CN101261293A - Electric power steady-state signal tracking measurement based on self-adapting filter - Google Patents

Abstract

The invention relates to an electricity power steady-state signal tracking measuring method based on a self-adapting filter. A group of self-adapting filters are designed according to a gradient descent method to produce a sample signal which can be automatically adjusted to fit the measured signals until the fitted difference is lower than the enacted scope, then the output of the self-adapting filters can accurately describe measured signals, thus the high-precision measurement and analysis of the electricity power steady-state signal can be achieved. The measuring method uses a closed loop calculating method which can analyze non-periodical sine wave sampling data caused by non-synchronous sampling and non-complete harmonic wave, etc., can judge and correct the distortion of the samples, and accurately and reliably realize the measurement of the steady state of the electricity power system. The measuring method is characterized by steady astringency, rapid convergence, precise testing, steady performance, good property of real time, strong anti-interference and robustness, and can be applied in different modes, such as the sampling way in a routine factory and gathered sampling in fixed frequency in a digital transformer substation.

Description

Electric power steady-state signal tracking measurement based on sef-adapting filter

Technical field

The present invention relates to a kind of electric power steady-state signal tracking measurement, particularly a kind of electric power steady-state signal tracking based on sef-adapting filter is measured.

Background technology

The accurate measurement of voltage, current signal and analysis are to carry out tidal current analysis control and the basis of measuring, and traditional electric power telemechanical device and measuring apparatus mainly adopt pays a upright leaf algorithm, integral algorithm or its improvement algorithm.

The problem of said method existence at present has:

1) traditional algorithm must be based upon on the basis of synchronized sampling of dispersion.In new digital transformer substation, the non-synchronous sampling mode of concentrating (fixed frequency sampling) will cause traditional algorithm result of calculation to exceed standard.When mains frequency deviation 10%, the error maximum can reach 6%.

2) but traditional measurement analytical approach Measurement and analysis first-harmonic and whole subharmonic but can not be analyzed non-whole subharmonic.It is example that 5% frequency deviation takes place with the third harmonic of fundamental voltage amplitude 5%, and the measuring error maximum can reach-0.8%.

3) traditional algorithm is an open-loop algorithm, and when the raw data distortion, erroneous measurements still passes to follow-up relevant link as measurement result.

Summary of the invention

Technical matters to be solved by this invention is, overcomes the shortcoming of prior art, provides a kind of measuring accuracy the high electric power steady-state signal tracking measurement based on sef-adapting filter.

The technical solution adopted for the present invention to solve the technical problems is as follows: 1, based on the electric power steady-state signal tracking measurement of sef-adapting filter, may further comprise the steps:

(1), measure beginning, the continuous sampling data that latch a cycle are initialize signal;

(2), the whether match of the sampled data that latchs in the determining step (1) and existing waveform, if test is finished in match, keep the result, measure and finish, if not match then goes to step (3);

(3), whether the error of the sampled data that latchs in the determining step (1) and existing waveform less than 5%, if error, then goes to step (4) less than 5%, if error is not less than 5%, then carries out FFT prediction link, prediction initial point, and then go to step (4);

(4), the auto adapted filtering iterative algorithm: by calculate to obtain one approach existing waveform with reference to waveform, the criterion function that this wave filter adopted is: J (t, A (t), ω (t), φ (t))=(u (t)-y (t)) ², the output of y in the above-mentioned formula (t) expression sef-adapting filter, and y (t)=A _mSin (ω _mT+ δ _m); U (t) represents electric power signal, and u (t)=A ₁Sin (ω ₁T+ δ ₁), derive to such an extent that the system of equations of sef-adapting filter is by the gradient descent method:

A′ _m＝2μ ₁·e·sinφ _m

ω′ _m＝2μ ₂·e·A _m·cosφ _m

φ′ _m＝ω _m+μ ₃ω′ _m

e(t，A(t)，ω(t)，φ(t))＝u(t)-y(t)

A ' in the above-mentioned system of equations _mBe reference waveform instantaneous value derivative, φ _mBe the instantaneous phase angle of reference waveform, ω ' _mBe reference waveform instantaneous angular velocity derivative, A _mBe reference waveform instantaneous value, φ ' _mBe the instantaneous phase angular derivative of reference waveform, μ ₁, μ ₂, μ ₃Be the step-length modifying factor, wherein, $0<{\mathrm{\&mu;}}_1<\frac{2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071002053300122.png,A20071002053300131.png"\; state="\{\{state\}\}">T</figure-callout>}}_0}$ , μ ₃＜T ₀ ²/ 3, μ ₂Changing segmentation with amplitude chooses;

(5), calculate the whether match of the waveform that obtains and existing waveform in the determining step (4), if test is finished in match, keep the result, measure end, if not match then goes to step (6);

(6), calculate the waveform that obtains in the comparison step (4) and have or not hop, if hop is arranged, then revise distortion value, go to step (4) then, if there is not hop, whether then judge iterations less than set point number, if iterations, then goes to step (4) less than set point number, if iterations is not less than set point number, then can't match, abandon measuring, measure and finish.

Beneficial effect of the present invention is as follows: the present invention is the characteristics according to the power system mesomeric state signal, utilize the gradient descent method to design one group of sef-adapting filter, generation can come the match measured signal by self-adjusting sample signal, and then finish the high-acruracy survey and the analysis of electric power steady-state signal, this mensuration adopts closed loop algorithm, can analyze non-synchronous sampling, sine wave sampled data non-periodic that non-whole subharmonic etc. cause, differentiate and the correction sampling distortion, accurately, realize the measurement of power system mesomeric state reliably, this mensuration has stable convergence, convergence rapidly, accurate testing, stable performance, real-time is better, and have anti-interference and advantage such as strong robustness, applicable to different modes such as conventional factory station sample mode and the cluster samplings of digital transformer substation fixed frequency.

Description of drawings

Fig. 1 is the electric power steady-state signal tracking measurement process flow diagram that the present invention is based on sef-adapting filter.

Fig. 2 is the theory diagram of invention based on the sef-adapting filter group of the electric power steady-state signal tracking measurement of sef-adapting filter.

Fig. 3 is the measuring process synoptic diagram of non-synchronous sampling data of the non-whole subharmonic of superposition that the present invention is based on the electric power steady-state signal tracking measurement of sef-adapting filter.

Fig. 4 be the present invention is based on sef-adapting filter the Fu Shi algorithm of electric power steady-state signal tracking measurement when frequency shift (FS) measuring error with the synoptic diagram of phase angle change.

Fig. 5 is wave filter output and an error synoptic diagram when the present invention is based on the equal saltus step of the frequency input signal of electric power steady-state signal tracking measurement of sef-adapting filter and amplitude.

Fig. 6 is the input signal that the present invention is based on the electric power steady-state signal tracking measurement of sef-adapting filter wave filter output and an error synoptic diagram when slowly changing.

Embodiment

With reference to the accompanying drawings and in conjunction with the embodiments the present invention is described in further detail.But the invention is not restricted to given example.

Direct measuring method different from the past, the present invention is the characteristics according to the power system mesomeric state signal, constructed one group of sef-adapting filter, generation can come the match measured signal by self-adjusting sample signal, up to error of fitting less than setting range, then the output of sef-adapting filter can the accurate description measured signal, has also just finished the high-acruracy survey and the analysis of electric power steady-state signal.The present invention has carried out respective design to this sef-adapting filter at the electric power steady-state signal feature, is example with the electric power signal first-harmonic, and electric power signal can be expressed as:

u(t)＝A ₁·sin(ω ₁·t+δ ₁) (1)

The output of sef-adapting filter is made as y (t)=A _mSin (ω _mT+ δ _m), the present invention has designed the criterion function of this sef-adapting filter:

J(t，A(t)，ω(t)，φ(t))＝(u(t)-y(t)) ² (2)

Adopt the gradient descent method can derive the system of equations of this sef-adapting filter:

A _m′＝2μ ₁·e·sinφ _m (3)

ω _m′＝2μ ₂·e·A _m·cosφ _m (4)

φ _m′＝ω _m+μ ₃ω _m′ (5)

e(t，A(t)，ω(t)，φ(t))＝u(t)-y(t) (6)

Utilize the nonlinear system stable theory strictly to prove that this sef-adapting filter can precise and stable conditionally measurement electric power signal.The process of proof shows satisfied $0<{\mathrm{\&mu;}}_1<\frac{2}{{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20071002053300122.png,A20071002053300131.png"\; state="\{\{state\}\}">T</figure-callout>}}_0}$ , μ ₃＜T ₀ ²/ 3, μ ₂With conditions such as amplitude change that segmentation is chosen, and initial e (t, A (t), ω (t), φ (t))=u (t)-y (t) hour, and sef-adapting filter is the Measurement and analysis electric power signal accurately.To getting the sef-adapting filter iterative equation after sef-adapting filter system of equations (3)-(6) discretize:

e _i＝u _i-y _i (7)

A _i+1＝A _i+A′ _i·Δt (8)

φ _i+1＝φ _i+φ _i′·Δt (9)

y _i+1＝A _i+1sinφ _i+1 (10)

The condition of convergence of application of formula (7)-(10) and sef-adapting filter can design the tracking measurement based on the electric power steady-state signal of sef-adapting filter.

Figure 1 shows that the program circuit of tracking measurement algorithm.Before each the measurement, subroutine is at first extracted the continuous sampling data of a cycle by sample frequency, deposit the signal buffer in.The result that subroutine utilized measured last time converts the initial point (when calculating for the first time, initial value gets zero) of sef-adapting filter.The conversion process mainly is the conversion of phase angle, and the sample region of need considering last time to measure is to the phase shift between the sample region of this measurement, and phase shift should be calculated by the mistiming between the frequency of measuring last time and two sample region.The phase shift computing method are as follows:

δ _(1，1)＝δ _(1，0)+ω _(1，0)*Δt (11)

δ in the formula _(1,1), δ _(1,0), ω _(1,0), the angular frequency that Δ t measured the initial phase angle of corresponding this sample region first-harmonic, the termination phase angle of measuring first-harmonic last time, last time respectively and the time interval of twice measurement.Can get the initial phase angle of each higher hamonic wave by similar approach.Initial phase angle δ with each harmonic _{(n, 1)}With the amplitude A that measured last time _{(n, 0)}And angular velocity omega _{(n, 0)}The substitution following formula draws each point predicted data (output of sef-adapting filter group).

$y_l=\underset{n=1}{\overset{x}{\mathrm{\&Sigma;}}}{A}_{(n,l)}\sin ({\mathrm{\&omega;}}_{(n,l)}*\mathrm{\&Delta;t}+{\mathrm{\&delta;}}_{(n,l)})---\left(12\right)$

If all the error of predicted values and measured value is all in the specification error scope, then illustrate prediction signal with the measured signal match, signal analysis and measurement are finished.

During the electrical network steady state measurement, most cases can directly utilize the Measurement and analysis result of last time to go this measured signal of match as forecast sample.In the device design, the consideration sampled point is intensive to have the characteristics of regular sinusoidal signal with the electrical network steady-state signal, and the input and output match verification of sef-adapting filter also can be adopted and take out an approximating method, has further reduced calculated amount.

If directly match failure, the general remark electric network state changes.If multi-point fitting is good, there have any error to occur suddenly to be big unusually, and this often illustrates that sampled data is disturbed, and can go to eliminate disturbance by the mode of revising input sampling data.Can specific aim carry out verification and correction like this to raw data.Under normal circumstances, before the author adopts once with the current sampled value of mean value correction of a back sampled data, can obtain ideal effect.If electric network state changes really, utilize the error of measurement result match input last time waveform bigger, then enter the prediction link.Signal changes slowly under the situation, generally restrains through 1～3 iteration foot.In design, generally get 3～10 times as maximum iteration time 3～5, also desirable.Based on similar consideration, when the single-point error surpassed 5%, subroutine directly jumped to the prediction link.

Adopt the fft analysis signal of revising coefficient in the prediction link, draw the amplitude and the phase angle of signal first-harmonic and each harmonic.Because FFT has done overfrequency compensation (adopting the survey frequency of last time), signal frequency can not be suddenlyd change in addition, and the result of FFT has possessed high accuracy.The initial phase angle of first-harmonic and each harmonic, amplitude and rated frequency are carried out verification and correction as each sef-adapting filter of initial point substitution, select corresponding sef-adapting filter modifying factor μ 2 according to the amplitude of measuring and calculating simultaneously, just can finish interative computation and tracking measurement.

In the interative computation process, error is the deviation between sampled data and the whole sef-adapting filter output valve summation.Error can be directly passed to each sef-adapting filter, revises in view of the above.All less than specification error, waveform match is described then as the error of whole measuring points, this interative computation program has been accused and has been finished, and can preserve result of calculation.Amplitude among the result and phase angle are used for follow-up vector calculus.Simultaneously, amplitude, phase angle, frequency are also as the selection foundation of waveform fitting initial point next time.Carry out in the process of waveform fitting or sef-adapting filter adjustment at every turn, all must revise initial point by amplitude, angular velocity and the phase angle of sef-adapting filter output.

Figure 2 shows that the theory diagram of sef-adapting filter group, whole Measurement and analysis process is finished by one group of identical sef-adapting filter of principle, and each sef-adapting filter is followed the tracks of the signal in the certain frequency scope.After the frequency range locking, each wave filter output is the component of measured signal in this frequency range, and all the superposition of wave filter output is measured signal.

The measuring process of tracking measurement algorithm shown in Figure 3.Fig. 3 (a) represents input signal, this signal is the waveform of stack 0.5V third harmonic and 0.4V quintuple harmonics on the fundamental signal of 5V, compares initial point, fundamental frequency skew 10%, magnitude shift 10%, three time and quintuple harmonics frequency are offset 10% (165Hz) and 5% (262.5Hz) respectively.Strictly speaking, this moment, input signal no longer was a periodic signal.The output waveform that Fig. 3 (b) expression sef-adapting filter simulation calculation draws, the measuring error distribution curve of Fig. 3 (c) expression iteration overall process.The signal fitting process is less than 4 iteration, and analytical error is less than 0.03%.The result shows, the sef-adapting filter of first-harmonic, third harmonic and quintuple harmonics correspondence still can match waveform separately, and in the frequency range of self, make fine setting, locking frequency is finished accurate measurement.And if adopt the direct computing of traditional algorithm, amplitude error will reach 8.4%, phase angle error is bigger, data are meaningless.

If sample frequency is fixed, and mains frequency skew 1% (49.5Hz), then the error of integral algorithm between-0.49% to 0.52%, the curve that error changes with the initial phase angle change of first sampled point as the curve of Fig. 4 1. shown in.Draw partially 10% the time when fundamental frequency, the error of integral algorithm can reach-3.56% to 6.83%, error with the curve of initial phase angle change as the curve of Fig. 4 2. shown in.Digital transformer substation generally adopts the fixed frequency sampling, and when mains frequency departed from 50Hz, sampled data can not directly be used the traditional algorithm technology.

Fig. 5 has embodied when power network signal amplitude, frequency all have saltus step, the time domain specification of sef-adapting filter output and error.The corresponding sampled point sequence number of horizontal ordinate among the figure, ordinate is a sample, unit is V.The signal input divides four-stage, and the stage 1,2,3,4 is corresponding 1-39 point, 40-239 point, 240-479 point, 480-900 point respectively.Wherein, Fig. 5 (a) is depicted as input signal, and its amplitude and frequency change stage by stage.In the stage 1, input signal is 0; Stages 2 signal frequency is that 50.625Hz, amplitude are 5.00V; Stages 3 signal frequency is that 49.375Hz, amplitude are 3.00V; Be the stage 4 at last, signal frequency is that 50.00Hz, amplitude are 4.00V.Fig. 5 (b) is depicted as the sef-adapting filter output signal; Fig. 5 (c) is depicted as the error of output.As seen from the figure, the sef-adapting filter output signal is followed the tracks of, the match input signal, and tracking time is grown (about 4 cycles) when signal changes greatly, stably locked input signal after, error is less than 0.03%.

The time domain specification of sef-adapting filter output and error when Fig. 6 represents that power network signal slowly changes.Fig. 6 (a) is depicted as input signal, and signal is changed to 1% between the stage 2,3,4; Amplitude is respectively 3V, 3.03V, 3V, and frequency is respectively 50Hz, 50.5Hz, 50Hz.Fig. 6 (b) is depicted as the sef-adapting filter output signal; Fig. 6 (c) is depicted as the error of output.As seen from the figure, the very fast tracking of sef-adapting filter output signal, match input signal accurately, have stably locked input signal in 1 cycle, and error is less than 0.03%, and overshoot is also very little in the adjustment process.

Claims (4)

1. based on the electric power steady-state signal tracking measurement of sef-adapting filter, may further comprise the steps:

(1), measure beginning, the continuous sampling data that latch a cycle are initialize signal;

(2), the whether match of the sampled data that latchs in the determining step (1) and existing waveform, if test is finished in match, keep the result, measure and finish, if not match then goes to step (3);

(3), whether the error of the sampled data that latchs in the determining step (1) and existing waveform less than 5%, if error, then goes to step (4) less than 5%, if error is not less than 5%, then carries out FFT prediction link, prediction initial point, and then go to step (4);

(4), the auto adapted filtering iterative algorithm: by calculate to obtain one approach existing waveform with reference to waveform, the criterion function that this wave filter adopted is: J (t, A (t), ω (t), φ (t))=(u (t)-y (t)) ², the output of y in the above-mentioned formula (t) expression sef-adapting filter, and y (t)=A _mSin (ω _mT+ δ _m); U (t) represents electric power signal, and u (t)=A ₁Sin (ω ₁T+ δ ₁), derive to such an extent that the system of equations of sef-adapting filter is by the gradient descent method:

A _m′＝2μ ₁·e·sinφ _m

ω _m′＝2μ ₂·e·A _m·cosφ _m

φ _m′＝ω _m+μ ₃ω _m′

e(t，A(t)，ω(t)，φ(t))＝u(t)-y(t)

A in the above-mentioned system of equations _m' be with reference to waveform instantaneous value derivative, φ _mBe the instantaneous phase angle of reference waveform, ω _m' be with reference to waveform instantaneous angular velocity derivative, A _mBe reference waveform instantaneous value, φ _m' be with reference to the instantaneous phase angular derivative of waveform, μ ₁, μ ₂, μ ₃Be the step-length modifying factor, wherein, $0<{\mathrm{\&mu;}}_1<\frac{2}{T_0}$ , μ ₃＜T ₀ ²/ 3, μ ₂Changing segmentation with amplitude chooses;

(5), calculate the whether match of the waveform that obtains and existing waveform in the determining step (4), if test is finished in match, keep the result, measure end, if not match then goes to step (6);

(6), calculate the waveform that obtains in the comparison step (4) and have or not hop, if hop is arranged, then revise distortion value, go to step (4) then, if there is not hop, whether then judge iterations less than set point number, if iterations, then goes to step (4) less than set point number, if iterations is not less than set point number, then can't match, abandon measuring, measure and finish.

2. the electric power steady-state signal tracking measurement based on sef-adapting filter according to claim 1 is characterized in that: when calculating for the first time, initialize signal gets zero.

3. the electric power steady-state signal tracking measurement based on sef-adapting filter according to claim 1 and 2 is characterized in that: setting the number of iterations scope in the step (6) is 3～10 times.

4. the electric power steady-state signal tracking measurement based on sef-adapting filter according to claim 3 is characterized in that: setting the number of iterations scope in the step (6) is 3～5 times.

Images