CN110531138A - A kind of Active Power Filter Harmonic Currents detection method - Google Patents
A kind of Active Power Filter Harmonic Currents detection method Download PDFInfo
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Abstract
The present invention discloses a kind of Active Power Filter Harmonic Currents detection method, wherein in ip‑iqOn the basis of Harmonic currents detection method, conventional phase locked loops are substituted using the phaselocked loop based on synchronous coordinate system；And adaptive least mean square algorithm is added and obtains fundamental wave sine and cosine component；Fixed step size is changed to variable step, be based on Sigmoid variable-step self-adaptive filter function, establish the nonlinear function model of new a step factor and error, solve fast convergence rate and steady-state error it is small on contradiction；The angular frequency of fundamental phase is finally updated to ip‑iqTransformation matrix is obtained in Harmonic currents detection method, three phase network electric current obtains harmonic component after a series of transformation.
Description
Technical field
The present invention relates to a kind of Active Power Filter Harmonic Currents detection methods, belong to Harmonic currents detection technology neck
Domain.
Background technique
With the development of modern industrial technology, the switch motion of power electronic equipment is filled with a large amount of harmonic wave into power grid
Component results in the serious distortion of voltage and current waveform in AC network, becomes most important harmonic source.Traditional electric power
System harmonics inhibition is prevented from the source of generation of harmonic wave, and nowadays, then uses passive power filter mostly
The devices such as (Passive Power Filter, PPF) or Active Power Filter-APF (Active Power Filter, APF) are filtered
Except harmonic wave.For the harmonic component and reactive current for effectively detecting power grid, Harmfulness Caused by Harmonics is reduced, the primary of Active Power Filter-APF is appointed
Business is the detection method for the advantages that selection is easily realized, calculation amount is small, real-time is good, highly reliable, precision is high.
Current most common detection method is Harmonic currents detection method on the basis of based on instantaneous reactive power theory.Instantaneously
Reactive power theory is divided into p-q Harmonic currents detection method and ip-iqHarmonic currents detection method.Wherein, three-phase voltage in actual electric network
Waveform is usually asymmetric and has distortion, in order to improve the deficiency that p-q Harmonic currents detection method is interfered by external voltage, research
Person proposes ip-iqHarmonic currents detection method, the detection method are to be believed by Detection and Extraction and network voltage with the sine of frequency same-phase
Number detection network voltage is substituted, increase significantly the use scope of Harmonic detection.For this purpose, it needs to power grid
The frequency and phase of voltage are quickly and accurately extracted, that is, so-called to network voltage progress locking phase.
Using phaselocked loop (Phase-looked Loop, PLL) accurately locking network voltage frequency be guarantee correctly to detect it is humorous
The important prerequisite of wave electric current, phaselocked loop are the phase informations for locking three-phase power grid voltage positive sequence fundamental component, while can also
For providing frequency information and amplitude information.In unbalanced source voltage or when being distorted, need to detect voltage fundamental component
Phase and frequency information replace this unbalanced voltage vector.
In view of importance of the phaselocked loop in grid-connected distributed generation system control structure, many scholars are studied.
Phase-lock technique wherein based on zero passage phase discriminator, the method are zero crossing and period according to detection network voltage come floating voltage
Phase, to obtain the phase and frequency information of network voltage, this method structure can simply be realized by analog circuit, but can only
Detect two voltage over zero, and can only at zero crossing could control information, detection speed is slow and power grid distortion imbalance is
It will affect the accuracy of zero crossing；Phase-locked loop method based on extended Kalman filter, this phase-locked loop method have sufficiently anti-
The state-space model of vector variation is reflected, but equally precision is not high in three-phase imbalance voltage and frequency discontinuity, and counted
Calculation amount is huge；Phaselocked loop (Synchronous Reference Frame PLL, SRF-PLL) based on synchronous coordinate system is mesh
The method of preceding relatively mainstream, is transformed into two-phase synchronous rotating frame for three-phase voltage, then through pi controller
It is zero that (Proportional Integral Controller), which controls reactive component, to realize the same of output and input phase
Step, phaselocked loop output phase parallactic angle is equal to virtual voltage phase angle at this time, can reach preferable dynamic and steady-state response, however, In
When imbalance of three-phase voltage, higher hamonic wave causes system response that can be deteriorated, and biggish negative phase-sequence fundamental component will lead to appearance 2 times
Harmonic wave.
Harmonic wave in network voltage has a great impact to the output accuracy of phaselocked loop, and the harmonic inhibition capability of phaselocked loop is
Refer to that phaselocked loop filters out effect to what high order in power grid and low-order harmonic interfered.Using low-pass filter, all-pass filter, Martin Hilb
Spy's transformation (Hilbert Transform), Kalman filtering (Kalman Filtering) or Second Order Generalized Integrator etc. are preposition
Filter can have the function that filter out harmonic wave, so that the phaselocked loop based on synchronous coordinate system while generating orthogonal signalling
With filter effect.But using low-pass filter, all-pass filter and the phase-locked loop structures of Hilbert transform, there are frequencies
Tracking performance is poor, to harmonic distortion sensitive issue；Using Kalman filter since it is desired that matrix inversion operation obtains most
Excellent gain factor, so operand is larger.Application No. is the patent documents of " 201110442281.2 " to disclose " based on instantaneous
The closed loop phase lock method and phase locking unit of reactive power theory ", the used software Phase-Lock basis in Instantaneous Power Theory
The preposition or postfilter of upper addition, although quick locking phase can be exported under load supplying environment, being averaged in the method
It is poor that filter filters out high frequency harmonic components effect.Further, it is also possible to by cascade it is some have the characteristics that certain filter or
The order of filter is improved to improve the filter effect of phaselocked loop, but this also increases system-computed burden simultaneously, therefore answers root
According to actual demand, tradeoff processing is carried out, designs most suitable phase-locked loop structures.
For such problems, the phaselocked loop based on synchronous coordinate system is used on the basis of conventional phase locked loops, by three-phase electricity
Net voltage is after the phaselocked loop based on synchronous coordinate system, the sine value and cosine value of circuit output phase, then by sine value and
Cosine value and three-phase power grid voltage carry out adaptive polo placement, obtain the fundamental voltage of three phase network, then carry out to fundamental voltage
Coordinate transform obtains fundamental voltage sine value and cosine value, avoids containing a large amount of radio-frequency components when network voltage distorts.It is adaptive
It should calculate using adaptive least mean square algorithm (Least Mean Square, LMS), on adaptive least mean square algorithm basis
On, fixed step size is changed to become long, establishes the nonlinear function model of new a step factor and error, solves fixed step size
Adaptive least mean square algorithm fast convergence rate and the small contradiction of steady-state error.
Summary of the invention
The purpose of the present invention is to provide a kind of Active Power Filter Harmonic Currents detection methods, for ip-iq harmonic wave
Phaselocked loop quickly and accurately extracts the frequency and phase of network voltage in electric current testing, using based on synchronous coordinate
The phaselocked loop of system, sine value and cosine value to three-phase power grid voltage and its phase carry out adaptive polo placement and obtain three phase network electricity
The fundamental wave component of pressure, then fundamental voltage is coordinately transformed, obtain fundamental voltage sine value and cosine value.Make it in network voltage
When occurring asymmetric, harmonic wave can be effectively filtered out, and improve to variable-step self-adaptive least mean square algorithm, solve fixed step size
Adaptive contradiction of the least mean square algorithm in convergence rate and steady-state error.
The purpose of the present invention is achieved by the following technical programs:
A kind of Active Power Filter Harmonic Currents detection method, comprising the following steps:
1) three-phase power grid voltage is passed through into the phase-lock-loop algorithm based on synchronous coordinate system, obtains practical three-phase power grid voltage phase
The sine value and cosine value of position；
2) sine value and cosine value of three-phase power grid voltage and actual phase are subjected to adaptive-filtering, certainly using fixed step size
Least mean square algorithm is adapted to, fundamental voltage is obtained, then fundamental voltage is substituted into the phase-lock-loop algorithm based on synchronous coordinate system again, obtains
To the angular frequency of fundamental voltage phase；
3) on the basis of fixed step size adaptive least mean square algorithm, fixed step size is changed to variable step, and be based on Sigmoid
Function (Sigmoid variable step least mean square, SVSLMS) improves, by square replacement of error
Error function makes error phase meanwhile, it is capable to obtain smaller step factor, makes algorithm at error very little (- 1≤e (n)≤1)
Step change is slow, reduces steady-state error.
4) angular frequency for the fundamental voltage that step 2) obtains is updated to ip-iqTransformation square is obtained in Harmonic currents detection method
Battle array, three phase network electric current obtain biphase current through matrixing, obtain two-phase instantaneous active DC component by low-pass filter,
Two-phase instantaneous active DC component is inverse transformed to obtain three-phase fundamental current, finally subtracts three-phase fundamental wave electricity with three phase network electric current
Stream obtains three phase harmonic electric current.
The purpose of the present invention can also be further realized by following technical measures:
Three-phase power grid voltage is passed through and is based on synchronous coordinate by a kind of aforementioned Active Power Filter Harmonic Currents detection method
The phase-lock-loop algorithm of system obtains the sine value and cosine value of practical three-phase power grid voltage phase, comprising the following steps: based on synchronization
Three-phase voltage is converted through Clarke when three-phase voltage balance, becomes it by three phase coordinate systems by coordinate system phase-lock-loop algorithm
Change to two-phase:
In formula, UabcFor three-phase voltage；Ua、Ub、UcRespectively A phase, B phase, C phase voltage, ω are angular frequency, and t is the time；
Coordinate transform are as follows:
In formula, T32For the transformation matrix of Clark transformation；
Uαβ=T32Uabc (3)
In formula, UαβFor the voltage under two phase coordinate system α, β；
For two-phase quadrature voltage Uα、Uβ, factor ω, calculation formula are extracted using derivative operation respectively are as follows:
To U'α(t) and U'β(t) derivative carries out quadratic sum operation, then carries out evolution, obtains voltage angular frequency, it may be assumed that
Again by two-phase coordinate system transformation to two-phase rotating coordinate system:
In formula, TdqFor coordinate transform, sin θ, cos θ are respectively sine value and cosine value；
Udq=TdqUαβ (8)
In formula, Ud、UqRespectively three-phase voltage resultant vector UabcProjection on d axis and q axis；
By controlling three-phase voltage resultant vector UabcU is projected on q axisqCarry out floating voltage phase, as d axis and UabcIt is overlapped
When, U at this timeq=0, stable state is formed, the phase angle obtained at this time is electric network voltage phase angle；Work as UqWhen > 0, d axis lags Uabc,
Need to increase the rotation angular frequency of dq coordinate system；Work as UqWhen < 0, the advanced U of d axisabc, need to reduce the rotation angular frequency of dq coordinate system
Rate.
Phase discriminator of the rotating coordinate system module as phaselocked loop, the U of outputqComponent is the input of loop filter, loop
Filter is a single order proportional integrator, single order proportional integrator kp+kiThe effect of/s is eliminated in phase detector output signal
HF noise signal, output ω and mains frequency initial value ω0It is added, obtained ωsTo voltage controlled oscillator, by integratorMake
For voltage controlled oscillator, ωsIt is converted into frequency through voltage controlled oscillator, obtains phase theta after integrating to frequency.
A kind of aforementioned Active Power Filter Harmonic Currents detection method, step 2) are described by three-phase power grid voltage and reality
The sine value and cosine value of phase carry out adaptive-filtering and obtain fundamental voltage using the adaptive least mean square algorithm of fixed step size,
The following steps are included:
The reference-input signal of system is α (n) and β (n), respectively indicates actual sine value and cosine value, corresponding to weigh
Value is ωα(n) and ωβ(n), the input d (n) of adaptive-filtering is uneven three-phase power grid voltage, passes through adaptive lowest mean square
Algorithm obtains output y (n), and y (n) is fundamental voltage, and systematic error signal e (n) is expressed as harmonic components.
The expression formula of fundamental voltage are as follows:
Y (n)=ωα(n)α(n)+ωβ(n)β(n) (10)
The harmonic components of network voltage are represented by, and subtract fundamental voltage with uneven three-phase power grid voltage:
E (n)=d (n)-y (n) (11)
Using the adaptive least mean square algorithm of fixed step size to weight ωα(n) and ωβ(n) it is updated, expression formula are as follows:
ωα(n+1)=ωα(n)+2μe(n)α(n) (12)
ωβ(n+1)=ωβ(n)+2μe(n)β(n) (13)
μ: the step-length being updated to weight determines the stability and convergence rate of algorithm.
Obtained fundamental voltage y (n) is repeated into step 1) and obtains the angular frequency of fundamental voltage*And phase theta*。
A kind of aforementioned Active Power Filter Harmonic Currents detection method, wherein step 3) is described using adaptive in fixed step size
On the basis of answering least mean square algorithm, fixed step size is changed to variable step, and improve based on Sigmoid function, including following step
It is rapid:
The adaptive least mean square algorithm of fixed step size convergence rate, tracking velocity and in terms of, to algorithm steps
The adjustment requirement of the long factor is conflicting.And variable-step self-adaptive least mean square algorithm is carried out by construction step factor
Weighed value adjusting makes algorithm have faster convergence rate and lesser steady-state error using variable step factor.In order into one
Step improves the performance of algorithm, proposes a kind of improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function.
The Sigmoid function of step factor μ (n) and error e (n):
In formula, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function.
It is obtained by formula (14), β/2 μ (n) <, and 0 < μ <, 1/ λmax, then βmax=2/ λmax, within this range algorithm must be
It is convergent.
Compared with the adaptive least mean square algorithm of fixed step size, variable step μ is variation, when algorithm enters stable state, error e
(n) when reaching minimum (e (n)=0), μ (n) becomes minimum (μ (n)=0), therefore the algorithm can obtain faster convergence speed simultaneously
Degree, tracking velocity and lesser steady-state error.
However, not having since Sigmoid function makes step-length too big in steady-state process (i.e. -1≤e (n)≤1) variation
Slowly varying characteristic, therefore use error e (n)2E (n) is replaced, after emulating by simlink, compares original Sigmoid letter
Number, error phase make algorithm (i.e. -1≤e (n)≤1) in error very little meanwhile, it is capable to obtain smaller step factor, and step-length becomes
Change slowly, improves deficiency of sigmoid function during adaptive steady-state process step-length adjusts.
Improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function:
In formula, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function.
Compared with prior art, the beneficial effects of the present invention are:
1. i of the present inventionp-iqHarmonic currents detection method is by Detection and Extraction and electricity compared to other detection methods
Net voltage substitutes detection network voltage with the sine value of phase and cosine value frequently together, also the same in the case where three phase network distortion
It is applicable in；
2. it is of the present invention based on the phaselocked loop of synchronous coordinate system compared to conventional phase locked loops for, in power grid three-phase
Energy effective detected amplitude, phase and frequency information when the balance of voltage, and preferable stable state and dynamic response can be reached, accurately
Extract three-phase voltage phase angle；
3. three-phase power grid voltage of the present invention is after the phaselocked loop based on synchronous coordinate system, circuit output phase
Sine and cosine value and three-phase power grid voltage are carried out adaptive polo placement by sine value and cosine value, obtain fundamental voltage, then to fundamental wave electricity
Pressure is coordinately transformed, and obtains the sine value and cosine value of fundamental voltage, avoid network voltage distort when, containing a large amount of high frequencies at
Point.
4. it is of the present invention on the Sigmoid functional foundations of former step factor u (n) and error e (n), it proposes new
Step factor u (n) and error e (n) between function, with error e (n)2E (n) is replaced, original Sigmoid function is compared,
Error phase keeps algorithm (- 1≤e (n)≤1) step change in error very little slow meanwhile, it is capable to obtain smaller step factor
Slowly, steady-state error is reduced, solves the adaptive least mean square algorithm of fixed step size on fast convergence rate and steady-state error are small
Contradiction.
Detailed description of the invention
Fig. 1 is the i based on instantaneous reactivep-iqHarmonic currents detection schematic diagram；
Fig. 2 inventive algorithm flow chart；
Fig. 3 is the phase-locked loop method figure based on synchronous coordinate system；
The adaptive least mean square algorithm schematic diagram of Fig. 4.
Specific embodiment
The invention will be further described with specific example with reference to the accompanying drawing.
In Three-Phase Shunt Active Power electric-power filter system, instruction current calculating has been sequentially connected in series in power network current side
Module occurs for module and compensation electric current.Wherein, Harmonic currents detection is carried out in instruction current computing module.
A kind of new harmonic current detecting method based on three-phase instantaneous reactive power theory is as shown in Figure 1, more traditional ip-
iqThree-phase power grid voltage is passed through the phase-lock-loop algorithm based on synchronous coordinate system, obtains practical three-phase electricity by Harmonic currents detection method
The sine value and cosine value of net voltage-phase, then the progress of the sine value and cosine value of three-phase power grid voltage and actual phase is adaptive
It should filter, obtain three-phase power grid voltage fundamental wave component, substitute into the phase-lock-loop algorithm based on synchronous coordinate system again, obtain fundamental voltage
The angular frequency of phase obtains transformation matrix C, and detection is substituted with the sinusoidal signal of phase with frequency by Detection and Extraction and network voltage
Network voltage.Three phase network electric current ia、ib、icThree-phase fundamental current i is obtained after a series of coordinate transformsaf,ibf,icf, most
Three phase network electric current is subtracted into three-phase fundamental current afterwards and obtains three phase harmonic electric current iah、ibh、ich。
It is inventive algorithm flow chart as shown in connection with fig. 2, the specific steps are as follows:
Step 1) Fig. 3 is based on synchronous coordinate system phase-lock-loop algorithm structure chart, when three-phase voltage balance, by three-phase voltage
It is converted through Clarke, makes it by three-phase coordinate system transformation to two-phase:
In formula, UabcFor three-phase voltage；Ua、Ub、UcRespectively A phase, B phase, C phase voltage, ω are angular frequency, and t is the time；
Coordinate transform are as follows:
In formula, T32For the transformation matrix of Clark transformation；
Uαβ=T32Uabc (3)
In formula, UαβFor the voltage under two phase coordinate system α, β；
For two-phase quadrature voltage Uα、Uβ, factor ω, calculation formula are extracted using derivative operation respectively are as follows:
To U'α(t) and U'β(t) derivative carries out quadratic sum operation, then carries out evolution, obtains voltage angular frequency, it may be assumed that
Again by two-phase coordinate system transformation to two-phase rotating coordinate system:
In formula, TdqFor coordinate transform, sin θ, cos θ are respectively sine value and cosine value；
Udq=TdqUαβ (8)
In formula, Ud、UqRespectively three-phase voltage resultant vector UabcProjection on d axis and q axis；
By controlling three-phase voltage resultant vector UabcU is projected on q axisqCarry out floating voltage phase, as d axis and UabcIt is overlapped
When, U at this timeq=0, stable state is formed, the phase angle obtained at this time is electric network voltage phase angle；Work as UqWhen > 0, d axis lags Uabc,
Need to increase the rotation angular frequency of dq coordinate system；Work as UqWhen < 0, the advanced U of d axisabc, need to reduce the rotation angular frequency of dq coordinate system
Rate.
Conventional phase locked loops are by phase discriminator (Phase Detector, PD), loop filter (Loop Filter, LF) and pressure
Oscillator (Voltage Controlled Oscillator, VCO) three basic units are controlled to constitute.Wherein phase discriminator is to input
Voltage signal makees phase identification, output error signal；Loop filter carries out high-frequency therapeutic treatment to error signal, filters out error signal
In high fdrequency component, obtain control signal；Voltage controlled oscillator is converted into frequency signal for signal is controlled, and result is fed back to mirror
Phase device constantly regulate phase difference by negative-feedback regu- lation, and until phase difference is zero, phaselocked loop enters phase locked state.
In conjunction with Fig. 3, phase discriminator of the rotating coordinate system module as phaselocked loop, the U of outputqComponent is the defeated of loop filter
Enter, loop filter is a single order proportional integrator, kp+kiThe effect of/s is that the high frequency eliminated in phase detector output signal is made an uproar
Acoustical signal, output ω and mains frequency initial value ω0It is added, obtained ωsTo voltage controlled oscillator, by integratorAs voltage-controlled
Oscillator, ωsIt is converted into frequency through voltage controlled oscillator, obtains phase theta after integrating to frequency.
Obtained practical sine value and cosine value and network voltage are carried out adaptive-filtering by step 2), obtain fundamental wave electricity
Pressure:
Adaptive least mean square algorithm system is by original input signal S+X0With reference-input signal X1Composition, system are passed through
Adaptive least mean square algorithm adjustment, so that output signal y (n) approaches X0, the X in being originally inputted is counteracted by subtracting each other0, make
Must be originally inputted only has ingredient S, while the error signal e (n) of output being fed back, and adjusts power by the error signal of feedback
Value, makes it be in optimum state, finally output error signal is made to contain only e (n), achievees the purpose that extraction is originally inputted middle S.
In conjunction with Fig. 4, the reference-input signal of system is α (n) and β (n), respectively indicates actual sine value and cosine value,
Corresponding weight is ωα(n) and ωβ(n), it is originally inputted the three-phase power grid voltage that d (n) is distortion, adaptively most by fixed step size
Small mean square algorithm obtains output y (n), and y (n) is fundamental voltage, and systematic error signal e (n) is expressed as harmonic components.
The expression formula of fundamental voltage are as follows:
Y (n)=ωα(n)α(n)+ωβ(n)β(n) (10)
The harmonic components of network voltage are represented by, and subtract fundamental voltage with the three-phase power grid voltage of distortion:
E (n)=d (n)-y (n) (11)
Using the adaptive least mean square algorithm of fixed step size to weight ωα(n) and ωβ(n) it is updated, expression formula are as follows:
ωα(n+1)=ωα(n)+2μe(n)α(n) (12)
ωβ(n+1)=ωβ(n)+2μe(n)β(n) (13)
μ: the step-length being updated to weight determines the stability and convergence rate of algorithm.
Obtained fundamental voltage y (n) is repeated into step 1) and obtains the angular frequency of fundamental wave*And phase theta*。
The adaptive least mean square algorithm of step 3) fixed step size, when reducing step factor μ, the stable state that can reduce algorithm is lost
It adjusts, so that algorithmic statement precision is improved, but lesser step-length can reduce convergence speed of the algorithm and tracking velocity.Fixed step size is certainly
Adapt to the convergent condition of least mean square algorithm are as follows: 0 < μ <, 1/ λmax, λmaxIt is the maximum spy of reference-input signal autocorrelation matrix
Value indicative, general μ take the constant less than 1.
Therefore, the adaptive least mean square algorithm of fixed step size convergence rate, tracking velocity and in terms of, to calculation
The adjustment requirement of method step factor is conflicting.And variable-step self-adaptive least mean square algorithm by construction step factor come
Weighed value adjusting is carried out, using variable step factor, makes algorithm that there is faster convergence rate and lesser steady-state error.In order to
The performance for further improving algorithm, proposes a kind of improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function.
The Sigmoid function of step factor μ (n) and error e (n):
In formula, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function.
It is obtained by formula (14), β/2 μ (n) <, and 0 < μ <, 1/ λmax, then βmax=2/ λmax, within this range algorithm must be
It is convergent.
Compared with the adaptive least mean square algorithm of fixed step size, variable step μ is variation, when algorithm enters stable state, error e
(n) when reaching minimum (e (n)=0), μ (n) becomes minimum (μ (n)=0), therefore the algorithm can obtain faster convergence speed simultaneously
Degree, tracking velocity and lesser steady-state error.
However, not having since Sigmoid function makes step-length too big in steady-state process (i.e. -1≤e (n)≤1) variation
Slowly varying characteristic, therefore use error e (n)2E (n) is replaced, after emulating by simlink, compares original Sigmoid letter
Number, error phase become algorithm (i.e. -1≤e (n)≤1) step-length in error very little meanwhile, it is capable to obtain smaller step factor
Change slowly, improves deficiency of sigmoid function during adaptive steady-state process step-length adjusts.
Improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function:
In formula, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function.
Step 4) produces transformation matrix C by the angular frequency of fundamental wave, with sine value cosine value, and expression formula is as follows:
If three-phase transient current is ia、ib、ic:
In formula: ω is angular frequency,For the initial phase angle of n-th electric current, InIt can be 1~n times electric current.Three-phase current is passed through
Clark transformation is simultaneously obtained according to formula (17):
In formula: iαAnd iβRespectively three-phase current transforms to the electric current in two-phase stationary coordinate system；
In formula: ipAnd iqFor instantaneous active and reactive current；
ip、iqInstantaneous active DC component is obtained after low-pass filter (LPF)With instantaneous reactive current DC componentBecauseIt is by three-phase fundamental current iaf,ibf,icfIt obtains, therefore can be via obtaining fundamental current i after inverse transformationaf,ibf,
icfIt obtains:
Then the harmonic current of three-phase current are as follows:
Therefore, iah、ibh、ichTo filter off obtained harmonic wave total amount after fundamental wave.
In addition to the implementation, the present invention can also have other embodiments, all to use equivalent substitution or equivalent transformation shape
At technical solution, be all fallen within the protection domain of application claims.
Claims (5)
1. a kind of Active Power Filter Harmonic Currents detection method, which is characterized in that comprise the steps of
1) three-phase power grid voltage is passed through into the phase-lock-loop algorithm based on synchronous coordinate system, obtains practical three-phase power grid voltage phase
Sine value and cosine value；
2) sine value and cosine value of three-phase power grid voltage and actual phase are subjected to adaptive-filtering, it is adaptive using fixed step size
Least mean square algorithm obtains fundamental voltage, then fundamental voltage is substituted into the phase-lock-loop algorithm based on synchronous coordinate system again, obtains base
The angular frequency of wave voltage phase；
3) on the basis of fixed step size adaptive least mean square algorithm, fixed step size is changed to variable step, and based on Sigmoid function into
Row improve, by error square replace error function, make error phase meanwhile, it is capable to obtain smaller step factor, algorithm made to exist
When error very little, i.e. step change is slow when -1≤e (n)≤1, reduces steady-state error；
4) angular frequency for the fundamental voltage that step 2) obtains is updated to ip-iqObtain transformation matrix in Harmonic currents detection method, three
Phase power network current obtains biphase current through matrixing, obtains two-phase instantaneous active DC component, two-phase wink by low-pass filter
Shi Yougong DC component is inverse transformed to obtain three-phase fundamental current, finally subtracts three-phase fundamental current with three phase network electric current and obtains three
Phase harmonic current.
2. a kind of Active Power Filter Harmonic Currents detection method as described in claim 1, which is characterized in that step 1) institute
It states three-phase power grid voltage by the phase-lock-loop algorithm based on synchronous coordinate system, obtains the sine of practical three-phase power grid voltage phase
Value and cosine value, comprising the following steps:
Three-phase voltage is converted through Clarke, makes it by three when three-phase voltage balance based on synchronous coordinate system phase-lock-loop algorithm
Phase coordinate system transforms to two-phase:
In formula, UabcFor three-phase voltage；Ua、Ub、UcRespectively A phase, B phase, C phase voltage, ω are angular frequency, and t is the time；
Coordinate transform are as follows:
In formula, T32For the transformation matrix of Clark transformation；
Uαβ=T32Uabc (3)
In formula, UαβFor the voltage under two phase coordinate system α, β；
For two-phase quadrature voltage Uα、Uβ, factor ω, calculation formula are extracted using derivative operation respectively are as follows:
To U'α(t) and U'β(t) derivative carries out quadratic sum operation, then carries out evolution, obtains voltage angular frequency, it may be assumed that
Again by two-phase coordinate system transformation to two-phase rotating coordinate system:
In formula, TdqFor coordinate transform, sin θ, cos θ are respectively sine value and cosine value；
Udq=TdqUαβ (8)
In formula, Ud、UqRespectively three-phase voltage resultant vector UabcProjection on d axis and q axis；
By controlling three-phase voltage resultant vector UabcU is projected on q axisqCarry out floating voltage phase, as d axis and UabcWhen coincidence, this
When Uq=0, stable state is formed, the phase angle obtained at this time is electric network voltage phase angle；Work as UqWhen > 0, d axis lags Uabc, need
Increase the rotation angular frequency of dq coordinate system；Work as UqWhen < 0, the advanced U of d axisabc, need to reduce the rotation angular frequency of dq coordinate system；
Phase discriminator of the rotating coordinate system module as phaselocked loop, the U of outputqComponent is the input of loop filter, loop filter
For a single order proportional integrator, single order proportional integrator kp+kiThe effect of/s is that the high frequency eliminated in phase detector output signal is made an uproar
Acoustical signal, output ω and mains frequency initial value ω0It is added, obtained ωsTo voltage controlled oscillator, by integratorAs voltage-controlled
Oscillator, ωsIt is converted into frequency through voltage controlled oscillator, obtains phase theta after integrating to frequency.
3. a kind of Active Power Filter Harmonic Currents detection method as described in claim 1, which is characterized in that step 2) institute
It states sine value and cosine value by three-phase power grid voltage and actual phase and carries out adaptive-filtering, it is adaptively minimum using fixed step size
Mean square algorithm obtains fundamental voltage, comprising the following steps:
The reference-input signal of system is α (n) and β (n), respectively indicates actual sine value and cosine value, corresponding weight is
ωα(n) and ωβ(n), the input d (n) of adaptive-filtering is uneven three-phase power grid voltage, passes through adaptive least mean square algorithm
Output y (n) is obtained, y (n) is fundamental voltage, and systematic error signal e (n) is expressed as harmonic components；
The expression formula of fundamental voltage are as follows:
Y (n)=ωα(n)α(n)+ωβ(n)β(n) (10)
The harmonic components of network voltage are represented by, and subtract fundamental voltage with uneven three-phase power grid voltage:
E (n)=d (n)-y (n) (11)
Using the adaptive least mean square algorithm of fixed step size to weight ωα(n) and ωβ(n) it is updated, expression formula are as follows:
ωα(n+1)=ωα(n)+2μe(n)α(n) (12)
ωβ(n+1)=ωβ(n)+2μe(n)β(n) (13)
μ: the step-length being updated to weight determines the stability and convergence rate of algorithm.
4. a kind of Active Power Filter Harmonic Currents detection method as described in claim 1, which is characterized in that step 3) institute
State using on the basis of fixed step size adaptive least mean square algorithm, fixed step size be changed to variable step, and based on Sigmoid function into
Row improves, comprising the following steps:
The adaptive least mean square algorithm of fixed step size convergence rate, tracking velocity and in terms of, to algorithm step-size because
The adjustment requirement of son is conflicting；And variable-step self-adaptive least mean square algorithm carries out weight by construction step factor
Adjustment makes algorithm have faster convergence rate and lesser steady-state error using variable step factor；In order to further change
The performance of kind algorithm, proposes a kind of improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function:
The Sigmoid function of step factor μ (n) and error e (n):
In formula, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function；
It is obtained by formula (14), β/2 μ (n) <, and 0 < μ <, 1/ λmax, then βmax=2/ λmax, algorithm must be convergence within this range
's；
Compared with the adaptive least mean square algorithm of fixed step size, variable step μ is variation, and when algorithm enters stable state, error e (n) reaches
When to minimum, i.e. e (n)=0, μ (n) become minimum, i.e. μ (n)=0, thus the algorithm can obtain simultaneously faster convergence rate,
Tracking velocity and lesser steady-state error；
However, not having slow since Sigmoid function changes step-length in steady-state process, i.e. -1≤e (n)≤1 too greatly
The characteristic of variation, therefore use error e (n)2E (n) is replaced, after emulating by simlink, compares original Sigmoid function, mistake
Poor to make algorithm in error very little mutually meanwhile, it is capable to obtain smaller step factor, i.e. step change is slow when -1≤e (n)≤1
Slowly, deficiency of sigmoid function during adaptive steady-state process step-length adjusts is improved；
Improvement variable-step self-adaptive least mean square algorithm based on Sigmoid function:
5. a kind of Active Power Filter Harmonic Currents detection method as claimed in claim 4, which is characterized in that formula (15)
In, α > 0, the shape of control function determines the speed that curve rises；β > 0, the value range of control function.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112325933A (en) * | 2020-10-29 | 2021-02-05 | 贵州电网有限责任公司 | Multi-energy system acquisition and preprocessing method and terminal based on edge calculation |
| CN112436775A (en) * | 2020-11-12 | 2021-03-02 | 武汉科技大学 | Crane steel rope resonance elimination control method, device, equipment, storage medium and terminal |
| CN112595893A (en) * | 2020-11-16 | 2021-04-02 | 闽南理工学院 | Power grid phase synchronization signal detection method based on adaptive filter |
| CN113111542A (en) * | 2021-05-12 | 2021-07-13 | 南方电网科学研究院有限责任公司 | Kalman filtering frequency tracking method and system based on S function |
| CN113992101A (en) * | 2021-12-28 | 2022-01-28 | 成都爱旗科技有限公司 | Current compensation method and device based on vector control of permanent magnet synchronous motor |
| CN115498896A (en) * | 2022-06-02 | 2022-12-20 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Vacuum on-load tap-changer test system and harmonic current source |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280593A (en) * | 2014-10-21 | 2015-01-14 | 国家电网公司 | Quick harmonic and reactive current detection method based on instantaneous reactive power theory |
| CN105353214A (en) * | 2015-12-22 | 2016-02-24 | 安徽工程大学 | Improved harmonic detection method |
| CN107102189A (en) * | 2017-04-14 | 2017-08-29 | 西南交通大学 | Variable step- size LMS harmonic current detecting method based on S function |
| CN108957130A (en) * | 2018-07-27 | 2018-12-07 | 中国南方电网有限责任公司 | A kind of trend of harmonic detection method of power based on instantaneous reactive power theory |
| CN109066678A (en) * | 2018-08-28 | 2018-12-21 | 西安航空职业技术学院 | A kind of improved APF system harmonics electric current detecting method |
| CN109188078A (en) * | 2018-10-17 | 2019-01-11 | 江苏师范大学 | A kind of variable step- size LMS adaptive harmonic current detection method |
-
2019
- 2019-07-08 CN CN201910608878.6A patent/CN110531138A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280593A (en) * | 2014-10-21 | 2015-01-14 | 国家电网公司 | Quick harmonic and reactive current detection method based on instantaneous reactive power theory |
| CN105353214A (en) * | 2015-12-22 | 2016-02-24 | 安徽工程大学 | Improved harmonic detection method |
| CN107102189A (en) * | 2017-04-14 | 2017-08-29 | 西南交通大学 | Variable step- size LMS harmonic current detecting method based on S function |
| CN108957130A (en) * | 2018-07-27 | 2018-12-07 | 中国南方电网有限责任公司 | A kind of trend of harmonic detection method of power based on instantaneous reactive power theory |
| CN109066678A (en) * | 2018-08-28 | 2018-12-21 | 西安航空职业技术学院 | A kind of improved APF system harmonics electric current detecting method |
| CN109188078A (en) * | 2018-10-17 | 2019-01-11 | 江苏师范大学 | A kind of variable step- size LMS adaptive harmonic current detection method |
Non-Patent Citations (4)
| Title |
|---|
| ZHANG YUAN等: "New LMS Adaptive Filtering Algorithm with Variable Step Size", 《2017 INTERNATIONAL CONFERENCE ON VISION IMAGE AND SIGNAL PROCESSING》 * |
| 宋志雄等: "基于箕舌线函数的变步长自适应谐波电流检测算法", 《电力***自动化》 * |
| 李慧: "基于瞬时无功理论的APF谐波检测算法研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
| 覃景繁等: "一种新的变步长LMS自适应滤波算法", 《数据采集与处理》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112325933A (en) * | 2020-10-29 | 2021-02-05 | 贵州电网有限责任公司 | Multi-energy system acquisition and preprocessing method and terminal based on edge calculation |
| CN112436775A (en) * | 2020-11-12 | 2021-03-02 | 武汉科技大学 | Crane steel rope resonance elimination control method, device, equipment, storage medium and terminal |
| CN112436775B (en) * | 2020-11-12 | 2022-04-22 | 武汉科技大学 | Crane steel rope resonance elimination control method, device, equipment, storage medium and terminal |
| CN112595893A (en) * | 2020-11-16 | 2021-04-02 | 闽南理工学院 | Power grid phase synchronization signal detection method based on adaptive filter |
| CN112595893B (en) * | 2020-11-16 | 2023-09-08 | 闽南理工学院 | Power grid phase synchronization signal detection method based on adaptive filter |
| CN113111542A (en) * | 2021-05-12 | 2021-07-13 | 南方电网科学研究院有限责任公司 | Kalman filtering frequency tracking method and system based on S function |
| CN113992101A (en) * | 2021-12-28 | 2022-01-28 | 成都爱旗科技有限公司 | Current compensation method and device based on vector control of permanent magnet synchronous motor |
| CN115498896A (en) * | 2022-06-02 | 2022-12-20 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Vacuum on-load tap-changer test system and harmonic current source |
| CN115498896B (en) * | 2022-06-02 | 2024-06-04 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Vacuum on-load tap-changer test system and harmonic current source |
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