CN104931772A - Method and system for voltage sag check based on digital morphological transform - Google Patents

Abstract

The invention discloses a method and a system for voltage sag check based on digital morphological transform. The demodulation process includes the following steps: setting the sampling frequency, and acquiring voltage signals of a distribution network according to the sampling frequency; selecting voltage signals at the time moments of n-i,..., n-2, n-1, n, n+1, n+2,..., n+i from the acquired voltage signals and combining the voltage signals into a first calculation sequence, and performing symmetric differential operation on the voltage signals in the first calculation sequence and combining the voltage signals into a second calculation sequence, wherein i<n; and performing Teager energy operator demodulation and digital morphological transform on the first calculation sequence and the second calculation sequence respectively, solving the voltage amplitude, judging whether there is a voltage sag, and calculating and saving the voltage amplitude and start and end moments. The invention provides an efficient, real-time and accurate means for voltage sag detection.

Description

A kind of voltage dip inspection method based on digital morphological conversion and system

Technical field

The present invention relates to short duration voltage variations detection field.More particularly, the present invention relates to a kind of voltage dip inspection method based on digital morphological conversion and system.

Background technology

Voltage dip is a kind of outstanding power quality problem in electric power system, and has become the main interference threatening the normal work of each responsive consumer safety of modern society.For effectively administering and improving such quality of power supply, must carry out accurately detecting fast to voltage dip.This is for ensureing that the growth of sensitive equipment safe and stable operation and national economy is significant.

Analyze in short-term the quality of power supply variation often adopt time frequency analyzing tool, in recent years because Teager energy operator has excellent temporal resolution, can real-time follow-up measured signal waveform change, started to apply to duration power quality disturbances.

Teager energy operator adopts sequence of calculation H (k) of regular length in disturbance voltage data process solving, and constantly update the element in sample sequence by sequence of calculation H (k) window slided.Although simple based on the algorithm of Teager energy operator, the noiseproof feature of algorithm itself is poor.

Digital morphological filtering is a kind of nonlinear filtering, mainly according to mathematical mor-phology principle, utilizes structural element constantly movement in the signal, investigates the mutual relationship between signal each several part, extracts useful signal.The morphological transformation that digital morphological filtering is done mainly comprises the cascading computing of dilation operation, erosion operation, modified opening operator, form closed operation and modal of morphological opening and closing.Due to done computing mainly Boolean calculation and a small amount of plus and minus calculation, compared with general low-pass filter, have and calculate the advantages such as simple, real-time is high.

Summary of the invention

An object of the present invention is to solve at least the problems referred to above and/or defect, and the advantage will illustrated at least is below provided.

A further object of the invention is to provide a kind of method detecting voltage dip and characteristic quantity thereof, by the algorithm based on Teager energy operator and digital morphological conversion, the change of tracking signal fast can not only also enhance the noise immunity of Teager energy operator itself, improve voltage dip and detect and the accuracy of characteristic quantity calculating and real-time.

A further object of the invention is to provide a kind of system detecting voltage dip and characteristic quantity thereof.

In order to realize according to these objects of the present invention and other advantage, provide a kind of voltage dip inspection method based on digital morphological conversion, comprising the following steps:

S1: setting sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

S2: choose n-i ... from the voltage signal gathered, n-2, n-1, n, n+1, n+2 ..., the voltage signal in n+i moment be combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

S3: the demodulation of Teager energy operator is carried out respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

S4: carry out digital morphological conversion to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment respectively, obtains the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

S5: the instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion;

S6: the threshold value of voltage magnitude and setting is compared:

If the voltage magnitude in n 1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

Preferably, described first sequence of calculation comprises the voltage signal in 5 moment.

Preferably, described step S2 specifically comprises the following steps:

S21: first sequence of calculation is combined in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

S22: as follows symmetric difference computing is carried out to the voltage signal in first sequence of calculation and is combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

Preferably, described step S3 specifically comprises the following steps:

S31: the computing of teager energy operator is carried out as follows to the voltage signal in n moment, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

S32: the computing of teager energy operator is carried out as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment:

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment.

Preferably, step S4 specifically comprises the following steps:

S41: the instantaneous energy in n moment is carried out digital conversion by following formula:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}/2，

Ψ(x(n))＝f(n)，

Ψ ^*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，...，0}，

n＝{1，2，...，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), the instantaneous energy Ψ (x (n)) that f (n) is the n moment, G [f (n), g (n)] is the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number.

S42: the method using step S41, draws the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n)).

Preferably, step S5 specifically comprises the following steps:

Voltage magnitude is obtained according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}(s*\left(n\right))},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.

Based on a voltage dip check system for Teager energy operator demodulation, comprising:

Data acquisition and memory module, it sets sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

The sequence of calculation forms module, it chooses n-i ... from the voltage signal gathered, n-2, n-1, n, n+1, n+2 ..., the voltage signal in n+i moment are combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

Instantaneous energy calculates and digital morphological conversion module, and it carries out the demodulation of Teager energy operator respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

Respectively digital morphological conversion is carried out to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment again, obtain the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

The instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion.

The identification of voltage dip and the computing module of characteristic quantity, according to the voltage magnitude asked for, it judges whether voltage dip occurs, the threshold value of voltage magnitude and setting compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

Preferably, described data acquisition and memory module also comprise initialization module, it distributes certain internal memory as data buffer, the multiple continuous print voltage signals setting sampling decision content F that gather are preserved in described data buffer, if F=0, then in first sequence of calculation, fill new voltage signal, if F=1, then first sequence of calculation does not recharge new voltage signal, and represents that initialization procedure process completes.

Preferably, the described sequence of calculation forms module and is combined into first sequence of calculation in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

The described sequence of calculation forms module and carries out symmetric difference computing as follows to the voltage signal in first sequence of calculation and be combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, x (n) represents the voltage signal in n moment, and s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

Preferably, described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to voltage signal, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

And by following formula, instantaneous energy is carried out digital conversion:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}/2，

Ψ(x(n))＝f(n)，

Ψ ^*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，...，0}，

n＝{1，2，...，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), f (n) had both been the instantaneous energy Ψ (x (n)) in n moment, G [f (n), g (n)] had both been the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number;

Described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment;

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment;

Fortune uses the same method, and draws the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n));

And obtain voltage magnitude according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}(s*\left(n\right))},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.

The invention has the advantages that: the present invention adopts the demodulation method based on Teager energy operator, from the voltage signal collected, choose n-i ..., n-2, n-1, n, n+1, n+2 ..., the voltage signal in n+i moment be combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n; Again the demodulation of Teager energy operator is carried out respectively to first sequence of calculation and second sequence of calculation, obtain the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment; Then respectively digital morphological conversion is carried out to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment, obtain the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion; The instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion; Finally the threshold value of voltage magnitude and setting is compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

The present invention to adjudicate with energy combine based on energy demodulating algorithm, digital morphological conversion, achieve the change of quick tracking signal, also enhance the noise immunity of Teager energy operator itself simultaneously, improve voltage dip detects and characteristic quantity calculates accuracy and real-time.

Part is embodied by explanation below by other advantage of the present invention, target and feature, part also will by research and practice of the present invention by those skilled in the art is understood.

Accompanying drawing explanation

Fig. 1 is the high-level schematic functional block diagram of voltage dip check system in one embodiment of the present of invention;

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail, can implement according to this with reference to instructions word to make those skilled in the art.

Based on a voltage dip inspection method for digital morphological conversion, comprise the following steps:

S1: setting sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

S2: choose n-i ... from the voltage signal gathered, n-2, n-1, n, n+1, n+2 ..., the voltage signal in n+i moment be combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

S3: the demodulation of Teager energy operator is carried out respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

S4: carry out digital morphological conversion to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment respectively, obtains the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

S5: the instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion;

S6: the threshold value of voltage magnitude and setting is compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

Wherein, described first sequence of calculation comprises the voltage signal in 5 moment.

Wherein, described step S2 specifically comprises the following steps:

S21: first sequence of calculation is combined in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

S22: as follows symmetric difference computing is carried out to the voltage signal in first sequence of calculation and is combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

Wherein, described step S3 specifically comprises the following steps:

S31: the computing of teager energy operator is carried out as follows to the voltage signal in n moment, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

S32: the computing of teager energy operator is carried out as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment:

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment.

Wherein, step S4 specifically comprises the following steps:

S41: the instantaneous energy in n moment is carried out digital conversion by following formula:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}/2，

Ψ(x(n))＝f(n)，

Ψ ^*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，...，0}，

n＝{1，2，...，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), the instantaneous energy Ψ (x (n)) that f (n) is the n moment, G [f (n), g (n)] is the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number.

S42: the method using step S41, draws the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n)).

Wherein, step S5 specifically comprises the following steps:

Voltage magnitude is obtained according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}(s*\left(n\right))},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.

As shown in Figure 1, a kind of voltage dip check system based on the demodulation of Teager energy operator, comprising:

Data acquisition and memory module, it sets sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

The sequence of calculation forms module, it chooses n-i ... from the voltage signal gathered, n-2, n-1, n, n+1, n+2 ..., the voltage signal in n+i moment are combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

Instantaneous energy calculates and digital morphological conversion module, and it carries out the demodulation of Teager energy operator respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

Respectively digital morphological conversion is carried out to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment again, obtain the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

The instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion.

The identification of voltage dip and the computing module of characteristic quantity, according to the voltage magnitude asked for, it judges whether voltage dip occurs, the threshold value of voltage magnitude and setting compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

Wherein, described data acquisition and memory module also comprise initialization module, it distributes certain internal memory as data buffer, the multiple continuous print voltage signals setting sampling decision content F that gather are preserved in described data buffer, if F=0, then in first sequence of calculation, fill new voltage signal, if F=1, then first sequence of calculation does not recharge new voltage signal, and represents that initialization procedure process completes.

Wherein, the described sequence of calculation forms module and is combined into first sequence of calculation in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

The described sequence of calculation forms module and carries out symmetric difference computing as follows to the voltage signal in first sequence of calculation and be combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, x (n) represents the voltage signal in n moment, and s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

Wherein, described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to voltage signal, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

And by following formula, instantaneous energy is carried out digital conversion:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}2/，

Ψ(x(n))＝f(n)，

Ψ*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，...，0}，

n＝{1，2，...，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), f (n) had both been the instantaneous energy Ψ (x (n)) in n moment, G [f (n), g (n)] had both been the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number;

Described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment;

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment;

Fortune uses the same method, and draws the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n));

And obtain voltage magnitude according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}(s*\left(n\right))},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.

Although the present invention/working of an invention scheme is open as above, it is not restricted to listed in instructions and embodiment utilization.It can be applied to various applicable the field of the invention completely.For those skilled in the art, can easily realize other amendment.Therefore do not deviating under the universal that claim and equivalency range limit, the present invention is not limited to specific details and illustrates here and the legend described.

Claims (10)

1., based on a voltage dip inspection method for digital morphological conversion, it is characterized in that, comprise the following steps:

S1: setting sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

S2: from gather voltage signal choose n-i ..., n-2, n-1, n, n+1, n+2 ..., the n+i moment voltage signal be combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

S3: the demodulation of Teager energy operator is carried out respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

S4: carry out digital morphological conversion to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment respectively, obtains the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

S5: the instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion;

S6: the threshold value of voltage magnitude and setting is compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

2., as claimed in claim 1 based on the voltage dip inspection method of digital morphological conversion, it is characterized in that, described first sequence of calculation comprises the voltage signal in 5 moment.

3., as claimed in claim 2 based on the voltage dip inspection method of digital morphological conversion, it is characterized in that, described step S2 specifically comprises the following steps:

S21: first sequence of calculation is combined in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

S22: as follows symmetric difference computing is carried out to the voltage signal in first sequence of calculation and is combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

4., as claimed in claim 3 based on the voltage dip inspection method of digital morphological conversion, it is characterized in that, described step S3 specifically comprises the following steps:

S31: the computing of teager energy operator is carried out as follows to the voltage signal in n moment, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

S32: the computing of teager energy operator is carried out as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment:

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment.

5., as claimed in claim 4 based on the voltage dip inspection method of digital morphological conversion, it is characterized in that, step S4 specifically comprises the following steps:

S41: the instantaneous energy in n moment is carried out digital conversion by following formula:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}/2，

Ψ(x(n))＝f(n)，

Ψ ^*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，…，0}，

n＝{1，2，…，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), the instantaneous energy Ψ (x (n)) that f (n) is the n moment, G [f (n), g (n)] is the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number.

S42: the method using step S41, makes f (n)=Ψ (S (n)), draw the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n)).

6., as claimed in claim 5 based on the voltage dip inspection method of digital morphological conversion, it is characterized in that, step S5 specifically comprises the following steps:

Voltage magnitude is obtained according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}\left(s^{*}\left(n\right)\right)},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.

7., based on a voltage dip check system for Teager energy operator demodulation, it is characterized in that, comprising:

Data acquisition and memory module, it sets sample frequency, gathers the voltage signal of power distribution network according to sample frequency;

The sequence of calculation forms module, its from gather voltage signal choose n-i ..., n-2, n-1, n, n+1, n+2 ..., the n+i moment voltage signal be combined into first sequence of calculation, voltage signal in first sequence of calculation is carried out symmetric difference computing and is combined into second sequence of calculation, wherein i < n;

Instantaneous energy calculates and digital morphological conversion module, and it carries out the demodulation of Teager energy operator respectively to first sequence of calculation and second sequence of calculation, obtains the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment;

Respectively digital morphological conversion is carried out to the instantaneous energy of the instantaneous energy of the voltage signal in n moment and the symmetric difference voltage signal in n moment again, obtain the instantaneous energy of the symmetric difference voltage signal in the n moment after the instantaneous energy of voltage signal in the n moment after digital morphological conversion and digital morphological conversion;

The instantaneous energy of the voltage signal in the n moment after being converted by digital morphological obtains voltage magnitude divided by the evolution of the instantaneous energy of the symmetric difference voltage signal in the n moment after digital morphological conversion.

The identification of voltage dip and the computing module of characteristic quantity, according to the voltage magnitude asked for, it judges whether voltage dip occurs, the threshold value of voltage magnitude and setting compared:

If the voltage magnitude in n-1 moment is greater than threshold value, and the voltage magnitude in n moment is less than threshold value, be then the start time of voltage dip depending on the n moment, and record start amplitude and the start time of voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is also less than threshold value, be then considered as the lasting moment that the n moment is voltage dip, returns the signal of step S3 to the n+1 moment and proceeds the demodulation of Teager energy operator;

If the voltage magnitude in n-1 moment is less than threshold value, and the voltage magnitude in n moment is not less than threshold value, being then considered as the n moment is voltage dip finish time, and the amplitude of end of record (EOR) voltage dip and finish time, terminate this voltage dip inspection.

8. as claimed in claim 7 based on the voltage dip check system of Teager energy operator demodulation, it is characterized in that, described data acquisition and memory module also comprise initialization module, it distributes certain internal memory as data buffer, the multiple continuous print voltage signals setting sampling decision content F that gather are preserved in described data buffer, if F=0, then in first sequence of calculation, fill new voltage signal, if F=1, then first sequence of calculation does not recharge new voltage signal, and represents that initialization procedure process completes.

9. as claimed in claim 8 based on the voltage dip check system of Teager energy operator demodulation, it is characterized in that, the described sequence of calculation forms module and is combined into first sequence of calculation in the following manner to voltage signal:

H(n)＝{x(n-2)，x(n-1)，x(n)，x(n+1)，x(n+2)}，

Wherein, H (n) represents first sequence of calculation, and x (n) represents the voltage signal in n moment;

The described sequence of calculation forms module and carries out symmetric difference computing as follows to the voltage signal in first sequence of calculation and be combined into second sequence of calculation:

The function expression of symmetric difference is: s (n)=[x (n+1)-x (n-1)]/2, S (n)={ s (n-1), s (n), s (n+1) },

Wherein, x (n) represents the voltage signal in n moment, and s (n) represents the symmetric difference voltage signal in n moment, and S (n) represents the second sequence of operations.

10. as claimed in claim 9 based on the voltage dip check system of Teager energy operator demodulation, it is characterized in that, described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to voltage signal, obtains the function of instantaneous energy:

The expression formula of instantaneous energy function is: Ψ (x (n))=x (n) ²+ x (n-1) x (n+1),

Wherein, Ψ (x (n)) represents the function of instantaneous energy, and x (n) represents the voltage signal in n moment;

And by following formula, instantaneous energy is carried out digital conversion:

The function expression of digital form conversion is:

G[f(n)，g(n)]＝{Oc(f(n))+Co(f(n))}/2，

Ψ(x(n))＝f(n)，

Ψ ^*(x(n))＝G[f(n)，g(n)]，

Oc(f(n))＝(f○g●g)(n)，

Co(f(n))＝(f●g○g)(n)，

$(f\&CirclePlus;g)\left(n\right)=\max \{f(n-m)+g\left(m\right)\},$

(f⊙g)(n)＝min{f(n+m)-g(m)}，

g(n)＝{0，0，…，0}，

n＝{1，2，…，55}，

Wherein, G [f (n), g (n)] be the digital conversion form of f (n), f (n) had both been the instantaneous energy Ψ (x (n)) in n moment, G [f (n), g (n)] had both been the instantaneous energy Ψ in the n moment through digital morphological converting digital morphological transformation ^*(x (n)), f (n) is list entries, g (n) is for structural element sequence and length of element n is 55, Oc (f (n)) is opening and closing operation, Co (f (n)) is make and break computing, (f zero g) (n) is digital morphological opening operation, (f ● g) (n) is digital morphological closed operation for dilation operation, (f ⊙ g) (n) is erosion operation, and n is natural number;

Described instantaneous energy calculates and digital morphological conversion module carries out the computing of teager energy operator as follows to the symmetric difference voltage signal in n moment, obtains the function of the instantaneous energy of the symmetric difference voltage signal in n moment;

The function expression of instantaneous energy is: Ψ (s (n))=s (n) ²+ s (n-1) s (n+1),

Wherein Ψ (s (n)) represents the function of the instantaneous energy of symmetric difference voltage signal, and s (n) represents the symmetric difference voltage signal in n moment;

Fortune uses the same method, and draws the instantaneous energy Ψ (s of the symmetric difference voltage signal in this moment after digital morphological converting digital morphological transformation ^*(n));

And obtain voltage magnitude according to following formula:

The expression formula of voltage magnitude is: $\left|A\right|=\mathrm{\&Psi;}\left(x^{*}\left(n\right)\right)/\sqrt{\mathrm{\&Psi;}\left(s^{*}\left(n\right)\right)},$

Wherein, | A| represents voltage magnitude, Ψ (x ^*(n)) represent the instantaneous energy after n moment digital conversion, Ψ (s ^*(n)) represent that the symmetry through the n moment of digital morphological converting digital morphological transformation splits the instantaneous energy of voltage signal.