 sampled points) Shi Fasheng voltage dip, amplitude is reduced to 75V by 300V, and the phase hit for being 30 degree along with angle,
Restore normal voltage in the moment of t=1.5, for the complex environment of simulating grid in actual work, by writing program in electricity to be measured
Joined in corrugating amplitude be the impulsive noise of 500V, the white Gaussian noise of 10dB and content be 3% triple-frequency harmonics and
The quintuple harmonics that content is 1%.
In order to analyze and the filtering performance of more different filters, article has selected four kinds of filters to building containing more
The voltage signal of kind disturbing factor is filtered, and one is the Butterworth low pass wave that common cutoff frequency is 75Hz
Device, secondly be band connection frequency be 30Hz and the Butterworth bandpass filter of 75Hz, thirdly be structural element being length 10, amplitude
The longitudinal cosine type morphological filter of 15 cosine wave structure, four be the structural element being mentioned above be triangle and cosine-shaped with one
The combined morphological filter of certainty ratio combination, it is 4 that wherein triangular structure length of element, which is 10 amplitudes, cosine-shaped structural element
Length is that 10 amplitudes are 11.Then by using the image generating function of matlab software by the desired voltage waveform of not Noise
Filter results different with four kinds have been plotted under the same coordinate system, convenient for doing performance comparison.
From filter result as can be seen that the result and reason that are obtained using longitudinal cosine type morphological filter and combination form filter
Think that voltage waveform essentially coincides, and remain the wave character at voltage jump point, and via Butterworth LPF and
There is phase delay in the waveform that bandpass filter obtains, signal-to-noise ratio is calculated to the data that emulation obtains, by longitudinal cosine type form
Signal-to-noise ratio after filter filtering is 33.6886dB, combined is then 33.8785dB, it was demonstrated that combined morphological filter exists
Performance when handling sophisticated signal is more excellent, more suitable for filtering for the first time to single-phase city's electric signal.
It is first first using combination form filter to the single-phase voltage signal of construction according to algorithm flow proposed by the present invention
Filtering, is configured to α β phase voltage for filtered signal using method of derivation, reuses cosine morphological filter and filter out because of difference
The noise signal of operation amplifier is interfered, and is finally that the linear type that 65 amplitudes are 0 filters with structural element length to dq transformation results
Device filters out non-straight flow, obtains voltage dip amplitude and phase-angle detection result is as shown in Figure 5.
It obtains result to emulation to analyze, at the moment of t=0.7 voltage dip occurs for system voltage, adopts in one later
In the sample period (i.e. 0.7s-0.7008s), amplitude by 292.3V falls to 170.3V, and i.e. theoretically voltage always falls amplitude 225
54.2%, and dropped in 8 sampled points later and always fall the 92% of amplitude and start gradually to tend towards stability, it is finally obtained
The error of amplitude and theoretical value, the testing result error of phase hit, can judge on this basis in engineering
The generation of voltage dip and the amplitude and phase angle for detecting Voltage Drop.
Traditional electric voltage temporary drop detecting method with morphological filter usually only uses linear type morphological filter, for
The adaptability of power grid complex environment is poor, and can amplify noise to a certain extent using the α β-dq algorithm of method of derivation, and article is being calculated
The two kinds of filters added in method process effectively overcome these problems, and emulation compares and reduces filter module under the conditions of
Influence to simulation result, as shown in Figure 6.
By the interpretation of result to Fig. 6 it is found that for complicated electric power signal, if having ignored some link of algorithm
The interference of middle noise can have an impact the precision of final result, and actual technology is difficult to accomplish to eliminate noise, therefore basis
Requirement of the system to measurement accuracy puts into suitable filter for algorithm flow different phase, can effectively improve detection effect,
Reduce loss.
Experimental verification
In order to which the detection performance of situation temporarily drops to virtual voltage in verification algorithm, a simulation has been built using indoor equipment is tested
The experiment porch that virtual voltage temporarily drops.The voltage dip under different situations is simulated by the experiment porch, and experiment is measured
Data bring into MATLAB software with text in method carried out simulating, verifying.Experiment measures 4 groups of voltage dip data altogether,
Voltage value before not falling is 282.8V, is divided into 75%, 50% and 25% 3 kind according to drop-off voltage amplitude, i.e., theoretically
Amplitude after Voltage Drop is respectively 70.7V, 141.4V and 212.1V, and the phase hit of 4 groups of data is 0 degree.Detection obtains
Result it is as shown in Figure 7.
The voltage waveform of emulation experiment acquisition is carried out it is found that testing result is more to manage using measured data by observing
The direct current signal thought demonstrates theoretical correctness.The further data that analysis experiment obtains, there is the testing result of amplitude
Very high theoretical precision, rear amplitude that four groups of data obtained fall (taking the average voltage after stablizing) be respectively 71.89V,
The error that 71.79V, 143.4V, 212.8V are compared with theoretical value is respectively less than 2%, and observation voltage is stable lasting from starting to drop into
Time, differ for 0.38ms-0.63ms, i.e., can complete detection in 0.7ms, since the data that experiment uses are temporary in voltage
It is not accompanied by phase hit at drop point, i.e. phase hit is theoretically fixed value.
In conclusion the present invention is proposed in the method that traditional dq is converted based on method of derivation and morphological filter combination
Improved voltage dip detection method, domain operation whens not being related to delay-angle etc. due to this method, and method of derivation and shape used
State filter is theoretically almost no-delay, therefore detection speed is fast, can be quickly and accurately positioned failure, for DVR and answers
The device design that the needs such as urgent telegram source quickly detect electrical energy power quality disturbance also has certain theoretical reference value.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make a variety of changes or modify within the scope of the claims, this not shadow
Ring substantive content of the invention.In the absence of conflict, the feature in embodiments herein and embodiment can any phase
Mutually combination.
Claims (2)
1. rapid detection method, feature temporarily drop in a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq
It is: includes the following steps:
S1, the structural element combined by a certain percentage using cosine-shaped and triangle filter the single-phase voltage signal detected for the first time
Wave;
S2, using by combination form filter filtered signal derivation for the first time, construct α β phase voltage;
S3, it is filtered out using cosine morphological filter because the noise signal of calculus of differences amplification is interfered;
S4, pass through dq transformation on this basis, and non-straight flow is filtered out using straight line mode filter to dq transformation results;
S5, voltage dip amplitude and phase angle are calculate by the following formula:
In formula:WithFor DC component,For the instantaneous voltage virtual value of single-phase voltage U,For the angle of initial phase
Angle value, i.e. phase angle.
2. a kind of single-phase voltage converted based on Morphologic filters and method of derivation α β-dq as described in claim 1 is temporarily dropped fastly
Fast detection method, it is characterised in that: in the step S2, constructed according to the single-phase voltage of actual measurementWith, then pass through
Following formula is transformed to DC componentWith;
In formula: ω is the angular speed that dq coordinate system is rotated relative to α β coordinate system, and t is the time of rotation.
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CN110687344A (en) * | 2019-10-24 | 2020-01-14 | 南京南瑞继保电气有限公司 | Single-phase voltage sag detection method and device, voltage restorer, equipment and medium |
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CN114325070A (en) * | 2021-12-13 | 2022-04-12 | 广西电网有限责任公司电力科学研究院 | High-robustness voltage sag detection method and system under extreme power grid working condition |
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